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Valles Marineris: The Grand Canyon of Mars
NSDL National Science Digital Library
This resource provides a general description of this system of canyons located just south of the Martian equator. Included are various images of the terrain: some photographic, some constructed from remotely sensed datasets. One set of images is presented in stereo and must be viewed with 3D glasses.
Western Candor Chasma, Valles Marineris
NASA Technical Reports Server (NTRS)
One of the most striking discoveries of the Mars Global Surveyor mission has been the identification of thousands of meters/feet of layers within the wall rock of the enormous martian canyon system, Valles Marineris.Valles Marineris was first observed in 1972 by the Mariner 9 spacecraft, from which the troughs get their name: Valles--valleys, Marineris--Mariner.Some hints of layering in both the canyon walls and within some deposits on the canyon floors were seen in Mariner 9 and Viking orbiter images from the 1970s. The Mars Orbiter Camera on board Mars Global Surveyor has been examining these layers at much higher resolution than was available previously.MOC images led to the realization that there are layers in the walls that go down to great depths. An example of the wall rock layers can be seen in MOC image 8403, shown above (C).MOC images also reveal amazing layered outcrops on the floors of some of the Valles Marineris canyons. Particularly noteworthy is MOC image 23304 (D, above), which shows extensive, horizontally-bedded layers exposed in buttes and mesas on the floor of western Candor Chasma. These layered rocks might be the same material as is exposed in the chasm walls (as in 8403--C, above), or they might be rocks that formed by deposition (from water, wind, and/or volcanism) long after Candor Chasma opened up.In addition to layered materials in the walls and on the floors of the Valles Marineris system, MOC images are helping to refine our classification of geologic features that occur within the canyons. For example, MOC image 25205 (E, above), shows the southern tip of a massive, tongue-shaped massif (a mountainous ridge) that was previously identified as a layered deposit. However, this MOC image does not show layering. The material has been sculpted by wind and mass-wasting--downslope movement of debris--but no obvious layers were exposed by these processes.Valles Marineris a fascinating region on Mars that holds much potential to reveal information about the early history and evolution of the red planet. The MOC Science Team is continuing to examine the wealth of new data and planning for new Valles Marineris targets once the Mapping Phase of the Mars Global Surveyor mission commences in March 1999.This image: Layers in western Candor Chasma northern wall. MOC image 8403 subframe shown at full resolution of 4.6 meters (15 feet) per pixel. The image shows an area approximately 2.4 by 2.5 kilometers (1.5 x 1.6 miles). North is up, illumination is from the left. Image 8403 was obtained during Mars Global Surveyor's 84th orbit at 10:12 p.m. (PST) on January 6, 1998.Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
NASA Astrophysics Data System (ADS)
Distinctive cloud trails are identified in Mars Reconnaissance Orbiter Mars Color Imager (MARCI) images over specific locations associated with Valles Marineris and Noctis Labyrinthus and at perihelion solar longitudes (LS = 230�-260�). High-contrast surface shadows are well defined, as cast from their eastern margins, supporting altitude and optical depth determinations. These relatively high altitude clouds (40-50 km) exhibit narrow latitudinal widths (25-75 km) in comparison to extended longitudinal dimensions (400-1000 km). MARCI multispectral imaging of cloud surface shadows in five wavelength channels (260, 320, 437, 546, and 653 nm) yields the wavelength dependence of cloud extinction optical depth, revealing a range of small cloud particle sizes (reff = 0.2-0.5 ?m) and moderate cloud optical depths (0.03-0.10 visible and 0.1-0.2 ultraviolet). Local time and temporal sampling characteristics of MARCI cloud images indicate that these clouds develop very rapidly in afternoon hours (1300-1500 LT), reach their full longitudinal extents within <2 h time scales, and often reoccur on successive afternoons. Mars Global Surveyor Mars Orbital Camera imaging in previous Mars years indicates these clouds are annually repeating. These observed characteristics suggest a cloud formation mechanism that is specific to �50 km horizontal and vertical scales, transports water vapor and dust upward from lower levels, exists during the afternoon, and is likely associated with the mesoscale atmospheric circulations induced by the near-equatorial canyons of Mars. Cloud particles formed in such updrafts would then be rapidly transported westward in the strong retrograde zonal circulation of the subsolar middle atmosphere in this season.
Clancy, R. Todd; Wolff, Michael J.; Cantor, Bruce A.; Malin, Michael C.; Michaels, Timothy I.
Stratigraphy of the Layered Terrain in Valles Marineris, Mars.
National Technical Information Service (NTIS)
The layered terrain in Valles Marineris provides information about its origin and the geologic history of this canyon system. Whether the terrain is sedimentary material deposited in a dry or lacustrine environment, or volcanic material related to the tec...
G. Komatsu R. G. Strom
Erosional landforms on the layered terrains in Valles Marineris
NASA Technical Reports Server (NTRS)
Many investigators have proposed potential lakes in Valles Marineris based on the relationship with outflow channels, and a proposed lacustrine origin of layered deposits. We have investigated the erosional style of the layered terrains and evaluated their potential origins as sedimentation in and erosional modification by these lakes. The erosional features that will be discussed are distributed in the central canyon area and classified into terraces and layered depressions. Many terraces can be explained by coastal erosion in lakes as well as by eolian erosion. The lack of terraces on the canyon walls is probably due to more recent sapping and mass wasting of materials with different mechanical response to erosion than the layered terrains. Catastrophic water discharges in Valles Marineris as hypothesized by an ocean model may have been the source of the lakes and the eventual catastrophic release of water from the canyons.
Komatsu, G.; Strom, R. G.; Gulick, V. C.; Parker, T. J.
Noctis Labyrinthus/Valles Marineris transition
NASA Technical Reports Server (NTRS)
(Released 27 May 2002) The Science The transition zone between maze-like troughs of Noctis Labyrinthus and the main Valles Marineris canyon system are shown in this THEMIS visible camera image. This huge system of troughs near the equator of Mars was most likely created by tectonic forces which pulled apart the crust. In the top third of the image, on the western side of the northernmost trough, a buildup of relatively bright material on the plateau has led to an overflow into the trough. Most of the bottom of this trough is covered by sediment deposited from the plateau above. On the right-hand side of this same trough, on the southern wall, there is a thin streak of darker material that also seems to originate from the plateau above. This is most likely a gully formation. This feature could also be a dust avalanche, but because no other similar features are seen, this is unlikely. Other dark material deposited by some unknown process can also be seen all around the easternmost ridge in the trough. Near the bottom of the canyon, layers from the center ridges and the canyon wall can be matched, indicating that the ridges are made of the same material as the wall. Near the bottom of the image, there is yet another depression. This trough is filled with sediment deposited from erosion of the trough wall and possibly from the plateau above. All around the walls of this trough a layer of rocky material can be also be seen. It appears that the areas directly below the rocky ledges are 'shielded' from landslide material from above. Finally, in the northwestern wall of this trough, there is an irregular pattern of very bright material not seen anywhere else in the image. Identifying similar formations in other THEMIS visible camera images could provide some context for its occurrence and help us understand how it was formed. The Story Tectonic forces wrenched apart the crust on Mars long ago, forming deep troughs at the Martian equator like the ones seen here. They occur in a transition zone between the maze-like region of Noctis Labyrinthus and the deep canyon system of Valles Marineris, the largest and 'grandest' canyon in the solar system. These cracks in the crust can give geologists a good idea of what has happened over the course of the planet's history. Find out a little yourself by taking a closer look at the western side of the trough in the top third of the image. Can you see how the bright sediment from the plateau above has been whisked over the side, overflowing and building up on the floor below? Follow the south wall of this same trough, and you'll come across a dark streak running down (toward the right side of the image). One possibility is that it could be a dust avalanche, but if that were so, you'd think it would have occurred much more often, in more places than just that one spot. Since it didn't, scientists believe it probably isn't a dust avalanche, but could be a gully instead. There's also some more dark material deposited all around the easternmost ridge in the trough as well. No one is quite sure how it formed there or exactly what it's made of. At the least, what geologists can tell is that the ridges in the trough are made of the same material as the canyon walls, since the layers in each of them match. Finding similarities like these can help piece together the story of Martian geology here. When scientists study THEMIS images, however, they are also on the lookout for anything that looks unusual. Try studying the dark depression that carves out the bottom of this image. It too is filled soft-looking sediments, probably deposited from erosion of the trough wall and possibly from the plateau above. Rocky outcrops all around the walls of this trough shield the areas directly below them from landslides from above. But all that seems pretty regular. Do you see anything that stands out? How about the odd pattern of brighter material that seems almost pasted on the northwestern wall of the trough like dried up glue? This material isn't found elsewhere in this image.
The Layer Cake Walls of Valles Marineris
NASA Technical Reports Server (NTRS)This image of the northern wall of Coprates Chasma, in Valles Marineris, was taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) at 1227 UTC (8:27 a.m. EDT) on June 16, 2007, near 13.99 degrees south latitude, 303.09 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 20 meters (66 feet) across. The region covered is just over 10 kilometers (6.2 miles) wide at its narrowest point. Valles Marineris is a large canyon system straddling Mars' equator, with a total size approximating the Mediterranean Sea emptied of water. It is subdivided into several interconnected 'chasmata' each hundreds of kilometers wide and, in some cases, thousands of kilometers long. The walls of several of the chasmata, including Coprates Chasma, expose a section of Mars' upper crust about 5 kilometers (3 miles) in depth. Exposures like these show the layers of rock that record the formation of Mars' crust over geologic time, much as the walls of the Grand Canyon on Earth show part of our planet's history. The upper panel of this montage shows the location of the CRISM image on a mosaic from the Mars Odyssey spacecraft's Thermal Emission Imaging System (THEMIS), taken in longer infrared wavelengths than measured by CRISM. The CRISM image samples the base of Coprates Chasma's wall, including a conspicuous horizontal band that continues along the wall for tens of kilometers to the east and west, and a topographic shelf just above that. The middle two panels show the CRISM image in visible and infrared light. In the middle left panel, the red, green, and blue image planes show brightness at 0.59, 0.53, and 0.48 microns, similar to what the human eye would see. Color variations are subdued by the presence of dust on all exposed surfaces. In the middle right panel, the red, green, and blue image planes show brightness at 2.53, 1.51, and 1.08 microns. These three infrared wavelengths are the 'usual' set that the CRISM team uses to provide an overview of infrared data, because dust has a less obscuring effect, and because they are sensitive to a wide variety of minerals. Layering is clearly evident in the wall rocks. The conspicuous band running along the base of the chasma wall appears slightly yellowish, and the scarp at the edge of the topographic bench appears slightly green. The bottom two panels use combinations of wavelengths to show the strengths of absorptions that provide 'fingerprints' of different minerals. In the lower left panel, red shows strength of a 0.53-micron absorption due to oxidized iron in dust, green shows strength of an inflection in the spectrum at 0.6 microns that may be related to rock coatings, and blue shows strength of a 1-micron absorption due to the igneous minerals olivine and pyroxene. The conspicuous horizontal band appears slightly blue, indicating a stronger signature of olivine and/or pyroxene. In the lower right panel, red is a measure of an absorption particular to olivine, green is a measure of a 2.3-micron absorption due to phyllosilicates (clay-like minerals formed when rock was subjected to liquid water), and blue is a measure of absorptions particular to pyroxene. The conspicuous horizontal band is now resolved into an upper portion richer in pyroxene, underlain by material richer in olivine than the rest of the wall rock. Also, erosion-resistant material forming the topographic bench is underlain by phyllosilicate-containing material exposed on the scarp. Taken together, these data reveal a layer cake-like composition of the crustal material exposed in Coprates Chasma's wall. Most of the rock is rich in pyroxene, which is expected because much of Mars' crust consists of volcanic basaltic rock. However discrete layers are richer in olivine, and in some layers the presence of phyllosilicates indicates interaction of rock with liquid water. Because the phyllosilicate-containing layer is low on the walls and deeply buried, it likely represents an early pe
Preliminary Admittance Estimates for the Valles Marineris, Mars
NASA Technical Reports Server (NTRS)
We use the gravity and topography fields derived from Mars Global Surveyor in conjunction with a multi-resolution localization admittance technique to constrain lithospheric structure for the trough system of Valles Marineris on Mars.
Anderson, F. Scott; Banerdt, W. B.
Erosional Landforms on the Layered Terrains in Valles Marineris.
National Technical Information Service (NTIS)
Many investigators have proposed potential lakes in Valles Marineris based on the relationship with outflow channels, and a proposed lacustrine origin of layered deposits. We have investigated the erosional style of the layered terrains and evaluated thei...
G. Komatsu R. G. Strom V. C. Gulick T. J. Parker
Melas Chasma: A Mars Pathfinder View of Valles Marineris.
National Technical Information Service (NTIS)
A Mars Pathfinder landing site in Melas Chasma (Valles Marineris) would yield significant science return, but is outside present mission constraints. In Melas Chasma, Mars Pathfinder could investigate minimally altered basaltic material, sedimentary depos...
A. H. Treiman S. Murchie
Slope stability analysis of Valles Marineris, Mars
NASA Astrophysics Data System (ADS)
Valles Marineris (VM) in the equatorial area of Mars exhibits several gravitational failures which resulted in a series of large landslides up to several hundred cubic kilometers in volume. Questions arise as to forces at play and rock strength in the stability of the walls of VM. In this work we address the stability analysis of the walls of VM by considering the strength of the materials of the chasma walls and the causes of landslides. Using finite element calculations and the limit analysis upper bound method, we explore the range of cohesion and friction angle values associated to realistic failure geometries, and compare predictions with the classical Culmann's wedge model. Our analysis is based both on synthetic, simplified slope profiles and also on the real shape of the walls of VM taken from the MOLA topographic data. Validation of the calibrated cohesion and friction angle values is performed by comparing the computed unstable cross sectional areas with the observed pre- and post-failure profiles and estimated failure surface geometry. This offers a link between rock mass properties, slope geometry and volume of the observed failure. Pseudo-static seismic analyses generated another set of dimensionless charts. Our pseudo-static analyses show that low seismicity events induced by meteoroids impacts compatible with the size of craters could be a cause for some of the observed landslides if poor rock properties for VM is assumed.
Vittorio De Blasio, Fabio; Battista Crosta, Giovanni; Castellanza, Riccardo; Utili, Stefano
Valles Marineris: a past glaciated valley landsystem along the Martian equator
NASA Astrophysics Data System (ADS)
Various ice-related features occurring on the floor of Valles Marineris suggest that this canyon system that stretches along the Martian equator has experienced a period of past glacial activity. Three regions of Valles Marineris were investigated, Coprates Chasma, Candor Chasma, and Ius Chasma. Geomorphological observations are based on images and altimetry analysis by using the Context Camera (CTX), the High Resolution Imaging Science Experiment (HiRISE) and MOLA PEDR single tracks. The study reveals some features reminiscent of a past glaciated valley landsystem in these regions. A line running along the base of valley wallslopes and associated with spur and gully morphology can be interpreted as a periglacial trimline. Other landforms on the floor of Candor Chasma can be interpreted as stagnant ice features such as polygonal terrains, chaotic terrains which look similar to terrestrial ablation moraines with kettle holes. Ancient ice probably also persists now in Candor Chasma in the form of a debris covered glacier with a surface elevation that is consistent with that of the trimline. In Coprates Chasma, hanging valleys provide additional evidence for the former existence of an extensive glacial filling of Valles Marineris. Terraced mounds resting on the floor of Coprates Chasma and around basement domes can be interpreted as stagnant remnants of stratified ice. Altogether, these landforms define a full glacial landsystem consistent with global climate models that predict glaciations in Valles Marineris during the Late Amazonian.
Gourronc, M.; Bourgeois, O.; M�ge, D.; Bultel, B.; Pochat, S.
Voluminous volcanism on early mars revealed in valles marineris
The relative rates and importance of impact cratering, volcanism, erosion, and the deposition of sediments to the early geological history of Mars are poorly known. That history is recorded in the upper crust of the planet, which is best exposed along the 4,000km-long canyon system called Valles Marineris. Previous studies of the stratigraphy of this region have assumed that it consists of megabreccia and fractured bedrock resulting from impacts, overlain by or interbedded with relatively thin layers of lava, and with the layering restricted to the uppermost level of the crust. Here we report new high-resolution images that reveal ubiquitous horizontal layering to depths of at least 8 km in the canyons. Megabreccia should be only coarsely layered and fractured bedrock should be unlayered, so these observations indicate that volcanic or sedimentary processes were much more important in early martian history than previously believed. Morphological and compositional data suggest that the layers were formed mainly by volcanic flood lavas. Mars was therefore probably very volcanically active during at least the first billion years and after the period when the heaviest impact bombardment had ended.
McEwen, A. S.; Malin, M. C.; Carr, M. H.; Hartmann, W. K.
Recurring Slope Lineae in Valles Marineris, Mars
NASA Astrophysics Data System (ADS)
Recurring slope lineae (RSL) are relatively low-albedo features up to a few m wide that extend down steep slopes from bedrock outcrops. Hundreds may form in rare locations, often associated with small channels. In the southern mid-latitudes, RSL appear and grow incrementally during the late southern spring through summer, and they favor equator-facing slopes--times and places with peak surface temperatures from ~250 to 300 K. RSL are recurring: they form and grow in the warm season, then fade and usually completely disappear in cold seasons. During the next warm season, similar but new features form and grow. For more, see McEwen et al., 2011, Science 333, 740. As of early 2012, 15 RSL sites had been confirmed between 52-32�S latitudes. Confirmation requires that we observe many new lineae forming at a site in more than one Mars year, distinguishing RSL from episodic dry mass wasting triggered by eolian, seismic, or impact activity. We have recently confirmed three sites in the equatorial region of Mars. Two of them are on the floor of Coprates Chasma and one is in central Valles Marineris, all near latitude 12S. They are on north-facing slopes and active in southern winter/northern summer (which may be the warmest season on these steep slopes, although in the southern hemisphere). The surface brightness temperatures from THEMIS remain in the range (>250 K) of the southern mid-latitude RSL sites when active, and the morphologies and geologic settings are also similar. We will continue monitoring these sites throughout the year, along with occasional monitoring of other candidate equatorial RSL sites. If RSL are due to flow of salty water, the equatorial sites may be of special interest for future exploration.
McEwen, A. S.; Dundas, C. M.; Byrne, S.; Mattson, S.; Ojha, L.; Schaefer, E.; Wray, J. J.
Formation of the layered deposits in the Valles Marineris, Mars
NASA Technical Reports Server (NTRS)
Evidence is presented for large standing bodies of water on Mars during past epochs. It is noted that the origin of the horizontally-layered deposits in the Valles Marineris can be best explained by formation in standing bodies of water. These lakes, if they existed, were most likely covered by ice. There are several geologically feasible mechanisms that could have led to formation to thick deposits in ice covered paleolakes in the Valles Marineris. Present data are insufficient to choose conclusively among the various possibilities.
Nedell, S. S.; Squyres, S. W.
Origin and evolution of the layered deposits in the Valles Marineris, Mars
NASA Astrophysics Data System (ADS)
Four hypotheses are discussed concerning the origin of the layered deposits in the Martian Valles Marineris, whose individual thicknesses range from about 70 to 300 m. The hypothesized processes are: (1) aeolian deposition; (2) deposition of remnants of the material constituting the canyon walls; (3) deposition of volcanic eruptions; and (4) deposition in standing bodies of water. The last process is chosen as most consistent with the rhythm and lateral continuity of the layers, as well as their great thickness and stratigraphic relationship with other units in the canyons. Attention is given to ways in which the sediments could have entered an ice-covered lake; several geologically feasible mechanisms are identified.
Nedell, S. S.; Squyres, S. W.; Andersen, D. W.
Characterization of Layered Deposits inside Valles Marineris
NASA Technical Reports Server (NTRS)
This report represents the final progress report on our study of the Melas Chasma region on Mars that was proposed as a landing site for the Mars Exploration Rover mission (MER). During this two-year proposal (which was extended over three years by a no-cost extension), we conducted a thorough study of the layered deposits in western Melas Chasma that had been the location of a high priority MER mission landing ellipse within Valles Marineris. All available data sets from orbiter missions, including MOC, MOLA, THEMIS visible and infrared images were all used to analyze this site. The major outcome of this work was a published paper in the Journal of Geophysics and Research Planets [Weitz et al., 2004]. Our geologic mapping and interpretation of the MOC images suggest the landing ellipse contains three main geomorphologic units: (1) a blocky deposit consisting of bright blocks in a darker matrix (BD); (2) sand sheets composed of dark dunes; and (3) landslide deposits emanating from the wallrock to the west [Weitz et al., 2003]. Furthermore, we propose that the morphology of the BD unit in western Melas is a mass wasting deposit composed of blocks of Interior Layered Deposits (ILDs) mixed in with wallrock material. However, more recent MOC images indicate that in the eastern portion of the ellipse and adjacent to a large hill, there are blocks of material resembling those seen in BD. Hence, we cannot rule out the source of BD was this hill. Unfortunately, sand dunes obscure much of the deposit around this hill, making it impossible to precisely determine the connection between the hill and BD, whereas BD can be traced directly to the southern Melas wallrock. If BD resulted from a mass wasting event in the southern wallrock, then we would expect the material to be concentrated further to the north, as now appears to be the case. In summary, the exact source location for BD continues to remain a mystery, but we favor an origin from either the southern wallrock [Weitz et el., 2002] or the eastern hill.
Weitz, Catherine; Anderson, Scott; Parker, Tim; Grant, John
Stability of rock slopes in Valles Marineris, Mars
NASA Astrophysics Data System (ADS)
New slope measurements from the Mars Orbiter Laser Altimeter (MOLA), in conjunction with the Rock Mass Rating system (RMR), permit inversions of slope height and angle from wallrock and interior deposits within Valles Marineris troughs for strength and lithology. Wallrock (50 < RMR < 65) is stronger than interior deposits (30 < RMR < 55). These values are consistent with layered igneous rock beneath wallrock slopes, with interior deposits consistent with partially indurated sedimentary or volcaniclastic rocks. Larger volumes of landslide debris relative to terrestrial slides are related to the reduced Martian gravity. Seismicity along trough-bounding normal faults likely triggered the landslides in the adjacent wallrock. The weaker interior deposits are located sufficiently far from a border fault (and on its hangingwall) to have remained stable during the seismogenic faulting in Valles Marineris.
Schultz, Richard A.
Formation of the layered deposits in the Valles Marineris, Mars
NASA Technical Reports Server (NTRS)
Thick sequences of layered deposits are found in the Valles Marineris, which exhibit fine, nearly horizontal layering, and are present as isolated plateaus of what were once more extensive deposits. It was argued that the morphology of the deposits is most consistent with origin in standing bodies of water. The conditions necessary for the existence of ice-covered Martian paleolakes are examined in detail and mechanisms for sediment deposition in them are considered. It was concluded that there are several geologically feasible mechanisms that could have led to the formation of thick deposits in ice-covered paleolakes in the Valles Marineris. Present data are insufficient to choose conclusively among the various possibilities. Several types of data from the Mars Observer mission will be useful in further characterizing the deposits and clarifying the process of their origin. The deposits should be considered important targets for a future Mars sample return mission.
Nedell, Susan S.; Squyres, Steven W.
Evidence of a Paleolake in the central Valles Marineris
NASA Astrophysics Data System (ADS)
The Valles Marineris (VM) canyon system of Mars is closely related to large flooding channels, some of which emerge full born from chaotic terrain in canyon floors. Coprates Chasma, one of the largest VM canyons, is connected at its eastern end to chaotic terrain Capri Chasma. Despite the likely large volumes of groundwater that discharged from Capri Chasma [1], no evidence of related fluvial activity in Coprates Chasma has thus far been reported. We present an analysis of the regional topography which, together with photogeologic interpretation of available imagery, suggests that ponding due to late-stage discharge of water from Capri Chasma chaotic terrain produced a shallow lake spanning parts of Melas, Coprates, Capri and Eos Chasmata (MCCE). Overflow of this lake at its eastern end resulted in delivery of water to downstream chaos regions and outflow channels. Our ponding hypothesis is motivated primarily by the identification of scarp and terrace features which, despite a lateral spread of about 1500 km, have similar elevations. Furthermore, these elevations correspond to the maximum ponding elevation of the region (-3562 m). Mean lake depth is 842 m. Simulated ponding in the MCCE system yields an overflow point at its eastern extremity, in Eos Chasma. The neighborhood of this overflow point contains clear indicators of fluvial erosion in a consistent east-west orientation (Figure 4). Specifically, scour marks suggest an eastward convergence of flow lines. Downstream of the overflow point, the direction set by the scour marks is paved by a smooth deposit leading directly to a scoured channel entering the next major region of chaotic terrain, Aurorae Chaos. The smooth deposit is likely made up of remnants of the interior deposit breached by the MCCE paleolake overflow. The next region of chaotic terrain downstream of Aurorae Chasma is Hydraotes Chaos, which lies in a relatively deep depression and would be the next significant ponding location for flow originating in the MCCE region. Crucially, it is also the only other Chryse Planitia chaos to exhibit terraces, which have been attributed a lacustrine origin by other authors [2]. References: [1] Carr M. H. (1979) JGR, 84, 2995-3007. [2] Ori G. G. and Mosangini C. (1998) JGR, 103, 22713-22724.
Harrison, K. P.
Landslide on Valles Marineris: morphology and flow dynamics
NASA Astrophysics Data System (ADS)
Introduction: Valles Marineris is known as a place of numerous and well preserved landslides on Mars. In comparison with terrestrial landslides, martian landslides are distinctive in their size and morphology. As a consequence of the topography of the canyon, the averaged drop height of these landslides is about 6.5 km and the averaged volume is about 102~4 km3[1], which is 2~3 orders of magnitude larger than terrestrial ones, at the exception of marine landslides[2]. As for the morphology, clear levees with longitudinal lineations are typical features of martian landslides, whereas surfaces of the terrestrial mass movements are dominated by a rather chaotic topography with, in some cases, the occurrence of transverse ridges. The characteristics of the deposits should reflect the dynamics of the emplacement and the subsurface material properties. In particular, there is a longstanding debate about the relation between the long run-out length and the existence of subsurface volatiles (water ice, clathrates, ground water) [1,3,4,5,6,7]. The motivation of our research is the fact that material properties are expected to be deduced from the morphology of the deposits and the knowledge of the flow dynamics. Then, the characteristics of subsurface materials partially collapsed as mass movements could be documented as a function of time, considering the age of each landslide. In this study, we focus on the longitudinal grooves which are found on the surface of landslide deposits at Valles Marineris (Fig.1). This pattern is a typical feature in the martian landslides[3], and extremely rarely observed in the terrestrial mass movements. The origin is not well clarified, but it seems strong relation with the flow style or physical property of transported materials. With the objective to determine the condition of formation of the lineations, the geometric characteristics (volume, surface, thickness, run-out length) of lineated and non-lineated landslides are compared. Then, the difference in flow dynamics are discussed based on the physics of granular flow. Topographic measurements are derived from HRSC and MOLA data. HRSC, MOC, THEMIS-VIS are used for the morphological observations. Result and Discussions: Not all the landslides have longitudinal lineation as shown in Fig.1. Almost half numbers of landslides observed in Valles Marineris show irregularly shaped knobby surface as shown in Fig.2. We classified all the landslides in this area as lineated type and knobby type, including a few exceptions. We compare two types of landslide by measured morphological parameters, such as volume, averaged thickness, area, maximum run-out (Lmax), and maximum drop height (Hmax). When we compare by volume and Hmax/Lmax plot, where Hmax/Lmax corresponds to the apparent coefficient of friction[2], a clear difference is recognized. Landslides of the lineated type show a negative correlation of Hmax/Lmax with volume, a similar trend to terrestrial dry landslides. On the other hand, the plots of knobby type concentrate in a small area at larger volumes without any clear correlation of two parameters. From the comparison at the plot of averaged thickness and total volume of deposit, lineated type show systematically thinner geometry than knobby type, bounded around 200 to 250 m. From the comparison of averaged thickness and root square of deposit area (Fig.5), a roughly linear correlation is reported for the lineated type. The square root of deposit area means the index length of horizontal shape of deposit. Usually the deposit of landslide at Valles Marineris spread out at flat broad valley floor showing semi-radialy spreaded shape. Thus it can be invoked as index length independent with actual horizontal deposit shape. The linear correlation of thickness and square of the deposit area for the lineated type implies that deposits shapes are homothetic, and keep similarity. This observation is striking given the large range of volumes reported. In contrast, a constant square of deposit area for thicknesses ranging from 100 to 600 meters is reported. T
Sato, H.; Kurita, K.; Baratoux, D.; Pinet, P.
Evidence for precipitation on Mars from dendritic valleys in the Valles Marineris area.
Dendritic valleys on the plateau and canyons of the Valles Marineris region were identified from Thermal Emission Imaging System (THEMIS) images taken by Mars Odyssey. The geomorphic characteristics of these valleys, especially their high degree of branching, favor formation by atmospheric precipitation. The presence of inner channels and the maturity of the branched networks indicate sustained fluid flows over geologically long periods of time. These fluvial landforms occur within the Late Hesperian units (about 2.9 to 3.4 billion years old), when Mars was thought to have been cold. Our results suggest a period of warmer conditions conducive to hydrological activity. PMID:15232103
Mangold, Nicolas; Quantin, Cathy; Ansan, V�ronique; Delacourt, Christophe; Allemand, Pascal
Part 2: Sedimentary geology of the Valles, Marineris, Mars and Antarctic dry valley lakes
NASA Technical Reports Server (NTRS)
Detailed mapping of the layered deposits in the Valles Marineris, Mars from high-resolution Viking orbiter images revealed that they from plateaus of rhythmically layered material whose bases are in the lowest elevations of the canyon floors, and whose tops are within a few hundred meters in elevation of the surrounding plateaus. Four hypotheses for the origin of the layered deposits were considered: that they are eolian deposits; that they are remnants of the same material as the canyon walls; that they are explosive volcanic deposits; or that they were deposited in standing bodies of water. There are serious morphologic objections to each of the first three. The deposition of the layered deposits in standing bodies of water best explains their lateral continuity, horizontality, great thickness, rhythmic nature, and stratigraphic relationships with other units within the canyons. The Martian climatic history indicated that any ancient lakes were ice covered. Two methods for transporting sediment through a cover of ice on a martian lake appear to be feasible. Based on the presently available data, along with the theoretical calculations presented, it appears most likely that the layered deposits in the Valles Marineris were laid down in standing bodies of water.
Nedell, Susan S.
Dark materials in Valles Marineris: Indications of the style of volcanism and magmatism on Mars
Rifting on the equatorial canyon system of Valles Marineris provides a unique view of the interior of the Martian crust to depths reaching 7 km, exposing several in situ bedrock units which testify to past volcanic and magmatic processes on Mars. A thick, regionally extensive deposit observed in Coprates and Juventae chasmata is interpreted on the basis of spectral reflectance, erosional morphology, and tendency for eolian mobilization to be composed of mafic glass, possibly an ancient Martian analogue of the lunar terra mantling deposits. Spectral mapping suggests that the dark floor-covering materials in the lower canyons are derived from this unit. A series of cliffs in the Ophir Chasma wall rock is interpreted to be exposures of resistant bedrock; the spectral signature of this massive and uniform unit most closely resembles that of terrestrial mafic rocks altered to or coated by crystalline hematite. Application of computer mapping techniques to probable young volcanic materials in the central troughs yields an inferred distribution of volcanic activity consistent with the interpretation of extrusion along faults near the margins of the canyon floors. This result supports the hypothesis that the valles originated through tectonic extension.
Geissler, P.E.; Singer, R.B. (Univ. of Arizona, Tucson (USA)); Lucchitta, B.K. (Geological Survey, Flagstaff, AZ (USA))
Mobility of large rock avalanches: evidence from Valles Marineris, Mars
Measurements of H/L (height of drop/length of runout) vs. volume for landslides in Valles Marineris on Mars show a trend of decreasing H/L with increasing volume. This trend, which is linear on a log-log plot, is parallel to but lies above the trend for terrestrial dry rock avalanches. This result and estimates of 104 to 105 Pa yield strength suggest that the landslides were not water saturated, as suggested by previous workers. The offset between the H/L vs. volume trends shows that a typical Martian avalanche must be nearly two orders of magnitude more voluminous than a typical terrestrial avalance in order to achieve the same mobility. This offset might be explained by the effects of gravity on flows with high yield strengths. These results should prove useful to future efforts to resolve the controversy over the mechanics of long-runout avalanches. -Author
McEwen, A. S.
Impact craters and landslide volume distribution in Valles Marineris, Mars
NASA Astrophysics Data System (ADS)
The landslides in the wide gorge system of Valles Marineris (Mars) exhibit volumes of the or-der of several hundred 1,000 km3 and runouts often in the excess of 80 km. Most landslides have occurred at the borders of the valleys, where the unbalanced weight of the 5-8 km high headwalls has been evidently sufficient to cause instability. Previous analysis has shown that the mechanical conditions of instability would not have been reached without external triggering fac-tors, if the wallslope consisted of intact rock. Among the factors that have likely promoted instability, we are currently analyzing: i) the possibility of rock weakening due to weathering; ii) the alternation of weak layers within more massive rock; weak layers might for example due to evaporites, the possible presence of ice table at some depth, or water; iii) weakening due to impact damage prior to the formation of Valles Marineris; studies of impact craters on Earth show that the volumes of damaged rock extends much deeper than the crater itself; iv) direct triggering of a landslide due to the seismic waves generated by a large meteoroid impact in the vicinity, and v) direct triggering of a landslide con-sequent to impact at the headwall, with impulsive release of momentum and short but intense increase of the triggering force. We gathered a large database for about 3000 Martian landslides that allow us to infer some of their statistical properties supporting our analyses, and especially to discriminate among some of the above listed predisposing and triggering factors. In particular, we analyse in this contribution the frequency distribution of landslide volumes starting from the assumption that these events are controlled by the extent of the shock damage zones. Relative position of the impact point and damage zones with respect to the Valles Marineris slopes could in fact control the released volumes. We perform 3D slope stability analy-sis under different geometrical constraints (e.g. crater size and position, slope angle and height, size of the relative shock damage zone) starting from rock mass properties calibrated in a previous study (Crosta et al., 2014). We report about the synthetic volume frequency distribution gen-erated by considering the most critical failure surfaces for the different geometrical constraints and the frequency distribution of craters on Mars surface (e.g., Hartmann and Neukum, 2001). 1. Crosta, G.B., Utili, S., De Blasio, F.V., Castellanza, R. (2014)Reassessing rock mass properties and slope instability triggering conditions in Valles Marineris, Mars.Earth Planetary Science Letters, 338, 329-343. http://dx.doi.org/10.1016/j.epsl.2013.11.053 2. Hartmann, W., and Neukum, G., (2001). Crater Chronology and the evolution of Mars. Space Science Reviews 96: 165-194.
De Blasio, Fabio
Valles Marineris, Mars: Are Pit Chains Formed by Erosion and Troughs by Tectonism.
National Technical Information Service (NTIS)
The origin of the Valles Marineris remains controversial. Erosional, tectonic, and hybrid processes have been proposed. To clarify these contradictions, the widths and depths of pit chains and troughs were compared and it was found that the features do no...
B. K. Lucchitta R. A. Balser L. M. Bertolini
Age and erosion rates of sulfate-rich Interior Layered Deposits of Valles Marineris
NASA Astrophysics Data System (ADS)
Since their discovery by Mariner 9, the Interior Layered Deposits (ILD) of Valles Marineris are still one of the most puzzling feature at the surface of Mars. Since the early investigation by the OMEGA spectrometer onboard Mars Express, it is known that these voluminous deposits are enriched in sulfates and may represent one of the largest reservoirs of hydrated minerals at the surface of Mars. Nowadays, with MRO dataset-especially HiRISE and CRISM-, we have a better knowledge of their composition, structure and stratigraphy. However, their age is still unknown and is subject of speculation. Three main theories are being debated. The first interprets the ILD to be older than Valles Marineris formation and to have been exhumed by the chasmata opening. Their composition enriched in sulfates is in agreement with this hypothesis; diapirism may have occurred. The second hypothesis argues that the ILD have filled the canyons during or right after their formation. Some observed stratigraphic relationships with the troughs are consistent with this hypothesis. The last theory argues that the ILD could be recent and be related to Amazonian equatorial ice deposition. One of the arguments supporting this theory is the lack of impact craters on the outcrops of these ILD, especially at high resolution. To address this question, we performed for each canyon of Valles Marineris a systematic analysis at high resolution of the stratigraphic relationship between the ILD and the others landforms observed in the canyon. We also systematically investigated the impact crater retention of the ILD over a large range of scales from chasmata scale to HiRISE image scale. We also counted crater on CTX images on landforms in stratigraphic relationship with the ILD. Our results allow us to deduce the timing of events and the erosion rates of the different surfaces. The investigation of stratigraphic relationships attests that the ILD postdate the formation of the canyons. Our crater counts on landforms postdating the ILD revealed that the ILD formed and were eroded early in the canyon history near 3.5 Gy. In almost each chasma, large impact craters have been emplaced on the ILD attesting to their old ages. The crater size distribution on ILD also reveals a long erosional history. Using the age deduced by that portion of the crater size distribution that follows the crater production slope, and the largest impact diameter not affected by erosion, we deduced the erosion rate of the different surfaces. At similar ages of formation, the ILD are one order in magnitude more erodible than others materials (landslides, trough floors...). According to these results, a simple aeolian erosion over the last 3.5 Gy is sufficient to explain the observed depletion in small impact craters on the ILD as compared to the surrounding surfaces.
Quantin, C.; Mangold, N.; Haubert, E.; Flahaut, J.; Le Deit, L.; Fueten, F.; Rossi, A.; Clenet, H.
Hydrated mineral stratigraphy of Ius Chasma, Valles Marineris
NASA Astrophysics Data System (ADS)
New high-resolution spectral and morphologic imaging of deposits on walls and floor of Ius Chasma extend previous geomorphic mapping, and permit a new interpretation of aqueous processes that occurred during the development of Valles Marineris. We identify hydrated mineralogy based on visible-near infrared (VNIR) absorptions. We map the extents of these units with CRISM spectral data as well as morphologies in CTX and HiRISE imagery. Three cross-sections across Ius Chasma illustrate the interpreted mineral stratigraphy. Multiple episodes formed and transported hydrated minerals within Ius Chasma. Polyhydrated sulfate and kieserite are found within a closed basin at the lowest elevations in the chasma. They may have been precipitates in a closed basin or diagenetically altered after deposition. Fluvial or aeolian processes then deposited layered Fe/Mg smectite and hydrated silicate on the chasma floor, postdating the sulfates. The smectite apparently was weathered out of Noachian-age wallrock and transported to the depositional sites. The overlying hydrated silicate is interpreted to be an acid-leached phyllosilicate transformed from the underlying smectite unit, or a smectite/jarosite mixture. The finely layered smectite and massive hydrated silicate units have an erosional unconformity between them, that marks a change in surface water chemistry. Landslides transported large blocks of wallrock, some altered to contain Fe/Mg smectite, to the chasma floor. After the last episode of normal faulting and subsequent landslides, opal was transported short distances into the chasma from a few m-thick light-toned layer near the top of the wallrock, by sapping channels in Louros Valles. Alternatively, the material was transported into the chasma and then altered to opal. The superposition of different types of hydrated minerals and the different fluvial morphologies of the units containing them indicate sequential, distinct aqueous environments, characterized by alkaline, then circum-neutral, and finally very acidic surface or groundwater chemistry.
Roach, Leah H.; Mustard, John F.; Swayze, Gregg; Milliken, Ralph E.; Bishop, Janice L.; Murchie, Scott L.; Lichtenberg, Kim
Hydrated mineral stratigraphy of Ius Chasma, Valles Marineris
New high-resolution spectral and morphologic imaging of deposits on walls and floor of Ius Chasma extend previous geomorphic mapping, and permit a new interpretation of aqueous processes that occurred during the development of Valles Marineris. We identify hydrated mineralogy based on visible-near infrared (VNIR) absorptions. We map the extents of these units with CRISM spectral data as well as morphologies in CTX and HiRISE imagery. Three cross-sections across Ius Chasma illustrate the interpreted mineral stratigraphy. Multiple episodes formed and transported hydrated minerals within Ius Chasma. Polyhydrated sulfate and kieserite are found within a closed basin at the lowest elevations in the chasma. They may have been precipitates in a closed basin or diagenetically altered after deposition. Fluvial or aeolian processes then deposited layered Fe/Mg smectite and hydrated silicate on the chasma floor, postdating the sulfates. The smectite apparently was weathered out of Noachian-age wallrock and transported to the depositional sites. The overlying hydrated silicate is interpreted to be an acid-leached phyllosilicate transformed from the underlying smectite unit, or a smectite/jarosite mixture. The finely layered smectite and massive hydrated silicate units have an erosional unconformity between them, that marks a change in surface water chemistry. Landslides transported large blocks of wallrock, some altered to contain Fe/Mg smectite, to the chasma floor. After the last episode of normal faulting and subsequent landslides, opal was transported short distances into the chasma from a few m-thick light-toned layer near the top of the wallrock, by sapping channels in Louros Valles. Alternatively, the material was transported into the chasma and then altered to opal. The superposition of different types of hydrated minerals and the different fluvial morphologies of the units containing them indicate sequential, distinct aqueous environments, characterized by alkaline, then circum-neutral, and finally very acidic surface or groundwater chemistry. ?? 2009 Elsevier Inc. All rights reserved.
Roach, L. H.; Mustard, J. F.; Swayze, G.; Milliken, R. E.; Bishop, J. L.; Murchie, S. L.; Lichtenberg, K.
Stratigraphic evidence of past fluvial activity in southern Melas Chasma, Valles Marineris, Mars
NASA Astrophysics Data System (ADS)
During the late Noachian and early Hesperian periods, listric faulting led to the development of a series of hanging depressions throughout the Valles Marineris canyon system [1]. One such depression, situated on the southern wall of Melas Chasma, forms an enclosed basin which has since undergone modification from the late Hesperian to Amazonian. There is a multitude of evidence suggesting that the basin (hereon in referred to as the Southern Melas Chasma Basin; SMCB) was once host to active fluvial processes, that at minimum lasted for several hundred years [2,3]. Central to this is what appears to be the remains of a palaeolake, which is approximately 80 by 40 kilometres in area. The palaeolake contains a complex sequence of sedimentary stratigraphy, which includes several structures that resemble deltas and/or submarine fans on both the east and west side of the basin [4], and appear to originate from a network of channels and valleys that terminate in the basin. Previous studies have shown that the western valley network has drainage densities similar to terrestrial values and a dendritic nature that is indicative of precipitation and surface runoff [3]. Higher resolution mapping of the SMCB is important to further understand the stratigraphic succession and geomorphology, and to quantify how long liquid water may have been present within the basin. For this study, new digital elevation models (DEMs) have been produced in SOCET SET using stereo images from the Context Camera (CTX) and the High Resolution Imaging Science Experiment (HiRISE), both aboard the Mars Reconnaissance Orbiter. The DEMs have been produced at ~6 and ~1 m/pixel vertical resolution for CTX and HiRISE respectively. There is approximately 150-200 m of sediment within the stratigraphic succession; some individual strata are less than 10 m thick. The delta/fan structures appear to occur at different stratigraphic positions low down within the sequence. Clinoform-like and cross-bedded structures are shown to occur near the top of the sequence (a contrast to the laterally expansive, planar beds below), which suggest a significant change in depositional conditions within the SMCB during the time liquid water was stable. References: 1. Andrews-Hanna, J. C. The formation of Valles Marineris: 3. Trough formation through super-isostasy, stress, sedimentation, and subsidence. J. Geophys. Res. 117, E06002 (2012). 2. Mangold, N., Quantin, C., Ansan, V., Delacourt, C. & Allemand, P. Evidence for precipitation on Mars from dendritic valleys in the Valles Marineris area. Science 305, 78-81 (2004). 3. Quantin, C. Fluvial and lacustrine activity on layered deposits in Melas Chasma, Valles Marineris, Mars. J. Geophys. Res. 110, E12S19 (2005). 4. Metz, J. M. et al. Sublacustrine depositional fans in southwest Melas Chasma. J. Geophys. Res. 114, E10002 (2009).
Davis, Joel; Grindrod, Peter
Layers within the Valles Marineris: Clues to the Ancient Crust of Mars - High Resolution Image
NASA Technical Reports Server (NTRS)
This high resolution picture of the Martian surface was obtained in the early evening of January 1, 1998 by the Mars Orbiter Camera (MOC), shortly after the Mars Global Surveyor spacecraft began it's 80th orbit. Seen in this view are a plateau and surrounding steep slopes within the Valles Marineris, the large system of canyons that stretches 4000 km (2500 mi) along the equator of Mars. The image covers a tiny fraction of the canyons at very high resolution: it extends only 9.8 km by 17.3 km (6.1 mi by 10.7 mi) but captures features as small as 6 m (20 ft) across. The highest terrain in the image is the relatively smooth plateau near the center. Slopes descend to the north and south (upper and lower part of image, respectively) in broad, debris-filled gullies with intervening rocky spurs. Multiple rock layers, varying from a few to a few tens of meters thick, are visible in the steep slopes on the spurs and gullies. Layered rocks on Earth form from sedimentary processes (such as those that formed the layered rocks now seen in Arizona's Grand Canyon) and volcanic processes (such as layering seen in the Waimea Canyon on the island of Kauai). Both origins are possible for the Martian layered rocks seen in this image. In either case, the total thickness of the layered rocks seen in this image implies a complex and extremely active early history for geologic processes on Mars.Malin Space Science Systems (MSSS) and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
Mineralogical and morphological study of the chaotic terrains of Valles Marineris, Mars: Insights into their geologic history
NASA Astrophysics Data System (ADS)
Following the OMEGA/Mars Express discovery of sulfates in the Valles Marineris area, a wide range of data, including the recent CRISM (The Compact Reconnaissance Imaging Spectrometer for Mars) observations, has been used to refine these detections. The present study focuses on three chasmata located at the border between the eastern end of Valles Marineris and at the onset of the chaotic terrains of Margaritifer Terra. Ganges Chasma, Capri Chasma and Juventae Chasma all share common features with the chaotic terrains, such as collapse plateaus and chaotic mounds, suggesting a aqueous history, but they are also affected by the east-west extensive tectonics of Valles Marineris and are thus considered part of the rift system. OMEGA and CRISM surveys show that, similarly to the rest of Valles Marineris, these three chasmata are filled with thick, massive sulfate-rich interior layered deposits (ILDs). A succession of a Mg monohydrated sulfate rich unit (characterized by diagnostic absorptions at 2.13 and 2.4 ?m) capped by a polyhydrated sulfate rich unit (1.9 and 2.4 ?m absorptions) is generally observed (Bishop et al., 2009; Flahaut et al., 2010). However, a number of other spectral features are noted, as additional absorptions between 2.2 and 2.3 ?m which could indicate the presence of hydrated silicates (clays or opaline silica) or additional ferric sulfates (e.g., Flahaut et al., 2010). More polyhydrated sulfates might be present as thin layers down in the ILD section in both Capri and Ganges Chasmata. The ILDs are distributed as mesas that might have been more extensive in the past, and that are overlapping the chaotic floor. CRISM data show that Fe/Mg-bearing phyllosilicates are detected in the upper part of the chaotic knobs that form the floor, thanks to their sharp 1.9 and 2.3 ?m spectral features. The mounds are surrounded by abundant dark sands forming ergs. CRISM spectra show a wide 1 ?m absorption feature, associated to weaker 2 ?m absorptions. This suggests that this sand is enriched in olivine, mixed with a high calcium pyroxene. It was previously suggested that this sand could potentially derive from the canyon walls (Chojnacki et al., 2012). However, it is not as abundant in other chasmata of Valles Marineris, suggesting a chaos-related origin. We argue that its source could be the extensive olivine-rich layer that is present in Margaritifer Terra and is exposed on the floor of at least eastern Capri and Ganges Chasmata (Flahaut et al., 2012). The units bearing these different signatures have different ages, allowing us to propose a reconstruction of part of the history of Valles Marineris. This history implies multiple water discharge episodes, during but also after the chaos emplacement, in the Hesperian and Amazonian periods. The water-rich history of this area, coupled with the unique geological record of Valles Marineris make these three chasmata prime targets for future Mars exploration.
Flahaut, J.; Bishop, J. L.; Fueten, F.; Quantin, C.; Van Westrenen, W.; Davies, G. R.
Sedimentation, volcanism, and ancestral lakes in the Valles Marineris: Clues from topography
NASA Technical Reports Server (NTRS)
Compilation of a simplified geologic/geomorphic map onto a digital terrain model of Valles Marineris has permitted quantitative evaluations of topographic parameters. The study showed that, if their interior layered deposits are lacustrine, the ancestral Valles Marineris must have consisted of isolated basins. If, on the other hand, the troughs were interconnected as they are today, the deposits are most likely to volcanic origin, and the mesas in the peripheral troughs may be table mountains. The material eroded from the trough walls was probably not sufficient to form all of the interior layered deposits, but it may have contributed significantly to their formation.
Lucchitta, B. K.; Isbell, N. K.; Howington-Kraus, A.
Topography of Valles Marineris: Implications for erosional and structural history
NASA Astrophysics Data System (ADS)
Compilation of a simplified geologic/geomorphic map onto digital terrain models of the Valles Marineris permitted an evaluation of elevations in the vicinity of the troughs and the calculation of depth of troughs below surrounding plateaus, thickness of deposits inside the troughs, volumes of void spaces above geologic/geomorphic units, and volumes of deposits. The central troughs north Ophir, north and central Candor, and north Melas Chasmata lie as much as 11 km below the adjacent plateaus. In Ophir and Candor chasmata, interior layered deposits reach 8 km in elevation. If the deposits are lacustrine and if all troughs were interconnected, lake waters standing 8 km high would have spilled out of Coprates Chasma onto the surrounding plateaus having surface elevations of only 4-5 km. On the other hand, the troughs may not have been interconnected at the time of interior-deposit emplacement; they may have formed isolated ancestral basins. The existence of such basins is supported by independent structural and stratigraphic evidence. The ancestral basins may have eventually merged, perhaps through renewed faulting, to form northern subsidiary troughs in Ophir and Candor Chasmata and the Coprates/north Melas/Ius graben system. The peripheral troughs are only 2-5 km deep, shallower than the central troughs. Chaotic terrain is seen in the peripheral troughs near a common contour level of about 4 km on the adjacent plateaus, which supports the idea of release of water under artesian pressure from confined aquifers. The layered deposits in the peripheral troughs may have formed in isolated depressions that harbored lakes and predated the formation of the deep outflow channels. (If these layered deposits are of volcanic origin, they may have been emplaced beneath ice in the manner of table mountains.) Areal and volumetric computations show that erosion widened the troughs by about one-third and that deposits occupy one-sixth of the interior space. Even though the volume eroded is larger than the volume deposited, topographic and geologic considerations imply that material eroded from trough walls was probably part of the interior layered deposits but not their sole source. Additional material may have come from subterranean piping, from reworking of local disintegration products on the floors, such as chaotic materials, or from eolian influx. But overall it is likely that the additional material is volcanic and that it forms mostly the upper, more diversely bedded layers of the interior deposits.
Lucchitta, B. K.; Isbell, N. K.; Howington-Kraus, A.
Pristine Noachian crust and key geologic transitions in the lower walls of Valles Marineris: Insights into early igneous processes on Mars
NASA Astrophysics Data System (ADS)
Valles Marineris is a unique vertical section through the uppermost kilometers of the martian crust. Its location, east of the Tharsis bulge, and its water-related history, fuel a great diversity of rock types in this area (Carr, M.H., Head, J.W. [2010]. Earth Planet. Sci. Lett. 294, 185-203). HiRISE and CRISM data available over the walls of the canyon were analyzed to infer the importance of magmatic and sedimentary processes through time. This contribution provides a complete morphologic and mineralogic characterization of the cross-section of rocks exposed in the canyon walls. Low-calcium pyroxene and olivine are detected in the lower portion of the walls, in association with morphologically distinct outcrops, leading to the idea that pristine Noachian crust might be exposed. Phyllosilicates are also present within the walls, but they appear to correspond to an alteration product. No proper sedimentary layers were observed within the walls of Valles Marineris at the resolution available today. All these detections are limited to the eastern portion of Valles Marineris, especially Juventae, Coprates, Capri, and Ganges chasmata. Preserved Noachian crustal material is rare on the martian surface and is rarely exposed in its pristine geologic context. Such detections lend precious information about early igneous processes. This survey also supports observations from the nearby impact crater central peaks (Quantin, C., Flahaut, J., Allemand, P. [2009]. Lunar Planet. Sci. 10; Quantin, C., Flahaut, J., Clenet, H., Allemand, P., Thomas, P. [2011]. Icarus, submitted for publication) and suggests that the western part of Valles Marineris may be cut into another material, consistent with lavas or volcanic sediments.
Flahaut, Jessica; Quantin, Cathy; Clenet, Harold; Allemand, Pascal; Mustard, John F.; Thomas, Pierre
Landslides as Indicators of the Past Extent of Interior Layered Deposits in Valles Marineris, Mars
NASA Astrophysics Data System (ADS)
Mounds of layered deposits, often several kilometres in height, are common in the canyons of Valles Marineris [1,2] and impact craters such as Gale Crater [3]. These interior layered deposits (ILDs) are important because they not only potentially preserve long sequences of Mars' stratigraphic record, but also because the common presence of abundant hydrous mineral phases implies aqueous activity crucial to studies of habitability. Despite their importance, no consensus exists regarding how ILDs form. Here we use landslides in Valles Marineris to gain insight into the previous extent and state of two large-scale ILDs. Using visible wavelength images and stereo digital terrain models we have identified three major occurrences of landslide deposits in Ophir Chasma, which are indicative of diversion or obstruction by material that is no longer present. The landslides in this study differ from most other landslides by increasing in height towards their front edges, showing distinctive concave scarp faces that are up to 500 m above the base level, and up to 400 m higher than the preceding part of the landslide deposit. These scarps are 1 - 2 km from, and mimic the shape of, the current extent of the ILD outer boundaries. Although not continuous throughout Ophir Chasma, the scarps extend between 20 and 50 km in length at different landslides, suggesting a common boundary at the northern edge of Ophir/Baetis Mensae. The most likely explanation for the formation of these scarps is that the leading edge of a landslide has piled up in front of an obstacle that has since been removed. Given the short timescale between landslide formation and the removal of the ILD obstacle material [4], it is likely that erosion alone is incapable of removing the material unless unrealistically high rates are assumed. Instead ice sublimation processes are likely to have been the dominant removal method, which implies that a significant amount of ice was present in the ILDs during the Amazonian [4]. References: [1] Nedell, S.S., et al. (1987), Icarus, 70, 409-441. [2] Lucchitta, B.K., et al. (1994), JGR, 99, 3783-3798. [3] Malin, M.C., K.S. Edgett (2000), Science, 290, 1927-1937. [4] Quantin, C., et al. (2004), Icarus, 172, 555.572.
Grindrod, Peter; Warner, Nicholas
On the Morphology and Transition of Valles Marineris Landforms: Rock Glaciers/Protalus Lobes vs. Landslides
NASA Astrophysics Data System (ADS)
The Valles Marineris canyon system exhibits a variety of different landforms associated with landslide mechanisms, ranging from several tens of meters to kilometers in length. They usually cover a surface of 1000 km2 and have an average volume of up to 5000 km3 [1-2]. It is assumed that they have been emplaced under wet as well as dry conditions from destabilized wall-rock and from surrounding sapping valleys [e.g., 1-3]. Absolute age determinations have furthermore shown that landslides in Valles Marineris span much of Martian history with ages as young as 50 Myr up to 3.5 Gyr [1]. Notwithstanding their individual ages and timespan during which they have been emplaced, landslides seem to have formed repetitively producing comparable morphologies and do not show substantial modifications throughout the last 3.5 Gy [1]. We here put our focus on a set of complex tongue-shaped landforms situated in the central parts of Valles Marineris at 283 �E, 8 �S which were previously identified as a single feature and for which a possible rock-glacier origin had been proposed [5]. This assumption implies environmental conditions which are not met today at such latitudes near the equator and which would contradict all observations related to the distribution of periglacial landforms on Mars, such as thermal contraction polygons, thermokarst features, and -- especially � lobate debris aprons [e.g., 6-11] which are considered to be Martian analogues for terrestrial rock glaciers. On the basis of our observations we come to the conclusion that the landforms discussed herein form a complex set of landslides derived from wall-rock sliding and/or from surrounding valleys. Consequently, different sources areas are reflected by the complexity of the landslides with several overlapping lobes and individual tongue-shaped features. Although the tongue-shaped morphology is characteristic of rock-glacier landforms, the assembly of furrows and ridges strongly suggests an origin caused by several short-termed events rather than slow creep mechansims. Overlapping lobes and faint compressional ridges as seen at this location are not caused by creep of mountain debris but by multiple events that took place at least as early as 300 Myr ago (with several resurfacing events) as crater counts suggest. Morphometric characteristics fit quite well to the trends proposed by others for landforms indicative of landsliding [12-13]. [1] C. Quantin et al. Icarus, 172:555-572, 2004. [2] C. Quantin et al. Planet. Space Sci., 52:1011-1022, 2004. [3] B. K. Lucchitta. J. Geophys. Res., 84(B14):8097-8113, 1979. [4] A. Lucas and A. Mangeney. Geophys. Res. Lett., 34:L10201, 2007. [5] W. Brian Whalley and Fethi Azizi. J. Geophys. Res., 108:E048032, 2003. [6] S. W. Squyres. Icarus, 34:600-613, June 1978. [7] S. W. Squyres. J. Geophys. Res., 84:8087-8096, December 1979. [8] N. Mangold et al. Planet. Space Sci., 50:385-401, 2002. [9] N. Mangold. Journal of Geophysical Research (Planets), 108:8021, 2003. [10] F. C. Chuang and D. A. Crown. Icarus, 179:24-42, December 2005. [11] H. Li et al. Icarus, 176: 382-394, 2005.[12] A. S. McEwen. Geology, 17:1111-1114, 1989. [13] K. P. Harrison and R. E. Grimm. Icarus, 163:247-362, 2003.
van Gasselt, S.; Hauber, E.; Dumke, A.; Schreiner, B.; Neukum, G.
Mineralogic Investigation of Capri/Ganges/Eos Chasmata, Mars: Insights into the Geologic History of Valles Marineris
NASA Astrophysics Data System (ADS)
We present here detailed analyses of Ganges, Capri, and Eos chasmata (Valles Marineris eastern end) using high-resolution morphologic and mineralogic data from the Mars Reconnaissance Orbiter (MRO) mission.
Flahaut, J.; Quantin, C.; Bishop, J. L.; Fueten, F.; Allemand, P.; Mangold, N.; Poulet, F.; Bibring, J.-P.
Layers within the Valles Marineris: Clues to the Ancient Crust of Mars
NASA Technical Reports Server (NTRS)This high resolution picture (right) of the Martian surface was obtained in the early evening of January 1, 1998 by the Mars Orbiter Camera (MOC), shortly after the Mars Global Surveyor spacecraft began it's 80th orbit. Seen in this view are a plateau and surrounding steep slopes within the Valles Marineris, the large system of canyons that stretches 4000 km (2500 mi) along the equator of Mars. The image covers a tiny fraction of the canyons at very high resolution: it extends only 9.8 km by 17.3 km (6.1 mi by 10.7 mi) but captures features as small as 6 m (20 ft) across. The highest terrain in the image is the relatively smooth plateau near the center. Slopes descend to the north and south (upper and lower part of image, respectively) in broad, debris-filled gullies with intervening rocky spurs. Multiple rock layers, varying from a few to a few tens of meters thick, are visible in the steep slopes on the spurs and gullies. Layered rocks on Earth form from sedimentary processes (such as those that formed the layered rocks now seen in Arizona's Grand Canyon) and volcanic processes (such as layering seen in the Waimea Canyon on the island of Kauai). Both origins are possible for the Martian layered rocks seen in this image. In either case, the total thickness of the layered rocks seen in this image implies a complex and extremely active early history for geologic processes on Mars.The left and center 'context' images are Viking mosaics reproduced at scales of 230 meters/pixel and 80 meters/pixel respectively. Outlines in these two images represent the location of the higher resolution image(s).Malin Space Science Systems (MSSS) and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
Geologic Analysis of a Possible Oasis and Environs in the Valles Marineris, Mars
NASA Astrophysics Data System (ADS)
We used Mars Global Surveyor data from TES, MOC, and MOLA to examine the geologic history of a region of interior layered deposits on the floor of western Candor Chasma in the Valles Marineris, Mars. This site was characterized by Geissler et al. (1993, Icarus 106) as having an unusual reddish color in multispectral images from Viking and Phobos missions. The red color was associated with two 20-km-long depressions and was thought to indicate the presence of crystalline ferric oxides (possibly hematite) in the layered deposits. Assuming that water was required to form the iron oxides via aqueous or hydrothermal alteration, these depressions may mark the site of a local oasis involving ponding or groundwater seepage in the canyon. Thermal inertia and dust index images from TES data of west Candor Chasma indicate that mantling and obscuration of local outcrops is not significant in the region of the possible oasis. To characterize the mineralogy of this area, we use multiple-endmember spectral mixture analysis (MESMA) to deconvolve TES emissivity data relative to laboratory spectra of minerals. This method identifies the minimum number of components (4 to 5) required to model the spectrum of each pixel in the spectral ranges of 307-507 cm-1 and 825-1301 cm-1 (66 TES channels) through iterative comparisons to a 33-component mineral spectral library. This library, adapted from that of ASU, includes pyroxenes, plagioclase feldspars, clays, micas, amphiboles, sulfates, carbonates, olivines, K-spar, gray hematite, and volcanic glass, plus 5 atmospheric endmembers and a blackbody. Although nanophase red hematite is undistinguished at TES wavelengths, mineral abundance maps indicate the presence of other Fe-rich minerals (such as nontronite and Fe-smectite) at this site. Gray hematite, hi-Ca clinopyroxene, Fe-rich olivine, and hi-Ca plagioclase minerals are also observed within layered deposits in the canyon walls and interior, as well as in dark materials at the base of canyon walls. These results suggest that we are mapping sites of alteration and volcanism in west Candor Chasma with the TES data. We are currently performing photoclinometric modeling of coregistered MOC (6 m/pixel) and MOLA (500 m/pixel) data via the method of Soderblom et al. (2002, LPS\\ #1254) to evaluate the orientation and possible origin of this layered deposit.
Gaddis, L. R.; Staid, M. I.; Titus, T. N.
Strike-slip faulting of ridged plains near Valles Marineris, Mars
NASA Technical Reports Server (NTRS)
This paper identifies and documents several well-preserved examples of Martian strike-slip faults and examines their relationships to wrinkle-ridges. The strike-slip faulting predates or overlaps periods of wrinkle-ridge growth southeast of Valles Marineris, and some wrinkle ridges may have nucleated and grown as a result of strike-slip displacements along the echelon fault arrays. Lateral displacements of several km inferred along these arrays may be related to tectonism in Tharsis.
Schultz, Richard A.
Strike-slip faulting of ridged plains near Valles Marineris, Mars
NASA Astrophysics Data System (ADS)
This paper identifies and documents several well-preserved examples of Martian strike-slip faults and examines their relationships to wrinkle-ridges. The strike-slip faulting predates or overlaps periods of wrinkle-ridge growth southeast of Valles Marineris, and some wrinkle ridges may have nucleated and grown as a result of strike-slip displacements along the echelon fault arrays. Lateral displacements of several km inferred along these arrays may be related to tectonism in Tharsis.
Schultz, R. A.
A network of lava tubes as the origin of Labyrinthus Noctis and Valles Marineris on Mars
NASA Astrophysics Data System (ADS)
The role of lava tube networks and lava channels is reassessed as the primordial stage of the volcano-erosional processes that formed the Labyrinthus Noctis-Valles Marineris system instead of a tectonic origin. The combined use of CTX, CRISM, HiRISE imagery, and MOLA profiles has provided valuable insight in the evolution of pit chains into fossae first and then chasmata later due to mass wasting processes caused by the erosional effect of the lava flows that draped Valles Marineris and other outflow channels. Although a quantitative evaluation of eruption rates is difficult even with digital terrain models (DTMs) because of the mixing between new flows and paleoflows, a comparison with Elysium and other Tharsis outflow channels suggests that the availability of lava supply is correlated to their widths. The images of ubiquitous lava flows rather than sporadic light-toned deposits strengthen the role of lava over that of water in the erosional processes that formed Labyrinthus Noctis and carved Valles Marineris like many other outflow channel on Mars. The erosional evolution of the outflow channels shows an increasing trend of age and a decreasing trend of depth from the sources on Tharsis to the mouths at Chryse Planitia. This finding, coupled with the observation of lava flows mantling Chryse Planitia, may have profound implications for the water inventories thought to have filled the lowlands with an ocean.
Leone, Giovanni
Slope stability analysis for Valles Marineris, Mars: a numerical analysis of controlling conditions and failure types
NASA Astrophysics Data System (ADS)
Valles Marineris (VM hereafter) in the equatorial area of Mars exhibits several gravitative failures often involving the whole 6-8 km thickness of the valley walls. The failures have resulted in a series of long-runout landslides up to several hundred cubic kilometres in volume (Quantin et al., 2004), and the formation of sub-circular alcoves perched on the top. Several questions arise as to forces at play in the stability of the walls of VM, the geometrical shape of the alcoves and the shape and long-runout of the landslides (see for example Lucas et al., 2011). In this work, we concentrate on the stability analysis of the walls of VM with two precise questions in mind starting from past studies (Bigot-Cormier and Montgomery, 2006; Neuffer and Schultz, 2006, Schultz, 2002). The first concerns the properties of the materials that give origin to instability. We performed several finite element and discrete element calculations tailored to slope stability analysis based on the genuine shape of the walls of VM taken from the MOLA topographic data. We considered stratified and differently altered/degraded materials to define the range of physical mechanical properties required for failure to occur and to explain the discrete distribution of failures along the VM valley flanks. A second question addressed in this work is the geometrical shape of the sub-circular alcoves. Normally, these shapes are commonplace for slopes made of uniform and isotropic properties, and are also observed in subaqueous environment. We performed calculations taking into consideration the progressive failure in the slope showing the final results in terms of surface failure geometry. Bigot-Cormier, F., Montgomery, D.R. (2007) Valles Marineris landslides: Evidence for a strength limit to Martian relief? Earth and Planetary Science Letters, 260, 1-2, 15, 179-186 Lucas, A., Mangeney, A., M�ge, D., and Bouchut, F., 2011. Influence of the scar geometry on landslide dynamics and deposits: Application to Martian landslides, J. Geophys. Res. - Planets, 116, E10001, DOI: 10.1144/1470-9236/05-042 Quantin, C., Allemand, P., Delacourt, C. (2004) Morphology and geometry of Valles Marineris landslides. Planetary and Space Science, 52, 11, 1011-1022 Neuffer, D.P., R.A. Schultz (2006) Mechanisms of slope failure in Valles Marineris, Mars. Quarterly Journal of Engineering Geology and Hydrogeology, 39,.3, 227-240 Schultz, R.A. (2002) Stability of rock slopes in Valles Marineris, Mars. Geophysical Research Letters, 29, 1932, doi:10.1029/2002GL015728
Crosta, G.; Castellanza, R.; De Blasio, F.; Utili, S.
Stratigraphy and erosional landforms of layered deposits in Valles Marineris, Mars
NASA Astrophysics Data System (ADS)
Satellite imagery is used to identify stratigraphy and erosional landforms of 13 layered deposits in the Valles Marineris region of Mars (occurring, specifically, in Gangis, Juventae, Hebes, Ophir-Candor, Melas, and Capri-Eos Chasmata), based on albedo and erosional styles. Results of stratigraphic correlations show that the stratigraphy of layered deposits in the Hebes, Juventae, and Gangis Chasmata are not well correlated, indicating that at least these chasmata had isolated depositional environments resulting in different stratigraphic sequences. On the other hand, the layered deposits in Ophir-Candor and Melas Chasmata appear to have been connected in each chasma. Some of the layered deposits display complexities which indicate changes in space and time in the dominant source materials.
Komatsu, G.; Geissler, P. E.; Strom, R. G.; Singer, R. B.
A Window into the History of Valles Marineris From Magnetic Field Measurement Analysis
NASA Astrophysics Data System (ADS)
Analysis and interpretation of magnetic field measurements can shed new light into the formation and evolution of Valles Marineris, one of the largest extensional features in the solar system. Valles Marineris is generally only weakly magnetized; the magnetic field is lower than ~20 nT at mapping orbit altitude over the western and central parts However, there are strong fields (~200 nT for low altitudes and ~50 nT at high altitudes) present in the eastern part; Xanthe Terra (to the north) and Nectaris Fossae (to the south) both have strong fields associated with them. Within these magnetized regions, Capri Mensa and the eastern portion of Coprates Chasma appear to be demagnetized. Capri Mensa is a mesa within Capri Chasma that is dated to be Hesperian in age, so the apparent demagnetization (or weaker magnetization) could be related to geologic processes that occurred when this feature formed. In contrast, Eos Mensa is more strongly magnetized than Capri Mensa and is dated to be Noachian. Coprates Chasma is demagnetized, but it is farther west and closer to Tharsis, so it is likely that magmatism-related thermal effects demagnetized this part of the crust. There is an apparent lack of magnetization associated with Shalbatana Vallis. We use inverse local Equivalent Source Dipoles methods to constrain the direction and intensity of magnetization of sources in this area. We also investigate lateral variations of the magnetized layer thickness to test if magnetic material was removed during chasmata formation. Detailed results of magnetic modeling will be presented.
Milbury, C.; Langlais, B.
A non-extensive statistics of the fault-population at the Valles Marineris extensional province, Mars.
NASA Astrophysics Data System (ADS)
A non extensive statistical physics approach is formulated and tested for the fault length distribution in the Valles Marineris extensional province, Mars. The approach is composed of the following parts: (1) the Tsallis entropy Sq (defined as Sq = kB(1 - ? i = 1Wpiq)/(q - 1), (2) maximization of the Tsallis entropy under appropriate constraints, (3) derivation of the cumulative distribution function (CDF) of the fault length population. In testing the model a non-extensive q parameter equal to 1.10 for independent, non-interacting faults and q = 1.75 for linked faults are estimated. The latter supports the conclusion that the fault system in the Valles Marineris extensional province, Mars, is a sub-extensive one and verifies with statistical physics terms the geological criteria introduced by Schultz (2000) to classify the faults in independent and linked, respectively.
Vallianatos, Filippos; Sammonds, Peter
MGS/TES-Odyssey/THEMIS-IR Analysis of Localized Low Albedo Regions in Valles Marineris
NASA Technical Reports Server (NTRS)
We are conducting a systematic analysis of small (approximately 10's of km), localized regions in Valles Marineris that display significant albedo differences relative to their surroundings. This analysis is based on a finding that the locations of the hematite deposits identified by [1] in the interior layered deposits of Valles Marineris typically coincide with regions having a low MGS/TES visible bolometric albedo [1,2]. Until recently, it was difficult to identify the morphology or geologic context of the regions containing the hematite deposits. However, with the recent advent of high-resolution (1/128 /pixel) MOLA grided topography and Mars Odyssey s THEMIS-IR instrument, it has been possible to better understand the morphologic context of TES observations. This analysis combines the use of PDS-released data from the MGS/TES visible bolometer and infrared spectrometer, the Odyssey/THEMIS Infrared imager, and MOLA grided topography. First, the TES infrared bolometer is used to identify regions of interesting albedo variability, and is overlaid on Viking controlled photomosaics for context. THEMIS-IR data, in conjunction with MOLA topography, is then used to: 1) identify the context and morphology of the area; and 2) identify spectrally unique regions at the km scale. In preparation for the latter, all the THEMIS planes are coregistered using an autocorrelation routine, the data are converted to brightness temperature and then each plane is normalized to the brightness temperature of the third plane (1261 cm-1). We then perform a 3-band search for color variations and a Principle Components Analysis (PCA) of the 8 unique bands in the THEMIS-IR dataset. Any variability is then investigated using both THEMIS-IR and TES spectra of the same regions. In both cases, the spectra are ratioed to near-simultaneously acquired spectra of adjacent or "average" regions that do not show this albedo variation, therefore allowing us to identify spectral variability unique to the area of interest. This procedure also allows us to account for calibration problems in THEMIS-IR data, and for any atmospheric effects in both the THEMIS-IR and the TES data.
NoeDobrea, E. Z.; Bell, J. F., III; Wolff, M. J.; Snook, K. J.
Geomorphological characteristics of the interior layered deposits (ILDs) of Melas Chasma, central Valles Marineris, Mars
NASA Astrophysics Data System (ADS)
Stretching almost 600 km in width, Melas Chasma is located in the central part of the Valles Marineris (VM) and is one of the lowest lying of the chasmata. Spectral mapping of this chasma, particularly using MEX's OMEGA instrument, has revealed a strong presence of water-altered minerals (roughly a quarter of all such detected minerals to date in the VM; Chojnacki & Hynek, 2008), in the form of monohydrated and polyhydrated sulphates. Most of the sulphate-bearing rocks in Melas are found in association with thinly layered deposits, occurring in outcrops on the chasma floor. So-called interior layered deposits (ILDs) throughout the Valles Marineris have been the subject of considerable recent research, particularly for their association with these water-altered minerals. Better understanding of the origin and evolution of these ILDs may help to shed more light on the past climatic conditions on Mars and the potentially complicated history of liquid water on the planet. Relatively little geomorphological study of the ILDs of Melas Chasma has been conducted to date with regard to the differing characteristics of the different sulphate-bearing rocks. For instance, areas corresponding to polyhydrated sulphates in the Melas ILDs show considerable different surface textures to those corresponding to monohydrated sulphates. Interestingly, the latter show some surface textures comparable to the wind eroded, yardang bearing surfaces of the Medusae Fossae Formation, located roughly 4000 km to the west on the opposite side of the Tharsis volcanic province. This aim of this work, conducted as part of the European Research Council supported eMars project, is to compile a thorough geomorphological survey of the Melas Chasma ILDs and, through this, construct workable hypotheses regarding their origin and evolution and the context of their water-altered mineral content. Furthermore, to contrast and compare the ILDs of Melas with other large-scale deposits, such as the Medusae Fossae Formation and to collate evidence to support Melas Chasma's potential as a suitable landing site for any future martian rover/lander missions.
Harrison, Samantha; Quantin-Nataf, Cathy
Erosional development of bedrock spur and gully topography in the Valles Marineris, Mars
NASA Technical Reports Server (NTRS)
Gully networks separated by resistant bedrock spurs are a common erosional feature along the escarpments that border the Valles Marineris. The resistant spur topography is best developed where the base of the slope is truncated by linear scarps interpreted as fault scarps. Regional variations in slope morphology imply that spur and gully topography undergoes a systematic progressive degradation through time associated with the erosional destruction of the basal fault scarps. The comparative morphometry of the divide networks indicates that the density of the spur networks and the number of first-order unbranched spurs decreases as the basal slope break becomes more sinuous. Abstraction of the spurs occurs through regolith storage in adjacent gullies at the slope base and the most degraded slope forms are entirely buried in talus. The basal fault scarps apparently control regolith transport by allowing debris to drain from the slope. As these basal scarps decay the slope base becomes increasingly sinuous and the slopes become transport limited. Dry mass-wasting may be the most important process acting on these slopes where a continually lowered base level is required to maintain the spur topography. In contrast to the Martian slopes, range front fault escarpments in the western U.S. show no systematic trend in spur network geometry as they are eroded. These weathering limited slopes are controlled by the more efficient removal of regolith through fluvial processes which rapidly create quasi-equilibrium drainage networks.
Patton, Peter C.
Numerical slope stability simulations of chasma walls in Valles Marineris/Mars using a distinct element method (dem).
NASA Astrophysics Data System (ADS)
NUMERICAL SLOPE STABILITY SIMULATIONS OF CHASMA WALLS IN VALLES MARINERIS/MARS USING A DISTINCT ELEMENT METHOD (DEM). B. Imre (1) (1) German Aerospace Center, Berlin Adlershof, email@example.com The 8- to 10-km depths of Valles Marineris (VM) offer excellent views into the upper Martian crust. Layering, fracturing, lithology, stratigraphy and the content of volatiles have influenced the evolution of the Valles Marineris wallslopes. But these parameters also reflect the development of VM and its wall slopes. The scope of this work is to gain understanding in these parameters by back-simulating the development of wall slopes. For that purpose, the two dimensional Particle Flow Code PFC2D has been chosen (ITASCA, version 2.00-103). PFC2D is a distinct element code for numerical modelling of movements and interactions of assemblies of arbitrarily sized circular particles. Particles may be bonded together to represent a solid material. Movements of particles are unlimited. That is of importance because results of open systems with numerous unknown variables are non-unique and therefore highly path dependent. This DEM allows the simulation of whole development paths of VM walls what makes confirmation of the model more complete (e.g. Oreskes et al., Science 263, 1994). To reduce the number of unknown variables a proper (that means as simple as possible) field-site had to be selected. The northern wall of eastern Candor Chasma has been chosen. This wall is up to 8-km high and represents a significant outcrop of the upper Martian crust. It is quite uncomplex, well-aligned and of simple morphology. Currently the work on the model is at the stage of performing the parameter study. Results will be presented via poster by the EGS-Meeting.
Imre, B.
Sulfates and Other Hydrated Minerals in Ius Chasma, Valles Marineris and Implications for Water Geochemistry
NASA Astrophysics Data System (ADS)
Ius Chasma is a linear trough in western Valles Marineris containing horst and graben structures, multiple landslides, and light-toned floor deposits. Elsewhere is Valles Marineris, sulfate deposits identified by OMEGA and CRISM are restricted to Interior Layered Deposits or nearby autochthonous loose material (Gendrin et al., 2005; Murchie et al., 2007; Murchie et al., in revision). In Ius Chasma, however, sulfates are found in thin floor units in enclosed depressions at the lowest elevations. Kieserite is at the lowest elevation, with polyhydrated sulfate and an unidentified hydrated phase, at higher elevations. Some poorly defined layering is visible on the HiRISE scale, but is not diagnostic. The total exposed thickness of kieserite is 300 m, with a total range in elevation of -4175 to -4475 m. The kieserite deposit is covered in places by pyroxene-bearing dunes. The polyhydrated sulfate outcrops range from -3515 to -4000 m. The unidentified hydrated phase outcrops between -3770 to -4100 m. The polyhydrated sulfate and unidentified hydrated material occur at the same elevations and do not have a clear stratigraphic relationship. Elsewhere in Ius Chasma, the unidentified hydrated material clearly drapes chasma floor units. The unidentified hydrated material is characterized by absorptions near 1.4 and 1.9 ?m, and a narrow doublet at 2.21 and 2.27 ?m. The deep ~1.9 ?m is due to the combination tone of the OH stretch and H2O bend and the ~1.4 ?m absorption is due to the 1st overtone of the OH stretch. Sulfates or other minerals with 2 or more water molecules per unit cell in their structure are necessary to account for deep water and hydroxyl absorptions in many spectra we observe. The doublet doesn't match any known sulfate, phyllosilicate, chloride, hydrated silica library spectra. Possibly a mixture of hydrated phases could explain this phase. The 2.21-2.26 ?m region is generally convex in sulfates, but gypsum (CaSO4 2H2O ) and jarosite group members (MFe3(SO4)2(OH)6) have absorptions there. However, neither sulfates' doublet matches the unidentified spectrum's minima. While there is no phyllosilicate that exactly matches the 2.21 and 2.27 ?m doublet, a combination of smectite clays, such as nontronite and montmorillonite, produces a similar doublet at 2.21 and 2.29 ?m. A third option that is spectrally close but not exact is hydrated silica. Hydrated silica has a wider absorption over 2.21- 2.25 ?m and its hydration bands are shifted to ~1.38 and ~1.91 ?m (Milliken et al., 2008). The location of kieserite in the lowest points of Ius Chasma, with polyhydrated sulfate exclusively found at higher elevations, suggests they were formed by nearly complete evaporation of a closed basin. Polyhydrated evaporites form first and then kieserite as the basin is drawn down. Originally, Ius Chasma may have been less connected to Melas Chasma than it is now (Peulvast and Masson, 1993). These sulfates may be evidence of an environment that supported isolated, evaporating basins. Better discrimination of the sulfate assemblages present and the stratigraphic relationships within the ILD is critical to understanding the environment during and since their formation.
Roach, L. H.; Mustard, J. F.; Murchie, S. L.; Milliken, R. E.; Crowley, J. K.; Bishop, J. L.; Arvidson, R. E.
Reassessing rock mass properties and slope instability triggering conditions in Valles Marineris, Mars
NASA Astrophysics Data System (ADS)
The rock walls of the Valles Marineris valleys (VM) in the equatorial area of Mars exhibit several gravitational failures which resulted in a series of large landslides up to several hundred cubic kilometers in volume. Questions arise as to forces at play and rock strength in the stability of the walls of VM. In this work we address the stability analysis of the walls of VM by considering the strength of the materials of the walls and the causes of landslides. Using finite element calculations and the limit analysis upper bound method, we explore the range of cohesion and friction angle values associated with realistic failure geometries, and compare predictions with the more classical Culmann's translational failure model. Our analysis is based both on synthetic, simplified slope profiles, and on the real shape of the walls of VM taken from the MOLA topographic data. Validation of the calibrated cohesion and friction angle values is performed by comparing the computed unstable cross sectional areas with the observed pre- and post-failure profiles, the estimated failure surface geometry and ridge crest retreat. This offers a link between rock mass properties, slope geometry and volume of the observed failure, represented in dimensionless charts. The role of groundwater flow and seismic action on the decrease of slope stability is also estimated. Pseudo-static seismic analyses provide another set of dimensionless charts and show that low seismicity events induced by meteoroid impacts, consistent with the size of craters, could be a cause for some of the observed landslides, if poor rock properties for VM are assumed. Analyses suggest that rock mass properties are more similar to their earth equivalents with respect to what has been previously supposed.
Crosta, Giovanni Battista; Utili, Stefano; De Blasio, Fabio Vittorio; Castellanza, Riccardo
The Mars Millenium Project: Canyons on Earth and Mars (title provided or enhanced by cataloger)
NSDL National Science Digital Library
This resource is part of a collection that compares the geology and weather of Earth and Mars. This particular page contrasts Earth's Grand Canyon with Valles Marineris on Mars. A beginner version is also available.
NSDL National Science Digital Library
This image of Mars includes a brief description and a zoom-in feature to view the image at closer range. The center of the scene shows the entire Valles Marineris canyon system. An audio option allows one to listen to the caption. A glossary is also provided.
Multi-sulfate and Iron Oxide Assemblages Within the Valles Marineris Interior Layered Deposits
NASA Astrophysics Data System (ADS)
MarsExpress OMEGA showed that many of the Interior Layered Deposits (ILDs) in Valles Marineris contain sulfates and proposed the sulfates as indicators of past aqueous activity in the Theiikian period (Gendrin etal, 2005; Bibring etal, 2005; Bibring etal, 2006). Better discrimination of the sulfate assemblages present and the stratigraphic relationships within the ILD is critical to understanding the environment during and since their formation. We present a method for identifying classes of sulfates present in a multi-sulfate exposure with MRO CRISM data. Multiple mineral phases can be defined by diagnostic absorptions in spatially distinct wavelength regions. Combinations of minerals phases is more complicated but can be resolved by identifying superposed absorption feature and assuming linear mixing. We focus on four wavelength regions: (a) 2.4 and 2.1 ?m, (b) 2.2 ?m, (c) 1.9 and 1.4 ?m, and (d) 0.9 ?m, in a methodical classification of possible sulfate types present. While there is some overlap in the wavelength regions, absorptions are sufficiently separate to be recognizable. Additionally, care must be taken to select geologically feasible minerals assemblages. (a) Hydrated sulfates have an absorption near 2.4 um due to probable interactions between the H2O and SO3 molecules (Cloutis etal, 2006). Monohydrated sulfates have a distinct absorption near 2.1 ?m due to combinations of H2O stretch and rotation vibrations of the single water molecule in a sulfate structure (Cloutis etal, 2006) which shifts with cation. Thus minerals such as kieserite (MgSO4 H2O) and szomolnokite (Fe2+SO4 H2O) can be distinguished in CRISM data. (b) The 2.21-2.26 ?m region is generally convex in sulfates, but gypsum (CaSO4 2H2O ) and jarosite group members (MFe3(SO4)2(OH)6) have absorptions there. The minimum within this wavelength region depends on the mineral present. (c)The ~1.9 ?m is due to the OH stretch and H2O bend combination tone and the ~1.4 ?m absorption is due to the 1st overtone of the OH stretch. Sulfates or other minerals with 2+ structural H2O are necessary for the deep water and hydroxyl absorptions in many spectra we observe. (d) Ferric and ferrous minerals have wide absorptions near 0.9 ?m due to charge transfer and electronic transition processes. Presence of a ~0.9 ?m absorption could indicate either a iron-bearing sulfate, a co-existing iron oxide, or both. Ferrous minerals such as olivine and pyroxene can be excluded by the position and width of their 1.0 and 2.0 ?m absorptions. An eastern Candor Chasma ILD has a multiple sulfate assemblage including mono- and polyhydrated sulfates with a variety of cations that are uniform within a specific layer. The sulfates are intimately or spatially mixed on the meter scale. The relative strengths of mono and polyhydrated sulfate absorptions vary with layering, indicating a degree of independence. Mineralogy and geomorphology is consistent with an evaporite sequence or groundwater alteration of ash or aeolian deposits. In addition, iron oxide spectral features overprint the sulfate spectra in some places and cut across layering in others, suggesting the iron-bearing phase may be either separate from the sulfate occurrences or spatially redistributed. Future work will better characterize the assemblage there and in other chasmata ILDs.
Roach, L. H.; Mustard, J. F.; Murchie, S. L.; Bishop, J. L.; Arvidson, R. E.; Morris, R. V.; Milliken, R. E.; Lichtenberg, K. A.
Composition and structures of the subsurface in the vicinity of Valles Marineris as revealed by central uplifts of impact craters
NASA Astrophysics Data System (ADS)
Despite recent efforts from space exploration to sound the martian subsurface with RADAR, the structure of the martian subsurface is still unknown. Major geologic contacts or discontinuities inside the martian crust have not been revealed. Another way to analyze the subsurface is to study rocks that have been exhumed from depth by impact processes. The last martian mission, MRO (Mars Reconnaissance Orbiter), put forth a great deal of effort in targeting the central peaks of impact craters with both of its high resolution instruments: CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) and HiRISE (High Resolution Science Experiment). We analyzed the composition with CRISM and the physical characteristics on HiRISE of the rocks exhumed from depth from 31 impact craters in the vicinity of Valles Marineris. Our analyses revealed the presence at depth of two kinds of material: massive light-toned rocks and intact layers. Exhumed light-toned massive rocks are enriched in low calcium pyroxenes and olivine. Hydrated phases such as smectites and putative serpentine are present and may provide evidence of hydrothermal processes. Some of the rocks may represent portions of the volatile-rich, pre-Noachian martian primitive crust. In the second class of central peaks, exhumed layers are deformed, folded, and fractured. Visible-near infrared (VNIR) spectra suggest that they are composed of a mixture of olivine and high calcium pyroxene associated with hydrated phases. These layers may represent a Noachian volcanic accumulation of up to 18 km due to Tharsis activity. The spatial distribution, as well as the in-depth distribution between the two groups of rocks exhumed, are not random and reveal a major geologic discontinuity below the Tharsis lava plateau. The contact may be vertical over several kilometers depth suggesting the pre-existence of a steep basin (early giant impact or subsidence basin) or sagduction processes.
Quantin, Cathy; Flahaut, Jessica; Clenet, Harold; Allemand, Pascal; Thomas, Pierre
One million cubic kilometers of fossil ice in Valles Marineris: relicts of a 3.5 Gy old glacial landsystem along the Martian equator
NASA Astrophysics Data System (ADS)
Self-consistent landform assemblages suggest that Valles Marineris, the giant valley system that stretches along the Martian equator, was entirely glaciated during Late Noachian to Early Hesperian times and still contains huge volumes of fossil ice. Some of these glacial landforms assemblages are illustrated here. A morphological boundary separating an upper spur-and-gully morphology from a smooth basal escarpment has been spectacularly preserved along valley walls throughout Valles Marineris. The boundary winds around topographic obstacles and displays long-wavelength variations in elevation. It is associated with lateral benches, hanging valleys and truncated spurs. Comparisons with terrestrial analogues indicate that it is most reasonably interpreted as a glacial trimline. Chasma floors are covered by various kinds of terrains, including hummocky terrains, platy terrains, lateral banks, layered benches and a draping mantle. Landforms in these terrains and their spatial relationship with the interpreted trimline suggest that they correspond to various disintegration stages of an ancient glacial fill, currently protected by a superficial cover of ablation till. Altogether, these landforms and terrains compose a full glacial landsystem with wet-based glaciers that were able to flow and slide over their beds. It was most probably fed by ice accumulating at low elevations directly from the atmosphere onto valley floors and walls, with only minor contributions from tributary glaciers flowing down from higher elevations. Similar fossil glacial landsystems dating back from the early Martian history are to be expected in many other low-latitude troughs such as chasmata, chaos, valleys, impact craters and other basins.
Bourgeois, O.; Gourronc, M.; M�ge, D.; Pochat, S.; Bultel, B.; Mass�, M.; Le Deit, L.; Le Mou�lic, S.; Mercier, D.
One million cubic kilometers of fossil ice in Valles Marineris: Relicts of a 3.5 Gy old glacial landsystem along the Martian equator
NASA Astrophysics Data System (ADS)
Self-consistent landform assemblages suggest that Valles Marineris, the giant valley system that stretches along the Martian equator, was entirely glaciated during Late Noachian to Early Hesperian times and still contains huge volumes of fossil ice. Some of these glacial landform assemblages are illustrated here, with representative examples selected in three regions: Ius Chasma, Central Candor Chasma and the junction between Coprates Chasma and Capri Chasma. A morphological boundary separating an upper spur-and-gully morphology from a smooth basal escarpment has been spectacularly preserved along valley walls throughout Valles Marineris. The boundary winds around topographic obstacles and displays long-wavelength variations in elevation. It is associated with lateral benches, hanging valleys and truncated spurs. Comparisons with terrestrial analogs indicate that it is most reasonably interpreted as a glacial trimline. Chasma floors are covered by various kinds of terrains, including hummocky terrains, platy terrains, lateral banks, layered benches and a draping mantle. Landforms in these terrains and their spatial relationship with the interpreted trimline suggest that they correspond to various disintegration stages of an ancient glacial fill, currently protected by a superficial cover of ablation till. Altogether, these landforms and terrains compose a full glacial landsystem with wet-based glaciers that were able to flow and slide over their beds. It was most probably fed by ice accumulating at low elevations directly from the atmosphere onto valley floors and walls, with only minor contributions from tributary glaciers flowing down from higher elevations. Similar fossil glacial landsystems dating back from the early Martian history are to be expected in many other low-latitude troughs such as chasmata, chaos, valleys, impact craters and other basins.
Gourronc, Marine; Bourgeois, Olivier; M�ge, Daniel; Pochat, St�phane; Bultel, Benjamin; Mass�, Marion; Le Deit, Laetitia; Le Mou�lic, St�phane; Mercier, Denis
Identification of ferric oxides in East Candor Chasma (Valles Marineris, Mars) with several methods of analysis of OMEGA/Mars Express data - geomorphological context
NASA Astrophysics Data System (ADS)
The mineralogical composition of the Martian surface is constrained by analysing the data of the visible and near infrared imaging spectrometer OMEGA onboard Mars Express. We use three independent methods (Spectral Angle Mapper (Kruse et al., 1993), modified Linear Unmixing Model (Combe et al., 2006) and Modified Gaussian Model (Sunshine et al., 1990)) and we detect ferric oxides in East Candor Chasma. Ferric signatures had previously been reported in Valles Marineris, Margaritifer Terra and Terra Meridiani (Gendrin et al., 2005). Ferric oxides appear to be distributed in isolated areas in East Candor Chasma. MOLA altimetry indicates that the oxides are preferentially located in topographic lows (Christensen et al., 2001; Gendrin et al., 2005). THEMIS and MOC images show that the signatures are systematically correlated with superficial deposits of low albedo, at the foot or on Interior Layered Deposits (ILD's). Some sulfates have been identified on some of the ILD's of the region (Gendrin et al., 2005). The spatial distribution of ferric oxides in regard with ILD suggests that they are genetically linked. A remobilization of ferric oxides from the ILD's could explain their accumulation around the ILD's.
Le Deit, L.; Gendrin, A.; Le Mouelic, S.; Combe, J.-Ph.; Bourgeois, O.; Mege, D.; Sotin, C.; Hauber, E.; Bibring, J.-P.
Coordinating CRISM Observations of Sulfates near Valles Marineris with the Subsurface Bright Salty Soils Exposed in Gusev Crater via Lab Experiments
NASA Astrophysics Data System (ADS)
CRISM has identified unique spectral signatures in inverted channels near Juventae Chasma and other chasmata in the greater Valles Marineris region [1] that are composed of light-toned layered sediments interpreted to be fluvial in origin [2]. These include a weak, broad feature near 1.45 ?m, a strong, broad band centered near 1.94 ?m, a sharp band at 2.23 ?m, and a shoulder or band near 2.4 ?m [3]. This signature is not characteristic of any single mineral; however, it is consistent with partially dehydrated ferricopiapite [original formula of Fe0.33Fe2(SO4)3(OH)�10H2O]. Our lab experiments show that incrementally heating this hydrated ferric sulfate to 300 �C at 1 atm changes the color, XRD pattern, and spectral properties of this mineral. The resulting spectral signature of our ferricopiapite heated to 300 �C matches well with the CRISM spectra of the material observed in inverted channels near Juventae Chasma. This result is of particular interest as ferricopiapite is the mineral thought to be present in the bright salty soils exposed by the Spirit rover at Paso Robles and other sites in combined analyses of the Pancam, M�ssbauer, Mini-TES and APXS data [4, 5, 6]. Other sulfate minerals possibly present in lower abundance include butlerite, (para)coquimbite, fibroferrite, and metahohmanite [4]. Continued lab experiments are underway to characterize the spectral properties of partially dehydrated ferricopiapite and other OH and H2O-bearing sulfates. Opaline silica is also found in these inverted channels near Juventae Chasma [1] and both monohydrated (szomolnokite and kieserite) and polyhydrated (e.g. ferricopiapite) sulfates are observed in the bright mounds inside the chasma [7]. Identification of partially dehydrated ferricopiapite in these inverted channels provides a link between the aqueous processes occurring in the plains outside the chasma and those processes that formed the light-toned layered mounds inside the chasma. Sulfate deposits in the greater Valles Marineris region are consistent with lithification and diagenetic modification of eolian sediments by evaporation of near-surface groundwater [8], processes similar to those inferred at Meridiani [9,10]. [1] Milliken R. E. et al. (2008) Geology, in press. [2] Weitz C. M. et al. (2008) GRL, doi:10.1029/2008GL035317, in press. [3] Bishop J. L. et al. (2008) JGR, to be submitted. [4] Lane M. D. et al. (2008) Am. Miner., 93, 728-739. [5] Parente M. et al. (2008) Icarus, in review. [6] Johnson J. R. et al. (2007) GRL, 34, L13202, doi:10.1029/2007GL029894. [7] Bishop J. L. et al. (2008) LPSC, abs. 2334. [8] Murchie S. L. et al. (2008) Nature, in revision. [9] Squyres S. W. et al. (2006) Science, 313, 1403- 1407. [10] Andrews-Hanna J. C. et al. (2007) Nature, 446, 163-166 doi:10.1038/nature05594.
Bishop, J. L.; Parente, M.; Lane, M.; Dyar, M. D.; Bish, D. L.; Sarrazin, P.; King, P.; McKeown, N.; Milliken, R.; Roach, L.; Swayze, G.; Weitz, C.; Murchie, S.; Mustard, J. F.
Surface Composition Differences in Martian Canyon
NASA Technical Reports Server (NTRS)
(Released 29 May 2002) Color differences in this daytime infrared image taken by the camera on NASA's Mars Odyssey spacecraft represent differences in the mineral composition of the rocks, sediments and dust on the surface. The image shows a portion of a canyon named Candor Chasma within the great Valles Marineris system of canyons, at approximately 5 degrees south latitude, 285 degrees east (75 degrees west) longitude. The area shown is approximately 30 by 175 kilometers (19 by 110 miles). The image combines exposures taken by Odyssey's thermal emission imaging system at three different wavelengths of infrared light: 6.3 microns, 7.4 microns and 8.7 microns.
A Marineris Vallis sample site
NASA Technical Reports Server (NTRS)
Consideration is given to the choice of a Marineris Vallis canyon site in that it may offer the widest possible variety of martian units with a minimum amount of roving. Researchers support this in the classical comparison of Marineris Vallis with the Grand Canyon of the U.S.A. It is well-known to American geologists that most of the geological units in the U.S. may be found here in one section. Might not the Martian canyon offer a similar selection but only more so in view of its much greater size. A system whereby this sampling may be effected is proposed based on a combination of a skip with a wire-line core-barrel method. The final design will depend more on the completeness of the core to be taken as the entire section is that long that the weight of the core of the whole section may well be prohibitive for return to Earth unless several returns are envisaged. The wire-line is operated from a static head-gear in much the same way as an oil well implying a lander not needing mobility of any kind - a destinct advantage.
Bridger, C. S.
Martian canyons and African rifts: Structural comparisons and implications
NASA Technical Reports Server (NTRS)
The resistant parts of the canyon walls of the Martian rift complex Valled Marineris were used to infer an earlier, less eroded reconstruction of the major roughs. The individual canyons were then compared with individual rifts of East Africa. When measured in units of planetary radius, Martian canyons show a distribution of lengths nearly identical to those in Africa, both for individual rifts and for compound rift systems. A common mechanism which scales with planetary radius is suggested. Martian canyons are significantly wider than African rifts. The overall pattern of the rift systems of Africa and Mars are quite different in that the African systems are composed of numerous small faults with highly variable trend. On Mars the trends are less variable; individual scarps are straighter for longer than on earth. This is probably due to the difference in tectonic histories of the two planets: the complex history of the earth and the resulting complicated basement structures influence the development of new rifts. The basement and lithosphere of Mars are inferred to be simple, reflecting a relatively inactive tectonic history prior to the formation of the canyonlands.
Frey, H. V.
Martian canyons and African rifts - Structural comparisons and implications
NASA Technical Reports Server (NTRS)
The resistant parts of the canyon walls of the Martian rift complex Valles Marineris have been used to infer an earlier, less eroded reconstruction of the major troughs. The individual canyons are compared with individual rifts of East Africa. When measured in units of planetary radius, Martian canyons show a distribution of lengths nearly identical to those in Africa, both for individual rifts and for compound rift systems. A common mechanism which scales with planetary radius is suggested. Martian canyons are significantly wider than African rifts. This is consistent with the longstanding idea that rift width is related to crustal thickness: most evidence favors a crust on Mars at least 50% thicker than that of Africa. The overall patterns of the rift systems of Africa and Mars are quite different in that the African systems are composed of numerous small faults with highly variable trend. On Mars the trends are less variable; individual scraps are straighter for longer than on earth. The basement and lithosphere of Mars are inferred to be simple, reflecting a relatively inactive tectonic history prior to the formation of the canyonlands.
Frey, H.
Surface Composition Differences in Martian Canyon
NASA Technical Reports Server (NTRS)
Color differences in this daytime infrared image taken by the camera on NASA's Mars Odyssey spacecraft represent differences in the mineral composition of the rocks, sediments and dust on the surface.The image shows a portion of a canyon named Candor Chasma within the great Valles Marineris system of canyons, at approximately 5 degrees south latitude, 285 degrees east (75 degrees west) longitude. The area shown is approximately 30 by 175 kilometers (19 by 110 miles).The image combines exposures taken by Odyssey's thermal emission imaging system at three different wavelengths of infrared light: 6.3 microns, 7.4 microns and 8.7 microns.NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The thermal emission imaging system was provided by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. Lockheed Martin Astronautics, Denver, is the prime contractor for the project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and JPL. JPL is a division of the California Institute of Technology in Pasadena.
Complex Floor Deposits Within Western Ganges Chasma, Valles Marineris
NASA Technical Reports Server (NTRS)
On October 26, 1997, MOC took this image of Mars 10 minutes after its closest approach to the planet (1:46 AM PST). The view shows the floor of western Ganges Chasma (7.8oS 51.8oW), covering an area 2.6 km (1.6 miles) wide by 45.4 km (28.2 miles) long at a resolution of 5 by 7.4 meters (16.4 by 24.3 feet) per picture element. The local time on Mars when the picture was taken was 4:35 PM.The center image (available at higher resolution as PIA01028) shows the northern portion of the area inscribed in the left image. The right image (PIA01029) shows the southern portion.Launched on November 7, 1996, Mars Global Surveyor entered Mars orbit on Thursday, September 11, 1997. The original mission plan called for using friction with the planet's atmosphere to reduce the orbital energy, leading to a two-year mapping mission from close, circular orbit (beginning in March 1998). Owing to difficulties with one of the two solar panels, aerobraking was suspended in mid-October and resumed in November 8. Many of the original objectives of the mission, and in particular those of the camera, are likely to be accomplished as the mission progresses.Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
NASA Technical Reports Server (NTRS)
(Released 7 June 2002) The Science This ancient sinuous river channel, located near 30o N, 299o W (61o E), was likely carved by water early in Mars history. Auqakuh Valles cuts through a remarkable series of rock layers that were deposited and then subsequently eroded. This change from conditions favoring deposition to those favoring erosion indicates that the environment of this region has changed significantly over time. In addition, the different rock layers seen in this image vary in hardness, with some being relatively soft and easily eroded, whereas others are harder and resistant. These differences imply that these layers vary in their composition, physical properties, and/or degree of cementation, and again suggest that major changes have occurred during the history of this region. Similar differences occur throughout the southwest U.S., where hard rock layers, such as the limestones and sandstones in the Grand Canyon, form resistant cliffs, whereas softer mudstones are easily eroded to form broad slopes. The Martian layers, such as the smooth, dark-toned mesas visible in numerous places to the right (east) of the channel, were once continuous across the region. As these layers have eroded, they have produced a wide array of textures, from smooth surfaces, to knobby terrains, to the unusual lobate patterns seen in the upper right of the image. The most recent activity in the region appears to be the formation of mega-ripples by the wind. These ripples, spaced approximately 75 m apart, form perpendicular to the wind direction, and can be seen following the pattern of the channel floor as it curves through this region. This pattern shows that even this relatively small channel, which varies in width from about 500 to 750 m throughout this image, acts to funnel the wind down the channel. The Story Auqakuh Vallis, an ancient river channel that winds its way down the center of this image, is the 'fossil' remains of an earlier, probably more watery time in Martian history. Now, you might think that Auqakuh has something to do with Aqua, the Latin word for water. Instead, Auqakuh is the word for Mars in the Quechuan language of the Incan Empire that once stretched across vast portions of South America. This Inca-honoring river channel cuts through a remarkable series of rock layers that expose a history of climate change in the region. The coarse, rugged, and wildly textured terrain was created as rock layers were first deposited, then eroded over time. Some of the rock layers are soft and easily eroded, while others are clearly harder and more resistant. From these differences, geologists can tell that the layers are made up of different materials, have different physical characteristics, and are either loosely or strongly cemented together. That suggests major environmental changes over time as well, since different kinds of rocks form under different conditions. Similar differences in rock layers occur throughout the Southwest of the United States. The next time you're visiting the Grand Canyon or hiking in similar terrain, notice where hard rock layers, such as limestones and sandstones, form resistant cliffs, whereas softer mudstones are easily eroded to form broad slopes along the canyon. Just in case the river channel in the above image looks more like a raised vein rather than a hollowed out channel, try looking at the half-circle depression on the left-hand side of the image, about a third of the way up. The bright features on the upper half streak down toward the bottom of the bowl. Once you focus on this for a while, your brain figures out that the channel must be depressed as well. Now that you can see that the channel cuts into the surface, click on the image for a closer look at the bottom of the channel. Mega-ripples about 82 yards apart line the channel floor as it curves through the region. This pattern shows that even this relatively small channel, which varies from about one-third to a half of a mile in width, funnels the wind down its curving length, creating per
NASA Technical Reports Server (NTRS)[figure removed for brevity, see original site] Released 18 July 2003Tader Valles, an ancient name for the present Segura River in Spain, is a set of small channels at mid-southern latitudes that is filled by smooth material with rounded margins. It is possible that this material is snow covered by a mantle of dust or dirt.Image information: VIS instrument. Latitude -49.4, Longitude 208.6 East (151.4 West). 19 meter/pixel resolution.Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.
Spatial and Temporal Relationships of Landslides in Valles Marineris, Mars: Constraints on Their Triggering Mechanisms
NASA Astrophysics Data System (ADS)
Two distinguishable martian landslide types, thick-skinned and thin-skinned, are characterized through systematic mapping of surface morphology, spectral data, and runout ratio in order to constrain landslide trigger and emplacement mechanisms.
Watkins, J.; Yin, A.
This historical film footage, originally produced in the early 1950s as part of a series by WOI-TV, shows atomic research at Ames Laboratory. The work was conducted in a special area of the Laboratory known as the "Hot Canyon."
This historical film footage, originally produced in the early 1950s as part of a series by WOI-TV, shows atomic research at Ames Laboratory. The work was conducted in a special area of the Laboratory known as the "Hot Canyon."
This historical film footage, originally produced in the early 1950s as part of a series by WOI-TV, shows atomic research at Ames Laboratory. The work was conducted in a special area of the Laboratory known as the "Hot Canyon."
NASA Technical Reports Server (NTRS)
This site is located at 16 deg N, 177 deg W on the flood plains of Marte Valles, which is perhaps the youngest channel system on Mars. The young age of this channel warrants investigation because of climatic implications for fluvial activities in recent geologic time. The paucity of craters makes this an excellent site in terms of safety requirements. Some of the objectives stated previously for the Maja Valles region would also apply to this site (grab bag of rock types, etc.).
Rice, Jim W.
National Technical Information Service (NTIS)
This site is located at 16 deg N, 177 deg W on the flood plains of Marte Valles, which is perhaps the youngest channel system on Mars. The young age of this channel warrants investigation because of climatic implications for fluvial activities in recent g...
J. W. Rice
NASA Technical Reports Server (NTRS)10 April 2004 Marte Valles is an outflow channel system that straddles 180oW longitude between the region south of Cerberus and far northwestern Amazonis. The floor of the Marte valleys have enigmatic platy flow features that some argue are formed by lava, others suggest they are remnants of mud flows. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an island created in the middle of the main Marte Valles channel as fluid---whether lava or mud---flowed past two older meteor impact craters. The craters are located near 21.5oN, 175.3oW. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.
Discontinuities in the shallow Martian crust at Lunae, Syria, and Sinai Plana
Detailed photoclinometric profiles across 125 erosional features and 141 grabens in the western equatorial region of Mars indicate the presence of three discontinuities within the shallow crust. Pits, troughs, and wall valleys (tributary canyons) within Noctis Layrinthus and Valles Marineris and escarpments within the fretted terrain of Sacra Fossae and Kasei Valles show distinct erosional base levels at depths of
Philip A. Davis; Matthew P. Golombek
Hydrated Minerals Associated with Interior Layered Deposits Near the Southern Wall of Melas Chasma, Valles Marineris, Mars
NASA Astrophysics Data System (ADS)
We identified a sequence of interior layered deposits over a portion of the southern wall and nearby floor of Melas Chasma using MRO CRISM data. Polyhydrated sulfates, monohydrated sulfates, and jarosite were identified in the ILDS.
Liu, Y.; Arvidson, R. E.; Li, R.; Wang, W.
Hydrated Minerals Associated with Interior Layered Deposits near the Southern Wall of Melas Chasma, Valles Marineris, Mars
NASA Astrophysics Data System (ADS)
MRO CRISM full resolution targeted mode hyperspectral image data (FRT00013F5B) centered at 10.22 S, 74.46 W over a portion of the southern wall and nearby floor of Melas Chasma show a sequence of interior layered deposits with distinct mineral associations. This study area is located to the southeast of the region analyzed by Roach et al. (2010, Icarus, 206, 253-268). The topography associated the deposits was examined using standard product elevation maps derived from HRSC data and used along with superposition relationships to help define the stratigraphic order. The bottom of the exposed section consists of repeating interbedded monohydrated and polyhydrated sulfate-bearing layers. Jarosite-bearing layers are found above this sequence, along with layers that have a 2.3 micrometer absorption tentatively identified as due to Fe/Mg smectite-bearing material. The top of the section is dominated by an areally extensive polyhydrated sulfate-bearing unit. Detailed results will be presented along with an analysis of the changing aqueous conditions inferred from the mineral associations.
Liu, Y.; Arvidson, R. E.
Central Valles Marineris: uncontrolled Mars Global Surveyor (MGS) Mars Orbital Camera (MOC) digital context photomosaic (250 megapixel resolution)
These images were processed from a raw format using Integrated Software for Images and Spectrometers (ISIS) to perform radiometric corrections and projection. All the images were projected in sinusoidal using a center longitude of 70 degrees. There are two versions of the mosaic, one unfiltered (vallesmos.tif), and one produced with all images processed through a box filter with an averaged pixel tone of 7.699 (vallesmosflt.tif). Both mosaics are ArcView-ArcInfo ready in TIF format with associated world files (*.tfw).
Noreen, Eric
NSDL National Science Digital Library
The first site from PBS.org, called Lost in the Canyon (1), offers an excellent online learning experience. Visitors learn about John Wesley Powell's expedition down the Colorado River, covered in transcripts from the companion television show and a timeline of Powell's life. Other features include an interactive lesson on running rapids and a look at the unique geologic history of the area. Next, from StudyWorks! Online comes the lesson entitled Sleuthing at the Grand Canyon: Using Rocks to Tell Us About the Past (2). Through basic descriptions, photographs, and illustrations, students learn how rocks form, how scientists use them to find out about past environments, and much more. The third site is provided by the Grand Canyon Monitoring and Research Center called The Grand Canyon Monitoring and Research Center Fiscal Year 2000-2004 Monitoring and Research Strategic Plan (3). Readers will discover the mission of the center, history of monitoring in the area, management strategies, research activities, and much more. Next is a site offered by Richard S. Naylor of Northeastern University's Department of Geology called Unconformities in the Grand Canyon (4). Visitors will find descriptions and photographs of several sites in the Grand Canyon that exhibit geologic unconformities or surfaces that represent a break in the geologic record. The fifth site is maintained by kaibob.org called the Geology of Grand Canyon (5). This site contains basic information on how the canyon was formed, where all the rock came from, why it looks like it does, and when it all happened. From NASA's Visible Earth Web site comes the 3-D View of Grand Canyon (6) page. The canyon can be viewed in a low or high resolution JPEG format, which shows the surrounding area, part of the Colorado river, and the canyon itself in dynamic colors. Part of Northern Arizona University, the seventh site is entitled Canyons, Culture, and Environmental Change: An Introduction to the Land Use History of the Colorado Plateau (7). The site provides an introduction to the environmental history of the Colorado Plateau and summarizes a vast body of research from multiple disciplines in an easily accessible format. The last site from NOAA's Colorado River Basin Forecast Center is the River Forecasts and Data page (8). Provided are data from various sites along the river that offer a wide range of relevant information such as simulated hydrographs.
Brieske, Joel A.
Hells Canyon Environmental Investigation.
National Technical Information Service (NTIS)
The results of an environmental investigation of the nonpower impacts on the Hells Canyon Complex resulting from water budget participation are presented. The water budget plan would increase flows in the Columbia and Snake Rivers between April 15 and Jun...
Ancient Observatories: Chaco Canyon
NSDL National Science Digital Library
This Exploratorium site offers an online "tour" of the sites and structures within Chaco Canyon, thought to have once been an ancient solar observatory. The different pages on the tour detail several of the most famous sites where significant solar alignments occur each year. A section called "seasons and solstices" provides further information.
Black Canyon Outreach Education
NSDL National Science Digital Library
This portal features links to K-12 outreach education units on the Black Canyon of the Gunnison National Park and Curecanti National Recreation Area. They focus on topics such as trees, habitats, fossils, animal adaptations, seasons, weather, the water cycle, mapping and geology. There are also downloadable activities for sutdents to perform either before or after their visits to the area.
The Nearshore Canyon Experiment
NASA Astrophysics Data System (ADS)
Observations collected in Fall 2003 during the Nearshore Canyon Experiment (NCEX) will be used to test hypotheses about the effect of complex continental-shelf bathymetry on surface gravity waves and on wave-driven circulation. Refraction, diffraction, reflection, scattering, and trapping by abrupt shelf bathymetry can result in dramatic alongshore variations in wave height and direction. Onshore of the irregular bathymetry, alongcoast changes in breaking waves can force complicated circulation, including alongshore flows that reverse direction across the surf zone and along the shoreline, and strong offshore-directed rip currents that may be an important mechanism for transport of water, sediment, and pollution between the surf zone and inner shelf. Observations for NCEX will be obtained along the southern California coast near two steep submarine canyons (separated alongshore by a few km) that cross the shelf from about 300-m water depth to just seaward of the surfzone near Black's Beach (famous for large waves) and La Jolla Shores (well known as a calm area with small waves). Frequency-directional spectra of incident waves estimated from observations offshore of the canyons will be used to initialize models that predict the effect of the canyons on infragravity waves, swell, sea, and wave-driven circulation. Model predictions will be tested with observations from alongshore arrays deployed near, between, and onshore (including the surf and swash zones) of the canyons. Arrays also will be deployed to investigate wave reflection and scattering from the steep canyon walls, and cross-shore changes in surf and swash zone circulation. Additional instrumentation will be used to study alongcoast changes in wave breaking and set-up, details of surface currents in the surf and swash, and breaking-induced turbulence and dissipation. The NCEX instrument arrays will be designed in collaboration with modelers, and near-real time data will be used to initialize and test model predictions. In addition, model forecasts will be used to guide placement of movable sensors, allowing predictions of nearshore waves and currents to be tested during the observational period. NCEX~team~members~are~listed~on http://science.whoi.edu/PVLAB/NCEX/ncex.html. Funding for NCEX is provided by the US Office of Naval Research and the National Science Foundation.
Elgar, S.
Sedimentary facies in submarine canyons
NASA Astrophysics Data System (ADS)
Submarine canyons are the major conduits by which sediment, pollutants and nutrients are transported from the continental shelf out into the deep sea. The sedimentary facies within these canyons are remarkably poorly understood because it has proven difficult to accurately sample these heterogeneous and bathymetrically complex environments using traditional ship-based coring techniques. This study exploits a suite of over 100 precisely located vibracores collected using remotely operated vehicles in ten canyons along the northern Californian margin, enabling better understanding of the facies that exist within submarine canyons, their distribution, and the processes responsible for their formation. The dataset reveals three major facies types within the submarine canyons: extremely poorly sorted, coarse-grained sands and gravels with complex and indistinct internal grading patterns and abundant floating clasts; classical normally graded thin bedded turbidites; and a variety of fine-grained muddy deposits. Not all facies are observed within individual canyons, in particular coarse-grained deposits occur exclusively in canyons where the canyon head cuts up to the modern day beach, whereas finer grained deposits have a more complex distribution that relates to processes of sediment redistribution on the shelf. Pairs of cores collected within 30 meters elevation of one another reveal that the coarse-grained chaotic deposits are restricted to the basal canyon floor, with finer-grained deposits at higher elevations on the canyon walls. The remarkable heterogeneity of the facies within these sediment cores illustrate that distinctive processes operate locally within the canyon. In the authors' experience the canyon floor facies represent an unusual facies rarely observed in ancient outcrops, which potentially results from the poor preservation of ancient coarse-grained canyon deposits in the geological record.
Sumner, E.; Paull, C. K.; Gwiazda, R.; Anderson, K.; Lundsten, E. M.; McGann, M.
NSDL National Science Digital Library
This lesson plan is part of the DiscoverySchool.com lesson plan library for grades 6-8. It focuses on the ecology of the Grand Canyon area. Students act as scientists investigating the damming of the Colorado River by the Glen Canyon dam and experimental flooding that took place in 1996. They then write a proposal as to whether or not more experimental flooding should be done on the area considering the ecological effects. It includes objectives, materials, procedures, discussion questions, evaluation ideas, extensions, suggested readings, and vocabulary. There are videos available to order which complement this lesson, an audio-enhanced vocabulary list, and links to teaching tools for making custom quizzes, worksheets, puzzles and lesson plans.
The continental slope is a steep, narrow fringe separating the coastal zone from the deep ocean. During low sea-level stands, slides and dense, sediment-laden flows erode the outer continental shelf and the continental slope, leading to the formation of submarine canyons that funnel large volumes of sediment and organic matter from shallow regions to the deep ocean1. During high sea-level
Miquel Canals; Pere Puig; Xavier Durrieu de Madron; Serge Heussner; Albert Palanques; Joan Fabres
Ancient Observatories: Chaco Canyon
NSDL National Science Digital Library
Located in the northwest corner of New Mexico, Chaco Canyon is a shallow, ten-mile canyon accessible only by washboard dirt roads. It is an area of tremendous cultural importance, as it was once the center of an elaborate system of buildings, roadways, and other construction. Intense building activity continued at the site until about AD 1150, and then it was quickly abandoned. Today, it is a National Historic Park and a UNESCO World Heritage Site. On this site created by the Exploratorium in San Francisco, visitors can learn about this unique place via sections that provide insight into its layout, its history of human habitation, and also its various celestial alignments. First-time visitors can click on the Sense of Place tab to view a time-lapse video of the site. The Time area is remarkable, as visitors can read an essay titled "How Old Is It?" and then watch "Migration Stories," which talks about the experiences that humans have had there over the centuries. The site is rounded out by the Observation area, which allows users to learn about how the canyon's unique qualities have fascinated visitors, explorers, and others.
NSDL National Science Digital Library
The true global geography of Mars first emerged with comprehensive maps from Mariner 9 and Viking during the 1970s. This visualization tours the Red Planet using the Viking dataset, hitting such features as the Valles Marineris canyons and the Olympus Mons volcano.
Crippen, Robert; Curkendall, Dave; Jacob, Joseph; Li, Peggy; Plesea, Lucian; Pomerantz, Marc
Unusual Spectral Unit in West Candor Chasma: Evidence for Hydrothermal or Aqueous Alteration.
National Technical Information Service (NTIS)
A spectrally distinctive unit on the floor of W. Candor Chasma (6 S, 76 W) in the central Valles Marineris may be a likely candidate for hydrothermal or aqueous alteration. This unusual material is noticeably redder than nearby plains and canyon floor-cov...
P. E. Geissler R. B. Singer
NASA Technical Reports Server (NTRS)
(Released 17 April 2002) The Science This image, located near 27.0S and 35.5W (324.5E), displays the intersection of Holden Crater with Uzboi Valles. This region of Mars contains a number of features that could be related to liquid water on the surface in the Martian past. Holden Crater contains finely layered sedimentary units that have been subsequently dissected. The hummucky terrain in the bottom half of the image is the remnants of this terrain, though the fine layers are not visible in this image at this resolution. The sedimentary units could have formed through deposition of material in a lacustrine type environment. Alternately, these layers could also be volcanic ash deposits. Uzboi Valles, which enters the crater from the southwest, is a catastrophic outflow channel that formed in the Martian past. The streamlined nature of the topographic features at the intersection of the crater with Uzboi Valles record the erosional pattern of flowing liquid water on the surface of Mars during the episodic outflow event. The Story Mars doesn't have a shortage of rugged terrain, and this area is no exception. While things look pretty quiet now, this cratered region was once the scene of some tremendous action. Long ago in Martian history, an incoming meteoroid probably smashed into the planet and produced a giant impact crater named Holden Crater, which stretches 88 miles across the Martian surface. The history of the area around Holden Crater doesn?t stop there. At some point, a catastrophic flood burst forth on the surface, forming an impressive outflow channel called Uzboi Valles. No one knows exactly how that happened, or whether the water might even have rushed into Holden Crater at some point, forming a long-ago lake. What we do know is that there is a lot of sedimentary material that could have formed in two hypothesized ways: in an ancient lake environment or as volcanic-ash deposits. Scientists are searching for the answers by studying the region where Uzboi Valles meets the crater. You can see the rough edge of Holden Crater running diagonally down in a sharply edged swath (from the top left-hand corner of this image to the center right-hand side). Just below it, running almost smoothly down the right-hand side of the image is an intriguing channel where water may once have flowed. Much of the terrain in the bottom half of the image, in fact, seems to be cut into a swish-swash of dissected sedimentary terrain. Sliced through in such a way, the terrain ends up carrying bunches of small, rounded hills called 'hummocks.' Earth can boast of its own rolling, hummocky terrain too, such as that found in the ravine-cut Missouri Hills and High Plains areas of South Dakota.
Germanium isotopic compositions in Canyon Diablo spheroids
By using ICP-MS, we have measured the concentrations and isotopic abundances of Ge in the following samples: (1) the iron meteorites Camp Verde, Toluca, Picacho, and Canyon Diablo; (2) Canyon Diablo spheroids; and (3) oxide rims and metallic cores obtained by grinding Canyon Diablo spheroids. Whole Canyon Diablo spheroids contain appreciably more Ge than does the bulk meteorite. Germanium is
S. Xue; Y.-L. Yang; G. S. Hall; G. F. Herzog
A proposed Laramide proto-Grand Canyon
The absence of �rim gravels� north of Grand Canyon and of �Canaan Peak-type� gravels south of Grand Canyon suggests that a paleocanyon, which intersected the transport of these gravels north and south, may have begun forming in the Laramide in approximately the same position as today's central Grand Canyon. This Laramide-age canyon is envisioned as having flowed generally from the
C. A. Hill; W. D. Ranney
The Energy Balance of an Urban Canyon
This study investigates the energy exchanges occurring within an urban canyon. It considers not only the energy balances of each of the canyon component surfaces (walls and floor), but also the balance of the canyon system and of the air volume contained therein. The results are based on measurements conducted in a specially instrumented canyon during a period of fine
M. Nunez; T. R. Oke
Duration and rates of discharge: Maja Valles, Mars
NASA Technical Reports Server (NTRS)
The 1600 km-long Maja Valles outflow system of Mars consists of three major divisions including the upper valley on Lunae Planum, the canyon section across Xanthe Terra, and the lower valley across western Chryse Planitia. Although water released from the source in Juventae Chasma could reach the terminus of the present day valley system in central Chryse Planitia within 44 hours, the original outflow did not traverse the Martian surface in a direct path. It ponded along its course on northern Lunae Planum and near the western edge of Chryse Planitia significantly prolonging the lifetime of surface flow. Calculation of pond volumes and discharge rates through various parts of the channel system indicates that water flowed through this system for nearly a (terrestrial) year. Discharge rates from the various basins along the Maja channels and the maximum flow rates within the various channels are calculated. With this data, it is possible to place reasonable estimates of the minimum length of time required to drain the various impoundments and the duration of flow in various parts of the channel system. The results of these calculations are discussed.
Dehon, R. A.; Pani, E. A.
Duration and rates of discharge - Maja Valles, Mars
NASA Astrophysics Data System (ADS)
The 1600 km-long Maja Valles outflow system of Mars consists of three major divisions including the upper valley on Lunae Planum, the canyon section across Xanthe Terra, and the lower valley across western Chryse Planitia. Although water released from the source in Juventae Chasma could reach the terminus of the present day valley system in central Chryse Planitia within 44 hours, the original outflow did not traverse the Martian surface in a direct path. It ponded along its course on northern Lunae Planum and near the western edge of Chryse Planitia significantly prolonging the lifetime of surface flow. Calculation of pond volumes and discharge rates through various parts of the channel system indicates that water flowed through this system for nearly a (terrestrial) year. Discharge rates from the various basins along the Maja channels and the maximum flow rates within the various channels are calculated. With this data, it is possible to place reasonable estimates of the minimum length of time required to drain the various impoundments and the duration of flow in various parts of the channel system. The results of these calculations are discussed.
de Hon, R. A.; Pani, E. A.
This data packet contains the Canyonville Canyon Waste Dump results of the various physical environmental sampling. Core samples were taken from the on site waste material. Vertical grab samples were made from these borings. The waste samples were screened fro volatile organic compounds (VOC) and logged for lithology. Soil samples were also tested for VOC. Composite sediment samples were taken using a coring device known as a clam gun. No surface water was available for testing from the intermittent Canyon Wash. The hydrogeology of the Canyon Waste Dump was inferred from lithologic logs and hydraulic data from the five monitoring wells located along the canyon floor. Groundwater was monitored through five wells. The soil vapor and air screening techniques used were adaptations of the EPA ERT and NIOSH methodologies. 4 figs., 9 tabs.
Land, M.D.; Brothers, R.R. (Tennessee Univ., Knoxville, TN (United States)); McGinn, C.W. (Oak Ridge National Lab., TN (United States))
1996 Grand Canyon Flood Analysis
NSDL National Science Digital Library
Mark Manone, Northern Arizona University Summary Analyze the effect of a 1996 controlled flood on a sandbar in Grand Canyon. This exercise uses Spatial Analyst and 3D Analyst Context Type and level of course ...
Manone, Mark
236-Z Canyon Utilization Study.
National Technical Information Service (NTIS)
The 236-Z canyon contains equipment for repurification of plutonium and recovery of plutonium from scrap material. To meet production requirements of Fast Flux Test Facility/Clinch River Breeder Reactor oxide with the existing plant, several new pieces of...
D. R . Dixon
The Devil Canyon-Bear Canyon Primitive Area, located about 10 mi northeast of Pasadena in the Angeles National Forest, Los Angeles County, California, is an area about 8 mi long by 6 mi wide. To evaluate the mineral-resource potential of the area, geologic examinations were made by foot traverses. Samples of fresh, altered, and mineralized rocks, of sand, gravel, and other sediments, and of some panned concentrates from stream sediments were collected and analyzed. The mineral-resource survey concluded that there is little promise for the occurrence of metallic resources.
Crowder, Dwight, F.; Fillo, Paul, V.
Creationism in the Grand Canyon, Texas Textbooks
AGU President Bob Dickinson, together with presidents of six other scientific societies, have written to Joseph Alston, Superintendent of Grand Canyon National Park, pointing out that a creationist book, The Grand Canyon: A Different View, is being sold in bookstores within the borders of the park as a scientific explanation about Grand Canyon geologic history. President Dickinson's 16 December letter
Peter Folger
Some insights into typical urban canyon airflows
NASA Astrophysics Data System (ADS)
Previous studies have suggested that the key characteristics of wind flows within an urban canyon can be determined from the relative geometry of the canyon; in particular from the height to width ratio of the canyon, and, to a lesser extent, from the length to height ratio. Further, it is often assumed that the flow at mid-canyon is essentially two-dimensional and little influenced by along-canyon flow. Analysis of data collected from a field program indicates that within canyon flow is more complex than this and that the channelling effect of the canyon must be included in any description of the flow. It is also shown that the relative geometry of the canyon is insufficient on its own to determine the fundamental nature of the flow. In the field program, based on a relatively long canyon, vortex-based "skimming flow" was observed. On the basis of previous wind tunnel and numerical studies, such a flow regime is not expected for this relatively low canyon. Further analysis of the wind data confirms previous work of Nakamura and Oke (1988, Atmospheric Environment 22, 2691-2700) concerning the relationship between above-roof wind direction and canyon-floor wind direction. An explanation of this relationship in terms of the channelling effect of the canyon is provided.
Johnson, G. T.; Hunter, L. J.
Currents in monterey submarine canyon
Flow fields of mean, subtidal, and tidal frequencies between 250 and 3300 m water depths in Monterey Submarine Canyon are examined using current measurements obtained in three yearlong field experiments. Spatial variations in flow fields are mainly controlled by the topography (shape and width) of the canyon. The mean currents flow upcanyon in the offshore reaches (>1000 m) and downcanyon in the shallow reaches (100-m amplitude isotherm oscillations and associated high-speed rectilinear currents. The 15-day spring-neap cycle and a ???3-day??? band are the two prominent frequencies in subtidal flow field. Neither of them seems directly correlated with the spring-neap cycle of the sea level.
Xu, J. P.; Noble, M. A.
Streamlined Islands in Ares Valles
NASA Technical Reports Server (NTRS)
(Released 10 June 2002) The Science Although liquid water is not stable on the surface of Mars today, there is substantial geologic evidence that large quantities of water once flowed across the surface in the distant past. Streamlined islands, shown here, are one piece of evidence for this ancient water. The tremendous force of moving water, possibly from a catastrophic flood, carved these teardrop-shaped islands within a much larger channel called Ares Valles. The orientation of the islands can be used as an indicator of the direction the water flowed. The islands have a blunt end that is usually associated with an obstacle, commonly an impact crater. The crater is resistant to erosion and creates a geologic barrier around which the water must flow. As the water flows past the obstacle, its erosive power is directed outward, leaving the area in the lee of the obstacle relatively uneroded. However, some scientists have also argued that the area in the lee of the obstacle might be a depositional zone, where material is dropped out of the water as it briefly slows. The ridges observed on the high-standing terrain in the leeward parts of the islands may be benches carved into the rock that mark the height of the water at various times during the flood, or they might be indicative of layering in the leeward rock. As the water makes its way downstream, the interference of the water flow by the obstacle is reduced, and the water that was diverted around the obstacle rejoins itself at the narrow end of the island. Therefore, the direction of the water flow is parallel to the orientation of the island, and the narrow end of the island points downstream. In addition to the streamlined islands, the channel floor exhibits fluting that is also suggestive of flowing water. The flutes (also known as longitudinal grooves) are also parallel to the direction of flow, indicating that the water flow was turbulent and probably quite fast, which is consistent with the hypothesized catastrophic floods that came through Ares Valles. The Story In symbolism only, these guppy-shaped islands and current-like flutes of land beside them may conjure up a mental image of a flowing Martian river. This picture would only be half-right. Scientifically, no fish ever swam this channel, but these landforms do reveal that catastrophic floods of rushing water probably patterned the land in just this way. Geologists who study flood areas believe that a tremendous force of moving water probably carved both the islands and the small, parallel, 'current-like' ridges around them. The blunt end of the islands (the 'heads' of the 'fish') are probably ancient impact craters that posed obstacles to the water as it rushed down the channel in torrents. Because a crater is resistant to erosion, it creates a geologic barrier around which the water must flow. As the water makes its way downstream, the crater's interference with the water flow is reduced, so the water that was diverted around the obstacle rejoins at the narrow end of the island (the 'tail' of the 'fish'). Therefore, from this information, you can tell that the water flowed from the southeast to the northwest. As a rule of thumb for the future, you can say that the narrow end of the island points downstream. The result may be the island behind the crater, but geologists disagree about the exact process by which the island forms. Some scientists argue that the erosive power of the water is directed outward, leaving the area behind, or in the lee of, the obstacle relatively untouched. Other scientists argue that the water slows when it encounters the crater obstacle, and small particles of sand and 'dirt' drop out of the water and are deposited in the lee. There's another small associated uncertainty too. Look closely at the edges of the islands and notice how the land is terraced. These ledges might mark the height of the water at various times during the flood . . . or they might be an indication that layering occurred. It all depends on your hypothesis. Like the stream
Hells Canyon Environmental Investigation, 1984
The results of an environmental investigation of the nonpower impacts on the Hells Canyon Complex resulting from water budget participation are presented. The water budget plan would increase flows in the Columbia and Snake Rivers between April 15 and June 15 to improve survival of migrating salmon and steelhead. The study was conducted using existing data and consultation with agencies
The Baca location {number_sign}1 geothermal field is located in north-central New Mexico within the western half of the Plio-Pleistocene valles Caldera. Steam and hot water are produced primarily from the northeast-trending Redondo Creek graben, where downhole temperatures exceed 500 F. Stratigraphically the reservoir region can be described as a five-layer sequence that includes (1) caldera fill and the upper units of the Bandelier ash flow tuff, (2) the lower members of this tuff, which comprise the main reservoir rock at Baca, (3) the Pliocene Paliza Canyon volcanics, (4) Tertiary sands and Paleozoic sedimentary rocks, and (5) Precambrian granitic basement. Production is controlled by fractures and faults that are ultimately related to activity in the Rio Grande Rift system. Geophysically, the caldera is characterized by a gravity minimum and a resistivity low. A 40-mgal gravity minimum over the caldera is due mostly to the relatively low-density volcanics and sediments that fill the caldera and probably bears no relation to deep-seated magmatic sources. Two-dimensional gravity modeling indicates that the depth to Precambrian basement in Redondo Canyon is probably at least 3 km and may exceed 5 km in eastern parts of the caldera. Telluric and magnetotelluric surveys have shown that the reservoir region is associated with low resistivity and that a deep low-resistivity zone correlates well with the depth of the primary reservoir inferred from well data.
Wilt, M.; Haar, S.V.
Amplification of bedrock canyon incision by wind
NASA Astrophysics Data System (ADS)
Bedrock canyons etch much of the surface of Earth and Mars, and commonly inform interpretations of long-term hydrologic or tectonic changes within these landscapes. However, many bedrock canyons (particularly on Mars) exist in arid environments where wind abrasion can dramatically alter surface morphology. Although it is hypothesized that wind carves or modifies bedrock canyons on Mars, the interplay of wind and fluvial processes in shaping canyon landscapes is, to our knowledge, unexplored. Consequently, here we exploit a natural experiment along the 4.09 Ma Puripicar ignimbrite, situated on the western slope of the Andes in the Atacama Desert and subject to significant erosion from both wind and rivers. The Puripicar exhibits a series of bedrock gorges nested behind a broad north-south escarpment whose southern half is protected from wind by a large topographic barrier. This shielding provides a natural control to examine the effects of wind abrasion on canyon morphology and in particular knickpoint retreat. Our results show that for a given drainage area, knickpoints in wind-affected canyons have incised an order of magnitude farther upstream than wind-protected canyons. In addition, wind-affected canyons are wider and have more streamlined aspect ratios for a given drainage area than wind-protected canyons. Aeolian abrasion appears to result in knickpoints with average slopes half those of shielded canyons (0.2 and 0.4, respectively). Lastly, although the magnitude of knickpoint retreat is larger in wind-affected canyons, the scaling exponent between knickpoint retreat and drainage area is virtually identical for wind-affected canyons (0.56, R = 0.71) and wind-protected canyons (0.60, R = 0.80). Taken together, our results suggest that fluvial incision and wind abrasion are coupled processes in this landscape: convergent canyons funnel wind towards knickpoints, thereby leading to enhanced aeolian abrasion rates at knickpoints. We speculate that the apparent drainage area dependence of knickpoint retreat in wind-affected canyons reflects the fact that larger rivers create wider canyon mouths. Larger canyons mouths, in turn, increase wind convergence and drive higher aeolian abrasion rates at the heads of larger canyons. This study is the first to demonstrate knickpoint retreat via wind abrasion, and highlights that even in landscapes where large river gorges are present, wind may still exert a dominant control on canyon morphology.
Perkins, J. P.; Finnegan, N. J.; de Silva, S. L.
Mineral resources of the Fish Creek Canyon, Road Canyon, and Mule Canyon Wilderness Study Areas, San Juan County, Utah
This book reports the Fish Creek Canyon (UT-060-204), Road Canyon(UT-060-201), and Mule Canyon (UT-060-205B) Wilderness Study Areas, which comprise 40,160 acres, 52,420 acres, and 5,990 acres, respectively, studied for their mineral endowment. A search of federal, state, and county records showed no current or previous mining-claim activity. No mineral resources were identified during field examination of the study areas. Sandstone
D. J. Bove; D. R. Shawe; G. K. Lee; W. F. Hanna; R. E. Jeske
77 FR 9265 - Glen Canyon Dam Adaptive Management Work Group
Federal Register 2010, 2011, 2012, 2013
...INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group AGENCY...SUMMARY: The Glen Canyon Dam Adaptive Management Work Group (AMWG...Secretary of the Interior concerning Glen Canyon Dam operations and other management...
77 FR 22801 - Glen Canyon Dam Adaptive Management Work Group
Federal Register 2010, 2011, 2012, 2013
...INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group AGENCY...SUMMARY: The Glen Canyon Dam Adaptive Management Work Group (AMWG...Secretary of the Interior concerning Glen Canyon Dam operations and other management...
78 FR 7810 - Glen Canyon Dam Adaptive Management Work Group
Federal Register 2010, 2011, 2012, 2013
...INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group AGENCY...SUMMARY: The Glen Canyon Dam Adaptive Management Work Group (AMWG...Secretary of the Interior concerning Glen Canyon Dam operations and other management...
78 FR 21415 - Glen Canyon Dam Adaptive Management Work Group
Federal Register 2010, 2011, 2012, 2013
...INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group AGENCY...SUMMARY: The Glen Canyon Dam Adaptive Management Work Group (AMWG...Secretary of the Interior concerning Glen Canyon Dam operations and other management...
76 FR 24516 - Glen Canyon Dam Adaptive Management Work Group
Federal Register 2010, 2011, 2012, 2013
...INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group AGENCY...SUMMARY: The Glen Canyon Dam Adaptive Management Work Group (AMWG...Secretary of the Interior concerning Glen Canyon Dam operations and other management...
History of the youngest members of the Valles Rhyolite, Valles Caldera, New Mexico using ESR dating method.
National Technical Information Service (NTIS)
The cooling history of the Valles caldera was studied by the electron spin resonance (ESR) dating method using Al and Ti centers in quartz grains which were separated from the youngest units of the Valles Rhyolite. The ESR apparent ages are much younger t...
K. Ogoh S. Toyoda S. Ikeda M. Ikeya F. Goff
Research Furthers Conservation of Grand Canyon Sandbars
Grand Canyon National Park lies approximately 25 km (15 mi) down-river from Glen Canyon Dam, which was built on the Colorado River just south of the Arizona-Utah border in Glen Canyon National Recreation Area. Before the dam began to regulate the Colorado River in 1963, the river carried such large quantities of red sediment, for which the Southwest is famous, that the Spanish named the river the Rio Colorado, or 'red river'. Today, the Colorado River usually runs clear below Glen Canyon Dam because the dam nearly eliminates the main-channel sand supply. The daily and seasonal flows of the river were also altered by the dam. These changes have disrupted the sedimentary processes that create and maintain Grand Canyon sandbars. Throughout Grand Canyon, sandbars create habitat for native plants and animals, supply camping beaches for river runners and hikers, and provide sediment needed to protect archaeological resources from weathering and erosion. Maintenance of sandbars in the Colorado River ecosystem, the river corridor that stretches from the dam to the western boundary of Grand Canyon National Park, is a goal of the Glen Canyon Dam Adaptive Management Program. The program is a federally authorized initiative to ensure that the mandates of the Grand Canyon Protection Act of 1992 are met through advances in information and resource management. The U.S. Geological Survey's Grand Canyon Monitoring and Research Center has responsibility for scientific monitoring and research efforts for the program. Extensive research and monitoring during the past decade have resulted in the identification of possible alternatives for operating Glen Canyon Dam that hold new potential for the conservation of sand resources.
Melis, Theodore S.; Topping, David J.; Rubin, David M.; Wright, Scott A.
MC-19 Margaritifer Sinus Region
NASA Technical Reports Server (NTRS)
Mars digital-image mosaic merged with color of the MC-19 quadrangle, Margaritifer Sinus region of Mars. Heavily cratered highlands, which dominate the Margaritifer Sinus quadrangle, are marked by large expanses of chaotic terrain. In the northwestern part, the major rift zone of Valles Marineris connects with a broad canyon filled with chaotic terrain. Latitude range -30 to 0, longitude range 0 to 45 degrees.
NASA Technical Reports Server (NTRS)
MGS MOC Release No. MOC2-542, 12 November 2003Outcrops of layered rock abound in the 'grand canyon of Mars,' the Valles Marineris. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image provides an example from the upper northeast wall of Ius Chasma. This picture is located near 7.7oS, 76.1oW. The picture is 3 km (1.9 mi) wide and illuminated by sunlight from the lower right.
A proposed Laramide proto-Grand Canyon
NASA Astrophysics Data System (ADS)
The absence of "rim gravels" north of Grand Canyon and of "Canaan Peak-type" gravels south of Grand Canyon suggests that a paleocanyon, which intersected the transport of these gravels north and south, may have begun forming in the Laramide in approximately the same position as today's central Grand Canyon. This Laramide-age canyon is envisioned as having flowed generally from the SW to NE; from the Peach Springs Canyon area to Mile 197 where it was captured by karst; then along a N. 60�E joint system to the Kanab Point area where it converged with drainage coming off the west side of the Kaibab arch. From there it flowed north along the west flank of the Kaibab arch to Paleogene Lake Claron. The critical idea suggested by this proposed model is that the modern Colorado River utilized Laramide paleotopography in establishing its course through the central Grand Canyon, with younger sections of the canyon integrating with it later, in the middle to late Miocene. This paleocanyon route, in association with headward erosion from the Grand Wash Cliffs toward the Kaibab arch after 16-17 Ma, helps account for the total volume of rock eroded from Grand Canyon, which cannot be explained by present-day incision rates.
Hill, C. A.; Ranney, W. D.
At the U.S. Department of Energy's Hanford Site in southeast Washington State, CH2M HILL Plateau Remediation Company (CH2M HILL) is underway on a first-of-a-kind project with the decommissioning and demolition of the U Canyon. Following the U.S. Environmental Protection Agency's Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) Record of Decision for the final remediation of the canyon, CH2M HILL is combining old and new technology and techniques to prepare U Canyon for demolition. The selected remedial action called first for consolidating and grouting equipment currently in the canyon into lower levels of the plant (openings called cells), after which the cell galleries, hot pipe trench, ventilation tunnel, drains and other voids below the operating deck and crane-way deck levels will be filled with approximately 20,000 cubic yards of grout and the canyon roof and walls demolished down to the approximate level of the canyon deck. The remaining canyon structure will then be buried beneath an engineered barrier designed to control potential contaminant migration for a 500-year life. Methods and lessons learned from this project will set the stage for the future demolition of Hanford's four other canyon-type processing facilities.
Grassland in the Valle Grande, Valles Caldera National Preserve, New Mexico, near sunrise.
NSDL National Science Digital Library
The Valle Grande in the Valles Caldera National Preserve, New Mexico is one of the National Science Foundation��s Ecology of Infectious Disease study sites. A recent study examined the role that local environmental changes play in deer mouse (Peromyscus maniculatus) and Sin Nombre virus distributions. Hantavirus Pulmonary Syndrome (HPS) is a human disease caused by infection with hantaviruses, which are maintained in rodent populations. HPS was recognized following an outbreak of pulmonary disease among humans in the U.S. Southwest in 1993, and infection with Sin Nombre virus (SNV) was traced to its reservoir, the deer mouse. The number of HPS cases varies both geographically and among years, and it has been hypothesized that the variation reflects environmental changes that affect rodent populations. This photograph originally appeared on the cover of Ecological Applications (17:1) in February of 2007.
Norris, Douglas E.
Flow dynamics around downwelling submarine canyons
NASA Astrophysics Data System (ADS)
Flow dynamics around a downwelling submarine canyon were analysed with the Massachusetts Institute of Technology general circulation model. Blanes Canyon (Northwest Mediterranean) was used for topographic and initial forcing conditions. Fourteen scenarios were modelled with varying forcing conditions. Rossby number and Burger number were used to determine the significance of Coriolis acceleration and stratification (respectively) and their impacts on flow dynamics. A new non-dimensional parameter (?) was introduced to determine the significance of vertical variations in stratification. Some simulations do see brief periods of upwards displacement of water during the 10 day model period, however, the presence of the submarine canyon is found to enhance downwards advection of density in all model scenarios. High Burger numbers lead to negative vorticity and a trapped anticyclonic eddy within the canyon, as well as an increased density anomaly. Low Burger numbers lead to positive vorticity, cyclonic circulation and weaker density anomalies. Vertical variations in stratification affect zonal jet placement. Under the same forcing conditions, the zonal jet is pushed offshore in more uniformly stratified domains. Offshore jet location generates upwards density advection away from the canyon, while onshore jets generate downwards density advection everywhere within the model domain. Increasing Rossby values across the canyon axis, as well as decreasing Burger values, increase negative vertical flux at shelf break depth (150 m). Increasing Rossby numbers lead to stronger downwards advection of a passive tracer (nitrate) as well as stronger vorticity within the canyon. Results from previous studies were explained within this new dynamic framework.
Spurgin, J. M.; Allen, S. E.
The Grand Canyon: How It Formed
NSDL National Science Digital Library
Today, in the deepest part of the Grand Canyon, the Colorado River flows past rocks that are 1.7 billion years old. This video describes how the river cut vertically through layers of pre-existing rock as the plateau beneath it was uplifted by tectonic forces. It also explains that other forces worked to widen the canyon, particluarly the activity of tributary streams and debris flows caused by flash flooding from intense rainfall or rapid snowmelt moving loose rock and boulders down canyon walls and side channels. A background essay and list of discussion questions are also provided.
A Diablo Canyon double feature
The current controversy and uncertainty surrounding the disposal of low-level radioactive waste makes it ever more prudent to develop methods to minimize its generation in the first place. As the industry is challenged with active opposition, missed deadlines, and political challenges, Pacific Gas and Electric`s Diablo Canyon nuclear station has implemented a plan to reduce waste generation from plant systems, from the modification and removal of plant equipment, and from the use of protective clothing and consumable contamination-control items. Our program has been extremely effective and may serve as a model for other nuclear power plants at a time of increasing processing and disposal costs. In 1994, for example, we were able to cut our radwaste generation in half-twice.
Miller, C.
Diablo Canyon refueling outage program
Management of outages has become one of the most talked about subjects in the nuclear power industry in the past several years. Many utilities do not perform refueling outages very well or in the past have had some outages that they would not like to repeat and in some cases do not even like to think about. With the growing cost of energy and the demands placed on utilities to improve capacity factors, it is very easy for management to focus on shortening refueling outage durations as a prime objective in improving overall corporate performance. So it is with Pacific Gas and Electric Company and the Diablo Canyon power plant. A review of their refueling outage performance reflects a utility that is responding to the nuclear industry's call for improved outage performance.
McLane, W.B.; Irving, T.L. (Pacific Gas and Electric Co., Avila Beach, CA (United States))
Mars Science Laboratory at Canyon
NASA Technical Reports Server (NTRS)
December 2, 2003NASA's Mars Science Laboratory travels near a canyon on Mars in this artist's concept. The mission is under development for launch in 2009 and a precision landing on Mars in 2010.Once on the ground, the Mars Science Laboratory would analyze dozens of samples scooped up from the soil and cored from rocks as it explores with greater range than any previous Mars rover. It would investigate the past or present ability of Mars to support life. NASA is considering nuclear energy for powering the rover to give it a long operating lifespan.NASA's Jet Propulsion Laboratory, Pasadena, Calif., is managing development of the Mars Smart Laboratory for the NASA Office of Space Science, Washington, D.C.
Lynch Canyon Combination Thermal Drive Project.
National Technical Information Service (NTIS)
The following report provides a summary of the Lynch Canyon Thermal Drive Project. This demonstration project was begun in 1978 and terminated in 1980. The project originally was divided into four phases; Geologic Evaluation, Injectivity Test, Field Devel...
J. R. Stair
Grand Canyon Railroad Depot: Historic Structure Report.
National Technical Information Service (NTIS)
This Historic Structure Report on the Grand Canyon Depot is intended to edit, augment, and revise existing documents as well as provide additional information. The report will provide a thorough description of the background, physical development, and sig...
D. Wittman H. Piza J. Petkovsek M. Zappanti W. Duecker
Structure of Flow in a Bedrock Canyon
NASA Astrophysics Data System (ADS)
Bedrock canyon incision is widely recognized as setting the pace of landscape evolution. A variety of models link flow and sediment transport processes to the bedrock canyon incision rate. The model components that represent sediment transport processes are quite well developed in some models. In contrast, the model components that represent fluid flow remain rudimentary. Part of the reason is that there have been relatively few observations of flow structure in a bedrock canyon. Here, we present observations of flow obtained using an array of three acoustic Doppler current profilers during a 524 km long continuous centerline traverse of the Fraser River, British Columbia, Canada as it passes through a series of bedrock canyons. Through this portion of the river, the channel alternates between gravel-bedded reaches that are deeply incised into semi-consolidated glacial deposits and solid bedrock-bound reaches. We present observations of flow through 41 bedrock bound reaches of the river, derived from our centerline traverses and more detailed three-dimensional mapping of the flow structure in 2 canyons. Our observations suggest that flow in the most well-defined canyons (deep, laterally constrained, completely bedrock bound) is far more complex than that in a simple prismatic channel. As flow enters the canyon, a high velocity core plunges from the surface to the bed, causing a velocity inversion (high velocities at the bed and low velocities at the surface). This plunging flow then upwells along the canyon wall, resulting in a three-dimensional flow with counter-rotating, along-stream eddies that diverge near the bed. We observe centerline ridges along the canyon floors that result from the divergence and large-scale surface boils caused by the upwelling. This flow structure causes deep scour in the bedrock channel floor, and ensures the base of the canyon walls are swept of debris that otherwise may be deposited due to lower shear stresses abutting the walls. The observations suggest that the rudimentary modeling approaches currently included in landscape evolution theories are inadequate to capture the morphodynamics of bedrock canyons.
Venditti, J. G.; Rennie, C. D.; Church, M. A.; Bomhof, J.; Lin, M.
Holocene Vegetation in Chaco Canyon, New Mexico
Well-preserved plant remains in packrat middens chronicle vegetation change in Chaco Canyon over the past 11,000 years. Early Holocene evidence of communities dominated by Douglas fir, Rocky Mountain juniper, and limber pine in the San Juan Basin calls for revision of traditional constructs based on fossil pollen. Middle and late Holocene vegetation in the canyon was pinyon-juniper woodland up until
Julio L. Betancourt; Thomas R. van Devender
Wintertime Boundary Layer Structure in the Grand Canyon.
NASA Astrophysics Data System (ADS)
Wintertime temperature profiles in the Grand Canyon exhibit a neutral to isothermal stratification during both daytime and nighttime, with only rare instances of actual temperature inversions. The canyon warms during daytime and cools during nighttime more or less uniformly through the canyon's entire depth. This weak stability and temperature structure evolution differ from other Rocky Mountain valleys, which develop strong nocturnal inversions and exhibit convective and stable boundary layers that grow upward from the valley floor. Mechanisms that may be responsible for the different behavior of the Grand Canyon are discussed, including the possibility that the canyon atmosphere is frequently mixed to near-neutral stratification when cold air drains into the top of the canyon from the nearby snow-covered Kaibab Plateau. Another feature of canyon temperature profiles is the sharp inversions that often form near the canyon rims. These are generally produced when warm air is advected over the canyon in advance of passing synoptic-scale ridges.Wintertime winds in the main canyon are not classical diurnal along-valley wind systems. Rather, they are driven along the canyon axis by the horizontal synoptic-scale pressure gradient that is superimposed along the canyon's axis by passing synoptic-scale weather disturbances. They may thus bring winds into the canyon from either end at any time of day.The implications of the observed canyon boundary layer structure for air pollution dispersion are discussed.
Whiteman, C. David; Zhong, Shiyuan; Bian, Xindi
Geologic Map of the Valles Caldera, Jemez Mountains, New Mexico
NASA Astrophysics Data System (ADS)
Valles caldera is famous as the type locality of large resurgent calderas (Smith and Bailey, 1968), the location of a classic 260-300 �C liquid-dominated geothermal system (Goff and Gardner, 1994), and the site of a long-lived late Pleistocene lake (Fawcett et al., 2011). We have published a detailed color geologic map of the Valles caldera and surrounding areas at 1:50,000 scale obtainable from New Mexico Bureau of Geology and Mineral Resources (geoinfo.nmt.edu/publications/maps/geologic/gm/79/). The new Valles map has been compiled from all or parts of nine 1:24,000 geologic maps completed between 2004 and 2008 (Bland, Cerro del Grant, Jarosa, Jemez Springs, Polvadera Peak, Redondo Peak, Seven Springs, Valle San Antonio, and Valle Toledo). Our map provides more detailed geology on the resurgent dome, caldera collapse breccias, post-caldera lava and tuff eruptions, intracaldera sedimentary and lacustrine deposits, and precaldera volcanic and sedimentary rocks than previous maps and incorporates recent stratigraphic revisions to the geology of the Jemez Mountains volcanic field. Three cross sections supported by surface geology, geophysical data and deep borehole logs (?4500 m) show an updated view of the caldera interior, depict a modern interpretation of caldera collapse and resurgence, and provide caldera-wide subsurface isotherms (?500 �C). A 30 page booklet included with the map contains extensive rock descriptions for 162 stratigraphic units and figures showing physiographic features, structural relations between Valles (1.25 Ma) and the earlier, comparably sized Toledo caldera (1.62 Ma), correlation charts of map units, and the distribution of pre- and post-caldera hydrothermal alteration styles, including recently documented zeolite-type alteration. Finally, the booklet includes a generalized model showing our interpretation of intracaldera structure and subjacent magma chambers, and relations of Valles to earlier Quaternary-Precambrian units.
Goff, F.; Gardner, J. N.; Reneau, S. L.; Kelley, S. A.; Kempter, K. A.; Lawrence, J. R.
Wilmington Submarine Canyon: a marine fluvial-like system.
Midrange sidescan sonar data show that a system of gullies and small channels feeds into large submarine canyons on the Middle Atlantic Continental Slope of the US. The surveyed canyons all have relatively flat floors, but they have different channel morphologies. Wilmington Canyon has a meandering channel that extends down the Continental Slope and across the Continental Rise, whereas two canyons south of Wilmington Canyon have straight channels that trend directly downslope onto the rise. The morphology of these submarine canyon systems is remarkably similar to that of terrestrial fluvial systems.-Authors
McGregor, B.; Stubblefield, W. L.; Ryan, W. B. F.; Twichell, D. C.
Layers Exposed at Polar Canyon
NASA Technical Reports Server (NTRS)This false-color subframe of an image from the High Resolution Imaging Science Experiment camera on NASA's Mars Reconnaissance Orbiter shows the north polar layered deposits at top and darker materials at bottom, exposed in a scarp at the head of Chasma Boreale, a large canyon eroded into the layered deposits. The polar layered deposits appear red because of dust mixed within them, but are ice-rich as indicated by previous observations. Water ice in the layered deposits is probably responsible for the pattern of fractures seen near the top of the scarp. The darker material below the layered deposits may have been deposited as sand dunes, as indicated by the crossbedding (truncation of curved lines) seen near the middle of the scarp. It appears that brighter, ice-rich layers were deposited between the dark dunes in places. Exposures such as these are useful in understanding recent climate variations that are likely recorded in the polar layered deposits. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace and Technology Corp., Boulder, Colo.
Mineral resources of the Fish Creek Canyon, Road Canyon, and Mule Canyon Wilderness Study Areas, San Juan County, Utah
This book reports the Fish Creek Canyon (UT-060-204), Road Canyon(UT-060-201), and Mule Canyon (UT-060-205B) Wilderness Study Areas, which comprise 40,160 acres, 52,420 acres, and 5,990 acres, respectively, studied for their mineral endowment. A search of federal, state, and county records showed no current or previous mining-claim activity. No mineral resources were identified during field examination of the study areas. Sandstone and sand and gravel have no unique qualities but could have limited local use for road metal or other construction purposes. However, similar materials are abundant outside the study areas. The three study areas have moderate resource potential for undiscovered oil and gas and low resource potential for undiscovered metals, including uranium and thorium, coal, and geothermal energy.
Bove, D.J.; Shawe, D.R.; Lee, G.K.; Hanna, W.F. (Geological Survey, Reston, VA (USA)); Jeske, R.E. (US Bureau of Mines (US))
Postcollapse Volcanism in the Valles Caldera, New Mexico: Magma System Dynamics During a Transition Between Large Volume Explosive and Small Volume Effusive Eruptions
NASA Astrophysics Data System (ADS)
The Valles Caldera formed during eruption of the ~250 km3 upper Bandelier Tuff at 1.26 Ma. Following caldera collapse a series of 3 intracaldera rhyolites (Deer Canyon, Redondo Creek and Del Medio) erupted within 54 ka. They are petrographically diverse, ranging from coarsely porphyritic (Deer Canyon type B, Redondo Creek) to nearly aphyric (Deer Canyon type A, Del Medio) and contain distinctive phenocryst assemblages. Disequilibrium textures are common and include resorbed quartz, strongly resorbed plagioclase, antirapikivi feldspars, and zoned sanidine and plagioclase. Plagioclase in Deer Canyon rhyolite ranges widely from labradorite (An60) to oligoclase (An24). Most are andesine in composition and often exhibit oscillatory zonation with overgrowths up to ~200 um wide. Alkali feldspars include both anorthoclase and sanidine with a total variability in Or content of ~50%. Plagioclase and alkali feldspars in Redondo Creek rhyolite show less variability, but similarly large ranges. One phenocryst exhibits an andesine core, oligoclase overgrowth, and sanidine rim. Del Medio rhyolite lacks plagioclase, but contains alkali feldspars (both anorthoclase and sanidine) with variability in Or content of ~30%. Patchy zonation is common, with Or content within phenocrysts varying by ~7%. Redondo Creek rhyolite ranges from ~72-74 wt.% SiO2 whereas Deer Canyon and Del Medio are high silica rhyolites with ~76-78 wt.% SiO2. Trace elements show more significant variability. Redondo Creek samples have low Nb, Rb, Sc, and Lu and high La, Sr, Ba and Hf compared to Del Medio samples. In contrast, Deer Canyon samples exhibit extreme variability in trace element concentrations (e.g., Nb ranging from 32-83 ppm). Incompatible trace element ratios (Th/Nb, Th/Yb, Ta/Yb) versus Nb plots show that Redondo Creek and Del Medio samples have distinctive, limited compositions, whereas Deer Canyon exhibits widely varying values (e.g., Th/Yb ranging from ~3.5-10.5). 238U/206Pb ion microprobe dating of zircons from Redondo Creek rhyolite show crystallization ages from 0.97 Ma to 1.60 Ma, with a mean age of 1.29 � 0.15 Ma. These ages range from the timing of eruption of Redondo Creek rhyolite to the eruption of the lower Bandelier Tuff (1.61 Ma). In contrast, zircons from Deer Canyon rhyolite (type A) range from 4.8 to 5.6 Ma, with a mean age of 5.3 � 0.3 Ma. All zircons are >3.6 Ma older than the eruption age of the Deer Canyon rhyolite. No zircons were recovered from Del Medio samples. These data indicate that postcollapse rhyolites erupted within 54 ka of caldera collapse represent distinct magma batches which are not comagmatic with each other, nor with the preceding upper Bandelier Tuff. Deer Canyon rhyolite represents two distinct melt compositions which were mingled and erupted quickly, such that sufficient time for homogenization did not occur. Type A Deer Canyon rhyolite was produced by remelting of a pre-caldera pluton at depth, whereas type B rhyolite originated within the residual Bandelier crystal mush by crystal-liquid separation. Redondo Creek rhyolite was produced by interaction of a hotter, more mafic magma with residual Bandelier crystal mush, production of new rhyolitic melt and crystal transfer, followed by interaction of this magma with a third, hotter, more K-rich rhyolitic melt prior to eruption. Del Medio rhyolite appears to be a single batch of crystal poor rhyolite separated from residual Bandelier crystal mush.
Spell, T. L.; Gibler, K. I.
Contemporary Sediment-Transport Processes in Submarine Canyons
NASA Astrophysics Data System (ADS)
Submarine canyons are morphological incisions into continental margins that act as major conduits of sediment from shallow- to deep-sea regions. However, the exact mechanisms involved in sediment transfer within submarine canyons are still a subject of investigation. Several studies have provided direct information about contemporary sedimentary processes in submarine canyons that suggests different modes of transport and various triggering mechanisms. Storm-induced turbidity currents and enhanced off-shelf advection, hyperpycnal flows and failures of recently deposited fluvial sediments, dense shelf-water cascading, canyon-flank failures, and trawling-induced resuspension largely dominate present-day sediment transfer through canyons. Additionally, internal waves periodically resuspend ephemeral deposits within canyons and contribute to dispersing particles or retaining and accumulating them in specific regions. These transport processes commonly deposit sediments in the upper- and middle-canyon reaches for decades or centuries before being completely or partially flushed farther down-canyon by large sediment failures.
Puig, Pere; Palanques, Albert; Mart�n, Jacobo
Contemporary sediment-transport processes in submarine canyons.
Submarine canyons are morphological incisions into continental margins that act as major conduits of sediment from shallow- to deep-sea regions. However, the exact mechanisms involved in sediment transfer within submarine canyons are still a subject of investigation. Several studies have provided direct information about contemporary sedimentary processes in submarine canyons that suggests different modes of transport and various triggering mechanisms. Storm-induced turbidity currents and enhanced off-shelf advection, hyperpycnal flows and failures of recently deposited fluvial sediments, dense shelf-water cascading, canyon-flank failures, and trawling-induced resuspension largely dominate present-day sediment transfer through canyons. Additionally, internal waves periodically resuspend ephemeral deposits within canyons and contribute to dispersing particles or retaining and accumulating them in specific regions. These transport processes commonly deposit sediments in the upper- and middle-canyon reaches for decades or centuries before being completely or partially flushed farther down-canyon by large sediment failures. PMID:23937169
Puig, Pere; Palanques, Albert; Mart�n, Jacobo
Overview of the Colorado River Canyon from the helicopter pad. ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
Overview of the Colorado River Canyon from the helicopter pad. View of the Nevada side where new bridge will cross canyon, view northwest - Hoover Dam, Spanning Colorado River at Route 93, Boulder City, Clark County, NV
43. and Design, Grand Canyon National Park, dated August 23, ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
43. and Design, Grand Canyon National Park, dated August 23, 1934, and September 17, 1934 (original located at Federal Records Center, Denver, Colorado, #113/3084-set of 2) SEWAGE PLANT ADDITION. - Water Reclamation Plant, Grand Canyon, Coconino County, AZ
Internal waves in Hudson Canyon with possible geological implications
NASA Astrophysics Data System (ADS)
Data from an array of instruments in Hudson Submarine Canyon for 15 weeks are qualitatively consistent with theoretical and laboratory results concerning the concentration of internal wave energy by canyon topographies. Internal wave energy was intensified at the head and near the floor of the canyon, with phase lags suggestive of propagation of internal waves up the canyon from the deep sea. Significant diurnal and semidiurnal internal tides were present, indicating their generation at the topographic relief around the canyon. Internal wave energy is apparently dissipated by mixing at the head of the canyon. A major storm during the experiment induced strong currents in the canyon. These currents are probably more important than internal waves as carriers of sediment except in the very head of the canyon.
Hotchkiss, Frances S.; Wunsch, Carl
Workshop on recent research in the Valles caldera
Over the last 5 years, there has been increased interest in the geology of the Jemez Mountains volcanic field, New Mexico. Of special interest is the Toledo-Valles caldera complex, which is targeted for research coring as part of the Continental Scientific Drilling Program. The general topics covered in this workshop were (1) hydrothermal systems and rock-water interactions, (2) volcanology and structural framework of the Jemez volcanic field, (3) determining the presence or absence of melt below the Valles caldera, and (4) deep coring and drilling technology. Separate abstracts were prepared for each presentation.
Heiken, G. (comp.)
27 CFR 9.152 - Malibu-Newton Canyon.
Code of Federal Regulations, 2010 CFR
...2010-04-01 2010-04-01 false Malibu-Newton Canyon. 9.152 Section 9.152...Viticultural Areas § 9.152 Malibu-Newton Canyon. (a) Name. The name of...described in this petition is �Malibu-Newton Canyon.� (b) Approved maps....
27 CFR 9.152 - Malibu-Newton Canyon.
Code of Federal Regulations, 2010 CFR
...2009-04-01 2009-04-01 false Malibu-Newton Canyon. 9.152 Section 9.152...Viticultural Areas § 9.152 Malibu-Newton Canyon. (a) Name. The name of...described in this petition is �Malibu-Newton Canyon.� (b) Approved maps....
75 FR 34476 - Glen Canyon Dam Adaptive Management Work Group
Federal Register 2010, 2011, 2012, 2013
...INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group AGENCY...renewing the charter for the Glen Canyon Dam Adaptive Management Work Group. The purpose...respect to the operation of Glen Canyon Dam and the exercise of other authorities...
27 CFR 9.217 - Happy Canyon of Santa Barbara.
Code of Federal Regulations, 2013 CFR
...2013-04-01 2013-04-01 false Happy Canyon of Santa Barbara. 9.217 Section...American Viticultural Areas § 9.217 Happy Canyon of Santa Barbara. (a) Name...viticultural area described in this section is �Happy Canyon of Santa Barbara�. For...
History of the youngest members of the Valles Rhyolite, Valles caldera, New Mexico using ESR dating method
The cooling history of the Valles caldera was studied by the electron spin resonance (ESR) dating method using Al and Ti centers in quartz grains which were separated from the youngest units of the Valles Rhyolite. The ESR apparent ages are much younger than fission track ages and {sup 39}Ar- {sup 40}Ar ages. Three possibilities are suggested, the first is that the ESR ages are real, the second is that ESR method did not work for these samples, and the third is that about 10--40 ka, the signal intensity was partially reduced by a thermal event such as proposed by Harrison et al. (1986). Research on the first and second possibilities is continuing. The third possibility might explain the difference between ESR ages and those by other methods (fission track and {sup 39}Ar- {sup 40}Ar). ESR dating has produced new insights regarding the history of the Valles caldera.
Ogoh, K.; Toyoda, S.; Ikeda, S.; Ikeya, M. (Osaka Univ., Toyonaka (Japan). Dept. of Physics); Goff, F. (Los Alamos National Lab., NM (United States))
Geology Fieldnotes: Bryce Canyon National Park, Utah
NSDL National Science Digital Library
Located on the Colorado Plateau in Utah, this canyon is comprised mostly of sedimentary rocks, and continues to be eroded and shaped by the Paria River. Its geologic and human history are outlined on this site, including the formation of the canyon, from the Cretaceous period (144 million years ago) to the present, and geologic features, such as fins, columns, pinnacles, and hoodoos. Visitor information, links to other resources, maps, and a teacher feature (resources for teaching geology with National Park examples) are also available.
Foos, Annabelle
Regional depositional history of the Miocene-Pleistocene Louisiana Slope, Green Canyon and Mississippi Canyon
A regional sequence-stratigraphic analysis was recently completed for the Tertiary slope sediments in Green Canyon, Ewing Bank, and Mississippi Canyon to provide a chronostratigraphic framework for basin reconstructions and predict lithofacies distributions of reservoir and seal rocks. Sixteen third-order sequences of lowstand deep-water deposits were interpreted for the middle Miocene-Pleistocene section. Thirty regional lithofacies maps were made of predominantly lowstand
D. L. Risch; A. N. Chowdhury; A. E. Hannan
Canyon conditions impact carbon flows in food webs of three sections of the Nazar� canyon
Submarine canyons transport large amounts of sediment and organic matter (OM) from the continental shelf to the abyssal plain. Three carbon-based food web models were constructed for the upper (300�750m water depth), middle (2700�3500m) and lower section (4000�5000m) of the Nazar� canyon (eastern Atlantic Ocean) using linear inverse modeling to examine how the food web is influenced by the characteristics
Dick van Oevelen; Karline Soetaert; R. Garcia; Henko C. de Stigter; Marina R. Cunha; Antonio Pusceddu; Roberto Danovaro
Barium and High Explosives in a Semiarid Alluvial System, Ca�on de Valle, New Mexico.
NASA Astrophysics Data System (ADS)
Barium and RDX (a military high explosive compound) were evaluated from 1998 to 2002 within a semiarid alluvial system, Ca�on de Valle (CdV), New Mexico. A high explosive (HE) machining facility discharged effluent containing these analytes to the canyon from 1951 to 1996. Surface water, alluvial groundwater, active channel sediments, and floodplain sediments were characterized along a 2 km long reach of canyon. Barium concentrations were higher in the alluvial groundwater than the surface water with the highest concentration centered approximately 500 m downgradient from the HE facility. Of the 21,000 kg of Ba estimated to be in CdV sediment in 1999, about 65% is estimated to have been contained in fine-grained floodplain deposits, 10% in the active channel, and 25% in coarse-grained deposits below the floodplains. The ratio of Ba concentration in fine grained deposits to the active channel increases downstream and increased over time. These data indicate that Ba from the effluent was first stored in the active channel where it could preferentially bind to fine sediment particles, and then was redistributed onto floodplains following scour and suspension during floods. The Ba residing within the floodplain sediments appears relatively stable, and remains isolated from surface water and alluvial groundwater. Approximately 5 kg of RDX was estimated to reside in CdV sediment, also preferentially in fine-grained sediment. RDX concentrations in groundwater were highest (up to 759 ug/L) during high flow snowmelt runoff. The highest average RDX concentration was from an alluvial well approximately 1000 m down gradient. There was a positive correlation between saturated thickness in CdV alluvial wells and RDX concentration. The strong correlation between RDX concentration and saturated thickness suggests that RDX resides in the vadose zone and mobilizes during wet periods when the effective saturated area increases. RDX and Ba show markedly different transport pathways through the alluvial system. Barium is readily sorbed and transported with the sediment fraction. In contrast, RDX is unbuffered and conservative. Thus as the alluvial system wets up, the RDX mobilizes. Knowledge of the distribution of Ba and RDX is critical to design and implementation of corrective measures for this system.
Reid, K. D.; Hickmott, D. D.; Reneau, S. L.; Newman, B. D.; Gram, P. E.; Heikoop, J. M.; Alcon, E. D.; Herrell, K. A.; Jercinovic, D. E.; Lawler, D. S.; Pietz, J. M.
Compositional range in the Canyon Diablo meteoroid
The compositional range within the Canyon Diablo (CD) iron meteorites associated with the formation of the Meteor Crater (Arizona) was examined, using the INAA to analyze a set of CD samples consisting of nine irons collected within 7 km of the Meteor Crater, four Arizona IAB irons that were identified by Wasson (1968) as transported CD fragments, and irons from
John T. Wasson; Xinwei Ouyang
Different Views of the Grand Canyon
Each year the spectacular scenery of the Grand Canyon of Arizona awes its more than 4,000,000 visitors. Just as its enormous scale dwarfs our human sense of space, its geology also dwarfs our human sense of time. Perhaps here, more than anywhere else on the planet, we can experience a sense of ``Deep Time.'' The colorful rocks exposed in the
Wilfred A. Elders
Tectonic development of Baltimore Canyon trough
New well data and a new gravity model across the southern end of Baltimore Canyon Trough provide a more complete history of the basin's tectonic evolution and deep crustal structure than was previously known. The basin, which formed during the separation of North America from Africa, narrows and shallows along strike, as basement depth decreases from about 18 km (59,000
B. A. Swift; C. W. Poag; D. S. Sawyer; J. A. Grow
Tectonic development of Baltimore Canyon Trough
New well data and a new gravity model across the southern end of Baltimore Canyon Trough provide a more complete history of the basin's tectonic evolution and deep crustal structure than was previously known. The basin, which formed during the separation of North America from Africa, narrows and shallows along strike, as basement depth decreases from about 18 km (59,000
B. A. Swift; C. W. Poag; D. S. Sawyer; J. A. Grow
Map Your Way to the Grand Canyon
ERIC Educational Resources Information Center
In the introductory assignment, each randomly assigned group spends about 10 to 15 minutes at each station. The author incorporates as much sensory stimulation in the activity as possible. At the first station, students view a PowerPoint show from a geology class the author participated in at the Grand Canyon. At station two, students look at a�
Yoder, Holly
December oil drilling seen for Baltimore Canyon
The U.S. Second Circuit Court of Appeals has opened the way for offshore exploration in the Baltimore Canyon, although further delays could develop from action by the Natural Resources Defense Council or the Coalition of Northeast Governors. Rising costs of pipeline construction were cited by the appeals court in its recommendation to proceed with the program. Exxon plans on December
Mt. Vernon Canyon Runaway Truck Escape Ramp.
National Technical Information Service (NTIS)
A gravel arrester bed type Runaway Truck Escape Ramp was built on a 5.2% downgrade along I-70 in Mt. Vernon Canyon, Colorado. The ramp was completed in July 1979 and to date it has stopped fifty-three runaway or potentially runaway trucks. Only two trucks...
R. L. Hayden
North Atlantic slope and canyon study. Volume 1. Executive summary
A field program to investigate the currents and sediment transport along the outershelf and upper slope along the southern flank of Georges Bank was conducted between 1980 and 1984. A major part of the field experiment was conducted in Lydonia Canyon, a large submarine canyon which cuts northward about 20 km into the continental shelf from the shelfbreak. A smaller experiment was conducted in Oceanographer Canyon to compare the currents in these two major canyons. The long-term current observations made in Lydonia and Oceanographer Canyons show that the current regime in these topographic features differs from the adjacent slope, and between canyons. Sediments near the head (depths shallower than about 600 m) in both Lydonia and Oceanographer are frequently resuspended. This frequent resuspension may allow the sediments to strip pollutants from the water column. Currents in Oceanographer Canyon are stronger and the sediments coarser than in Lydonia at comparable depths.
Butman, B.
Creationism in the Grand Canyon, Texas Textbooks
NASA Astrophysics Data System (ADS)
AGU President Bob Dickinson, together with presidents of six other scientific societies, have written to Joseph Alston, Superintendent of Grand Canyon National Park, pointing out that a creationist book, The Grand Canyon: A Different View, is being sold in bookstores within the borders of the park as a scientific explanation about Grand Canyon geologic history. President Dickinson's 16 December letter urges that Alston clearly separate The Grand Canyon: A Different View from books and materials that discuss the legitimate scientific understanding of the origin of the Grand Canyon. The letter warns the Park Service against giving the impression that it approves of the anti-science movement known as young-Earth creationism, or that it endorses the advancement of religious tenets disguised as science. The text of the letter is on AGU's Web site http://www.agu.org/sci_soc/policy/sci_pol.html. Also, this fall, AGU sent an alert to Texas members about efforts by intelligent design creationists aimed at weakening the teaching of biological evolution in textbooks used in Texas schools. The alert pointed scientists to a letter, drafted by AGU, together with the American Institute of Physics, the American Physical Society, the Optical Society of America, and the American Astronomical Society, that urged the Texas State Board of Education to adopt textbooks that presented only accepted, peer-reviewed science and pedagogical expertise. Over 550 scientists in Texas added their names to the letter (http://www.agu.org/sci_soc/policy/texas_textbooks.pdf ), sent to the Board of Education on 1 November prior to their vote to adopt a slate of new science textbooks. The Board voted 11-5 in favor of keeping the textbooks free of changes advocated by groups supporting intelligent design creationism.
Folger, Peter
Anatomy of La Jolla submarine canyon system; offshore southern California
An autonomous underwater vehicle (AUV) carrying a multibeam sonar and a chirp profiler was used to map sections of the seafloor within the La Jolla Canyon, offshore southern California, at sub-meter scales. Close-up observations and sampling were conducted during remotely operated vehicle (ROV) dives. Minisparker seismic-reflection profiles from a surface ship help to define the overall geometry of the La Jolla Canyon especially with respect to the pre-canyon host sediments. The floor of the axial channel is covered with unconsolidated sand similar to the sand on the shelf near the canyon head, lacks outcrops of the pre-canyon host strata, has an almost constant slope of 1.0� and is covered with trains of crescent shaped bedforms. The presence of modern plant material entombed within these sands confirms that the axial channel is presently active. The sand on the canyon floor liquefied during vibracore collection and flowed downslope, illustrating that the sediment filling the channel can easily fail even on this gentle slope. Data from the canyon walls help constrain the age of the canyon and extent of incision. Horizontal beds of moderately cohesive fine-grained sediments exposed on the steep canyon walls are consistently less than 1.232 million years old. The lateral continuity of seismic reflectors in minisparker profiles indicate that pre-canyon host strata extend uninterrupted from outside the canyon underneath some terraces within the canyon. Evidence of abandoned channels and point bar-like deposits are noticeably absent on the inside bend of channel meanders and in the subsurface of the terraces. While vibracores from the surface of terraces contain thin (< 10 cm) turbidites, they are inferred to be part of a veneer of recent sediment covering pre-canyon host sediments that underpin the terraces. The combined use of state of the art seafloor mapping and exploration tools provides a uniquely detailed view of the morphology within an active submarine canyon.
Paull, C. K.; Caress, D. W.; Lundsten, E.; Gwiazda, R.; Anderson, K.; McGann, M.; Conrad, J.; Edwards, B.; Sumner, E. J.
Big Canyon Creek Ecological Restoration Strategy.
He-yey, Nez Perce for steelhead or rainbow trout (Oncorhynchus mykiss), are a culturally and ecologically significant resource within the Big Canyon Creek watershed; they are also part of the federally listed Snake River Basin Steelhead DPS. The majority of the Big Canyon Creek drainage is considered critical habitat for that DPS as well as for the federally listed Snake River fall chinook (Oncorhynchus tshawytscha) ESU. The Nez Perce Soil and Water Conservation District (District) and the Nez Perce Tribe Department of Fisheries Resources Management-Watershed (Tribe), in an effort to support the continued existence of these and other aquatic species, have developed this document to direct funding toward priority restoration projects in priority areas for the Big Canyon Creek watershed. In order to achieve this, the District and the Tribe: (1) Developed a working group and technical team composed of managers from a variety of stakeholders within the basin; (2) Established geographically distinct sub-watershed areas called Assessment Units (AUs); (3) Created a prioritization framework for the AUs and prioritized them; and (4) Developed treatment strategies to utilize within the prioritized AUs. Assessment Units were delineated by significant shifts in sampled juvenile O. mykiss (steelhead/rainbow trout) densities, which were found to fall at fish passage barriers. The prioritization framework considered four aspects critical to determining the relative importance of performing restoration in a certain area: density of critical fish species, physical condition of the AU, water quantity, and water quality. It was established, through vigorous data analysis within these four areas, that the geographic priority areas for restoration within the Big Canyon Creek watershed are Big Canyon Creek from stream km 45.5 to the headwaters, Little Canyon from km 15 to 30, the mainstem corridors of Big Canyon (mouth to 7km) and Little Canyon (mouth to 7km). The District and the Tribe then used data collected from the District's stream assessment and inventory, utilizing the Stream Visual Assessment Protocol (SVAP), to determine treatment necessary to bring 90% of reaches ranked Poor or Fair through the SVAP up to good or excellent. In 10 year's time, all reaches that were previously evaluated with SVAP will be reevaluated to determine progress and to adapt methods for continued success. Over 400 miles of stream need treatment in order to meet identified restoration goals. Treatments include practices which result in riparian habitat improvements, nutrient reductions, channel condition improvements, fish habitat improvements, invasive species control, water withdrawal reductions, improved hydrologic alterations, upland sediment reductions, and passage barrier removal. The Nez Perce Soil and Water Conservation District (District) and the Nez Perce Tribe Department of Fisheries Resource Management Watershed Division (Tribe) developed this document to guide restoration activities within the Big Canyon Creek watershed for the period of 2008-2018. This plan was created to demonstrate the ongoing need and potential for anadromous fish habitat restoration within the watershed and to ensure continued implementation of restoration actions and activities. It was developed not only to guide the District and the Tribe, but also to encourage cooperation among all stakeholders, including landowners, government agencies, private organizations, tribal governments, and elected officials. Through sharing information, skills, and resources in an active, cooperative relationships, all concerned parties will have the opportunity to join together to strengthen and maintain a sustainable natural resource base for present and future generations within the watershed. The primary goal of the strategy is to address aquatic habitat restoration needs on a watershed level for resident and anadromous fish species, promoting quality habitat within a self-sustaining watershed. Seven objectives have been developed to support this goal: (1) Identify factors limiting quality
Rasmussen, Lynn; Richardson, Shannon
Candor Chasma - Massive (non-layered) material expos
NASA Technical Reports Server (NTRS)
One of the most striking discoveries of the Mars Global Surveyor mission has been the identification of thousands of meters/feet of layers within the wall rock of the enormous martian canyon system, Valles Marineris.Valles Marineris was first observed in 1972 by the Mariner 9 spacecraft, from which the troughs get their name: Valles--valleys, Marineris--Mariner.Some hints of layering in both the canyon walls and within some deposits on the canyon floors were seen in Mariner 9 and Viking orbiter images from the 1970s. The Mars Orbiter Camera on board Mars Global Surveyor has been examining these layers at much higher resolution than was available previously.MOC images led to the realization that there are layers in the walls that go down to great depths. An example of the wall rock layers can be seen in MOC image 8403, shown above (C).MOC images also reveal amazing layered outcrops on the floors of some of the Valles Marineris canyons. Particularly noteworthy is MOC image 23304 (D, above), which shows extensive, horizontally-bedded layers exposed in buttes and mesas on the floor of western Candor Chasma. These layered rocks might be the same material as is exposed in the chasm walls (as in 8403--C, above), or they might be rocks that formed by deposition (from water, wind, and/or volcanism) long after Candor Chasma opened up.In addition to layered materials in the walls and on the floors of the Valles Marineris system, MOC images are helping to refine our classification of geologic features that occur within the canyons. For example, MOC image 25205 (E, above), shows the southern tip of a massive, tongue-shaped massif (a mountainous ridge) that was previously identified as a layered deposit. However, this MOC image does not show layering. The material has been sculpted by wind and mass-wasting--downslope movement of debris--but no obvious layers were exposed by these processes.Valles Marineris a fascinating region on Mars that holds much potential to reveal information about the early history and evolution of the red planet. The MOC Science Team is continuing to examine the wealth of new data and planning for new Valles Marineris targets once the Mapping Phase of the Mars Global Surveyor mission commences in March 1999.This image: Massive (non-layered) material exposed in central Candor Chasma. MOC image 25205 subframe shown at 11.7 meters (38.4 feet) per pixel resolution. Image shows the southern tip of a massive 'interior deposit' that points like a giant tongue from Ophir Chasma (to the north) down into the center of Candor Chasma. The ridged and grooved bright unit is the 'interior deposit'. South of this ridged unit is a low elevation surface mantled by dark dunes and sand. Image covers an area approximately 5.7 by 5.7 kilometers (3.5 x 3.5 miles). North is approximately up, illumination is from the lower right. Image 25205 was obtained during Mars Global Surveyor's 252nd orbit at 2:45 p.m. (PDT) on April 20, 1998.Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
Western Candor Chasma - Layers exposed near the middle
NASA Technical Reports Server (NTRS)
One of the most striking discoveries of the Mars Global Surveyor mission has been the identification of thousands of meters/feet of layers within the wall rock of the enormous martian canyon system, Valles Marineris.Valles Marineris was first observed in 1972 by the Mariner 9 spacecraft, from which the troughs get their name: Valles--valleys, Marineris--Mariner.Some hints of layering in both the canyon walls and within some deposits on the canyon floors were seen in Mariner 9 and Viking orbiter images from the 1970s. The Mars Orbiter Camera on board Mars Global Surveyor has been examining these layers at much higher resolution than was available previously.MOC images led to the realization that there are layers in the walls that go down to great depths. An example of the wall rock layers can be seen in MOC image 8403, shown above (C).MOC images also reveal amazing layered outcrops on the floors of some of the Valles Marineris canyons. Particularly noteworthy is MOC image 23304 (D, above), which shows extensive, horizontally-bedded layers exposed in buttes and mesas on the floor of western Candor Chasma. These layered rocks might be the same material as is exposed in the chasm walls (as in 8403--C, above), or they might be rocks that formed by deposition (from water, wind, and/or volcanism) long after Candor Chasma opened up.In addition to layered materials in the walls and on the floors of the Valles Marineris system, MOC images are helping to refine our classification of geologic features that occur within the canyons. For example, MOC image 25205 (E, above), shows the southern tip of a massive, tongue-shaped massif (a mountainous ridge) that was previously identified as a layered deposit. However, this MOC image does not show layering. The material has been sculpted by wind and mass-wasting--downslope movement of debris--but no obvious layers were exposed by these processes.Valles Marineris a fascinating region on Mars that holds much potential to reveal information about the early history and evolution of the red planet. The MOC Science Team is continuing to examine the wealth of new data and planning for new Valles Marineris targets once the Mapping Phase of the Mars Global Surveyor mission commences in March 1999.Layers exposed near the middle of western Candor Chasma. MOC image 23304 subframe shown at 10.7 meters (35 feet) per pixel. Two layered buttes (upper right and lower right) and a layered or stepped mesa (center right) are shown. The image covers an area approximately 5.5 by 5.5 kilometers (3.4 x 3.4 miles). North is approximately up, illumination is from the lower right. Image 23304 was obtained during Mars Global Surveyor's 233rd orbit at 9:23 a.m. (PDT) on April 11, 1998.Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
3D View of Grand Canyon, Arizona
NASA Technical Reports Server (NTRS)The Grand Canyon is one of North America's most spectacular geologic features. Carved primarily by the Colorado River over the past six million years, the canyon sports vertical drops of 5,000 feet and spans a 445-kilometer-long stretch of Arizona desert. The strata along the steep walls of the canyon form a record of geologic time from the Paleozoic Era (250 million years ago) to the Precambrian (1.7 billion years ago).The above view was acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument aboard the Terra spacecraft. Visible and near infrared data were combined to form an image that simulates the natural colors of water and vegetation. Rock colors, however, are not accurate. The image data were combined with elevation data to produce this perspective view, with no vertical exaggeration, looking from above the South Rim up Bright Angel Canyon towards the North Rim. The light lines on the plateau at lower right are the roads around the Canyon View Information Plaza. The Bright Angel Trail, which reaches the Colorado in 11.3 kilometers, can be seen dropping into the canyon over Plateau Point at bottom center. The blue and black areas on the North Rim indicate a forest fire that was smoldering as the data were acquired on May 12, 2000.Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, Calif., is the U.S. Science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface.The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for surface mapping, and monitoring dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats, monitoring potentially active volcanoes, identifying crop stress, determining cloud morphology and physical properties, wetlands Evaluation, thermal pollution monitoring, coral reef degradation, surface temperature mapping of soils and geology, and measuring surface heat balance.
Lava Flows in the Grand Canyon
NASA Technical Reports Server (NTRS)
Over vast expanses of time, natural processes like floods and volcanoes deposit layers of rock on the Earth's surface. To delve down through layers of rock is to explore our planet's history. Sometimes rock layers are exposed through human activity, such as drilling or excavation. Other times, rivers carve through the rock. One of the best, and most well-known, examples of a river exposing ancient rocks is Colorado River in Arizona's Grand Canyon. What fewer people know is that the Grand Canyon also has a history of relatively recent (on geologic time scales) volcanism. The evidence--hardened lava--spills down the canyon walls all the way to the river. On June 22, 2003, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this image of the Grand Canyon, near 36.2 degrees north latitude and 113.2 degrees west longitude. ASTER detects light visible to human eyes as well as 'invisible' infrared light. Because different minerals reflect different portions of the light spectrum, ASTER can see varying mineral compositions of the rocks it observes, as well as detecting vegetation. In this three-dimensional visualization, lava fields appear brownish gray, darker than the layers of limestone, sandstone and other rock in the canyon. Vegetation appears green, and sparsely vegetated areas appear mustard. Water in the Colorado River is blue-purple. Geologists estimate that between 1.8 million and 400,000 years ago, lava flows actually dammed the Colorado River more than a dozen times. Some of the lava dams were as high as 600 meters (about 1,969 feet), forming immense reservoirs. Over time, enough water and sediment built up to push the river flow over the tops of these dams and eventually erode them away. Today, remnants of these lava dams remain throughout the area, along with the much older rock layers they cover. Among the most well known examples of these 'frozen' lava cascades is Lava Falls, which spills down to the river next to a cinder cone known as Volcan's Throne. Numerous flows spread down into Whitmore Canyon, a Colorado River tributary, as well.
Geomorphology and evolution of the gigantic Murray canyons on the Australian southern margin
The Murray canyons are a group of deeply incised submarine canyons on a steep 400?km section of the continental slope off Kangaroo Island, South Australia. Some of the canyons are amongst the largest on Earth. The canyons, some 80?km long, descend from the shelf edge to the abyssal plain 5200?m deep. Sprigg Canyon, the deepest and one of the largest,
Hill Pj; P. De Deckker; Exon Nf
Canyon conditions impact carbon flows in food webs of three sections of the Nazar� canyon
NASA Astrophysics Data System (ADS)
Submarine canyons transport large amounts of sediment and organic matter (OM) from the continental shelf to the abyssal plain. Three carbon-based food web models were constructed for the upper (300-750 m water depth), middle (2700-3500 m) and lower section (4000-5000 m) of the Nazar� canyon (eastern Atlantic Ocean) using linear inverse modeling to examine how the food web is influenced by the characteristics of the respective canyon section. The models were based on an empirical dataset consisting of biomass and carbon processing data, and general physiological data constraints from the literature. Environmental conditions, most notably organic matter (OM) input and hydrodynamic activity, differed between the canyon sections and strongly affected the benthic food web structure. Despite the large difference in depth, the OM inputs into the food webs of the upper and middle sections were of similar magnitude (7.98�0.84 and 9.30�0.71 mmol C m -2 d -1, respectively). OM input to the lower section was however almost 6-7 times lower (1.26�0.03 mmol C m -2 d -1). Carbon processing in the upper section was dominated by prokaryotes (70% of total respiration), though there was a significant meiofaunal (21%) and smaller macrofaunal (9%) contribution. The high total faunal contribution to carbon processing resembles that found in shallower continental shelves and upper slopes, although the meiofaunal contribution is surprisingly high and suggest that high current speeds and sediment resuspension in the upper canyon favor the role of the meiofauna. The high OM input and conditions in the accreting sediments of the middle canyon section were more beneficial for megafauna (holothurians), than for the other food web compartments. The high megafaunal biomass (516 mmol C m -2), their large contribution to respiration (56% of total respiration) and secondary production (0.08 mmol C m -2 d -1) shows that these accreting sediments in canyons are megafaunal hotspots in the deep-sea. Conversely, carbon cycling in the lower canyon section was strongly dominated by prokaryotes (86% of respiration) and the food web structure therefore resembled that of lower slope and abyssal plain sediments. This study shows that elevated OM input in canyons may favor the faunal contribution to carbon processing and create hotspots of faunal biomass and carbon processing along the continental shelf.
van Oevelen, Dick; Soetaert, Karline; Garcia, R.; de Stigter, Henko C.; Cunha, Marina R.; Pusceddu, Antonio; Danovaro, Roberto
Holocene vegetation in chaco canyon, new Mexico.
Well-preserved plant remains in packrat middens chronicle vegetation change in Chaco Canyon over the past 11,000 years. Early Holocene evidence of communities dominated by Douglas fir, Rocky Mountain juniper, and limber pine in the San Juan Basin calls for revision of traditional constructs based on fossil pollen. Middle and late Holocene vegetation in the canyon was pinyon-juniper woodland up until Anasazi occupation between 1000 and 800 years ago. Instead of climate, Anasazi fuel needs may explain the drastic reduction of pinyon and juniper after 1230 years ago. The lack of pinyon-juniper recovery over the past millennium has implications for contemporary forest and range ecology. PMID:17839658
Betancourt, J L; VAN Devender, T R
Grand Canyon Monitoring and Research Center
NSDL National Science Digital Library
Created in 1995, the Grand Canyon Monitoring and Research Center (GCMRC) was created in order to measure the effects of Glen Canyon Dam operations on natural and physical resources along the Colorado River. As such, the GCMRC's projects also monitor and examine the biological, cultural, and physical resources of the entire Colorado River ecosystem. The materials on their site are divided into five primary sections, including "News & Info", "Research", and "Products". In the "News & Info" area visitors can learn about the endangered species that reside in the area covered by the GCMRC and also take a look at their outreach materials, which include fact sheets, posters, and transcripts from recent symposia. The "Research" area is a bit more technical in nature, containing papers on water flow simulations and elevation data. The site is rounded out by the "Products" area, where visitors can look over new publications and evaluate simulation models.
Land- and resource-use issues at the Valles Caldera
The Valles Caldera possesses a wealth of resources from which various private parties as well as the public at large can benefit. Among the most significant of these are the geothermal energy resource and the natural resource. Wildlife, scenic, and recreational resources can be considered components of the natural resource. In addition, Native Americans in the area value the Valles Caldera as part of their religion. The use of land in the caldera to achieve the full benefits of one resource may adversely affect the value of other resources. Measures can be taken to minimize adverse affects and to maximize the benefits of all the varied resources within the caldera as equitably as possible. An understanding of present and potential land and resource uses in the Caldera, and who will benefit from these uses, can lead to the formulation of such measures.
Intemann, P.R.
Core log: Valles caldera No. 2A, New Mexico
Scientific core hole VC-2A was drilled into the western ring-fracture zone at Sulphur Springs in the Valles caldera, New Mexico. VC-2A, the second scientific core hole in the caldera, was cored through a faulted and brecciated sequence of intracauldron tuffs and volcaniclastic rocks to a depth of 528 m. As of November 1, 1986, the unequilibrated bottom-hole temperature was 212/degree/C. The rocks penetrated are intensely altered and host sub-ore grade stockwork molybdenite mineralization between 25 and 125 m. This report contains a detailed core log to aid researchers in their studies of the Valles caldera magma hydrothermal system. 3 refs., 2 figs.
Starguist, V.L.
Numerical estimation of the effective albedo of an urban canyon
Summary��The paper focuses on the absorption of shortwave radiation in an urban street canyon. To test the effective albedo of the\\u000a canyon an analytic solution of the multiple reflection problem is applied. The infinitesimally long canyon is divided into\\u000a slices and a matrix of view factors for the slices is defined. Incoming shortwave radiation includes direct and diffuse parts\\u000a and
K. Fortuniak
Flood Geology and the Grand Canyon: A Critique
Four claims of Flood Geology�as they are related to the Grand Canyon and specifically to the book Grand Canyon: A Different View�are evaluated by directly addressing Young Earth Creationist arguments, by showing rock features that belie these claims, and by presenting the most up-to-date scientific theories on the origin of the Grand Canyon. We conclude that Young Earth Creationism promotes
Carol A. Hill; Stephen O. Moshier
Holocene sedimentary activity in a non-terrestrially coupled submarine canyon: Cook Strait Canyon system, New Zealand
NASA Astrophysics Data System (ADS)
The Cook Strait Canyon system, located between the North and South islands of New Zealand, is a large (1800 km2), multi-branching, shelf-indenting canyon on an active subduction margin. The canyon comes within 1 km of the coast, but does not intercept fluvial or littoral sediment systems and is therefore defined as a non-terrestrially coupled system. Sediment transport associated with a strong tidal stream, and seafloor disturbance related to numerous high-activity faults, is known from previous studies. Little is known, however, about the rates of sedimentary activity in the canyon and the processes driving it. A substantial dataset of EM300 multibeam bathymetry, gravity cores, 3.5 kHz seismic reflection profiles, camera and video transects and current meter data have been collected across the region between 2002 and 2011. The canyon system therefore provides an excellent study area for understanding sediment transport in a non-coupled submarine canyon system. Analysis of the data reveals a two-staged sediment transport system where: (1) oceanographic (tidal) processes mobilise sediment from the continental shelf and transport it to depocentres in the upper-central canyons, and (2) tectonic (earthquake) processes remobilise sediment that is transported through the lower canyon to the deep ocean. Tidal boundary-layer currents within the canyon reach velocities up to 0.53 m/s and are capable of mobilising fine sand in the central reach of the upper canyons. The velocity is higher at the canyon rim and capable of mobilising coarse sand. Sediment depocentres resulting from this tidally forced sediment transport have a well formed geomorphology within the mid-upper canyon arms of Cook Strait and Nicholson Canyons. Pseudo-static stability modelling, supported by sediment core analysis, indicates that sediment accumulated in the upper canyons fails during seismic events approximately every 100 years. The 100 year return period ground shaking-level (peak ground acceleration, ignoring the effect of the water column above the seabed) at this site is estimated to be 0.23g. Fresh rock outcrops and bed-scour in the lower canyon floor indicate that remobilised material is transported to the deep ocean. The processes identified here are likely to be analogous to those occurring in many non-coupled shelf-indenting canyons on active margins globally, and provide a framework within which the biological response to geomorphic processes in submarine canyons can be assessed.
Mountjoy, J. J.; Micallef, A.; Stevens, C. L.; Stirling, M. W.
Search for Aqueous Minerals in Parana Valles, Mars
NASA Astrophysics Data System (ADS)
Search for Aqueous Minerals in Parana Valles, Mars S. Talib, J.B. Dalton and J.M. Moore We have performed a compositional analysis of surface deposits in Parana Valles using a combination of Mars Observer Laser Altimeter (MOLA), Mars Observer Camera (MOC), Thermal Emission Spectrometer (TES) and Thermal Emission Imaging Subsystem (THEMIS) observations. Parana Valles lies within a well-defined basin in the southern highlands and contains a well-developed watershed drainage network (Barnhart et al., 2007). The strong evidence of hydrologic activity suggests that aqueously-derived minerals may be sufficiently abundant to be detected through orbital remote sensing. We examined MOLA observations to determine locations of smaller basins within Parana, where ponding and sedimentation may have occurred. Mosaics of MOC images were then examined to identify albedo differences which could indicate mineral deposits. THEMIS night-time thermal infrared mosaics were examined to identify regions of high thermal inertia, which may be swept clear of surface dust. Finally, image cubes from TES were compiled. The TES data were culled following the method of Stockstill et al. (2005) to eliminate orbital tracks of high atmospheric dust or water ice cloud composition. A Dust Cover Index (Ruff and Christensen 2002) was computed for TES data and used to reject observations obscured by high surface dust. Once the TES image cube had been reduced, regions of interest were defined based on the areas determined likely to contain minerals of aqueous origin based on the MOLA, MOC, and THEMIS observations. A linear spectral mixture model was then applied to these spectra using the Arizona State University Thermal Emission Spectral Library (Christensen et al., 2000) to estimate mineral abundances. We found that the surface mineralogy of Parana Valles is dominated by mixtures of phyllosilicates, feldspars, olivines and pyroxenes. This is consistent with chemically-weathered basaltic material.
Talib, Saveelah; Dalton, J. B.; Moore, J. M.
36 CFR 7.8 - Sequoia and Kings Canyon National Parks.
Code of Federal Regulations, 2010 CFR
...2010-07-01 false Sequoia and Kings Canyon National Parks. 7.8 Section 7... § 7.8 Sequoia and Kings Canyon National Parks. (a) Dogs and cats...lands within Sequoia and Kings Canyon National Parks. (i)...
36 CFR 7.8 - Sequoia and Kings Canyon National Parks.
Code of Federal Regulations, 2010 CFR
...2009-07-01 false Sequoia and Kings Canyon National Parks. 7.8 Section 7... § 7.8 Sequoia and Kings Canyon National Parks. (a) Dogs and cats...lands within Sequoia and Kings Canyon National Parks. (i)...
75 FR 439 - Glen Canyon Dam Adaptive Management Work Group (AMWG)
Federal Register 2010, 2011, 2012, 2013
...INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group (AMWG...SUMMARY: The Glen Canyon Dam Adaptive Management Program (AMP) was...Decision on the Operation of Glen Canyon Dam Final Environmental Impact Statement...
78 FR 54482 - Charter Renewal, Glen Canyon Dam Adaptive Management Work Group
Federal Register 2010, 2011, 2012, 2013
...4073000] Charter Renewal, Glen Canyon Dam Adaptive Management Work Group AGENCY...renewing the charter for the Glen Canyon Dam Adaptive Management Work Group. The purpose...concerning the operation of Glen Canyon Dam and the exercise of other authorities...
33 CFR 165.1155 - Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California.
Code of Federal Regulations, 2013 CFR
... false Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California...1155 Security Zone; Diablo Canyon Nuclear Power Plant, Avila Beach, California...a 2,000 yard radius of Diablo Canyon Nuclear Power Plant centered at position...
Continental Scientific Drilling Program: Valles Caldera, New Mexico
The U.S. Continental Scientific Drilling Program attempts to develop a better understanding of the geologic and hydrologic mechanisms within the continental crust, under the auspices of an interagency group comprising the US Department of Energy, the National Science Foundation, and the U.S. Geological Survey. Ten years of research and drilling in the Valles caldera of northern New Mexico has provided a new understanding of volcanism and geothermal systems within a large caldera. Situated at the intersection of the Rio Grande rift and the Jemez volcanic lineament, the Valles caldera and Toledo calderas were formed during two massive eruptions 1.1 and 1.5 M a that vented approximately 300 to 400 km{sup 3} of high-silica rhyolitic tephra. The research at the Valles/Toledo caldera has provided more than 3000 m of corehole samples, which are stored in a repository in Grand Junction, Colorado, and are accessible to the public. This research has also helped support theories of mineral deposition within hydrothermal systems-hot water circulating through breccias, leaching elements from the rocks, and later depositing veins of economically valuable materials.
Ascension Submarine Canyon, California - Evolution of a multi-head canyon system along a strike-slip continental margin
Ascension Submarine Canyon, which lies along the strike-slip (transform) dominated continental margin of central California, consists of two discrete northwestern heads and six less well defined southeastern heads. These eight heads coalesce to form a single submarine canyon near the 2700 m isobath. Detailed seismic stratigraphic data correlated with 19 rock dredge hauls from the walls of the canyon system, suggest that at least one of the two northwestern heads was initially eroded during a Pliocene lowstand of sea level ???3.8 m.y. B.P. Paleogeographic reconstructions indicate that at this time, northwestern Ascension Canyon formed the distal channel of nearby Monterey Canyon and has subsequently been offset by right-lateral, strike-slip faulting along the San Gregorio fault zone. Some of the six southwestern heads of Ascension Canyon may also have been initially eroded as the distal portions of Monterey Canyon during late Pliocene-early Pleistocene sea-level lowstands (???2.8 and 1.75 m.y. B.P.) and subsequently truncated and offset to the northwest. There have also been a minimum of two canyon-cutting episodes within the past 750,000 years, after the entire Ascension Canyon system migrated to the northwest past Monterey Canyon. We attribute these late Pleistocene erosional events to relative lowstands of sea level 750,000 and 18,000 yrs B.P. The late Pleistocene and Holocene evolution of the six southeastern heads also appears to have been controlled by structural uplift of the Ascension-Monterey basement high at the southeastern terminus of the Outer Santa Cruz Basin. We believe that uplift of this basement high sufficiently oversteepened submarine slopes to induce gravitational instability and generate mass movements that resulted in the erosion of the canyon heads. Most significantly, though, our results and interpretations support previous proposals that submarine canyons along strike-slip continental margins can originate by tectonic trunction and lateral offset. ?? 1986.
Nagel, D. K.; Mullins, H. T.; Greene, H. G.
Geotechnical Considerations of Canyon Formation: the Case of Cap de Creus Canyon, Mediterranean Sea
A portion of the Cap de Creus has been selected for a detailed analysis of slope instability. The selected area is located on the north side of the Canyon between water depth ranging between 150 m and 750 m. This sector, which presents geomorphic evidences of landsliding, has been sampled at three different water depths along a line perpendicular to
M. Sansoucy; J. Locat; H. J. Lee
Suspended Sediment over Redondo Submarine Canyon and Vicinity, Southern California.
National Technical Information Service (NTIS)
Redondo Canyon, which is the southern half of Santa Monica Bay, is one of several deeply-incised submarine valleys which cross the nearshore shelf off southern California. Sediments in the vicinity of the canyon consist primarily of fine sands and sandy s...
R. M. Beer
Space, evolution, and function in the houses of Chaco Canyon
The prehistoric cultural landscape of Chaco Canyon is made up of monumental great houses and small houses. The Chaco Canyon architectural record has been extensively studied, yet the relationship between great and small houses remains a fundamental problem of Southwest archaeology. By using space syntax access analyses, I examine in this research the spatial organisation of great and small houses
Wendy Bustard
Benthic foraminifera of a Miocene canyon and fan
We present benthic foraminiferal assemblage data from an exhumed Miocene canyon and fan system from the Tabernas Basin (SE Spain). The presence of good indicator taxa and unique assemblages occupying specific environments allows the distinction of slope, canyon and fan environments within the Tabernas Basin by foraminiferal assemblages alone. Five assemblages are defined on the basis of the occurrence of
M. Rogerson; T. J. Kouwenhoven; G. J. van der Zwaan; B. J. O'Neill; C. J. van der Zwan; G. Postma; K. Kleverlaan; H. Tijbosch
The Grand Canyon of the Yellowstone Online Tour
NSDL National Science Digital Library
This Yellowstone National Park website offers an online tour of the Grand Canyon of the Yellowstone. Prominent viewpoints of the canyon are highlighted with photos and information concerning their history. Other stops include information on giant glacial boulders and waterfalls. Similar tours of the Old Faithful area, the Norris Geyser Basin, the Fountain Paint Pots, and the Mammoth Hot Springs are also available online.
Park, Yellowstone N.
The Grand Canyon: The Top Two Rock Layers
NSDL National Science Digital Library
Watch this short video clip to learn more about the rock layers of the Grand Canyon. This video discusses the two sandstone formations that comprise the uppermost part of the canyon. The video also discusses how the two sandstone layers were formed.
Seismological shoot-out at Diablo Canyon
The Pacific Gas and Electric Co.'s right to operate a nuclear power plant at California's Diablo Canyon has been contested for eight years at 36 federal and four state hearings, three licensing appeals, and two congressional inquiries. The utility announced that design errors in the structural supports were discovered just as the plant appeared ready for operation. Corrections will be technically straightforward, but the political and legal ramifications may cause further delays by supporting the claims of environmental groups that the plant cannot withstand an earthquake. A review of the debate indicates that the developing field of seismic engineering is still imprecise because the theoretical bases remain untested. (DCK)
Smith, R.J.
20140430_Green Machine Florida Canyon Hourly Data
Employing innovative product developments to demonstrate financial and technical viability of producing electricity from low temperature geothermal fluids, coproduced in a mining operation, by employing ElectraTherm's modular and mobile heat-to-power "micro geothermal" power plant with output capacity expected in the 30-70kWe range. The Green Machine is an Organic Rankine Cycle power plant. The Florida Canyon machine is powered by geothermal brine with air cooled condensing. The data provided is an hourly summary from 01 April to 30 April 2014.
Joe Thibedeau
North Atlantic slope and canyon study. Volume 2. Final report
A field program to investigate the currents and sediment transport along the outershelf and upper slope along the southern flank of Georges Bank was conducted between 1980 and 1984. A major part of the field experiment was conducted in Lydonia Canyon, a large submarine canyon which cuts northward about 20 km into the continental shelf from the shelfbreak. A smaller experiment was conducted in Oceanographer Canyon to compare the currents in these two major canyons. Long-term current observations were made at 20 locations in or adjacent to Lydonia Canyon, and at 9 stations on the continental slope. Detailed semi-synoptic hydrographic observations were made on 9 cruises. The currents associated with Gulf Stream warm core rings (WCR's) strongly affect the flow along the outer shelf and upper slope; eastward currents in excess of 75cm/s were associated with WCR's.
Butman, B.
Active geologic processes in Barrow Canyon, northeast Chukchi Sea
Circulation patterns on the shelf and at the shelf break appear to dominate the Barrow Canyon system. The canyon's shelf portion underlies and is maintained by the Alaska Coastal Current (A.C.C.), which flows northeastward along the coast toward the northeast corner of the broad Chukchi Sea. Offshelf and onshelf advective processes are indicated by oceanographic measurements of other workers. These advective processes may play an important role in the production of bedforms that are found near the canyon head as well as in processes of erosion or non-deposition in the deeper canyon itself. Coarse sediments recovered from the canyon axis at 400 to 570 m indicate that there is presently significant flow along the canyon. The canyon hooks left at a point north of Point Barrow where the A.C.C. loses its coastal constriction. The left hook, as well as preferential west-wall erosion, continues down to the abyssal plain of the Canada Basin at 3800 m. A possible explanation for the preferential west-wall erosion along the canyon, at least for the upper few hundred meters, is that the occasional upwelling events, which cause nutrient-rich water to flow along the west wall would in turn cause larger populations of burrowing organisms to live there than on the east wall, and that these organisms cause high rates of bioerosion. This hypothesis assumes that the dominant factor in the canyon's erosion is biological activity, not current velocity. Sedimentary bedforms consisting of waves and furrows are formed in soft mud in a region on the shelf west of the canyon head; their presence there perhaps reflects: (a) the supply of fine suspended sediments delivered by the A.C.C. from sources to the south, probably the Yukon and other rivers draining northwestern Alaska; and (b) the westward transport of these suspended sediments by the prevailing Beaufort Gyre which flows along the outer shelf. ?? 1982.
Eittreim, S.; Grantz, A.; Greenberg, J.
Hanging canyons of Haida Gwaii, British Columbia, Canada: Fault-control on submarine canyon geomorphology along active continental margins
NASA Astrophysics Data System (ADS)
Faulting commonly influences the geomorphology of submarine canyons that occur on active continental margins. Here, we examine the geomorphology of canyons located on the continental margin off Haida Gwaii, British Columbia, that are truncated on the mid-slope (1200-1400 m water depth) by the Queen Charlotte Fault Zone (QCFZ). The QCFZ is an oblique strike-slip fault zone that has rates of lateral motion of around 50-60 mm/yr and a small convergent component equal to about 3 mm/yr. Slow subduction along the Cascadia Subduction Zone has accreted a prism of marine sediment against the lower slope (1500-3500 m water depth), forming the Queen Charlotte Terrace, which blocks the mouths of submarine canyons formed on the upper slope (200-1400 m water depth). Consequently, canyons along this margin are short (4-8 km in length), closely spaced (around 800 m), and terminate uniformly along the 1400 m isobath, coinciding with the primary fault trend of the QCFZ. Vertical displacement along the fault has resulted in hanging canyons occurring locally. The Haida Gwaii canyons are compared and contrasted with the Sur Canyon system, located to the south of Monterey Bay, California, on a transform margin, which is not blocked by any accretionary prism, and where canyons thus extend to 4000 m depth, across the full breadth of the slope.
Harris, Peter T.; Barrie, J. Vaughn; Conway, Kim W.; Greene, H. Gary
Atmospheric Fragmentation of the Canyon Diablo Meteoroid
NASA Technical Reports Server (NTRS)
About 50 kyr ago the impact of an iron meteoroid excavated Meteor Crater, Arizona, the first terrestrial structure widely recognized as a meteorite impact crater. Recent studies of ballistically dispersed impact melts from Meteor Crater indicate a compositionally unusually heterogeneous impact melt with high SiO2 and exceptionally high (10 to 25% on average) levels of projectile contamination. These are observations that must be explained by any theoretical modeling of the impact event. Simple atmospheric entry models for an iron meteorite similar to Canyon Diablo indicate that the surface impact speed should have been around 12 km/s [Melosh, personal comm.], not the 15-20 km/s generally assumed in previous impact models. This may help explaining the unusual characteristics of the impact melt at Meteor Crater. We present alternative initial estimates of the motion in the atmosphere of an iron projectile similar to Canyon Diablo, to constraint the initial conditions of the impact event that generated Meteor Crater.
Pierazzo, E.; Artemieva, N. A.
Transient wind-driven upwelling in a submarine canyon: A process-oriented modeling study
A hydrodynamic model is employed to study flow near a submarine canyon during conditions of upwelling-favorable coastal winds. Findings reveal that up-canyon flow is the rapid geostrophic adjustment to barotropic pressure gradients establishing across the canyon. Stratification leads to the formation of a cyclonic eddy within the canyon, trapping neutrally buoyant matter, and limits the upwelling depth only when a
Jochen K�mpf
Physical modeling of tidal resonance in a submarine canyon
NASA Astrophysics Data System (ADS)
observations in submarine canyons poleward of 30� are usually dominated by the semidiurnal (M2) tidal frequency, which is superinertial at these latitudes. Observations from a submarine canyon at 44�N (the Gully, Nova Scotia) suggest that canyons can be dominated by the subinertial (K1) tidal frequency if length scales are correct for resonance of the K1 frequency. A model of the Gully was constructed in a tank on a rotating table and tidal currents generated to determine factors that influence resonance. Resonance curves were fit to measurements from the laboratory canyon for a range of stratifications, background rotation rates, and forcing amplitudes. Dense water was observed upwelling onto the continental shelf on either side of the laboratory canyon and traveled at least one canyon width along the shelf. Friction values measured in the laboratory were much higher than expected, probably due to upwelled water surging onto the shelf on each tidal cycle, similar to a tidal bore. By scaling observations from the laboratory to the ocean and assuming friction in the ocean is also affected by water traveling onto the shelf, a resonance curve for the ocean was created. Because of the broad resonance curve, the diurnal tide remains strong year round at the Gully, even as stratification at the shelf break changes. Dense water surging onto the shelf on tidal frequencies may affect friction and mixing at other nonresonant canyons.
Sou�f, K. E.; Allen, S. E.
Continuous monitoring of carbon monoxide in a deep street canyon
NASA Astrophysics Data System (ADS)
The results of a 1-week continuous monitoring campaign of carbon monoxide in a deep street canyon in the city of Naples are reported. CO was selected as a passive pollutant emitted by vehicle exhausts. The geometry of the canyon is: width W=5.8m and height H=33m (aspect ratio AR= H/ W=5.7). The monitoring campaign was carried out from 14 to 20 June 2006. CO concentration level was measured at pedestrian level ( h=2.5m) and roof top level ( h=25m). In the same period traffic flow in the street canyon was manually measured and the CO emission rate from vehicle exhausts was evaluated using the COPERT procedure. Meteorological conditions (wind velocity and direction) are also reported and their effect on CO concentration level in the canyon is discussed. Due to its geometry the street canyon monitored may be considered almost ideal. The results show that the deep street canyon is a "hot spot" compared with roads with high traffic flows in the urban area of Naples, and that significant differences exist between concentration levels at pedestrian and roof top level. Some insights into the effect and relative importance of meteorological parameters on the air quality in the canyon are also given. The monitoring data collected have been made available on the web and can be used by other researchers to test air dispersion models.
Murena, Fabio; Favale, Giuseppe
Significance of the fine drainage pattern for submarine canyon evolution: The Foix Canyon System, Northwestern Mediterranean Sea
NASA Astrophysics Data System (ADS)
Submarine gullies are relatively small valleys that occur in a variety of submarine slopes. They are very common in continental slopes and in submarine canyon heads and flanks, where they often form tributary networks. Gullies are smaller than submarine canyons, though there is no standardised size criterion to distinguish between them. Gullies and gully networks have been often viewed as initial steps in the development of larger submarine canyons and more mature drainage networks. The shelf-incising submarine Foix Canyon System (FCS) is located in the northwestern Mediterranean Sea. Numerous, well-developed and morphologically diverse gullies carve its two heads and flanks. The objective of this study is to analyse the drainage network of the FCS and decipher the role of gullies in its evolution. Submarine gully and canyon networks were extracted from swath bathymetry data of 50 m grid size using Geographic Information Systems (GIS). A systematic morphometric analysis was carried out on drainage network of the FCS by using the Horton-Strahler method. Our results show that the FCS is formed by 1660 streams, 1000 km in total length, which can be classified to six stream orders. To detect relevant morphological changes along valley sections, the drainage density, the stream frequency and the drainage area relief parameters were applied. Furthermore, a branching index (Ib) was developed to characterise the geometry of the submarine drainage network. In the canyon heads Ib values are ~ 1.7, which correspond to a dendritic network, whereas Ib in the canyon branches displays values of ~ 2.2 corresponding to a pinnate one. At a finer scale, we have identified two types of canyon flank gullies, namely "rim gullies" and "toe gullies": (1) rim gullies form large, dendritic networks that extend from the canyon thalweg up to the canyon rim, and (2) toe gullies form smaller pinnate networks restricted to the lower part of the canyon flanks. The formation and development of rim gullies are interpreted as the main process responsible for canyon head growth and across-flank transport of material from the continental shelf. Toe gullies, on the other hand, are the morphological expression of the rejuvenation of rim gullies and the canyon itself. Axial incision and toe gully formation are interpreted as the result of bottom-to-top erosive processes acting at different scales, in response to regional and local changes of the factors controlling the system, respectively. This study helps to identify a variety of gullies and the processes they result from and provides a morphometric methodology to characterise submarine drainage networks at fine resolution scales.
Tubau, Xavier; Lastras, Galderic; Canals, Miquel; Micallef, Aaron; Amblas, David
Water quality of Canyon Lake, central Texas
The volume-weighted average concentrations of the principal dissolved constituents in Canyon Lake on the Guadalupe River in central Texas are usually less than 240 milligrams per liter of dissolved solids, 20 milligrams per liter of chloride, and 30 milligrams per liter of sulfate. The water, which is very hard, has a volume-weighted average concentration of hardness of about 200 milligrams per liter. There is little seasonal variation in the volume-weighted average concentrations of the principal dissolved constituents. Thermal stratification of the lake usually begins during March and persists until September or October. Stratification results in significant seasonal and areal variations in dissolved oxygen, which in turn result in higher concentrations of dissolved iron, dissolved manganese, and total ammonia during the summer. Oxygen used in the stabilization of unoxidized material in the lake is not replaced during summer stagnation. The depth-integrated concentration of dissolved oxygen averaged less than 4.0 milligrams per liter during summer stagnation and about 9.0 milligrams per liter during winter circulation. The concentrations of dissolved iron and dissolved manganese, which varied seasonally, were closely related to the concentrations of dissolved oxygen. Reducing conditions in the hypolimnion often result in the dissolution of iron and manganese from bottom sediments in the deep parts of the lake. At site Dc, a deep site on an arm of Canyon Lake, the summer concentrations of dissolved iron averaged 860 micrograms per liter and the concentration of dissolved manganese averaged 390 micrograms per liter. The concentrations of total ammonia in the lake usually were less than 0.2 milligram per liter except in the hypolimnion (bottom stratum) during summer stagnation when nitrate and nitrite are reduced to ammonia. The closure of Canyon Dam resulted in a change in the monthly average water temperature of the Guadalupe River downstream from the dam. Prior to closure, the maximum monthly average water temperature for the Guadalupe River near Sattler, which was 29.0? degrees Celsius, occurred during June or July. Since closure of the dam, the maximum monthly average water temperature, which is 19.0? degrees Celsius, occurs during September or November.
Roddy, W. R.; Waddell K. M.
Geotechnical Considerations Of Submarine Canyon Formation: The Case Of Cap De Creus Canyon
A portion of the Cap de Creus canyon, situated in the Gulf of Lion, has been selected for a detailed analysis of slope instability.\\u000a This sector has been chosen because of morphological evidence for slide. Three piston cores have been taken at different water\\u000a depths along an axis perpendicular to the thalweg and a box core has also been taken
M. Sansoucy; Jacques Locat; H. Lee
NSDL National Science Digital Library
This series of modules integrates printable images of Mars into classroom activities. Four broad topics cover the exploration of Mars and the Pathfinder missions, the great Martian floods and the Pathfinder landing site, the canyon Valles Marineris, and water on Mars. Each topic has several discrete activities associated with it that can be used independently. There are supporting materials for teachers as well as background information on the images. There are two curriculum modules for grades 4-10, one for grades 6-12 and one for grades 9-12.
NSDL National Science Digital Library
This NASA (National Aeronautics and Space Administration) planet profile provides data and images of the planet Mars. These data include planet size, orbit facts, distance from the Sun, rotation and revolution times, temperature, atmospheric composition, density, surface materials and albedo. Images with descriptions include surface features such as canyons, volcanoes, Viking 1 and 2 landing sites, the South Pole, plateaus, the Schiaparelli Crater, Amazonis Plains, Cerberus Crater, Valles Marineris, Chasma, Olympis Mons, and images of Mars two moons Phobos and Deimos. Images were taken by the Viking 1 and 2 Landers and the Viking Orbiter Spacecraft.
Report Summary, Final Hells Canyon Environmental Investigation.
The Northwest Electric Power Planning and Conservation Act of 1980 provided for the establishment of a Regional Power Planning Council (Regional Council) and mandated the development of a Columbia River Basin Fish and Wildlife Program (F&W Program). The F&W Program was adopted by the Regional Council in November 1982. and is intended to mitigate fish and wildlife losses resulting from the development of hydroelectric dams on the Columbia and Snake Rivers. One element of the FLW Program is the Water Budget. It calls for additional flows in the Columbia and Snake Rivers between April 15 and June 15 to improve the survival of juvenile salmon and steelhead migrating downstream. The Snake River's contribution to the Water Budget is 20,000 cubic feet per second-months (A volume of water equal to a flow of 20.000 cubic feet per second, 24 hours per day, for a period of a month) over and above water that would normally flow for power production. The water for the Water Budget would come out of Idaho Power Company's (IPCo) Hells Canyon Complex and the Corps of Engineers' (Corps) Dvorshak Reservoir. IPCo's Hells Canyon Complex consists of three dams, Brownlee, Oxbow, and Hells Canyon. Brownlee, at the upstream end, contains a large reservoir and controls flow to the lower dams. IPCo's participation in the Water Budget could affect the level of the Brownlee Reservoir and flows downstream of the Hells Canyon Complex on the Snake River. In light of this, Bonneville Power Administration (BPA) and IPCo contracted with the consulting firm of CH2!4 Hill to study the potential changes that could occur to the environment. The Environmental Investigation (EI) takes into account concerns that were expressed by the public at a series of public meetings held in the Snake River area during June 1983 and again during September 1984. Existing information and consultations with agencies which have management responsibilities in the project area formed the basis for the data used in the EI. This document summarizes the findings of the final EI in the following areas: (1) natural features, water use, and air and water quality; (2) fish, wildlife, and vegetation; (3) land use, recreation, and aesthetics; and (4) historical and archaeological resources. The EI provides information to be used by IPCo as they assess the effect on the system operations (power and nonpower) resulting from Water Budget participation. BPA and IPCo are continuing to discuss the prospects for IPCo's involvement in implementation of the Water Budget on the Snake River. When IPCo reaches a decision on whether and to what extent it wishes to participate in a Water Budget agreement with BPA, the proposed agreement will be subject to analysis under the National Environmental Policy Act (NEPA). That analysis will consider alternatives, significance of impacts to the environment, and mitigative measures.
United States. Bonneville Power Administration.
Compositional range in the Canyon Diablo meteoroid
NASA Technical Reports Server (NTRS)
The compositional range within the Canyon Diablo (CD) iron meteorites associated with the formation of the Meteor Crater (Arizona) was examined, using the INAA to analyze a set of CD samples consisting of nine irons collected within 7 km of the Meteor Crater, four Arizona IAB irons that were identified by Wasson (1968) as transported CD fragments, and irons from Las Vegas (Nevada) and Moab (Utah) that Buchwald (1975) suggested to be transported CD fragments. Results show that the irons named Helt Township, Idaho, Las Vegas, Mamaroneck, Moab, and Pulaski County are, most likely, mislabeled CD specimens. On the other hand, meteorites named Alexander County, Allan Hills A77283, Ashfork, Fairfield, and Rifle are identified as compositionally distinct independent falls.
Wasson, John T.; Ouyang, Xinwei
Licensing process at Diablo Canyon nuclear powerplant
George Maneatis of Pacific Gas and Electric Co. and Nunzio Palladino of the Nuclear Regulatory Commission (NRC) were the principal witnesses at a hearing held to discuss some of the concerns about the Diablo Canyon nuclear plant relating to earthquake vulnerability and quality assurance during construction. The utility and NRC both responded when the earthquake fault and the construction and design errors were discovered to verify the seismic as well as non-seismic design of the plant, but public confidence has not been restored. The committee was exploring how much the licensing procedure itself contributed to the loss of public confidence. Testimony was also heard from two panels of concerned citizens and their consultants. An appendix with additional statements and responses follows their testimony. (DCK)
Not Available
Compositional range in the Canyon Diablo meteoroid
The Ir distribution in the IAB Canyon Diablo meteorites associated with the formation of Meteor Crater, Arizona, ranges from 2.1 to 2.5 {mu}g/g with peaks at 2.17 and 2.34 {mu}g/g. Only Ir, Ni, and Cu show appreciably more variance in the large set of specimens than observed within a single specimen. The Ir peaks may reflect random sampling of the large (40-100 m), fractionated meteoroid or the presence of two distinct metallic regions differing in composition. None of the other elements they determined show strong correlations with Ir; the Au range is strikingly small (1.5-1.6 {mu}g/g). The presence of chondritic silicates and high contents of planetary-type noble gases in IAB indicates that these solidified rapidly following melting, as expected if they originated as pools of impact-generated melt on a chondritic body. The absence of fractional crystallization trends is consistent with such a model. That 14 of 15 Ir contents fall into two peaks suggests the possibility that the meteoroid included two pools. The alternative that the distribution is continuous can be tested by the study of additional specimens; those from the crater rim are particularly important since these are largely shrapnel spalled from the trailing hemisphere of the meteoroid. Their studies show that the irons named Helt Township, Idaho, Las Vegas, Mamaroneck, Moab, and Pulaski County are probably mislabelled Canyon Diablo specimens; Jenny's Creek and Jenkins are also compositionally indistinguishable. Alexander County, Allan Hills A77283, Ashfork, Fairfield, and Rifle are compositionally distinct, independent falls.
Wasson, J.T.; Ouyang, Xinwei (Univ. of California, Los Angeles (USA))
Analysis of Recorded Colorado River Boating Accidents in Glen Canyon for 1980, 1982, and 1984, and in Grand Canyon for 1981 through 1983.
National Technical Information Service (NTIS)
Recorded boating accidents for three boating seasons on the Glen and Grand Canyon sections of the Colorado River (between Glen Canyon Dam and Diamond Creek) are analyzed to determine whether a significant correlation existed between accident occurrence an...
A. H. Underhill, M. H. Hoffman, R. E. Borkan
Fossil Woodwardia virginica Foliage From the Middle Miocene Yakima Canyon
NSDL National Science Digital Library
Fossil Woodwardia virginica foliage from the middle Miocene Yakima Canyon flora of central Washington State, USA. Vegetative and fertile features of this fossil are remarkably similar to those of the modern ""Virginia chain fern"" of the Atlantic coastal region, USA.
Kathleen B. Pigg (Arizona State University;Department of Plant Biology ADR;POSTAL)
Sequoia and Kings Canyon National Parks Action Plan.
National Technical Information Service (NTIS)
As participants in the Climate Friendly Parks program, Sequoia and Kings Canyon National Parks belong to a network of parks that are putting climate friendly behavior at the forefront of sustainability planning in national parks. By conducting an emission...
Initiation and Frequency of Debris Flows in Grand Canyon, Arizona.
National Technical Information Service (NTIS)
Debris flows occur in 600 tributaries of the Colorado River in Grand Canyon, Arizona when intense precipitation causes slope failures in bedrock or colluvium. These slurries transport poorly sorted sediment, including very large boulders that form rapids ...
P. G. Griffiths R. H. Webb T. S. Melis
Experimental evaluation of solids suspension uniformity in canyon process vessels.
National Technical Information Service (NTIS)
Experimental evaluation of solids suspension in canyon process vessels was performed at several paddle agitator speeds and different volume levels in a geometrically similar vessel. The paddle agitator speeds examined were 280, 370, 528, and 686 rpm and v...
N. M. Hassan
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
3. VIEW OF DIABLO CANYON LOOKING DOWNSTREAM FROM THE VALVE HOUSE AT ELEVATION 1044, 1989. - Skagit Power Development, Diablo Dam, On Skagit River, 6.9 miles upstream from Newhalem, Newhalem, Whatcom County, WA
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
1. GENERAL VIEW OF SHOSHONE HYDROELECTRIC PLANT IN GLENWOOD CANYON, VIEW TO THE NORTHEAST ALONG U.S. 6 AND THE COLORADO RIVER. - Shoshone Hydroelectric Plant Complex, 60111 U.S. Highway 6, Glenwood Springs, Garfield County, CO
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
60. SUPPORT CARRIAGE ASSEMBLY AT ISLIP CANYON SHOWING CURVED RAILS AND FLOATING BARGE IN BACKGROUND, February 16, 1948. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA
Thirty-Five Years at Pajarito Canyon Site.
National Technical Information Service (NTIS)
A history of the research activities performed at the Pajarito Canyon Site from 1946 to 1981 is presented. Critical assemblies described include: the Topsy assembly; Lady Godiva; Godiva 2; Jezebel; Flattop; the Honeycomb assembly for Rover studies; Kiwi-T...
H. C. Paxton
The Shape of Trail Canyon Alluvial Fan, Death Valley
NASA Technical Reports Server (NTRS)
A modified conic equation has been fit to high-resolution digital topographic data for Trail Canyon alluvial fan in Death Valley, California. Fits were accomplished for 3 individual fan units of different age.
Farr, Tom G.; Dohrenwend, John C.
Management of radioactive chemical waste can be a complicated business. H Canyon and F/H Analytical Labs are two facilities present at the Savannah River Site in Aiken, SC that are at the forefront. In fact H Canyon is the only large-scale radiochemical processing facility in the United States and this processing is only enhanced by the aid given from F/H Analytical Labs. As H Canyon processes incoming materials, F/H Labs provide support through a variety of chemical analyses. Necessary checks of the chemical makeup, processing, and accountability of the samples taken from H Canyon process tanks are performed at the labs along with further checks on waste leaving the canyon after processing. Used nuclear material taken in by the canyon is actually not waste. Only a small portion of the radioactive material itself is actually consumed in nuclear reactors. As a result various radioactive elements such as Uranium, Plutonium and Neptunium are commonly found in waste and may be useful to recover. Specific processing is needed to allow for separation of these products from the waste. This is H Canyon's specialty. Furthermore, H Canyon has the capacity to initiate the process for weapons-grade nuclear material to be converted into nuclear fuel. This is one of the main campaigns being set up for the fall of 2012. Once usable material is separated and purified of impurities such as fission products, it can be converted to an oxide and ultimately turned into commercial fuel. The processing of weapons-grade material for commercial fuel is important in the necessary disposition of plutonium. Another processing campaign to start in the fall in H Canyon involves the reprocessing of used nuclear fuel for disposal in improved containment units. The importance of this campaign involves the proper disposal of nuclear waste in order to ensure the safety and well-being of future generations and the environment. As processing proceeds in the fall, H Canyon will have a substantial number of samples being sent to F/H Labs. All analyses of these samples are imperative to safe and efficient processing. The important campaigns to occur would be impossible without feedback from analyses such as chemical makeup of solutions, concentrations of dissolution acids and nuclear material, as well as nuclear isotopic data. The necessity of analysis for radiochemical processing is evident. Processing devoid of F/H Lab's feedback would go against the ideals of a safety-conscious and highly accomplished processing facility such as H Canyon.
Weinheimer, E.
Properties of Saltstone Prepared Containing H-Canyon Waste
Saltstone slurries were prepared from solutions made from H-Canyon waste and evaluated for processing properties. Salt solutions prepared with a 1:1 ratio of Tank 50H simulant and H-Canyon blended waste produced slurries that met the processing requirements in Table 2 of the Task Technical and Quality Assurance Plan (TTQAP). Additions of set retarder and antifoam were necessary to meet these
Diablo Canyon plant information management system and integrated communication system
The implementation of a comprehensive maintenance system called the plant information management system (PIMS) at the Diablo Canyon plant, together with its associated integrated communication system (ICS), is widely regarded as the most comprehensive undertaking of its kind in the nuclear industry. This paper provides an overview of the program at Diablo Canyon, an evaluation of system benefits, and highlights the future course of PIMS.
Stanley, J.W.; Groff, C.
Safety Evaluation for Packaging (onsite) T Plant Canyon Items
This safety evaluation for packaging (SEP) evaluates and documents the ability to safely ship mostly unique inventories of miscellaneous T Plant canyon waste items (T-P Items) encountered during the canyon deck clean off campaign. In addition, this SEP addresses contaminated items and material that may be shipped in a strong tight package (STP). The shipments meet the criteria for onsite shipments as specified by Fluor Hanford in HNF-PRO-154, Responsibilities and Procedures for all Hazardous Material Shipments.
B-Plant Canyon Ventilation Control System Description
Project W-059 installed a new B Plant Canyon Ventilation System. Monitoring and control of the system is implemented by the Canyon Ventilation Control System (CVCS). This document describes the CVCS system components which include a Programmable Logic Controller (PLC) coupled with an Operator Interface Unit (OIU) and application software. This document also includes an Alarm Index specifying the setpoints and technical basis for system analog and digital alarms.
A submarine canyon conduit under typhoon conditions off Southern Taiwan
The function of a submarine conduit under typhoon conditions is examined. The study site is the Kao-ping river, shelf, and submarine canyon (KPRSC) system located off southern Taiwan on a wave-dominated microtidal coast. The head of the canyon is located approximately 1km off the river mouth. Two comprehensive 1-month field experiments were carried out in 2000 and 2002 during the
James T. Liu; Hui-Ling Lin; Jia-Jang Hung
Results of mineral surveys indicate that the Chama River Canyon Wilderness and contiguous roadless area in new Mexico have a probable mineral-resource potential for copper with associated uranium and silver. Gypsum occurs throughout the area, exposed in the canyon walls. Further study of the wilderness should concentrate on exploratory drilling to test the oil and gas potential of Pennsylvanian strata and evaluate vanadium anomalies in the Todilto as a prospecting guide for locating uranium.
Ridgley, Jennie, L.; Light, Thomas, D.
Continuous monitoring of carbon monoxide in a deep street canyon
The results of a 1-week continuous monitoring campaign of carbon monoxide in a deep street canyon in the city of Naples are reported. CO was selected as a passive pollutant emitted by vehicle exhausts. The geometry of the canyon is: width W=5.8m and height H=33m (aspect ratio AR=H\\/W=5.7). The monitoring campaign was carried out from 14 to 20 June 2006.
Fabio Murena; Giuseppe Favale
2008 High-Flow Experiment at Glen Canyon Dam Benefits Colorado River Resources in Grand Canyon National Park
On March 5, 2008, the Department of the Interior began a 60-hour high-flow experiment at Glen Canyon Dam, Arizona, to determine if water releases designed to mimic natural seasonal flooding could be used to improve downstream resources in Glen Canyon National Recreation Area and Grand Canyon National Park. U.S. Geological Survey (USGS) scientists and their cooperators undertook a wide range of physical and biological resource monitoring and research activities before, during, and after the release. Scientists sought to determine whether or not high flows could be used to rebuild Grand Canyon sandbars, create nearshore habitat for the endangered humpback chub, and benefit other resources such as archaeological sites, rainbow trout, aquatic food availability, and riverside vegetation. This fact sheet summarizes research completed by January 2010.
Melis, Theodore S.; Topping, David J.; Grams, Paul E.; Rubin, David M.; Wright, Scott A.; Draut, Amy E.; Hazel, Joseph E., Jr.,; Ralston, Barbara E.; Kennedy, Theodore A.; Rosi-Marshall, Emma; Korman, Josh; Hilwig, Kara D.; Schmit, Lara M.
Is Canyon Width a Diagnostic Indicator of the Discharge of Megafloods on Earth and Mars?
NASA Astrophysics Data System (ADS)
On Earth, large floods have carved steep-walled and amphitheater-headed canyons from the Pleistocene (e.g. Box Canyon, ID) through the Holocene (e.g. Asbyrgi Canyon, Iceland), to historic times (e.g. Canyon Lake Gorge, TX). The geologic record on Mars suggests that similar floods have carved canyons by waterfall retreat about 3.5 billion years ago, when the red planet was wetter and possibly warmer. We currently lack robust paleo-hydraulic tools to reconstruct the discharge of ancient floods, especially on Mars where sediment sizes are obscured from observation. To address this issue, we hypothesize that the width of canyon escarpment is controlled by the hydraulics of the canyon-carving flood due to focusing of the flood into the canyon head. We compiled field data from multiple canyons and floods on Earth and Mars and show that there is a correlation between estimated flood discharge and canyon headwall width. To explore what sets this relationship, we identified five important parameters using dimensional analysis: the Froude number, the ratio of backwater length to canyon length, the ratio of backwater length to flood width, the ratio of canyon width to flood width, and the topographic slope upstream of the canyon. We used the hydraulic numerical modeling suite ANUGA to simulate overland flow over different canyon geometries and flood parameters to systematically explore the relative bed shear stresses along the canyon rim as a metric for flow focusing. Results show that canyons that exceed a certain length, scaling with the hydraulic backwater length, have shear stresses at their heads that are significantly higher than near the canyon mouth. Shear stresses along the rim of the canyon sidewalls are limited, in comparison to stresses along the canyon head, when the flood width is of the order of the backwater length. Flow focusing only occurs for subcritical flow. Together, these results suggest that canyons may only grow from a perturbation that is large enough to instigate flow focusing. Once canyon growth is initiated, the equilibrium width of canyons may arise from the competition between the cross-stream backwater effects along the canyon sidewalls, which promote widening of the escarpment, and the geometry of the canyon flood system, which promote a drying of the canyon sidewalls. These results show promise for a new paleohydraulic tool to infer discharges of ancient floods on Earth and Mars.
Lapotre, M. G.; Lamb, M. P.
Screening of antibacterial activity of Amaicha del Valle (Tucum�n, Argentina) propolis.
Propolis is extensively used in Argentine folk medicine. Alcoholic extracts of propolis from four localities of Amaicha del Valle (El Paraiso, La Banda Este, La Banda Oeste and El Molino), Province of Tucum�n and from Cerrillos, Province of Santiago del Estero, Argentina were prepared. All showed antibacterial activity against Gram positive bacteria, the propolis from La Banda Este being the most active (MIC = 7.8 microg/ml) against Streptococcus piogenes, an antibiotic resistant bacterium. Thin layer chromatographic (TLC) separation profiles of propolis from Amaicha del Valle region were similar but differ from the alcoholic extract of the propolis from Cerrillos, another phytogeographical region of Argentina (provincia chaque�a). Bioautographic assays of the TLC profiles showed that several separated compounds of the Amaicha del Valle propolis have antibacterial activity. The difference in composition between Amaicha del Valle and Cerrillos propolis coincides with a different phytogeographical formation. PMID:10624867
Nieva Moreno, M I; Isla, M I; Cudmani, N G; Vattuone, M A; Sampietro, A R
Vegetation Survey and Preliminary Ecological Assessment of Valles Caldera National Preserve, New Mexico.
National Technical Information Service (NTIS)
With the acquisition of the Valles Caldera National Preserve (VCNP) has come the need for comprehensive biological inventories to support sound natural resources management. Fundamental components of this effort are the development of a vegetation map and...
E. Muldavin P. Tonne
Petrology of Westwater Canyon member, Morrison Formation, East Chaco Canyon drilling project, New Mexico-comparison with Grants mineral belt
The results of this report are based on 47 samples of Westwater Canyon Sandstone, Morrison Formation (Upper Jurassic). The 250 to 350 ft (75 to 100-m) thick Westwater Canyon Member is 80 percent fine- to medium-grained arkosic sandstone and 20 percent interbedded red and green mudstones. Nine zones of low-grade uranium mineralization were intercepted by five drill holes. The alteration
R. T. Hicks; R. M. Lowry; R. S. Della Valle; D. G. Brookins
SRTM Anaglyph: Pinon Canyon region, Colorado
NASA Technical Reports Server (NTRS)
Erosional features are prominent in this view of southern Colorado taken by the Shuttle Radar Topography Mission (SRTM). The area covers about 20,000square kilometers and is located about 50 kilometers south of Pueblo, Colorado. The prominent mountains near the left edge of the image are the Spanish Peaks, remnants of a 20 million year old volcano. Rising 2,100 meters (7,000 feet) above the plains to the east, these igneous rock formations with intrusions of eroded sedimentary rock historically served as guiding landmarks for travelers on the Mountain Branch of the Santa Fe Trail.Near the center of the image is the Pinon Canyon Maneuver Site, a training area for soldiers of the U.S. Army from nearby Fort Carson. The site supports a diverse ecosystem with large numbers of big and small game, fisheries, non-game wildlife, forest, range land and mineral resources. It is bounded on the east by the dramatic topography of the Purgatoire River Canyon, a 100 meter (328 feet) deep scenic red canyon with flowing streams, sandstone formations and exposed geologic processes.This anaglyph was produced by first shading a preliminary SRTM elevation model. The stereoscopic effect was then created by generating two differing perspectives, one for each eye. When viewed through special glasses, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and cover the right eye with a blue filter.Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on Feb. 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR)that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense, and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC.Size: 177.8 x 111.3 kilometers ( 110.5 x 69.2 miles) Location: 37.5 deg. North lat., 104 deg. West lon. Orientation: North toward the top Original Data Resolution: SRTM 1 arcsecond (30 meters or 99 feet) Image Data: Shaded and colored SRTM elevation model
.��The Mangala Valles system is an ?\\u000a ?900�km fluvially carved channel system located southwest of the Tharsis rise and is unique among the martian outflow channels\\u000a in that it heads at a linear fracture within the crust as opposed to a collapsed region of chaos as is the case with the circum-Chryse\\u000a channels. Mangala Valles is confined within a broad,
Gil J. Ghatan; James W. Head; Lionel Wilson
Inner gorge�slot canyon system produced by repeated stream incision (eastern Alps): Significance for development of bedrock canyons
NASA Astrophysics Data System (ADS)
Many inner bedrock gorges of the Alps show abrupt downstream changes in gorge width, as well as channel type and gradient, as a result of epigenetic incision of slot canyons. Many slot canyons also are associated with older gorge reaches filled with Quaternary deposits. The age of slot canyons and inner bedrock gorges, however, commonly is difficult to constrain. For the inner-bedrock gorge system of the Steinberger Ache catchment (eastern Alps), active slot canyons as well as older, abandoned gorge reaches filled with upper W�rmian proglacial deposits record three phases of gorge development and slot�canyon incision. A 234U/230Th age of cement of 29.7 � 1.8 ka in fluvial conglomerates onlapping the flank of an inner gorge fits with late W�rmian valley-bottom aggradation shortly before pleniglacial conditions; in addition, the age indicates that at least the corresponding canyon reach must be older. During advance of ice streams in the buildup of the Last Glacial Maximum (LGM), the catchment was blocked, and a proglacial lake formed. Bedrock gorges submerged in that lake were filled with fluviolacustrine deposits. During the LGM, the entire catchment was overridden by ice.
Sanders, Diethard; Wischounig, Lukas; Gruber, Alfred; Ostermann, Marc
77 FR 67391 - Notice of Proposed Supplementary Rules on Public Land in Water Canyon, Humboldt County, NV
Federal Register 2010, 2011, 2012, 2013
...Proposed Supplementary Rules on Public Land in Water Canyon, Humboldt County, NV AGENCY...and resources on public land within the Water Canyon Recreation Area. These proposed...restrictions included within the decisions of the Water Canyon Recreation Area Management...
76 FR 47237 - Notice of Public Meeting for the Glen Canyon Dam Adaptive Management Work Group Federal Advisory...
Federal Register 2010, 2011, 2012, 2013
...Notice of Public Meeting for the Glen Canyon Dam Adaptive Management Work Group Federal Advisory...SUMMARY: The Glen Canyon Dam Adaptive Management Work Group (AMWG...Secretary of the Interior concerning Glen Canyon Dam operations and other management...
77 FR 55829 - Western Area Power Administration; Grapevine Canyon Wind Project Record of Decision (DOE/EIS-0427)
Federal Register 2010, 2011, 2012, 2013
...Power Administration; Grapevine Canyon Wind Project Record of Decision (DOE/EIS-0427...interconnect its proposed Grapevine Canyon Wind Project (Project) to Western's Glen...Statement (EIS) for Grapevine Canyon Wind Project was published in the Federal...
Hematite-bearing materials surrounding Candor Mensa in Candor Chasma, Mars: Implications for hematite origin and post-emplacement modification
NASA Astrophysics Data System (ADS)
The Valles Marineris canyon system on Mars is of enduring scientific interest in part due to the presence of interior mounds that contain extensive layering and water-altered minerals, such as crystalline gray hematite and hydrated sulfates. The presence of hematite and hydrated sulfate minerals is important because their host rock lithologies provide information about past environments that may have supported liquid water and may have been habitable. This work further defines the association and relationship between hematite-bearing materials and low albedo (presumably aeolian) deposits and layered materials, identifies physical characteristics that are strongly correlated with the presence of hematite, and refines hypotheses for the origin and post-emplacement modification (including transport) of these hematite-bearing and associated materials. There are only three regions surrounding Candor Mensa where hematite has been identified, even though morphologic properties are similar throughout the entire mensa. Three possible explanations for why hematite is only exposed in these regions include: (1) the topographic structure of the mensa walls concentrates hematite at the base of the layered deposits, influencing the ability to detect hematite from orbit; (2) the presence of differing amounts of �dark mantling material� and hematite-free erosional sediment; (3) the potential fracturing of the mensa and the influence of these structures on fluid flow and subsequent digenesis. The observations of hematite-bearing materials in this work support the hypothesis that hematite is eroding from a unit in the Candor Mensa interior layered deposits (ILD) and is being concentrated as a lag deposit adjacent to the lower layers of Candor Mensa and at the base in the form of dark aeolian material. Due to the similar geologic context associated with hematite-bearing and ILD materials throughout the Valles Marineris canyon system, the insight gained from studying these materials surrounding Candor Mensa can likely be applicable to similar layered deposits throughout Valles Marineris.
Fergason, R. L.; Gaddis, L. R.; Rogers, A. D.
Discovery of two new large submarine canyons in the Bering Sea
The Beringian continental margin is incised by some of the world's largest submarine canyons. Two newly discovered canyons, St. Matthew and Middle, are hereby added to the roster of Bering Sea canyons. Although these canyons are smaller and not cut back into the Bering shelf like the five very large canyons, they are nonetheless comparable in size to most of the canyons that have been cut into the U.S. eastern continental margin and much larger than the well-known southern California canyons. Both igneous and sedimentary rocks of Eocene to Pliocene age have been dredged from the walls of St. Matthew and Middle Canyons as well as from the walls of several of the other Beringian margin canyons, thus suggesting a late Tertiary to Quaternary genesis of the canyons. We speculate that the ancestral Yukon and possibly Anadyr Rivers were instrumental in initiating the canyon-cutting processes, but that, due to restrictions imposed by island and subsea bedrock barriers, cutting of the two newly discovered canyons may have begun later and been slower than for the other five canyons. ?? 1984.
Carlson, P. R.; Karl, H. A.
Observations of environmental change in Grand Canyon, Arizona
Few scientific data have been collected on pre-dam conditions of the Colorado River corridor through Grand Canyon National Park. Using historical diaries, interviews with pre-dam river runners (referred to as the ?Old Timers?), and historical scientific data and observations, we compiled anecdotal information on environmental change in Grand Canyon. The most significant changes are the: lowering of water temperature in the river, near-elimination of heavily sediment-laden flows, erosion of sand bars, invasion of non-native tamarisk trees, reduction in driftwood, development of marshes, increase in non-native fish at the expense of native fishes, and increase in water bird populations. In addition, few debris flows were observed before closure of Glen Canyon Dam, which might suggests that the frequency of debris flows in Grand Canyon has increased. Other possible changes include decreases in bat populations and increases in swallow and bighorn sheep populations, although the evidence is anecdotal and inconclusive. These results provide a perspective on managing the Colorado River that may allow differentiation of the effects of Glen Canyon Dam from other processes of change.
Webb, Robert H.; Melis, Theodore S.; Valdez, Richard A.
Software Configuration Management Plan for the B-Plant Canyon Ventilation Control System
Project W-059 installed a new B Plant Canyon Ventilation System. Monitoring and control of the system is implemented by the Canyon Ventilation Control System (CVCS). This Software Configuration Management Plan provides instructions for change control of the CVCS.
75 FR 10308 - Fire Management Plan, Final Environmental Impact Statement, Record of Decision, Grand Canyon...
Federal Register 2010, 2011, 2012, 2013
...DEPARTMENT OF THE INTERIOR National Park Service Fire Management Plan, Final Environmental Impact...Environmental Impact Statement for the Fire Management Plan, Grand Canyon National...availability of the Record of Decision for the Fire Management Plan, Grand Canyon...
78 FR 79436 - Boulder Canyon Project-Post-2017 Resource Pool
Federal Register 2010, 2011, 2012, 2013
...Boulder Canyon Project--Post-2017 Resource Pool AGENCY: Western Area Power Administration...Boulder Canyon Project (BCP) post-2017 resource pool marketing criteria and is calling...established general eligibility criteria and a resource pool (Post-2017 Resource Pool)...
40 CFR 51.309 - Requirements related to the Grand Canyon Visibility Transport Commission.
Code of Federal Regulations, 2011 CFR
...Grand Canyon Visibility Transport Commission. 51.309...AGENCY (CONTINUED) AIR PROGRAMS REQUIREMENTS...Grand Canyon Visibility Transport Commission. ...non-fossil low or no air emission technologies...Plan Schedule. Each Transport Region State...
40 CFR 51.309 - Requirements related to the Grand Canyon Visibility Transport Commission.
Code of Federal Regulations, 2012 CFR
...Grand Canyon Visibility Transport Commission. 51.309...AGENCY (CONTINUED) AIR PROGRAMS REQUIREMENTS...Grand Canyon Visibility Transport Commission. ...non-fossil low or no air emission technologies...Plan Schedule. Each Transport Region State...
Hydrogeology and Tritium Transport in Chicken Creek Canyon, Lawrence Berkeley National Laboratory, Berkeley, California.
National Technical Information Service (NTIS)
This study of the hydrogeology of Chicken Creek Canyon was conducted by the Environmental Restoration Program (ERP) at Lawrence Berkeley National Laboratory (LBNL). This canyon extends downhill from Building 31 at LBNL to Centennial Road below. The leadin...
I. Javandel P. D. Jordan
75 FR 76650 - Proposed Modification of Class E Airspace; Bryce Canyon, UT
Federal Register 2010, 2011, 2012, 2013
...This action proposes to modify Class E airspace at Bryce Canyon, UT to accommodate Area Navigation (RNAV) Global Positioning System (GPS) Standard Instrument Approach Procedures at Bryce Canyon Airport. The FAA is proposing this action...
77 FR 74470 - Notice of Availability for the Draft Environmental Impact Statement for the Gregory Canyon...
Federal Register 2010, 2011, 2012, 2013
...Draft Environmental Impact Statement for the Gregory Canyon Landfill Project, San Diego County, CA AGENCY: Department of the...Environmental Impact Statement (EIS) for the proposed Gregory Canyon Landfill Project in San Diego County, CA. The project proponent...
Pliocene���Pleistocene history of the Gippsland Basin outer shelf and canyon heads, southeast Australia
The Gippsland Basin on Australia's southeastern continental margin is host to a number of large shelf-breaching canyons that form part of the Bass Canyon system. Analysis of high-resolution bathymetry data and biostratigraphically controlled shallow seismic data across the shelf and upper slope and associated canyon heads shows that widespread erosion at the canyon heads began in the earliest Pleistocene (CN13a,
J. K. Mitchell; G. R. Holdgate; M. W. Wallace
Influence of a dam on fine-sediment storage in a canyon river
Glen Canyon Dam has caused a fundamental change in the distribution of fine sediment storage in the 99-km reach of the Colorado River in Marble Canyon, Grand Canyon National Park, Arizona. The two major storage sites for fine sediment (i.e., sand and finer material) in this canyon river are lateral recirculation eddies and the main-channel bed. We use a combination
Joseph E. Hazel Jr; David J. Topping; John C. Schmidt; Matt Kaplinski
Numerical modeling of tectonic and aeolian processes on Mars
This dissertation reports on two numerical studies for the surface evolution of Mars. The first study focuses on three models for the tectonic formation of the Valles Marineris. The second study models the disposition, transport pathways, and history of sand on Mars. Three types of terrestrial rift models were formulated for the lithospheric conditions of the Valles Marineris to understand
Fletcher Scott Anderson
Grand Canyon, Arizona as seen from STS-66
NASA Technical Reports Server (NTRS)
Snow covers the Kaibab Plateau on the northern side of the Colorado River in this November, 1994 view of the Grand Canyon. North is to the bottom of this view. The Colorado River has created a canyon which cuts through billions of years of geologic time. The Grand Canyon is 446 kilometers (277 miles) long, averages 16 kilometers (10 miles) wide, and is approximately 1.6 kilometers (1 mile) deep. The Coconino Plateau is located on the upper left side of the view, or to the south of the Colorado River. The direction of the flow of the Colorado River is from the east to the west. Eventually the river turns south and empties into the Gulf of California. The southern portion of Lake Powell in Utah can be seen at the bottom center of the view.
Street Canyon Atmospheric Composition: Coupling Dynamics and Chemistry
NASA Astrophysics Data System (ADS)
Atmospheric composition within the urban environment, particularly within street canyons (formed by a road running between two rows of buildings), has a direct effect on the air quality of an environment in which a large majority of people live and work. The composition of air within a street canyon is determined by the composition of background air mixed in from above, advection of air into and out of the canyon, vehicle exhaust and other emissions from within the street, together with the mixing and chemical processing of pollutants within the canyon. This occurs on a timescale of a few seconds to minutes and as a result, within-canyon atmospheric processes can have a significant effect on atmospheric composition on such timescales. This paper outlines a modelling study of street canyon atmospheric composition, integrating the combined effects of emissions, dynamics and chemistry. This work builds upon an existing dynamical model of canyon atmospheric motion (Large Eddy Simulation (LES) model) by adding a detailed chemical reaction scheme. Previous studies have considered basic NOx-O3 cycles with only a small number of chemical reactions included. Initially, a zero-dimensional box model was used to develop and assess the accuracy of a suitable reduced chemical scheme to be included within the LES. The reduced chemical scheme, based upon a subset of the Master Chemical Mechanism (MCM), includes 51 chemical species and 136 reactions. Vehicle emissions taken from the UK National Atmospheric Emissions Inventory (NAEI) were subsequently added to the box model. These elements were then combined with the canyon dynamics simulated by the Large Eddy Simulation (LES) model. Results demonstrate that the enhanced model is a suitable tool to be used to further investigate the combined effects of mixing and chemical processing upon air quality within the street canyon. Subsequently, a number of key questions relating to urban atmospheric composition are addressed using the model, for example: How different is the air quality in the street canyon from the overlying, background atmosphere and how does this depend on the dynamics? What is the spatial and temporal variability in pollutant levels? Initial results show a significant difference in the initial concentration of OH and NO when comparing canyon averaged LES model results with the results obtained using a zero- dimensional box model with equivalent emissions and external mixing applied. A large peak in OH is observed in the LES results shortly after emissions are introduced, followed by a rapid decline until equilibrium is reached (at around 60 minutes). A smaller change in the box model output is observed with a steady decline in OH levels after emissions are added. Initial NO levels are higher for the LES by up to ? 23%. These observations are a likely to be due to inhomogeneous emissions within the LES, resulting in higher concentrations of NO. This effect is far less pronounced for the box model due to instantaneous mixing of pollutants. At longer timescales, the results of the LES come into closer agreement with the box model as conditions within the canyon become well mixed.
Bright, V.; Bloss, W. J.; Cai, X.
The State of the Colorado River Ecosystem in Grand Canyon: A Report of the Grand Canyon Monitoring and Research Center 1991-2004
This report is an important milestone in the effort by the Secretary of the Interior to implement the Grand Canyon Protection Act of 1992 (GCPA; title XVIII, secs. 1801-1809, of Public Law 102-575), the most recent authorizing legislation for Federal efforts to protect resources downstream from Glen Canyon Dam. The chapters that follow are intended to provide decision makers and the American public with relevant scientific information about the status and recent trends of the natural, cultural, and recreational resources of those portions of Grand Canyon National Park and Glen Canyon National Recreation Area affected by Glen Canyon Dam operations. Glen Canyon Dam is one of the last major dams that was built on the Colorado River and is located just south of the Arizona-Utah border in the lower reaches of Glen Canyon National Recreation Area, approximately 15 mi (24 km) upriver from Grand Canyon National Park (fig. 1). The information presented here is a product of the Glen Canyon Dam Adaptive Management Program (GCDAMP), a federally authorized initiative to ensure that the primary mandate of the GCPA is met through advances in information and resource management. The U.S. Geological Survey`s (USGS) Grand Canyon Monitoring and Research Center (GCMRC) has responsibility for the scientific monitoring and research efforts for the program, including the preparation of reports such as this one.
Edited by Gloss, Steven P.; Lovich, Jeffrey E.; Melis, Theodore S.
Live (stained) benthic foraminifera from the Cap-Ferret Canyon (Bay of Biscay, NE Atlantic): A comparison between the canyon axis and the surrounding areas
NASA Astrophysics Data System (ADS)
Living (Rose Bengal stained) benthic foraminiferal faunas were investigated at 13 deep-sea stations sampled in the Cap-Ferret Canyon area (NE Atlantic). One station (151 m) is located on the continental shelf close to the canyon head. All other stations are located along 2 bathymetric transects: 7 sites along the canyon axis with depths ranging from 300 to 3000 m and 5 stations along the adjacent flank with depths ranging from 300 m to 2000 m. Sedimentological analyses indicate that the Cap-Ferret Canyon is at present inactive in terms of sediment gravity flow. Compared to stations on the adjacent flank, canyon-axis stations are generally characterised by shallow oxygen penetration depths, high diffusive oxygen uptakes (DOU) and high lipid contents. Higher mineralisation rates recorded in the canyon axis are likely due to a preferential focusing of labile organic matter in the canyon axis. Foraminiferal standing stocks do not exhibit any straightforward correlation with the different descriptors of organic matter available in the sediment. However, foraminiferal standing stock and diversity along the canyon axis are generally higher than on the adjacent flank. Canyon axis sites yield dominant species that are similar to those at adjacent flank and open slope stations located at comparable water depths. However, intermediate and deep infaunal species were only recorded in the lower canyon axis, where high amounts of organic matter were observed in deeper sediment layers. Finally, the faunal composition in the Cap-Ferret Canyon is different compared to the nearby Cap-Breton Canyon, where sediment gravity flows are active. The absence of pioneer species and the occurrence of highly specialized taxa are both consistent with the much more stable conditions in terms of hydro-sedimentary conditions prevailing in the Cap-Ferret Canyon.
Duros, P.; Fontanier, C.; Metzger, E.; Cesbron, F.; Deflandre, B.; Schmidt, S.; Buscail, R.; Zaragosi, S.; Kerherv�, P.; Rigaud, S.; Delgard, M.-L.; Jorissen, F. J.
The Glen Canyon Dam Adaptive Management Program: An experiment in science-based resource management
In 1996, Glen Canyon Dam Adaptive Management (GCDAMP) program was established to provide input on Glen Canyon Dam operations and their affect on the Colorado Ecosystem in Grand Canyon. The GCDAMP is a bold experiment in federal resource management that features a governing partnership with all relevant stakeholders sitting at the same table. It is a complicated, difficult process where
m kaplinski
78 FR 123 - Diablo Canyon, Independent Spent Fuel Storage Installation; License Amendment Request...
Federal Register 2010, 2011, 2012, 2013
...Docket No. 72-26; NRC-2012-0312] Diablo Canyon, Independent Spent Fuel Storage...the provisions of 10 CFR Part 72 at its Diablo Canyon Independent Spent Fuel Storage...associated with spent fuel storage at the Diablo Canyon ISFSI. Specifically, the...
75 FR 12315 - Pacific Gas and Electric Company; Diablo Canyon Independent Spent Fuel Storage Installation...
Federal Register 2010, 2011, 2012, 2013
...NRC-2009-0569] Pacific Gas and Electric Company; Diablo Canyon Independent Spent Fuel Storage...and Electric Company (PG&E) for the Diablo Canyon Independent Spent Fuel Storage Installation (ISFSI), located at the Diablo Canyon Nuclear Power Plant, Unit...
76 FR 54487 - Charter Renewal, Glen Canyon Dam Adaptive Management Work Group
Federal Register 2010, 2011, 2012, 2013
...Reclamation Charter Renewal, Glen Canyon Dam Adaptive Management Work Group AGENCY...renewing the charter for the Glen Canyon Dam Adaptive Management Work Group. The purpose...respect to the operation of Glen Canyon Dam and the exercise of other authorities...
78 FR 42799 - Glen Canyon Dam Adaptive Management Work Group Meetings
Federal Register 2010, 2011, 2012, 2013
...X30-0594-0913-700-00-0-0, 4073000] Glen Canyon Dam Adaptive Management Work Group Meetings...SUMMARY: The Glen Canyon Dam Adaptive Management Work Group (AMWG...Secretary of the Interior concerning Glen Canyon Dam operations and other management...
Sedimentary features and processes in the Nazar� and Set�bal submarine canyons, west Iberian margin
Here we present part of the first complete sidescan sonar dataset of the Nazar� and Set�bal Canyons, west Iberian margin, which, in combination with multibeam bathymetry, shallow seismic profiles and precise piston coring of intra-canyon targets, are used to characterise the sedimentary dynamics of these deep-sea settings. The results show that Nazar� and Set�bal Canyons are highly complex environments. They
Raquel G. Arzola; Russell B. Wynn; Galderic Lastras; Douglas G. Masson; Philip P. E. Weaver
Axial Channel Morphology Fill and Movement Within Submarine Canyons off California
Axial channels of seven submarine canyons off California have recently been investigated with ultrahigh resolution multibeam surveys. Vibracores collected from remotely operated vehicles (ROVs) provide ground truth data on the materials within the axis of six of these canyons. Acoustic beacons were used to track movement of the seafloor within the axis of Monterey Canyon. Multibeam bathymetry (0.15 m vertical
C. K. Paull; D. W. Caress; W. Ussler; E. Lundsten; H. Thomas
Early Agriculture in the Eastern Grand Canyon of Arizona, USA
Abandoned fields in Colorado River alluvium in the eastern Grand Canyon show signs of primitive agriculture. Presence of maize pollen in association with buried soils near Comanche Creek suggests that farming began prior to 3130 yr B.P. Cotton pollen, identified in buried soils near Nankoweap Creek, dates to 1310 yr B.P., approximately 500 years earlier than previously reported anywhere on the Colorado Plateau. Farming spanned three millennia in this reach of the canyon. Entrenchment, starting approximately 700 yr B.P., making water diversion to fields infeasible, was likely responsible for field abandonment. ?? 2000 John Wiley & Sons, Inc.
Davis, S. W.; Davis, M. E.; Lucchitta, I.; Finkel, R.; Caffee, M.
Happy Canyon - A new type of enstatite achondrite
NASA Technical Reports Server (NTRS)
Mineralogical and chemical characteristics of the Happy Canyon meteorite, found in 1971 near Wayside, Texas, show it to be a new type of enstatite achondrite occupying the gap between the recrystallized enstatite chondrites and the igneous, crystalline, unbrecciated enstatite chondrites. Although the bulk composition of the specimen is consistent with that of an E6 enstatite chondrite, it has a crystal cumulate texture. There are minor amounts of metal and troilite which have survived extensive weathering. The Happy Canyon meteorite may represent an E6 composition which has melted and reprecipitated at a slightly higher oxidation state, possibly in the core of a small parent body.
Olsen, E. J.; Bunch, T. E.; Jarosewich, E.; Noonan, A. F.; Huss, G. I.
Reviewing the success of intentional flooding of the Grand Canyon
A description and evaluation of the results of an intentional flooding experiment at the Grand Canyon are described. The purpose of the 7-day release of flood waters from the Glen Canyon Dam was to determine if managed floods have the ability to predictably restore the riverine environment. A summary of environmental conditions leading to the experiment is provided and flood results are listed. Initial results showed significant improvement in the size and number of the river`s beaches, creation of backwater habitat for endangered species, and no adverse impact to the trout fishery, Indian cultural sites, and other resources.
Wirth, B.D. [Bureau of Reclamation, Salt Lake City, UT (United States)
Scientific core hole VC-2A, Valles Caldera, New Mexico
This report details the remedial action activities that were necessary to complete scientific core hole Valles caldera {number sign}2A (VC-2A) before it was relinquished to the landowners. Sandia National Laboratories, acting as the Geoscience Research Drilling Office (GRDO), managed the coring operations. Los Alamos National Laboratory (Los Alamos) obtained the proper drilling permits with the New Mexico State Engineers Office (SEO). A legal agreement between Los Alamos and the landowners states that the Laboratory will give the landowners the completed core hold with casing, well head, and other hardware at the end of May 1991, or earlier if scientific investigations were completed. By May 1988, the Science Team completed the planned scientific investigations in the VC-2A core hole. Upon the insistence of the GRDO, the New Mexico Oil Conservation Division (OCD) inspected the core hole, declared jurisdiction, and required that the 11.43- by 11.43-cm annular cement job be repaired to comply with OCD regulations. These regulations state that there must be a return to surface of cement in all cementing operations. We successfully completed a squeeze cementing operation and relinquished the core hold to the landowners in November 1988 to the satisfaction of the OCD, SEO, the landowners, and Los Alamos. 7 refs., 4 figs., 1 tab.
Musgrave, J.; Goff, S. (Los Alamos National Lab., NM (USA)); Turner, T. (Turner (Tom), Salt Lake City, UT (USA))
Geotechnical Considerations of Canyon Formation: the Case of Cap de Creus Canyon, Mediterranean Sea
NASA Astrophysics Data System (ADS)
A portion of the Cap de Creus has been selected for a detailed analysis of slope instability. The selected area is located on the north side of the Canyon between water depth ranging between 150 m and 750 m. This sector, which presents geomorphic evidences of landsliding, has been sampled at three different water depths along a line perpendicular to the axis of the canyon. These cores have been analyzed in order to determine the nature of the sediments along with their geotechnical and rheological properties. At the top of the slope, the geotechnical signature suggests that clay sediments are normally consolidated as a result of a regular and steady sedimentation. In contrast, a highly overconsolidated clayey sediment has been encountered in the core taken on the slope, about 60 m below the headwall escarpment which is about 30 m high with a slope of 27 degrees. The third sampling site is at the toe where the slope is 3 degrees. The geotechnical profile of this zone suggests that depositional events, such as debris flows and turbidity currents, occur frequently, under a more or less erosive regime. The geotechnical and rheological properties have been used for failure (sliding conditions) and post-failure analyses (mobility). The stability of the flank has been analyzed with Slope/W, using limit equilibrium methods. The analysis of the initial geometry with drained conditions indicates that the flank is stable, with a static safety factor of 1,7 (neglecting any seismic our excess pore pressure effects). Results of various scenarios on failure development have been tested, and show that axial incision appears to be the main process, largely as drained failures. Post-failure evolution has been modeled with Bing software. Final length and height of the deposit has been analyzed for different initial sliding mass geometries. The analysis has shown that the deposition of soft mudflow layers could only occur by considering superficial failures originating just above the toe of the slope.
Sansoucy, M.; Locat, J.; Lee, H. J.
Multi-stage uplift of the Colorado Plateau and the age of Grand Canyon and precursor canyons
NASA Astrophysics Data System (ADS)
Debates about the age of Grand Canyon link to debates about the timing of surface uplift(s) of the Colorado Plateau- Rocky Mountain (CP-RM) region. One "old Grand Canyon" model proposes that a paleocanyon of almost the same depth and location as today's Grand Canyon was carved by a NE-flowing "California" paleoriver 80-70 Ma, then was re-used at ~55 Ma by a SW-flowing "Arizona" paleoriver. This model postulates the CP-RM region was uplifted to near modern elevations during the Laramide orogeny. A second model postulates a 17 Ma Grand Canyon; this time corresponds to Basin and Range extension and postulated mantle-driven surface uplift. The "young Grand Canyon" model postulates that >2/3 of modern Grand Canyon was carved by W-flowing Colorado River that became integrated to the Gulf of California at 5-6 Ma during Neogene mantle-driven uplift of the CP/RM region. Thermochronologic data are poised to substantially resolve these debates. Our thermochronology dataset combines published and new apatite fission-track and helium analyses, and joint thermal history modeling using both systems. This dataset reveals three major cooling episodes: 1) a multi-stage Sevier-Laramide contraction episode from about 90 Ma to 50 Ma with structural relief on upwarps on the order 0.5-1 km, compatible with a similar magnitude of surface uplift; 2) 30-20 Ma cooling that was associated with denudation and northward cliff retreat of most of the Mesozoic section from Grand Canyon region; 3) <10 Ma cooling that is best documented in eastern Grand Canyon as part of a general pattern of decreasing age of cooling/denudation to the NE. Combined geologic and thermochronologic data define the age and 3-D geometry of Cenozoic paleotopography that led to Grand Canyon carving. Combined AHe and AFT data indicate 2-4 km of sedimentary rocks covered the Grand Canyon region until about 40 Ma, negating the California River model. These strata were not removed from the Marble Canyon area until after about 25 Ma, negating the Arizona River hypothesis. However, significant paleorelief and paleovalleys were present and their geometry is coming into focus. 1) A long-recognized N-flowing "Peach Springs paleocanyon" existed from Eocene to about 17 Ma and potentially helped carve a paleocanyon along the Hurricane fault, from Truxton to river mile (RM) 225-190. Drill data and modern topography suggest that the NE slope of this paleodrainage has been inverted to a modern SW slope by surface tilting of the CP. 2) An "East Kaibab" paleocanyon was carved across the southern Kaibab uplift to below the Kaibab surface during 30-20 Ma exhumation. This Miocene paleocanyon extended from RM 65 to 116 in the present position of Upper Granite Gorge and may have flowed west (Crooked Ridge River) or east (as an outlet for the 18 Ma Peach Springs paleocanyon). These data support a model of multiple exhumation episodes leading to a 5-6 Ma Grand Canyon that was mainly carved by the W-flowing Colorado River, but that re-used and deepened older paleovalley segments
Karlstrom, K. E.; Lee, J. P.; Kelley, S. A.; Crow, R.
MEVTV workshop on tectonic features on Mars
The state of knowledge of tectonic features on Mars was determined and kinematic and mechanical models were assessed for their origin. Three sessions were held: wrinkle ridges and compressional structure; strike-slip faults; and extensional structures. Each session began with an overview of the features under discussion. In the case of wrinkle ridges and extensional structures, the overview was followed by keynote addresses by specialists working on similar structures on the Earth. The first session of the workshop focused on the controversy over the relative importance of folding, faulting, and intrusive volcanism in the origin of wrinkle ridges. The session ended with discussions of the origin of compressional flank structures associated with Martian volcanoes and the relationship between the volcanic complexes and the inferred regional stress field. The second day of the workshop began with the presentation and discussion of evidence for strike-slip faults on Mars at various scales. In the last session, the discussion of extensional structures ranged from the origin of grabens, tension cracks, and pit-crater chains to the origin of Valles Marineris canyons. Shear and tensile modes of brittle failure in the formation of extensional features and the role of these failure modes in the formation of pit-crater chains and the canyons of Valles Marineris were debated. The relationship of extensional features to other surface processes, such as carbonate dissolution (karst) were also discussed.
Watters, T.R.; Golombek, M.P.
MEVTV Workshop on Tectonic Features on Mars
NASA Technical Reports Server (NTRS)
The state of knowledge of tectonic features on Mars was determined and kinematic and mechanical models were assessed for their origin. Three sessions were held: wrinkle ridges and compressional structure; strike-slip faults; and extensional structures. Each session began with an overview of the features under discussion. In the case of wrinkle ridges and extensional structures, the overview was followed by keynote addresses by specialists working on similar structures on the Earth. The first session of the workshop focused on the controversy over the relative importance of folding, faulting, and intrusive volcanism in the origin of wrinkle ridges. The session ended with discussions of the origin of compressional flank structures associated with Martian volcanoes and the relationship between the volcanic complexes and the inferred regional stress field. The second day of the workshop began with the presentation and discussion of evidence for strike-slip faults on Mars at various scales. In the last session, the discussion of extensional structures ranged from the origin of grabens, tension cracks, and pit-crater chains to the origin of Valles Marineris canyons. Shear and tensile modes of brittle failure in the formation of extensional features and the role of these failure modes in the formation of pit-crater chains and the canyons of Valles Marineris were debated. The relationship of extensional features to other surface processes, such as carbonate dissolution (karst) were also discussed.
Watters, Thomas R. (editor); Golombek, Matthew P. (editor)
Submarine canyons as important habitat for cetaceans, with special reference to the Gully: A review
NASA Astrophysics Data System (ADS)
There has been much research interest in the use of submarine canyons by cetaceans, particularly beaked whales (family Ziphiidae), which appear to be especially attracted to canyon habitats in some areas. However, not all submarine canyons are associated with large numbers of cetaceans and the mechanisms through which submarine canyons may attract cetaceans are not clearly understood. This paper reviews some of the cetacean associations with submarine canyons that have been anecdotally described or presented in scientific literature and discusses the physical, oceanographic and biological mechanisms that may lead to enhanced cetacean abundance around these canyons. Particular attention is paid to the Gully, a large submarine canyon and Marine Protected Area off eastern Canada for which there exists some of the strongest evidence available for submarine canyons as important cetacean habitat. Studies demonstrating increased cetacean abundance in the Gully and the processes that are likely to attract cetaceans to this relatively well-studied canyon are discussed. This review provides some limited evidence that cetaceans are more likely to associate with larger canyons; however, further studies are needed to fully understand the relationship between the physical characteristics of canyons and enhanced cetacean abundance. In general, toothed whales (especially beaked whales and sperm whales) appear to exhibit the strongest associations with submarine canyons, occurring in these features throughout the year and likely attracted by concentrating and aggregating processes. By contrast, baleen whales tend to occur in canyons seasonally and are most likely attracted to canyons by enrichment and concentrating processes. Existing evidence thus suggests that at least some submarine canyons are important foraging areas for cetaceans, and should be given special consideration for cetacean conservation and protection.
Moors-Murphy, Hilary B.
Water-Temperature Data for the Colorado River and Tributaries Between Glen Canyon Dam and Spencer Canyon, Northern Arizona, 1988-2005
The regulation of flow of the Colorado River by Glen Canyon Dam began in 1963. This resulted in significant changes to the downstream ecosystem of the Colorado River in Grand Canyon, contributing to the initiation of the Glen Canyon Environmental Studies program in 1982, followed by establishment of the Glen Canyon Dam Adaptive Management Program in 1996. This report describes a water-temperature dataset collected through these programs for the reach of the Colorado River and selected tributaries between Glen Canyon Dam and Spencer Canyon (approximately 261 river miles) in northern Arizona from 1988 to 2005. The primary purposes of the report are to summarize the methods of data collection, processing, and editing; to present summary statistics; and to make the data described in the report available.
Voichick, Nicholas; Wright, Scott A.
Isotopic and geochemical constraints on the origin and evolution of postcollapse rhyolites in the Valles Caldera, New Mexico
NASA Astrophysics Data System (ADS)
Ring-fracture rhyolites of the Valles Caldera (VC) were examined to determine the evolution of the magma system following eruption of the upper Bandelier Tuff (UBT) and subsequent caldera collapse. Volcanism began with eruption of Deer Canyon (DC), Redondo Creek, and Del Medio (DM) rhyolites during the interval 1140-1133 ka. Quartz delta O-18 for the UBT, (average +8.3 %), DC (+7.9 %), and DM (+8.7 %) rhyolites indicate no significant lowering of delta O-18 following caldera collapse. In contrast, DM rhyolites record low epsilon(sub Nd) of -3.6 to -3.8 relative to the UBT (-2.7) and variable initial 87-Sr/86-Sr (0.70923-0.71307). Del Abrigo (DA) and Santa Rosa I rhyolites (973-915 ka) exhibit lower epsilon(Sub Nd) (-4.4 to -4.6) and initial 87-Sr/86-Sr (0.70707-0.71009), as well as shifts in compatible and incompatible trace element ratios. Seco, San Luis, and Santa Rosa II rhyolites (800-787 ka) have epsilon(Sub Nd) (-4.0 to -4.3) similar to the 973 to 915 ka rhyolites but lower initial 87-Sr/86-Sr (0.70616-0.70747). After a hiatus of 230 ka, San Antonio (SA), South Mountain (SM), and La Jara (LJ) rhyolites (557-521 ka) were erupted with epsilon(Sub Nd) of -3.7 to 4.3, distinctly lower initial 87-Sr/86-Sr of 0.70513-0.70553 and less evolved trace element compositions. The youngest rhyolites, the El Cajete-Banco Bonito group (EC-BB) (300-170 ka) are petrographically and geochemically distinct with the highest epsilon(Sub Nd) (-2.7 to -3.0) and the lowest initial 87-Sr/86-Sr (0.70464-0.70478) of postcollapse rhyolites. The isotopic data indicate that Valles rhyolites are not direct melts of Proterozoic basement (epsilon(Sub Nd) of -10 to -15) and indicate a significant mantle-derived (basaltic) component. Elevated initial 87-Sr/86-Sr is restricted to rhyolites depleted in Sr (less than 10 ppm) and probably reflects minor upper crustal assimilation. Calculated magma delta 0-18 values (+6.6 to +7.0 %) indicate no substantial supracrustal sediment in the source region, nor interaction with hydrothermal fluids (or altered wall rock) in the upper crust. The intermittent volcanic activity and the heterogeneity of petrographic, geochemical, and isotopic compositions from one eruptive interval to the next suggests that these rhyolites were vented from a series of temporally and spatially separated magma chambers. Parental melts supplied to these magma chambers were most probably produced by basalt-induced fusion events in a hybridized deep crustal environment.
Spell, Terry L.; Kyle, Philip R.; Thirlwall, Matthew F.; Campbell, Andrew R.
Field trip guide to the Valles Caldera and its geothermal systems
This field trip guide has been compiled from extensive field trips led at Los Alamos National Laboratory during the past six years. The original version of this guide was designed to augment a workshop on the Valles Caldera for the Continental Scientific Drilling Program (CSDP). This workshop was held at Los Alamos, New Mexico, 5-7 October 1982. More stops were added to this guide to display the volcanic and geothermal features at the Valles Caldera. The trip covers about 90 miles (one way) and takes two days to complete; however, those who wish to compress the trip into one day are advised to use the designated stops listed in the Introduction. Valles Caldera and vicinity comprise both one of the most exciting geothermal areas in the United States and one of the best preserved Quaternary caldera complexes in the world.
Goff, F.E.; Bolivar, S.L.
Basaltic Ring Structures as an Analog for Ring Features in Athabasca Valles, Mars
NASA Technical Reports Server (NTRS)
Basaltic ring structures (BRSs) are enigmatic, quasi-circular landforms in eastern Washington State that were first recognized in 1965. They remained a subject of geologic scrutiny through the 1970 s and subsequently faded from the spotlight, but recent Mars Orbiter Camera (MOC) images showing morphologically similar structures in Athabasca Valles, Mars, have sparked renewed interest in BRSs. The only known BRSs occur in the Channeled Scabland, a region where catastrophic Pleistocene floods from glacial Lake Missoula eroded into the Miocene flood basalts of the Columbia Plateau. The geologic setting of the martian ring structures (MRSs) is similar; Athabasca Valles is a young channel system that formed when catastrophic aqueous floods carved into a volcanic substrate. This study investigates the formation of terrestrial BRSs and examines the extent to which they are appropriate analogs for the MRSs in Athabasca Valles.
Jaeger, W. L.; Keszthelyi, L. P.; Burr, D. M.; Emery, J. P.; Baker, V. R.; McEwen, A. S.; Miyamoto, H.
Submarine landsliding and canyon evolution on the northern KwaZulu-Natal continental shelf, South Africa, SW Indian Ocean
The morphometric and geomorphological analysis of landslides found within several submarine canyons of varying sizes and morphologies from the northern KwaZulu-Natal continental shelf, South Africa, provides insight into submarine canyon evolution. Six large shelf indenting canyons are recognised (Leven, North and South Leadsman, Diepgat, Wright, and White Sands) interspersed with smaller canyons that occur prominently in the northernmost Mabibi area.
Andrew Green; Ron Uken
Geology Fieldnotes: Bighorn Canyon National Recreation Area, Montana/Wyoming
NSDL National Science Digital Library
This site contains Bighorn Canyon National Recreation Area information, including geology, maps, photographs, visitor information, and links for additional facts about this area of Wyoming and Montana. Included are details about the geologic history of the area, formations, the Pryar and Bighorn Mountains, and the exploration history of the land.
Forest Restoration in Campgrounds at Kings Canyon National Park, California
Intensive campground use at the Grant Grove area of Kings Canyon National Park, California, has compacted the soil and left areas without understory vegetation or tree recruitment. To better inform the restoration of these sites after closure, we tested natural regeneration potential and planting and soil restoration methods. The tested methods included plant- ing with container stock and direct seeding,
Susan B. Infalt; Truman P. Young
Redetermination of lead isotopic composition in Canyon Diablo troilite
Redetermination of the lead isotopic composition in Canyon Diablo ; troilite shows that the original analysis was overcorrected for analytical ; fractionation. The new analysis indicates that the lead in nodule CDN-1 is a ; mixture of primordial lead plus a small amount of common lead. (auth)
When less is less: Waste minimization at Diablo Canyon
At Diablo Canyon power plant, Pacific Gas and Electric has implemented a minimization plan to reduce the generation of radioactive waste. The plan encompasses wastes generated from plant systems, from the modification of plant systems and structures, and from the use of protective clothing and contamination control consumables.
Miller, C.C. [Pacific Gas & Electric Company, Avila Beach, CA (United States)
Observations of the Internal Tide in Monterey Canyon
Data from two shipboard experiments in 1994, designed to observe the semidiurnal internal tide in Monterey Canyon, reveal semidiurnal currents of about 20 cm s21, which is an order of magnitude larger than the estimated barotropic tidal currents. The kinetic and potential energy (evidenced by isopycnal displacements of about 50 m) was greatest along paths following the characteristics calculated from
Emil T. Petruncio; Leslie K. Rosenfeld; Jeffrey D. Paduan
The Grand Canyon of the Yellowstone by Lucien Powell
This large (74" X 114.5") oil painting was done by Lucien W. Powell and is on loan to the Geological Survey from the Smithsonian National Museum of American Art. The title of the painting is The Grand Canyon of the Yellowstone. Object ID: USGS-575066...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
9. COULTERVILLE ROAD VIEW AND MERCED RIVER CANYON. NOTE CUT FACE OF STANDING ROCK AT RIGHT. LOOKING N. GIS: N-37 42 52.1 / W-119 43 17.5 - Coulterville Road, Between Foresta & All-Weather Highway, Yosemite Village, Mariposa County, CA
Grand Canyon Trekkers: School-Based Lunchtime Walking Program
ERIC Educational Resources Information Center
The incidence of childhood overweight is especially troubling among low income Latino youth. Grand Canyon Trekkers (GCT) was implemented as a quasi-experimental study in 10 Title 1 elementary schools with a large Latino population to examine the effects of a 16-week structured walking program on components of health-related physical fitness: Body�
Hawthorne, Alisa; Shaibi, Gabriel; Gance-Cleveland, Bonnie; McFall, Sarah
Grand Canyon, Colorado as seen from STS-62
NASA Technical Reports Server (NTRS)
In this view, the Colorado River can be seen flowing southwest from top left to bottom center-right. The dark wider sections of the river are the water surface of Lake Powell (center, and top left), 110 miles long in a straight line. Grand Canyon National Monument lies lower right, centered on the Grand Canyon of the Colorado River, a 10 mile-wide gash carved more than 5,000 feet deep by the Colorado. The Canyon has cut into the Kaibab Plateau, an uplifted area visible here as a forested area with snow on the highest northern parts. The surrounding parts of the Colorado Plateau are sparsely occupied by brush vegetation and appear yellow-brown. The dark area top right is the wooded country of Black Mesa in Navajoland, divided from Lake Powell by the San Juan River. Four Corners is just outside the pictures (top) where the states of Arizona, Utah, Colorado and New Mexico meet. The Henry Mountains appear top left. Apart from Grand Canyon National Monument, several other famous national mo
Grand Canyon Investigations: 131 years in the field
Staff at the USGS Central Region Library created two displays for an open-house in celebration of National Library Week, April, 2010. This display on USGS scientific investigtations of the Grand Canyon displays field records, historical photography,historical surveying equipment, and publications fr...
Grand Canyon Investigations: 131 Years in the Field
Staff at the USGS Central Region Library created two displays for an open-house in celebration of National Library Week, April, 2010. This display on USGS scientific investigtations of the Grand Canyon displays field records, historical photography,historical surveying equipment, and publications fr...
Context view from NE ridge of Daybreak Canyon running NE ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
Context view from NE ridge of Daybreak Canyon running NE from lookout tower shows fire line on right and NE side of lookout tower in the far distance. Tree in foreground is Pondaross Pine that survived fires of 1991 and 1994. Camera is pointed SW with wide-angle lens. - Chelan Butte Lookout, Summit of Chelan Butte, Chelan, Chelan County, WA
The Fact Book, 1991-1992. College of the Canyons.
ERIC Educational Resources Information Center
Intended for use by decision makers involved in the planning and management of the College of the Canyons (CC) in Valencia, California, the eight sections of this fact book present information and data on the college, the college district, finances, and facilities. Section I discusses CC's mission, institutional values, planning assumptions,�
College of the Canyons, Valencia, CA.
Microorganisms from the late precambrian of the grand canyon, Arizona.
An assemblage of cellularly well-preserved, filamentous and spheroidal plant microfossils has been detected in a cherty pisolite bed of the late Precambrian Chuar Group from the eastern Grand Canyon of the Colorado River. This newly discovered microflora, probably among the youngest Precambrian biological communities now known, appears to be of both evolutionary and biostratigraphic significance. PMID:17835936
Schopf, J W; Ford, T D; Breed, W J
Carbonaceous aerosol particles from common vegetation in the Grand Canyon
The problem of visibility reduction in the Grand Canyon due to fine organic aerosol particles in the atmosphere has become an area of increased environmental concern. Aerosol particles can be derived from many emission sources. In this report, we focus on identifying organic aerosols derived from common vegetation in the Grand Canyon. These aerosols are expected to be significant contributors to the total atmospheric organic aerosol content. Aerosol samples from living vegetation were collected by resuspension of surface wax and resin components liberated from the leaves of vegetation common to areas of the Grand Canyon. The samples were analyzed using high-resolution gas chromatography/mass spectrometry (GC/MS). Probable identification of compounds was made by comparison of sample spectra with National Institute of Standards and Technology (NIST) mass spectral references and positive identification of compounds was made when possible by comparison with authentic standards as well as NIST references. Using these references, we have been able to positively identify the presence of n-alkane and n-alkanoic acid homolog series in the surface waxes of the vegetation sampled. Several monoterpenes, sesquiterpenes, and diterpenes were identified also as possible biogenic aerosols which may contribute to the total organic aerosol abundance leading to visibility reduction in the Grand Canyon.
Hallock, K.A.; Mazurek, M.A. (Brookhaven National Lab., Upton, NY (United States)); Cass, G.R. (California Inst. of Tech., Pasadena, CA (United States). Dept. of Environmental Engineering Science)
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
66. VAL BRIDGE AND BARGES FLOATING FROM ISLIP CANYON TO THE VAL SITE, April 12, 1948. (Original photograph in possession of Dave Willis, San Diego, California.) - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA
In September of 1975 and again in March and June of 1976, water quality survey runs were made in Hells Canyon (17060103, 17060101) to obtain information on the Snake River and its major tributaries within the area. The surveys included 5 Snake River stations from above Johnson B...
Thirty-five years at Pajarito Canyon Site
A history of the research activities performed at the Pajarito Canyon Site from 1946 to 1981 is presented. Critical assemblies described include: the Topsy assembly; Lady Godiva; Godiva 2; Jezebel; Flattop; the Honeycomb assembly for Rover studies; Kiwi-TNT; PARKA reactor; Big Ten; and Plasma Cavity Assembly.
Paxton, H.C.
Anomalous topography on the continental shelf around Hudson Canyon
Recent seismic-reflection data show that the topography on the Continental Shelf around Hudson Canyon is composed of a series of depressions having variable spacings (< 100 m to 2 km), depths (1-10 m), outlines, and bottom configurations that give the sea floor an anomalous "jagged" appearance in profile. The acoustic and sedimentary characteristics, the proximity to relict shores, and the areal distribution indicate that this rough topography is an erosional surface formed on Upper Pleistocene silty sands about 13,000 to 15,000 years ago by processes related to Hudson Canyon. The pronounced southward extension of the surface, in particular, may reflect a former increase in the longshore-current erosion capacity caused by the loss of sediments over the canyon. Modern erosion or nondeposition of sediments has prevented the ubiquitous sand sheet on the Middle Atlantic shelf from covering the surface. The "anomalous" topography may, in fact, be characteristic of areas near other submarine canyons that interrupt or have interrupted the longshore drift of sediments. ?? 1979.
Knebel, H. J.
36 CFR 7.4 - Grand Canyon National Park.
Code of Federal Regulations, 2013 CFR
...Colorado River within Grand Canyon National Park, upstream from Diamond Creek at approximately river mile 226: (1) No person shall...the Superintendent to terminate the permit at any time. (v) A permit may be revoked at any time for the convenience...
Theta13 Neurino Experiement at the Diablo Canyon Power Plant.
National Technical Information Service (NTIS)
This summary document describes the results of conceptual design and cost estimates performed by LBNL Engineering staff between October 10, 2003 and March 12, 2004 for the proposed (theta)(sub 13) neutrino experiment at the Diablo Canyon Power Plant (DCPP...
D. Oshatz
When did the Grand Canyon Begin to Form?
NSDL National Science Digital Library
This post, originally published in the Connecting News with National Science Education Standards blog, deals with the findings suggesting the Grand Canyon is two to three times older than commonly believed. Ideas for engaging students in a thoughtful discussion about these research findings are provided.
Lefever, Mary; Hamilton, Carolyn
Thermal and air flow characteristics in a deep pedestrian canyon under hot weather conditions
NASA Astrophysics Data System (ADS)
The present paper reports the results of a specific experiment carried out in a deep pedestrian canyon in Athens, Greece. The air flow inside and outside the canyon as well as the air and surface temperatures inside the canyon are measured for a period of seven continuous days during the whole day and night period. The air flow characteristics inside the canyon are analyzed. For perpendicular wind speeds, the air flow inside the canyon is characterized by either a circulatory vortex driven by the ambient air flow or a double vortex flow where the upper one is driven by the ambient air flow and the lower one is driven in the opposite direction by the circulation above. When the ambient air blows parallel to the canyon, the measured wind data inside the canyon indicate a flow in the same direction. When the air flows at a certain angle to the canyon axis, the measured data indicate that a spiral vortex is induced along the canyon length. The spatial and temporal variation of the surface and air temperature distribution inside the canyon is analyzed. The heat island intensity in the canyon is estimated based on measurements from a reference station.
Santamouris, M.; Papanikolaou, N.; Koronakis, I.; Livada, I.; Asimakopoulos, D.
Deep flow variability in a deeply incised Mediterranean submarine valley (Blanes canyon)
NASA Astrophysics Data System (ADS)
Deep flow variability in Blanes canyon is analyzed by means of a unique dataset in which the canyon was instrumented at its axis and at the two canyon walls, from March 2003 to July 2004. The mean intensity of deep currents range between 3.5 cm s-1 (at the canyon axis, 1500 m) and 5.4 cm s-1 (upstream canyon wall, 900 m). A wavelet analysis shows that the energy is concentrated in the 2-30 day band, and it is mainly associated to single (not periodical, not wave-related) events, uncoupled at the different canyon sites. An empirical orthogonal function analysis shows two main patterns of current variability explaining 65% of the total variance. The first mode represents intensifications of the typical along-bathymetry pattern of currents over the canyon. The second mode corresponds to near-bottom upwelling events along the canyon axis with water exiting the canyon through the canyon head. After discussing possible forcing mechanisms, it is here suggested that such deep upwelling events are associated to offshore displacements of the Northern Current. Namely, the interaction of the current with the particular shape of the canyon topography at large depths (>1800 m) would be responsible for the observed deep upwelling events.
Jorda, G.; Flexas, M. M.; Espino, M.; Calafat, A.
Small Mammal Sampling in Mortandad and Los Alamos Canyons, 2005
As part of an ongoing ecological field investigation at Los Alamos National Laboratory, a study was conducted that compared measured contaminant concentrations in sediment to population parameters for small mammals in the Mortandad Canyon watershed. Mortandad Canyon and its tributary canyons have received contaminants from multiple solid waste management units and areas of concern since establishment of the Laboratory in the 1940s. The study included three reaches within Effluent and Mortandad canyons (E-1W, M-2W, and M-3) that had a spread in the concentrations of metals and radionuclides and included locations where polychlorinated biphenyls and perchlorate had been detected. A reference location, reach LA-BKG in upper Los Alamos Canyon, was also included in the study for comparison purposes. A small mammal study was initiated to assess whether potential adverse effects were evident in Mortandad Canyon due to the presence of contaminants, designated as contaminants of potential ecological concern, in the terrestrial media. Study sites, including the reference site, were sampled in late July/early August. Species diversity and the mean daily capture rate were the highest for E-1W reach and the lowest for the reference site. Species composition among the three reaches in Mortandad was similar with very little overlap with the reference canyon. Differences in species composition and diversity were most likely due to differences in habitat. Sex ratios, body weights, and reproductive status of small mammals were also evaluated. However, small sample sizes of some species within some sites affected the analysis. Ratios of males to females by species of each site (n = 5) were tested using a Chi-square analysis. No differences were detected. Where there was sufficient sample size, body weights of adult small mammals were compared between sites. No differences in body weights were found. Reproductive status of species appears to be similar across sites. However, sample size prevents a detailed examination of reproduction composition. Because of small sample size of some species and differences that might occur on a seasonal basis, additional sampling would need to be conducted to further evaluate sex ratios, body weights, and reproductive characteristics.
Kathy Bennett, Sherri Sherwood, and Rhonda Robinson
Travel Time Distribution Modeling in the Valles Caldera, New Mexico
NASA Astrophysics Data System (ADS)
Modeling the transit times of catchment waters is of paramount importance in hydrology. The distribution of the time it takes for individual water molecules to move through a hydrologic system (a.k.a., the travel time distribution) is a fundamental characterization of a catchment. Travel time distributions are affected by a variety of physical characteristics of catchments (e.g., vegetation type, degree of soil development) that depend on the amount of solar energy the catchment receives. These characteristics, therefore, can be considered a function of aspect. The goal of this research is to constrain travel time distributions on a series of eight radial mountain streams having different slope aspects on Redondo Peak, a resurgent dome in the center of the Valles Caldera, near Los Alamos, New Mexico. Redondo Peak is an excellent natural laboratory for this type of experiment because all aspects are represented on different sides of the mountain while the internal geology and climate are relatively consistent. To model the transit time distributions of each catchment, variations of chemical load of the snowpack, isotopic compositions of meltwater samples, and snowcover distribution data from closely related studies are coupled with periodic stream and precipitation samples that are analyzed for stable water isotopes content. Additional information comes from a network of temperature sensors to monitor the distribution of snowmelt and headwater stream discharge as well as a series of flumes to capture the flows from the streams. The travel time distributions determined in this project provide a bottom up approach to verify catchment-scale models.
Broxton, P. D.; Troch, P. A.; Brooks, P. D.; Lyon, S. W.; Gustafson, J. R.; Veatch, W. C.
Structural development of McKelligon Canyon, Franklin Mountains, Texas
McKelligon Canyon is located in the south-central Franklin Mountains of west Texas. The Franklin Mountains are a north-south-trending, tilted fault block mountain range. Most workers who have studied the Franklins agree that range uplift occurred after the Cenomanian. Rio Grande rift extension and Laramide age compression are the most commonly cited mechanisms for range uplift. Recently, McKelligon Canyon was suggested to contain Laramide thrust faults at several locations. This study, however, shows that the canyon's structural pattern is characterized by much extensional faulting. No evidence of thrust faults or other compressional features were found. Steep, northeast-dipping (55-80{degree}) normal faults, which strike N60W and N10W, are the primary structures within the canyon. These faults are oblique to the general north-south trend of the range and have a maximum vertical offset, as measured by stratigraphic separation, of approximately 650 m. Strain values obtained from oriented limestone samples collected from the field suggest an early Rio Grande rift origin of the sturctures found in this area. Additionally, paleokarst collapse breccias occur in abundance throughout the study area and are confined to the McKelligon Canyon Formation and the lower 2-3 m of the Scenic Drive Formation. The presence of karsting in the upper part of the Scenic Drive Formation and the overlying Florida Mountains Formation could not be verified in the field. These karst features appear to be randomly distributed as seen on the surface, however, this may be due to preferred differential erosion.
Stacy, J.K.; Julian, F.E. (Univ. of Texas, El Paso (United States))
Thermal bioclimate in idealized urban street canyons in Campinas, Brazil
NASA Astrophysics Data System (ADS)
Among several urban design parameters, the height-to-width ratio (H/W) and orientation are important parameters strongly affecting thermal conditions in cities. This paper quantifies changes in thermal comfort due to typical urban canyon configurations in Campinas, Brazil, and presents urban guidelines concerning H/W ratios and green spaces to adapt urban climate change. The study focuses on thermal comfort issues of humans in urban areas and performs evaluation in terms of physiologically equivalent temperature (PET), based on long-term data. Meteorological data of air temperature, relative humidity, wind speed and solar radiation over a 7-year period (2003-2010) were used. A 3D street canyon model was designed with RayMan Pro software to simulate the influence of urban configuration on urban thermal climate. The following configurations and setups were used. The model canyon was 500 m in length, with widths 9, 21, and 44 m. Its height varied in steps of 2.5 m, from 5 to 40 m. The canyon could be rotated in steps of 15�. The results show that urban design parameters such as width, height, and orientation modify thermal conditions within street canyons. A northeast-southwest orientation can reduce PET during daytime more than other scenarios. Forestry management and green areas are recommended to promote shade on pedestrian areas and on fa�ades, and to improve bioclimate thermal stress, in particular for H/W ratio less than 0.5. The method and results can be applied by architects and urban planners interested in developing responsive guidelines for urban climate issues.
Abreu-Harbich, Loyde V.; Labaki, Lucila C.; Matzarakis, Andreas
Giant Scours on the Eel Canyon Fan
NASA Astrophysics Data System (ADS)
Previously available surface vessel multi-beam data collected on the deep-sea fan directly down channel from the mouth of Eel Canyon off of Northern California show a train of at least 8 giant elongated asymmetric depressions that look like giant scour features. High-resolution multi-beam bathymetry (vertical precision of 0.15 m and horizontal resolution of 1.0 m) and 1-4.5 kHz Chirp seismic reflection profiles were collected in July 2011 over two of these large topographic depressions. The surveys were conducted using an autonomous underwater vehicle (AUV) during two 17.5-hour-long dives in 2,717 to 2,533 m water depths and focused on a 4.8 km long by 4.0 km wide area. An inertial navigation system combined with a Doppler velocity sonar allowed the AUV to fly pre-programmed grids at 3 knots while maintaining an altitude of 50 m above the seafloor. Our high-resolution surveys reveal the fine-scale morphology and shallow seafloor structure of two of these giant scours. The two depressions are up to 100 m deeper than the surrounding seafloor, up to 3.4 km long (N-S axis), up to 1.8 km wide (E-W axis), and markedly asymmetric in the E-W depth profile. Distinctive arcuate scarps which slope at ~ 27� form the eastern (upstream) edge of both depressions. While the seafloor surrounding these scarps is smooth, the scarp face shows horizontal lineations that are interpreted to be outcrops of bedding surfaces. Apparently seafloor erosion focused on the face of this scarp has exposed an ~100 m thick stratigraphic section. The bathymetry also shows numerous E-W oriented ridges ~180 m in length and perpendicular to the overall trace of these scarp, resulting in a serrated or scalloped appearance. The ridges on the scarp faces have an average spacing of 70 m and are separated by intervening gullies. Whether these ridges represent more resistant joints or are a consequence of lateral variations in overriding erosive flows is unclear. The deepest areas within these depressions are immediately at the foot of the scarp where there is an abrupt transition to a nearly flat-floored sediment pond, which extends ~250 m west from the base of the scarp. From there the slope (~3�) gently rises for ~1.5 km before merging with the surrounding seafloor on the west side of each depression. Chirp data show laterally continuous reflectors on these long slopes that are parallel to the seafloor, indicating that these slopes are covered by a rather uniform drape of accumulated sediment. Collectively, these observations suggest that the depressions are massive scours that experience erosion on their upstream side and fill on their down stream side. These scours appear to be an example of features attributed to cyclic steps in large energetic marine flows. Remotely operated vehicle dives to sample within these features are planned for August 2011.
Lundsten, E.; Caress, D. W.; Paull, C. K.; Thomas, H.; Anderson, K.; Gwiazda, R.
Aircraft Accident Report - Grand Canyon Airlines Flight Canyon 5 De Havilland Twin Otter, DHC-6-300, N75GC Grand Canyon National Park Airport, Tusayan, Arizona, September 27, 1989.
National Technical Information Service (NTIS)
The report explains the crash of a Grand Canyon Airlines de Havilland DHC-6-300 Twin Otter sightseeing flight at the Grand Canyon National Park Airport on September 27, 1989. The safety issues discussed in the report are airline procedures for go-around m...
Walnut Canyon National Monument: An Archeological Survey. Archeological Investigations in the Walnut Canyon Drainage, North Central Arizona.
National Technical Information Service (NTIS)
The 1985 survey of Walnut Canyon recorded 242 sites, of which the majority were prehistoric. The first period of occupation dates to the Sunset phase, from A.D. 800 to 950, when the southeast section of the monument was most obviously occupied; there is s...
A. R. Baldwin J. M. Bremer
Petrology of Westwater Canyon member, Morrison Formation, East Chaco Canyon drilling project, New Mexico-comparison with Grants mineral belt
The results of this report are based on 47 samples of Westwater Canyon Sandstone, Morrison Formation (Upper Jurassic). The 250 to 350 ft (75 to 100-m) thick Westwater Canyon Member is 80 percent fine- to medium-grained arkosic sandstone and 20 percent interbedded red and green mudstones. Nine zones of low-grade uranium mineralization were intercepted by five drill holes. The alteration of Westwater Canyon sandstones in the East Chaco Canyon project area is similar to the alteration of sandstones near ore deposits in the Grants mineral belt. Magnetite grains located in and near mineralization display more severe dissolution than do grains far removed from mineralization. Typically, clay minerals replace feldspar along cleavages. A widely observed alteration feature is the dissolution of feldspar grain centers, leaving a thin shell of albite. Authigenic hematite occurs in feldspar cleavages and in the matrix of some detrital mudstone clasts. The authigenic clay mineralogy of the 47 samples does not vary significantly. Nests of authigenic kaolinite make up less than 50 percent of the -2 micron fraction. Grain coatings of authigenic chlorite have an edge-to-face or rosette habit and account for about one-third of the authigenic clay minerals. Mixed-layer illite-montmorillonite also forms grain coatings. Preliminary chemical analyses of the samples indicate a low uranium content in the whole-rock samples (about 2 ppM).
Hicks, R.T.; Lowry, R.M.; Della Valle, R.S.; Brookins, D.G.
Archaeological Investigations at Eleven Sites of Welsh Canyon in the Pinon Canyon Maneuver Site, Las Animas County, Colorado.
National Technical Information Service (NTIS)
In the summer of 1996 New Mexico State University under a cooperative agreement with the National Park Service and the United States Army conducted archaeological research consisting of subsurface testing and mapping of 11 sites in Welsh Canyon at the Pin...
E. Hill L. L. Loendorf V. W. Schiavitti
Cosmogenic 3He ages and frequency of late Holocene debris flows from Prospect Canyon, Grand Canyon, USA
Lava Falls Rapid, which was created and is maintained by debris flows from Prospect Canyon, is the most formidable reach of whitewater on the Colorado River in Grand Canyon and is one of the most famous rapids in the world. Debris flows enter the Colorado River at tributary junctures, creating rapids. The frequency of debris flows is an important consideration when management of regulated rivers involves maintenance of channel morphology. We used cosmogenic 3He, 14C, and historical photographs to date 12 late Holocene and historic debris flows from Prospect Canyon. The highest and oldest deposits from debris flows on the debris fan yielded a 3He date of about 3 ka, which indicates predominately late Holocene aggradation of one of the largest debris fans in Grand Canyon. The deposit, which has a 25-m escarpment caused by river reworking, crossed the Colorado River and raised its base level by 30 m for an indeterminate although likely short period. We mapped depositional surfaces of 11 debris flows that occurred after 3 ka. Two deposits inset against the highest deposit yielded 3He ages of about 2.2 ka, and at least two others followed shortly afterwards. At least one of these debris flows also dammed the Colorado River. The most recent prehistoric debris flow occurred no more than 0.5 ka. The largest historic debris flow, which constricted the river by 80%, occurred in 1939. Five other debris flows occurred after 1939; these debris flows constricted the Colorado River by 35-80%. Assuming the depositional volumes of late Holocene debris flows can be modeled using a lognormal distribution, we calculated recurrence intervals of 15 to more than 2000 years for debris flows from Prospect Canyon.
Cerling, T. E.; Webb, R. H.; Poreda, R. J.; Rigby, A. D.; Melis, T. S.
Morphotectonics and evolutionary controls on the Pearl River Canyon system, South China Sea
NASA Astrophysics Data System (ADS)
The Pearl River Canyon system is a typical canyon system on the northern continental slope of the South China Sea, which has significant implications for hydrocarbon exploration. Through swath bathymetry in the canyon area combined with different types of seismic data, we have studied the morphotectonics and controlling factors of the canyon by analyzing its morphology and sedimentary structure, as well as the main features of the continental slope around the canyon. Results show that the Pearl River Canyon can be separated into three segments with different orientations. The upper reach is NW-oriented with a shallowly incised course, whereas the middle and lower reaches, that are located mainly in the Baiyun Sag, have a broad U-shape and have experienced consistent deposition. Seventeen deeply-cut canyons have developed in the slope north of the Baiyun Sag, playing an important role in the sedimentary processes of the middle and lower reaches of the Pearl River Canyon. These canyons display both asymmetrical V- and U-shapes along their lengths. Numerous buried channels can be identified below the modern canyons with unidirectionally migrating stacking patterns, suggesting that the canyons have experienced a cyclic evolution with several cut and fill phases of varying magnitude. These long established canyons, rather than the upper reach of the Pearl River Canyon, are the main conduits for the transport of terrigenous materials to the lower slope and abyssal basin during lowstand stage, and have contributed to the formation of vertically stacked deep-water fans in the middle reach. Canyon morphology is interpreted as a result of erosive sediment flows. The Pearl River Canyon and the 17 canyons in the slope area north of the Baiyun Sag probably have developed since the Miocene. Cenozoic tectonics, sea level change and sediment supply jointly control the morphology and sedimentary structure. The middle and lower reaches of the Pearl River Canyon developed on the paleo-terrain of the Baiyun Sag, which has been a persistently rapid depositional environment, receiving most of the materials transported via the canyons.
Ding, Weiwei; Li, Jiabiao; Li, Jun; Fang, Yinxia; Tang, Yong
Holocene canyon activity under a combination of tidal and tectonic forcing
NASA Astrophysics Data System (ADS)
The majority of submarine canyon systems that are active during sea level highstands are coupled to terrestrial or littoral sediment transport systems (e.g. high sediment-yield rivers, wave-base sediment disturbance). However, non-coupled canyon systems can also exhibit sedimentary activity. Characterising the nature, origin, and spatial and temporal influence of the processes responsible for this sedimentary activity is important to understand the extent of sediment and carbon transfer to the deep sea, the impact of sedimentary flows on biological colonisation and diversity, and the control of recent seafloor processes on canyon morphology. The Cook Strait canyon system, between the North and South islands of New Zealand, is a large (1800 km2), multi-branching, shelf-indenting canyon on an active subduction margin. The canyon comes within 1 km of the coast, but does not intercept fluvial or littoral sediment systems and is therefore defined as a non-terrestrially-coupled system. Sediment transport on the continental shelf, associated with a strong tidal stream, and seafloor disturbance related to numerous high-activity faults is known from previous studies. Little is known, however, about the rates of sedimentary activity in the canyon and the processes driving it. The canyon system therefore provides an excellent study area for understanding sediment transport in a non-coupled submarine canyon system. Analysis of EM300 multibeam bathymetry, gravity cores, 3.5 kHz seismic reflection profiles, camera and video transects and current meter data reveals a system where oceanographic (tidal) and tectonic (earthquake) processes are moving sediment from the continental shelf, through the upper canyon, and finally to the deep ocean. Sediment accumulation rates may reach several mm/yr in the upper canyons, with data suggesting minimum rates of 0.5 mm/yr. We demonstrate that tidal currents are sufficient to mobilise fine to medium sand around and within the upper canyon heads, and transported sediment is accumulating in upper canyon depocentres. Based on pseudo-static stability modelling, and supported by sediment core records, we estimate that earthquake triggered failure occurs approximately every 100 years. Lower canyon geomorphology indicates that failed material is being conveyed down the length of the canyon system to the deep ocean. Thus, while flushing rates may be low, the Cook Strait Canyon system can be considered to be an active sedimentary system during the current sea level high stand. The processes identified here are likely to be analogous to those occurring in many non-coupled shelf indenting canyons on tectonically active margins globally, and provide a framework within which the biological response to intermediate disturbance geomorphic processes in submarine canyons can be assessed.
Mountjoy, Joshu; Micallef, Aaron; Stevens, Craig; Stirling, Mark
Constructional canyons built by sheet-like turbidity currents: Observations from offshore Brunei Darussalam
NASA Astrophysics Data System (ADS)
Submarine canyon formation and deepening are typically attributed to erosional processes. We present data from an industry-grade seismic volume located offshore Brunei Darussalam illustrating how topography typically associated with erosional processes can be produced under conditions of net sediment deposition. This data was generated via subsurface mapping in the vicinity of a shale-cored anticline on the Quaternary continental- slope. Three canyons traverse the structure at right-angles to the crest line with maximum canyon relief of 165 m. Subsurface mapping reveals that the structure is a site of net sediment deposition and defines a background sedimentation pattern that decreases gradually with distance from the shelf-edge. Profiles down canyon axes reveal local minima in deposit thickness over the anticline hinge that are associated with high downstream gradients. Deposition on ridges adjacent to canyons also displays local minima at the anticline hinge, but these minima are not correlated with gradient. A comparison of canyon axis and ridge deposition shows that somewhat higher rates of sedimentation on the ridges resulted in the preservation and growth of the submarine canyons with time. Laterally persistent seismic reflectors and depositional packages suggest that the canyon forming currents were sheet-like flows, extending for many kilometers in the strike direction. The currents drained into canyons as they approached the anticline hinge, leaving only a small supra-canyon fraction available to deposit sediment on the non-channelized zones.
Straub, K. M.; Mohrig, D.
Headless submarine canyons and fluid flow on the toe of the Cascadia accretionary complex
Headless submarine canyons with steep headwalls and shallowly sloping floors occur on both the second and third landward vergent anticlines on the toe of the Cascadia accretionary complex off central Oregon (45 ??N, 125?? 30??W). In September 1993, we carried out a series of nine deep tow camera sled runs and nine ALVIN dives to examine the relationship between fluid venting, structure and canyon formation. We studied four canyons on the second and third landward vergent anticlines, as well as the apparently unfailed intercanyon regions along strike. All evidence of fluid expulsion is associated with the canyons; we found no evidence of fluid flow between canyons. Even though all fluid seeps are related to canyons, we did not find seeps in all canyons, and the location of the seeps within the canyons differed. On the landward facing limb of the second landward vergent anticline a robust cold seep community occurs at the canyon's inflection point. This seep is characterized by chemosynthetic vent clams, tube worms and extensive authigenic carbonate. Fluids for this seep may utilize high-permeability flow paths either parallel to bedding within the second thrust ridge or along the underlying thrust fault before leaking into the overriding section. Two seaward facing canyons on the third anticlinal ridge have vent clam communities near the canyon mouths at approximately the intersection between the anticlinal ridge and the adjacent forearc basin. No seeps were found along strike at the intersection of the slope basin and anticlinal ridge. We infer that the lack of seepage along strike and the presence of seeps in canyons may be related to fluid flow below the forearc basin/slope unconformity (overpressured by the impinging thrust fault to the west?) directed toward canyons at the surface.
Orange, D. L.; McAdoo, B. G.; Moore, J. C.; Tobin, H.; Screaton, E.; Chezar, H.; Lee, H.; Reid, M.; Vail, R.
Seismic stratigraphy and development of Avon canyon in Benin (Dahomey) basin, southwestern Nigeria
NASA Astrophysics Data System (ADS)
Interpretation of a grid of high resolution seismic profiles from the offshore eastern part of the Benin (Dahomey) basin in southwestern Nigeria area permitted the identification of cyclic events of cut and fill associated with the Avon canyon. Seismic stratigraphic analysis was carried out to evaluate the canyon morphology, origin and evolution. At least three generations of ancient submarine canyons and a newly formed submarine canyon have been identified. Seismic reflection parameters of the ancient canyons are characterized by transparent to slightly transparent, continuous to slightly discontinuous, high to moderate amplitude and parallel to sub-parallel reflections. Locally, high amplitude and chaotic reflections were observed. The reflection configurations consist of regular oblique, chaotic oblique, progradational and parallel to sub-parallel types. These seismic reflection characteristics are probably due to variable sedimentation processes within the canyons, which were affected by mass wasting. Canyon morphological features include step-wise and spoon-shaped wall development, deep valley incision, a V-shaped valley, similar orientation in the southeast direction, and simple to complex erosion features in the axial floor. The canyons have a composite origin, caused partly by lowering of the sea level probably associated with the formation of the Antarctic Ice Sheet about 30 Ma ago and partly by complex sedimentary processes. Regional correlation with geological ages using the reflectors show that the canyons cut through the Cretaceous and lower Tertiary sediments while the sedimentary infill of the canyon is predominantly Miocene and younger. Gravity-driven depositional processes, downward excavation by down slope sediment flows, mass wasting from the canyon walls and variation in terrigenous sediment supply have played significant roles in maintaining the canyons. These canyons were probably conduits for sediment transport to deep-waters in the Gulf of Guinea during their period of formation.
Olabode, S. O.; Adekoya, J. A.
Critical Climate Controls and Information Needs for the Glen Canyon Adaptive Management Program and Environmental Assessment in the Grand Canyon Region
Climatic drivers of episodic to interdecadal variations to the observed changes in the flood magnitude, timing and spatial scales affect the sediment inputs to the Colorado River ecosystem. Since the 1963 closure of Glen Canyon Dam, the dominant sole major supplier of sand to the Colorado River in the upper portion of Grand Canyon is the Paria River, which supplies
T. S. Melis; S. Jain; D. J. Topping; R. S. Pulwarty; J. K. Eischeid
Adaptive Management of Glen Canyon Dam: Two Decades of Large Scale Experimental Treatments Intended to Benefit Resources of the Colorado River in Grand Canyon, USA
Glen Canyon Dam was closed in 1963, primarily to store water for the rapidly developing southwestern United States. The dam's hydropower plant, with a generating capacity of up to 1,300 megawatts of electrical energy, was initially operated without daily peaking constraints from 1966 to 1990, resulting in daily tides on the Colorado River through Grand Canyon National Park of up
Theodore Melis
A tectonically controlled basin-fill within the Valle del Cauca, West-Central Colombia
Tertiary strata of the Valle del Cauca reflect a forearc/foreland basin tectonic history spanning a period from pre-uplift of the Cordillera Central to initiation of uplift of the Cordillera Occidental. Stratigraphy of the Valle del Cauca begins with Jurassic-Cretaceous rocks of exotic and/or volcanic provenance and of oceanic origin. Unconformably overlying these are Eocene to Oligocene basal quartz-rich sandstones, shallow marine algal limestones, and fine-grained fluvial/deltaic mudstones and sandstones with coalbeds. These Eocene to Oligocene deposits represent a period of low tectonic activity. During late Oligocene to early Miocene, increased tectonic activity produced conglomeratic sediments which were transported from east to west, apparently derived from uplift of the Cordillera Central, and deposited within a fluvial to deltaic setting. East-west shortening of the Valle del Cauca basin folded the Eocene to early Miocene units, and additional uplift of the Cordillera Central during the later Miocene resulted in syn-tectonic deposition of alluvial fans. After additional fold and thrust deformation of the total Eocene-Miocene basin-fill, tectonic activity abated and Pliocene-Quaternary alluvial and lacustrine strata were deposited. Within the framework of this depositional and tectonic history of the Valle del Cauca, hydrocarbon exploration strategies can be formulated and evaluated.
Rine, J.M.; Keith, J.F. Jr.; Alfonso, C.A.; Ballesteros, I.; Laverde, F.; Sacks, P.E.; Secor, D.T. Jr. (Univ. of South Carolina, Columbia (United States)); Perez, V.E.; Bernal, I.; Cordoba, F.; Numpaque, L.E. (Ecopetrol, Bogota (Colombia))
Acantholachesilla gen. n. (Psocodea:'Psocoptera': Lachesillidae: Eolachesillinae: Graphocaeciliini) from Valle del Cauca, Colombia.
Acantholachesilla saltoensis gen. et sp. n. is described from Valle del Cauca, Colombia, in the Lachesillidae, tribe Graphocaeciliini (Eolachesillinae). The genus is related to Dagualachesilla and Dagualachesilloides that occur in the same area, differing from them in the male clunial projection, phallosome, and female subgenital plate and gonapophyses. PMID:24989767
Aldrete, Alfonso N Garc�a; Manchola, Oscar Fernando Saenz; Obando, Ranulfo Gonz�lez
Amenazas comerciales del Acuerdo Can-Mercosur para los sectores productivos del Valle del Cauca
El Acuerdo de Complementaci�n Econ�mica, suscrito entre la Comunidad Andina (CAN) y el Mercado Com�n del Sur (MERCOSUR), marca un avance hacia una integraci�n econ�mica y pol�tica m�s profunda en Am�rica Latina. Por tal raz�n, el objetivo del presente art�culo es identificar los sectores del Valle del Cauca que revelan desventajas competitivas relativas, por lo que se pueden ver potencialmente
Lya Paola Sierra Su�rez; Jos� Tom�s Pel�ez Soto
Tectonic pressurization of aquifers in the formation of Mangala and Athabasca Valles, Mars
Mangala and Athabasca Valles are the type examples of a distinct class of outflow channels that debouch directly from extensional tectonic features. We here demonstrate that the tectonic events responsible for the formation of the graben and fissures at the sources of the channels would have likely resulted in a near-instantaneous pressurization of the surrounding aquifers. Subsequent drainage of the
Jeffrey C. Hanna; Roger J. Phillips
Screening of antibacterial activity of Amaicha del Valle (Tucum�n, Argentina) propolis
Propolis is extensively used in Argentine folk medicine. Alcoholic extracts of propolis from four localities of Amaicha del Valle (El Paraiso, La Banda Este, La Banda Oeste and El Molino), Province of Tucum�n and from Cerrillos, Province of Santiago del Estero, Argentina were prepared. All showed antibacterial activity against Gram positive bacteria, the propolis from La Banda Este being the
M. I. Nieva Moreno; M. I. Isla; N. G. Cudmani; M. A. Vattuone; A. R. Sampietro
Teaching in French in the Primary Schools of the Valle D'Aosta, Italy.
ERIC Educational Resources Information Center
Recent activation of a 1940 Italian law allowing equal amounts of elementary school subject area instruction in French and Italian in the Valle D'Aosta (Italy) are described. The plan uses paired bilingual teachers who alternate both languages and grades during the school day. Extension of the program to higher grades is discussed. (six�
Street, Jack D.
Channeling episodes of Kasei Valles, Mars, and the nature of ridged plains material
NASA Technical Reports Server (NTRS)
The geologic mapping compiled at 1:500,000 scale of the northern Kasei Valles area of Mars (MTMs 25062 and 25067) indicates (1) at least three periods of Kasei Valles channeling, (2) the development of Sacra Fossae (linear depressions on Tempe Terra and Lunae Planum) in relation to Kasei channeling episodes, and (3) the nature of ridged plains material dissected by Kasei Valles on northern Lunae Planum. (The three channeling periods consists of two flood events and a later, sapping related event). These findings suggest hydrologic conditions and processes that formed Kasei Valles and associated features and terrains. It is concluded that an early period of flooding, whose source is perhaps buried beneath lava flows of Tharsis Montes, may have eroded streamlined features in northern Lunae Planum. Also, later floods originating from Echus Chasma formed after the initial flooding and the mesas adjacent to the plateau. The Sacra Fossae formed after the initial flooding and during the second flooding by sapping, outbreak, scarp retreat, and collapse along joints and fractures in ridged plains materials.
Chapman, Mary G.; Tanaka, Kenneth L.
Hydrology in the Durius Valles Region: Evaluation of Possible Correlation with Volcanism and Magnetic Anomalies
NASA Technical Reports Server (NTRS)
We envision the contribution of subglacial flows, hydrothermalism and sapping in the Durius Valles system and the consequences in term of climate on Mars in recent geological times. We evaluate the possible correlation of the hydrology with volcanism and magnetic anomalies.
Cabrol, Natalie A.; Marinangeli, Lucia; Grin, Edmond A.
Learning Disabilities and the New Reductionism: A Response to Reid and Valle
ERIC Educational Resources Information Center
The purpose of this article is to respond to Reid and Valle's article "The Discursive Practice of LD: Implications for Instruction and Parent?School Relations" in this issue. Our response to the discursive analysis is organized around two major themes: (a) the issue of balance in the scholarship on learning disabilities (LD) and (b) the centrality�
Neufeld, Paul; Hoskyn, Maureen
Geophysical and Hydrological Characterization of Alluvial Fans in the Valle El Sauz Encinillas, Chihuahua, M�xico
The Valle El Sauz Encinillas (VESE) is located 92 km north of Chihuahua City, M�xico. Despite being the principal aquifer feeding Chihuahua City, and being flanked by two well studied geological features (Bloque Calera-Del Nido to the West, and the Sierra Pe�a Blanca to the East), a lack of available hydrogeological data prevails in the valley. The goals of this
A. Villalobos-Arag�n; R. Ch�vez-Aguirre; A. Osuna-Vizcarra; V. V. Espejel-Garc�a
Restoring Anadromous Fish Habitat in Big Canyon Creek Watershed; Anadromous Fish Habitat Restoration in the Nichols Canyon Subwatershed, 1999 Annual Report.
Nez Perce Soil & Water Conservation District (NPSWCD) undertook the Nichols Canyon Subwatershed Steelhead Trout Habitat Improvement Project in the spring of 1999. This Project is funded through a grant provided by the Bonneville Power Administration. The Project's purpose is to install and implement agricultural best management practices (BMPs) and riparian restorations to improve steelhead trout spawning and rearing habitat in the Nichols Canyon subwatershed of Big Canyon Creek. Improvements to spawning and rearing habitat in lower Big Canyon Creek tributaries will enhance natural production of the species in Big Canyon Creek and ultimately the Clearwater River. The following report is a summation of the activities undertaken by the NPSWCD in the first year of the project.
Koziol, Deb (Nez Perce Soil and Water Conservation District, Lewiston, ID)
Environmental geochemistry of the Bingham Canyon porphyry copper deposit, Utah
At the Bingham Canyon porphyry copper deposit, sulfide mineralization progresses outward from a low-grade core through the following general zones: (1) molybdenite, (2) chalcopyrite-bornite, (3) chalcopyrite-pyrite, (4) pyrite, and (5) sphalerite-galena. The low-grade core and the molybdenite zone are composed of net neutralizing rock and will generally not acidify when exposed to surface weathering conditions. The copper-bearing zones of the
Richard K. Borden
A simple model for calculating air pollution within street canyons
NASA Astrophysics Data System (ADS)
This paper introduces the Semi-Empirical Urban Street (SEUS) model. SEUS is a simple mathematical model based on the scaling of air pollution concentration inside street canyons employing the emission rate, the width of the canyon, the dispersive velocity scale and the background concentration. Dispersive velocity scale depends on turbulent motions related to wind and traffic. The parameterisations of these turbulent motions include two dimensionless empirical parameters. Functional forms of these parameters have been obtained from full scale data measured in street canyons at four European cities. The sensitivity of SEUS model is studied analytically. Results show that relative errors in the evaluation of the two dimensionless empirical parameters have less influence on model uncertainties than uncertainties in other input variables. The model estimates NO2 concentrations using a simple photochemistry scheme. SEUS is applied to estimate NOx and NO2 hourly concentrations in an irregular and busy street canyon in the city of Buenos Aires. The statistical evaluation of results shows that there is a good agreement between estimated and observed hourly concentrations (e.g. fractional bias are ?10.3% for NOx and�+7.8% for NO2). The agreement between the estimated and observed values has also been analysed in terms of its dependence on wind speed and direction. The model shows a better performance for wind speeds >2�m�s?1 than for lower wind speeds and for leeward situations than for others. No significant discrepancies have been found between the results of the proposed model and that of a widely used operational dispersion model (OSPM), both using the same input information.
Venegas, Laura E.; Mazzeo, Nicol�s A.; Dezzutti, Mariana C.
Canyon Creek: A late Pleistocene vertebrate locality in interior Alaska
The Canyon Creek vertebrate-fossil locality is an extensive road cut near Fairbanks that exposes sediments that range in age from early Wisconsin to late Holocene. Tanana River gravel at the base of the section evidently formed during the Delta Glaciation of the north-central Alaska Range. Younger layers and lenses of fluvial sand are interbedded with arkosic gravel from Canyon Creek that contains tephra as well as fossil bones of an interstadial fauna about 40,000 years old. Solifluction deposits containing ventifacts, wedge casts, and rodent burrows formed during a subsequent period of periglacial activity that took place during the maximum phase of Donnelly Glaciation about 25,000-17,000 years ago. Overlying sheets of eolian sand are separated by a 9500-year-old paleosol that may correlate with a phase of early Holocene spruce expansion through central Alaska. The Pleistocene fauna from Canyon Creek consists of rodents (indicated by burrows), Mammuthus primigenius (woolly mammoth), Equus lambei (Yukon wild ass), Camelops hesternus (western camel), Bison sp. cf. B. crassicornis (large-horned bison), Ovis sp. cf. O. dalli (mountain sheep), Canis sp. cf. C. lupus (wolf), Lepus sp. cf. L. othus or L. arcticus (tundra hare), and Rangifer sp. (caribou). This assemblage suggests an open landscape in which trees and tall shrubs were either absent or confined to sheltered and moist sites. Camelops evidently was present in eastern Beringia during the middle Wisconsin interstadial interval but may have disappeared during the following glacial episode. The stratigraphic section at Canyon Creek appears to demonstrate that the Delta Glaciation of the north-central Alaska Range is at least in part of early Wisconsin age and was separated from the succeeding Donnelly Glaciation by an interstadial rather than interglacial episode. ?? 1981.
Weber, F. R.; Hamilton, T. D.; Hopkins, D. M.; Repenning, C. A.; Haas, H.
Grand Canyon Exercise: Geological Time, History, and Sedimentary Environments.
NSDL National Science Digital Library
This site presents a take-home web-based project for introductory geology students. The exercise has the students interpreting the sedimentary geology (lithology and fossils) of the Grand Canyon to create a geological history for the region. It is an open-ended exercise with no absolutely correct answer; it involves students acting as scientists - that is, the way real scientists think and combine information to come up with explanations.
Perkins, Dexter
Bedded barite in East Northumberland Canyon, Nye County, Nevada
Bedded barite has been identified in the course of stratigraphic studies by the U.S. Geological Survey in and near East Northumberland Canyon, Toquima Range, Nye County, Nev. The barite beds are interlayered in black chert of probable Ordovician age. The barite rock is mostly dark gray and massive, has a specific gravity averaging about 4.0, and contains, by chemical analysis, 70.7 to 93.9 percent BaSO4.
Shawe, Daniel R.; Poole, F. G.; Brobst, Donald Albert
Science Sampler: Map your way to the Grand Canyon
NSDL National Science Digital Library
How do urban eighth graders from the flatlands of Indiana capture the poetry and grandeur of the Grand Canyon without ever leaving the classroom? By talking and touching and seeing and smelling and listening and...writing. Enhance your eighth-grade geology unit by implementing this inquiry-based activity that stimulates the senses and uses writing as a means of assessment and as a creative outlet into your science curriculum.
Yoder, Holly
Outage differences between Diablo Canyon and Unterweser power plants
Diablo Canyon (DCPP) of Pacific Gas and Electric Company and Unterweser (KKU) of PreussenElektra have had an ongoing exchange program since 1989, which includes mutual visits by their employees at the optimum time for observing outages. Both DCPP and Unterweser use four-loop pressurized water reactors (PWRs), DCPP with two 1,100-MW units and KKU with a single 1,300-MW unit. Unterweser finished
Electrical resistance sensors record spring flow timing, Grand Canyon, Arizona
Springs along the south rim of the Grand Canyon, Arizona, are important ecological and cultural resources in Grand Canyon National Park and are discharge points for regional and local aquifers of the Coconino Plateau. This study evaluated the applicability of electrical resistance (ER) sensors for measuring diffuse, low-stage (<1.0 cm) intermittent and ephemeral flow in the steep, rocky spring-fed tributaries of the south rim. ER sensors were used to conduct a baseline survey of spring flow timing at eight sites in three spring-fed tributaries in Grand Canyon. Sensors were attached to a nearly vertical rock wall at a spring outlet and were installed in alluvial and bedrock channels. Spring flow timing data inferred by the ER sensors were consistent with observations during site visits, with flow events recorded with collocated streamflow gauging stations and with local precipitation gauges. ER sensors were able to distinguish the presence of flow along nearly vertical rock surfaces with flow depths between 0.3 and 1.0 cm. Laboratory experiments confirmed the ability of the sensors to monitor the timing of diffuse flow on impervious surfaces. A comparison of flow patterns along the stream reaches and at springs identified the timing and location of perennial and intermittent flow, and periods of increased evapotranspiration.
Adams, E. A.; Monroe, S. A.; Springer, A. E.; Blasch, K. W.; Bills, D. J.
Do urban canyons influence street level grass pollen concentrations?
In epidemiological studies, outdoor exposure to pollen is typically estimated using rooftop monitoring station data, whilst exposure overwhelmingly occurs at street level. In this study the relationship between street level and roof level grass pollen concentrations was investigated for city centre street canyon environments in Aarhus, Denmark, and London, UK, during the grass pollen seasons of 2010 and 2011 respectively. For the period mid-day to late evening, street level concentrations in both cities tended to be lower than roof-level concentrations, though this difference was found to be statistically significant only in London. The ratio of street/roof level concentrations was compared with temperature, relative humidity, wind speed and direction, and solar radiation. Results indicated that the concentration ratio responds to wind direction with respect to relative canyon orientation and local source distribution. In the London study, an increase in relative humidity was linked to a significant decrease in street/roof level concentration ratio, and a possible causative mechanism involving moisture mediated pollen grain buoyancy is proposed. Relationships with the other weather variables were not found to be significant in either location. These results suggest a tendency for monitoring station data to overestimate exposure in the canyon environment. PMID:24037300
Peel, Robert George; Kennedy, Roy; Smith, Matt; Hertel, Ole
Human rhinovirus capsid dynamics is controlled by canyon flexibility.
Quantitative enzyme accessibility experiments using nano liquid chromatography electrospray mass spectrometry combined with limited proteolysis and isotope-labeling was used to examine the dynamic nature of the human rhinovirus (HRV) capsid in the presence of three antiviral compounds, a neutralizing Fab, and drug binding cavity mutations. Using these methods, it was found that the antivirals WIN 52084 and picovir (pleconaril) stabilized the capsid, while dansylaziridine caused destabilization. Site-directed mutations in the drug-binding cavity were found to stabilize the HRV14 capsid against proteolytic digestion in a manner similar to WIN 52084 and pleconaril. Antibodies that bind to the NIm-IA antigenic site and penetrate the canyon were also observed to protect the virion against proteolytic cleavage. These results demonstrate that quantifying the effects of antiviral ligands on protein "breathing" can be used to compare their mode of action and efficacy. In this case, it is apparent that hydrophobic antiviral agents, antibodies, or mutations in the canyon region block viral breathing. Therefore, these studies demonstrate that mobility in the canyon region is a major determinant in capsid breathing. PMID:14517058
Reisdorph, Nichole; Thomas, John J; Katpally, Umesh; Chase, Elaine; Harris, Ken; Siuzdak, Gary; Smith, Thomas J
Geomorphic characterization of four shelf-sourced submarine canyons along the U.S. Mid-Atlantic continental margin
NASA Astrophysics Data System (ADS)
Shelf-sourced submarine canyons are common features of continental margins and are fundamental to deep-sea sedimentary systems. Despite their geomorphic and geologic significance, relatively few passive margin shelf-breaching canyons worldwide have been mapped using modern geophysical methods. Between 2007 and 2012 a series of geophysical surveys was conducted across four major canyons of the US Mid-Atlantic margin: Wilmington, Baltimore, Washington, and Norfolk canyons. More than 5700 km2 of high-resolution multibeam bathymetry and 890 line-km of sub-bottom CHIRP profiles were collected along the outer shelf and uppermost slope (depths of 80-1200 m). The data allowed us to compare and contrast the fine-scale morphology of each canyon system. The canyons have marked differences in the morphology and orientation of canyon heads, steepness and density of sidewall gullies, and the character of the continental shelf surrounding canyon rims. Down-canyon axial profiles for Washington, Baltimore and Wilmington canyons have linear shapes, and each canyon thalweg exhibits morphological evidence for recent, relatively small-scale sediment transport. For example, Washington Canyon displays extremely steep wall gradients and contains ~100 m wide, 5-10 m deep, v-shaped incisions down the canyon axis, suggesting modern or recent sediment transport. In contrast, the convex axial thalweg profile, the absence of thalweg incision, and evidence for sediment infilling at the canyon head, suggest that depositional processes strongly influence Norfolk Canyon during the current sea-level high-stand. The north walls of Wilmington, Washington and Norfolk canyons are steeper than the south walls due to differential erosion, though the underlying cause for this asymmetry is not clear. Furthermore, we speculate that most of the geomorphic features observed within the canyons (e.g., terraces, tributary canyons, gullies, and hanging valleys) were formed during the Pleistocene, and show only subtle modification by Holocene processes active during the present sea-level high-stand.
Obelcz, Jeffrey; Brothers, Daniel; Chaytor, Jason; Brink, Uri ten; Ross, Steve W.; Brooke, Sandra
Hydraulics of outburst floods spilling over a steep-walled canyon: Implications for paleo-discharges on Mars
NASA Astrophysics Data System (ADS)
Canyons carved by outburst floods are common landforms on Earth and Mars. These canyons are generally found in fractured basalts and jointed sedimentary rocks. Flood-carved canyons commonly have steep headwalls and a roughly constant width, and are often thought to have formed from upstream headwall propagation due to waterfall erosion. Because morphology is readily available from satellite imagery, these canyons offer a unique opportunity to quantify the discharge of rare, catastrophic paleo-floods on Earth and Mars. However, mechanistic relationships that relate canyon size to flood discharge have yet to be developed. We propose that the width of a canyon headwall in fractured rock is set by the spatial distribution of erosion around the rim of the canyon, which is controlled by the distribution of shear stresses induced by the overflowing water as it is focused into the canyon head. We test this hypothesis by performing a series of numerical simulations of flood-water focusing using ANUGA Hydro, a 2D-depth averaged, fully turbulent, hydraulic numerical modeling suite allowing for Froude-number transitions. The numerical simulations were designed to explore five dimensionless variables: the aspect ratio of the canyon (length normalized by width), the canyon width to flood-water width ratio, the canyon width to normal-flow depth ratio, the Froude number, and the topographic gradient upstream of the canyon. Preliminary results show that flow focusing leads to increased shear stresses at the canyon head compared to the sides of the canyon for subcritical floods and higher canyon aspect ratios. This suggests that proto-canyons start growing from a topographic defect in all directions until they reach a critical length for the side walls to dry. Once this critical length is attained, canyons focus most of the flood waters into their heads, and propagate upstream only, maintaining roughly constant widths. Preliminary results suggest that canyon width may be used to reconstruct the discharge of paleo-flood events on Mars and Earth.
Lapotre, Mathieu; Lamb, Michael
Evolution of Paleogene submarine Canyon-Fan systems, southern Sacramento basin, California
The evolutionary development of the Paleogene Martinez and Meganos Submarine Canyon and Fan systems of the southern Sacramento basin was controlled by a complex interplay of eustatic sea level change and tectonism. In this brief synthesis, the authors postulated that eustatic sea level changes were the dominant or controlling factor, and tectonism, although significant, was of secondary importance. The development of the Paleogene canyon and fan systems is correlated with low sea level stands or regressions at 60 Ma and 56 Ma. Intermittent tectonism, beginning at least 5-10 m.y. earlier, particularly along the western and southwestern margins of the Sacramento basin, controlled the location of the canyon and fan systems. The controlling tectonic elements of the southern basin were north-trending, high-angle faults related to the Kirby Hills and Midland fault zones and the Diablo-Kirby Hills(.) uplift. Both canyons were probably active (that is, channeling coarse sediment to their fans) during most of the late Paleocene. The authors suggest that canyon activity was maintained by south-flowing longshore drift or feeder systems, down-canyon gravity flows (turbidites, etc) and up-down canyon current systems, all of which are typical of modern, active submarine canyon and fan systems. The canyons filled with fine-grained sediments when the canyons were beheaded or separated from the longshore drift system by rising sea level, or when tectonism(.) shifted the major river drainage that supplied the canyon with sediment. Truncation and erosion of the canyon-fill and fan facies of the late Paleocene-early Eocene Meganos Formation along the Diablo outcrop belt was primarily due to the major early middle Eocene lowstand (49.5 Ma).
Fischer, P.J.; Cherven, V.B.; Almgren, A.A.
Colorado River sediment transport: 1. Natural sediment supply limitation and the influence of Glen Canyon Dam
Analyses of flow, sediment-transport, bed-topographic, and sedimentologic data suggest that before the closure of Glen Canyon Dam in 1963, the Colorado River in Marble and Grand Canyons was annually supply-limited with respect to fine sediment (i.e., sand and finer material). Furthermore, these analyses suggest that the predam river in Glen Canyon was not supply-limited to the same degree and that
David J. Topping; David M. Rubin; L. E. Vierra
Distribution and transport of suspended particulate matter in Monterey Canyon, California
From August 1993 to August 1994, six moorings that measure current, temperature, salinity, and water clarity were deployed along the axis of Monterey Canyon to study the circulation and transport of water and suspended particulate matter through the canyon system. The moorings occupied three sites that are morphologically different: a narrow transverse section (axis width 900 m) at 1450 m water depth, a wide transverse section at 2837 m, and a third site in the fan valley axis farther offshore at 3223 m that recorded for 3 yr. In addition, CTD/transmissometer casts were conducted within and near the Monterey Canyon during four cruises. Our data show a mainly biogenic, surface turbid layer, a limited intermediate nepheloid layer, and a bottom nepheloid layer. There is a consistent presence of a turbid layer within the canyon at a water depth of about 1500 m. Tidal flow dominates at all sites, but currents above the canyon rim and within the canyon appear to belong to two distinct dynamic systems. Bottom intensification of currents plays an important role in raising the near-bottom shear stress high enough that bottom sediments are often, if not always, resuspended. Mean flow pattern suggests a convergence zone between the narrow and wide site: the near-bed (100 m above bottom where the lowest current meter was located) mean transport is down-canyon at the 1450-m site, while the near-bottom transport at the 2837-m site is up-canyon, at a smaller magnitude. Transport at the 3223-m site is dominantly NNW, cross-canyon, with periods of up-canyon flow over 3 yr. A very high-turbidity event was recorded 100 m above the canyon bottom at the narrow site. The event started very abruptly and lasted more than a week. This event was not detected at either of the deeper sites. A canyon head flushing event is likely the cause. ?? 2002 Elsevier Science B.V. All rights reserved.
Xu, J. P.; Noble, M.; Eittreim, S. L.; Rosenfeld, L. K.; Schwing, F. B.; Pilskaln, C. H.
Semiannual patterns of erosion and deposition in upper Monterey Canyon from serial multibeam bathymetry
Recently acquired 3-m-resolution 244 kHz multibeam seafl oor bathymetry (0.5 m depth precision) reveals geomorphology at suffi cient detail to interpret small-scale fea- tures and short-term processes in the upper 4 km of Monterey Canyon, California. The study area includes the continental shelf and canyon features from 10 m to 250 m depth. The canyon fl oor contains an axial
Douglas P. Smith; Genoveva Ruiz; Rikk Kvitek; Pat J. Iampietro
Canyon Effects on Nearshore Infragravity Waves During NCEX
NASA Astrophysics Data System (ADS)
Infragravity waves become increasingly important as the water depth gets shallower and wind generated waves become saturated due to wave breaking. Infragravity wave energy is composed of wave-group forced long waves and reflected leaky waves and trapped edge waves. Typically conditions on a approximately alongshore uniform beach are consisdered (e.g. Herbers et al., 1994, van Dongeren et al., 2003). Here we examine the alongshore variability in the infragravity conditions induced by nearby canyons utilizing a 2D-surfbeat model (Reniers et al., 2004). The model simulates the propagation of both leaky and trapped infragravity waves that are generated by directionally spread wave groups. Model computations are used to examine the potential reflection (Inman et al., 1976, Huntley et al., 1981) of shore-trapped edge waves from the canyon walls by considering various model-scenarios with and without the canyons. Computational results will be compared with observations of infragravity conditons obtained from an alongshore array of pressure and velocity meters situated just north of the canyon (MacMahan et al., 2004, this conference). References Herbers, T.H.C., Steve Elgar and R.T. Guza, 1994: Infragravity-frequency (0.005 0.05 Hz) motions on the shelf. Part 1: Forced waves. J. Phys. Oc., 25, 1063-1079. Huntley, D. A., R. T. Guza and E. B. Thornton, 1981, "Field Observations of Surf Beat: Part I, Progressive Edge Waves", J. Geophys. Res., 86, 6451-6466. Inman, D.L., C.E. Nordstrom and R.E. Flick, 1976: Currents in sub-marine canyons: An air-sea-land interaction, Ann. Rev. Fluid Mech., 8, 275-310. MacMahan, J., E.B. Thornton, A. Reniers and T.P. Stanton, 2004, The Torrey Pines Rip-currents, this conference. Reniers, A.J.H.M., E.B. Thornton and J.A. Roelvink, 2004: Morphodynamic modeling of an embayed beach under wave-group forcing, J. Geophys. Res., 109, C01030, doi:10.1029/2002JC001586. Van Dongeren, A.R., A.J.H.M. Reniers, J.A. Battjes and I.A. Svendsen, 2003, "Numerical modeling of infragravity wave response during Delilah." J. Geoph. Res, 108 (C9), 4-1-19
Reniers, A.; Macmahan, J.; Thornton, E.; Stanton, T.
Geothermal data for 95 thermal and nonthermal waters of the Valles Caldera - southern Jemez Mountains region, New Mexico
Field, chemical, and isotopic data for 95 thermal and nonthermal waters of the southern Jemez Mountains, New Mexico are presented. This region includes all thermal and mineral waters associated with Valles Caldera and many of those located near the Nacimiento Uplift, near San Ysidro. Waters of the region can be categorized into five general types: (1) surface and near surface meteoric waters; (2) acid-sulfate waters (Valles Caldera); (3) thermal meteoric waters (Valles Caldera); (4) deep geothermal and derivative waters (Valles Caldera); and (5) mineralized waters near San Ysidro. Some waters display chemical and isotopic characteristics intermediate between the types listed. The object of the data is to help interpret geothermal potential of the Jemez Mountains region and to provide background data for investigating problems in hydrology, structural geology, hydrothermal alterations, and hydrothermal solution chemistry.
Goff, F.; McCormick, Trujillo, P.E. Jr.; Counce, D.; Grigsby, C.O.
Modeling Floods in Athabasca Valles, Mars, Using CTX Stereo Topography
NASA Astrophysics Data System (ADS)
Among the most remarkable landforms on Mars are the outflow channels, which suggest the occurrence of catastrophic water floods in the past. Athabasca Valles has long been thought to be the youngest of these channels [1-2], although it has recently become clear that the young crater age applies to a coating lava flow [3]. Simulations with a 2.5-dimensional flood model have provided insight into the details of flood dynamics but have also demonstrated that the Digital Elevation Model (DEM) from the Mars Orbiter Laser Altimeter (MOLA) Mission Experiment Gridded Data Records includes significant artifacts at this latitude at the scales relevant for flood modeling [4]. In order to obtain improved topography, we processed stereo images from the Context Camera (CTX) of the Mars Reconnaissance Orbiter (MRO) using methods developed for producing topographic models of the Moon with images from the Lunar Reconnaissance Orbiter Camera, a derivative of the CTX camera. Some work on flood modeling with CTX stereo has been published by [5], but we will present several advances, including corrections to the published CTX optical distortion model and improved methods to combine the stereo and MOLA data. The limitations of current methods are the accuracy of control to MOLA and the level of error introduced when the MRO spacecraft is not in a high-stability mode during stereo imaging, leading to jitter impacting the derived topography. Construction of a mosaic of multiple stereo pairs, controlled to MOLA, allows us to consider flow through the cluster of streamlined islands in the upper part of the channel [6], including what is suggested to be the best example of flood-formed subaqueous dunes on Mars [7]. We will present results from running a flood model [4, 8] through the high-resolution (100 m/post) DEM covering the streamlined islands and subaqueous dunes, using results from a lower-resolution model as a guide to the inflow. By considering a range of flow levels below estimated peak flow, we can examine the flow behavior at the site of the apparent subaqueous dunes and, in particular, assess whether the flow in this area is uniquely conducive to the formation of such bedforms [e.g., 9]. [1] Berman D. C. and Hartmann W. K. (2002) Icarus 159, 1-17. [2] Burr D. M. et al. (2002) Icarus 159, 53-73. [3] Jaeger W. L. et al. (2010) Icarus 205, 230-243. [4] Keszthelyi L. P. et al. (2007) GRL 34, L21206. [5] McIntyre et al. (2012) JGR 117, E03009. [6] Burr D. (2005) Geomorphology 69, 242-252. [7] Burr D. M. et al. (2004) Icarus 171, 68-83. [8] Denlinger R. P. and O'Connell D. R. H. (2008) J. Hyd. Eng. 134, 1590-1602. [9] Kleinhans M. G. (2005) JGR 110, E12003.
Dundas, C. M.; Keszthelyi, L. P.; Denlinger, R. P.; Thomas, O. H.; Galuszka, D.; Hare, T. M.; Kirk, R. L.; Howington-Kraus, E.; Rosiek, M.
Morphology of Submarine Canyons in the Palomares Margin (East of Alboran Sea, western Mediterranean)
NASA Astrophysics Data System (ADS)
Morphological analysis on the Palomares Margin has been done using high-resolution swath bathymetry data collected during the MARSIBAL-06 (2006) cruise on board of the R/V BIO Hesp�rides. Complemented with data from GEBCO 2000 and Ifremer (Medimap Group, 2007) the data-set provides the first complete bathymetric mosaic of the Palomares Margin. The bathymetric mosaic allows to study the physiographic provinces of the Palomares Margin and to conduct, for the first time, a detailed morphological analysis of the two main sediment-transfer conduits: the Gata and the Alias-Almanzora Canyons. The Gata Canyon extends for 64km from the outer shelf to the base of the slope with a general W-E direction. A tributary system of canyons originates at the shelf break and continues on the slope until they merge at 1230m water depth. The walls of the canyons are characterized by repeated slides. Perpendicular profiles to the Canyon pathway reveal gentle transversal "V" asymmetrical shapes with a marked axial incision on the canyon floor (highs between 65 to 103m in the southern flank, and between 30-90m in the northern flank ). The transition from an erosional canyon to a deposition channel is located at 2100m water depth, and is characterized by trapezoidal shapes on transversal profiles accompanied of lower relieves (40-65m). At the mouth of the canyon-channel system no sedimentary lobes are observed. The Alias-Almanzora canyon (73km long and preferential direction W-E) is located North of the Gata Canyon and extends from the continental shelf to the base of the slope. A tributary system to the Alias- Almanzora canyon-head locates less than 150m from the coast, facing a fluvial drainage system onland. Proximal tributary canyons and gullies feed the main canyon until it merges in the continental slope at 1516m water depth. The tributary system exhibits a marked "V" shape in transverse profiles and marked axial incisions. Down slope, transversal profiles have trapezoidal shapes. Longitudinal profiles show convex-up sections along the tributary system and concave-up sections from the merge in the main canyon down slope. The transition from an erosional canyon to a depositional channel is located at 2100m water depth. The mouth of the Alias-Almanzora Canyon-channel system is characterized by distributaries channels and lobated features. Morphological analyses from these Canyons indicate they have different origin and evolution. The connection of the Alias-Almanzora Canyon to a fluvial drainage system offshore suggests the canyon formed by erosion of the continental shelf edge during sea-level low stand periods, when entrapment of sediment on deltas and reduced sediment transport through submarine canyons occurred. The Gata Canyon has instead developed by head wards erosion and gravitational instabilities. Both canyon systems are highly influenced by recent tectonics, and structural trends influence their location and changes in pathways. Contribution from Projects SAGAS CTM2005-08071-03-01 and TOPO-IBERIA CSD2006-00041 (R & D National Plan of the Ministry of Science and Technology and FEDER funding, Spain).
Perez-Hernandez, S.; Comas, M. C.; Escutia, C.
Restoring Anadromous Fish Habitat in Big Canyon Creek Watershed; Anadromous Fish Habitat Restoration in the Nichols Canyon Subwatershed, 2000 Annual Report.
Nez Perce Soil & Water Conservation District (NPSWCD) undertook the Nichols Canyon Subwatershed Steelhead Trout Habitat Improvement Project in the spring of 1999 with funding from a grant through the Bonneville Power Administration. The Project's purpose is to install and implement agricultural best management practices (MBPS) and riparian restorations with the goal of improving steelhead trout spawning and rearing habitat in the subwatershed. Improvements to fish habitat in the Big Canyon Creek tributaries enhances natural production of the species in Big Canyon Creek and ultimately the Clearwater River. This report is a summation of the progress made by the NPSWCD in the Project's second year.
Koziol, Deb (Nez Perce Soil and Water Conservation District, Lewiston, ID)
Unusually high food availability in Kaikoura Canyon linked to distinct deep-sea nematode community
NASA Astrophysics Data System (ADS)
Kaikoura Canyon, on the eastern New Zealand continental margin, is the most productive, non-chemosynthetic deep-sea habitat described to date, with megafaunal biomass 100-fold higher than those of other deep-sea habitats. The present study, which focused on free-living nematodes, provides the first comparison of faunal community structure and diversity between Kaikoura Canyon and nearby open slope habitats. Results show substantially higher food availability in the canyon relative to open slope sediments, which probably reflects greater levels of primary productivity above the canyon, coupled with downwelling and/or topographically-induced channelling, which serves to concentrate surface-derived organic matter along the canyon axis. This high food availability appears to be responsible for the elevated nematode biomass in Kaikoura Canyon, with values exceeding all published nematode biomass data from canyons elsewhere. There was also markedly lower local species diversity of nematodes inside the canyon relative to the open slope habitat, as well as a distinct community structure. The canyon community was dominated by species, such as Sabateria pulchra, which were absent from the open slope and are typically associated with highly eutrophic and/or disturbed environments. The presence of these taxa, as well as the low observed diversity, is likely to reflect the high food availability, and potentially the high levels of physically and biologically induced disturbance within the canyon. Kaikoura Canyon is a relatively small habitat characterised by different environmental conditions that makes a disproportionate contribution to deep-sea diversity in the region, despite its low species richness.
Leduc, D.; Rowden, A. A.; Nodder, S. D.; Berkenbusch, K.; Probert, P. K.; Hadfield, M. G.
Submarine canyons: hotspots of benthic biomass and productivity in the deep sea.
Submarine canyons are dramatic and widespread topographic features crossing continental and island margins in all oceans. Canyons can be sites of enhanced organic-matter flux and deposition through entrainment of coastal detrital export, dense shelf-water cascade, channelling of resuspended particulate material and focusing of sediment deposition. Despite their unusual ecological characteristics and global distribution along oceanic continental margins, only scattered information is available about the influence of submarine canyons on deep-sea ecosystem structure and productivity. Here, we show that deep-sea canyons such as the Kaikoura Canyon on the eastern New Zealand margin (42 degrees 01' S, 173 degrees 03' E) can sustain enormous biomasses of infaunal megabenthic invertebrates over large areas. Our reported biomass values are 100-fold higher than those previously reported for deep-sea (non-chemosynthetic) habitats below 500 m in the ocean. We also present evidence from deep-sea-towed camera images that areas in the canyon that have the extraordinary benthic biomass also harbour high abundances of macrourid (rattail) fishes likely to be feeding on the macro- and megabenthos. Bottom-trawl catch data also indicate that the Kaikoura Canyon has dramatically higher abundances of benthic-feeding fishes than adjacent slopes. Our results demonstrate that the Kaikoura Canyon is one of the most productive habitats described so far in the deep sea. A new global inventory suggests there are at least 660 submarine canyons worldwide, approximately 100 of which could be biomass hotspots similar to the Kaikoura Canyon. The importance of such deep-sea canyons as potential hotspots of production and commercial fisheries yields merits substantial further study. PMID:20444722
De Leo, Fabio C; Smith, Craig R; Rowden, Ashley A; Bowden, David A; Clark, Malcolm R
77 FR 61658 - Idaho Northern & Pacific Railroad Company-Discontinuance of Trackage Rights Exemption-in Canyon...
Federal Register 2010, 2011, 2012, 2013
...Discontinuance of Trackage Rights Exemption--in Canyon, Payette and Washington Counties, ID On September 19, 2012, Idaho...and milepost 465.91, at Caldwell Junction, in Canyon, Payette and Washington Counties, Idaho.\\1\\ The line...
33 CFR 165.840 - Regulated Navigation Area, Gulf of Mexico: Mississippi Canyon Block 20, South of New Orleans, LA.
Code of Federal Regulations, 2011 CFR
...2013-07-01 false Regulated Navigation Area, Gulf of Mexico: Mississippi Canyon Block 20, South of New Orleans...District § 165.840 Regulated Navigation Area, Gulf of Mexico: Mississippi Canyon Block 20, South of New...
Clustered streamlined forms in Athabasca Valles, Mars: Evidence for sediment deposition during floodwater ponding
A unique clustering of layered streamlined forms in Athabasca Valles is hypothesized to reflect a significant hydraulic event. The forms, interpreted as sedimentary, are attributed to extensive sediment deposition during ponding and then streamlining of this sediment behind flow obstacles during ponded water outflow. These streamlined forms are analogous to those found in depositional basins and other loci of ponding in terrestrial catastrophic flood landscapes. These terrestrial streamlined forms can provide the best opportunity for reconstructing the history of the terrestrial flooding. Likewise, the streamlined forms in Athabasca Valles may provide the best opportunity to reconstruct the recent geologic history of this young Martian outflow channel. ?? 2005 Elsevier B.V. All rights reserved.
Burr, D.
Mangala Valles, Mars: Investigations of the Source of Flood Water and Early Stages of Flooding
NASA Technical Reports Server (NTRS)
Mangala Valles, an approx. 900 km long north-south trending outflow channel located southwest of the Tharsis rise, extends northward from one of the Memnonia Fossae graben across the southern highlands, terminating at the dichotomy boundary. Previous Viking-based analyses suggest that the water that carved the channel was expelled from the graben, possibly during two distinct flood events, one in the Late Hesperian and one in the Latest Hesperian/Early Amazonian. The mechanism by which the water was transported to the graben, and ultimately to the surface remained ambiguous, although two general scenarios were proposed: melting of near surface ground ice via nearby Tharsis lava flows, and tapping of a near surface aquifer via faulting associated with the graben. Here we use MOLA altimetric data and MOC and THEMIS images to reexamine Mangala Valles and the surrounding region. Further, we develop a new model for the production and transport of the floodwater.
Ghatan, Gil J.; Head, James W.; Wilson, L.; Leask, H. J.
Small mammal study of Sandia Canyon, 1994 and 1995
A wide range of plant and wildlife species utilize water discharged from facilities at Los Alamos National Laboratory (LANL). The purpose of this study was to gather baseline data of small mammal populations and compare small mammal characteristics within three areas of Sandia Canyon, which receives outfall effluents from multiple sources. Three small mammal trapping webs were placed in the upper portion of Sandia Canyon, the first two were centered in a cattail-dominated marsh with a ponderosa pine overstory and the third web was placed in a much drier transition area with a ponderosa pine overstory. Webs 1 and 2 had the highest species diversity indices with deer mice the most commonly captured species in all webs. However, at Web 1, voles, shrews, and harvest mice, species more commonly found in moist habitats, made up a much greater overall percentage (65.6%) than did deer mice and brush mice (34.5%). The highest densities and biomass of animals were found in Web 1 with a continual decrease in density estimates in each web downstream. There is no statistical difference between the mean body weights of deer mice and brush mice between sites. Mean body length was also determined not to be statistically different between the webs (GLM [deer mouse], F = 0.89, p = 0.4117; GLM [brush mouse], F = 2.49, p = 0.0999). Furthermore, no statistical difference between webs was found for the mean lean body masses of deer and brush mice (GLM [deer mouse], F = 2.54, p = 0.0838; GLM [brush mouse], F = 1.60, p = 0.2229). Additional monitoring studies should be conducted in Sandia Canyon so comparisons over time can be made. In addition, rodent tissues should be sampled for contaminants and then compared to background or control populations elsewhere at the Laboratory or at an off-site location.
Bennett, K.; Biggs, J.
Aerodynamic effects of trees on pollutant concentration in street canyons.
This paper deals with aerodynamic effects of avenue-like tree planting on flow and traffic-originated pollutant dispersion in urban street canyons by means of wind tunnel experiments and numerical simulations. Several parameters affecting pedestrian level concentration are investigated, namely plant morphology, positioning and arrangement. We extend our previous work in this novel aspect of research to new configurations which comprise tree planting of different crown porosity and stand density, planted in two rows within a canyon of street width to building height ratio W/H=2 with perpendicular approaching wind. Sulfur hexafluoride was used as tracer gas to model the traffic emissions. Complementary to wind tunnel experiments, 3D numerical simulations were performed with the Computational Fluid Dynamics (CFD) code FLUENT using a Reynolds Stress turbulence closure for flow and the advection-diffusion method for concentration calculations. In the presence of trees, both measurements and simulations showed considerable larger pollutant concentrations near the leeward wall and slightly lower concentrations near the windward wall in comparison with the tree-less case. Tree stand density and crown porosity were found to be of minor importance in affecting pollutant concentration. On the other hand, the analysis indicated that W/H is a more crucial parameter. The larger the value of W/H the smaller is the effect of trees on pedestrian level concentration regardless of tree morphology and arrangement. A preliminary analysis of approaching flow velocities showed that at low wind speed the effect of trees on concentrations is worst than at higher speed. The investigations carried out in this work allowed us to set up an appropriate CFD modelling methodology for the study of the aerodynamic effects of tree planting in street canyons. The results obtained can be used by city planners for the design of tree planting in the urban environment with regard to air quality issues. PMID:19596394
Buccolieri, Riccardo; Gromke, Christof; Di Sabatino, Silvana; Ruck, Bodo
Estudio semi�tico de El embrujado de Ram�n del Valle-Incl�n
El embrujado by Ram�n del Valle-Incl�n, published first in 1913, did not enjoy a positive reception from the public and the critics. The play was not actually produced\\u000a on stage until 1931 by the Teatro Mu�oz Seca. Even though critical reception was a bit more positive this time, the play did\\u000a not achieve great public success. This essay constitutes a
Inma C�vico Lyons
Antimicrobial activity of flavonoids in medicinal plants from Taf� del Valle (Tucum�n, Argentina).
Preliminary studies of flavonoids have been realised in five native species from Taf� del Valle (Tucum�n, Argentina) used in popular medicine. Most of compounds detected were flavonoids mono and dihydroxylated in B ring. Screening for antimicrobial activity against Gram positive and Gram negative microorganisms has been realised with Lippia turbinata, Satureja parvifolia, Sambucus peruviana, Verbena officinalis and Chenopodium graveolens. The total extracts of flavonoids of each plant were tested and four species studied showed antimicrobial activity. PMID:11025172
Hern�ndez, N E; Tereschuk, M L; Abdala, L R
Recirculating flow and sedimentation in the Colorado River in Grand Canyon, Arizona
Debris fans debouching into the bottom of Grand Canyon create rapids and flow separation in the Colorado River. The patterns of flow and the behavior of recirculation zones formed by flow separation are consistent throughout the Canyon's length. Zones of recirculating flow occur along the margin of channel expansions. Recirculation zones are comprised of one primary eddy; secondary eddies and
John C. Schmidt
Analysis of Water Flow Problems in the Hells Canyon Reach of the Snake River.
National Technical Information Service (NTIS)
The problems associated with water flow and operation of dams in the Hells Canyon area of the Snake River in Idaho were surveyed and possible solutions were examined. Conflicts between Idaho Power Company projects and plans for the Hells Canyon Recreation...
J. H. Coffin
Age and diet of fossil California condors in Grand Canyon, Arizona
A dozen new radiocarbon dates, together with a thorough review of its fossil distribution, shed new light on the time and probable cause of extinction of the California condor, Gymnogyps californianus, in Grand Canyon, Arizona. The radiocarbon data indicate that this species became extinct in Grand Canyon, and other parts of the inland West, more than 10,000 years ago in
Age and Diet of Fossil California Condors in Grand Canyon, Arizona
A dozen new radiocarbon dates, together with a thorough review of its fossil distribution, shed new light on the time and probable cause of extinction of the California condor, Gymnogyps californianus, in Grand Canyon, Arizona. The radiocarbon data indicate that this species became extinct in Grand Canyon, and other parts of the inland West, more than 10,000 years ago in
Steven D. Emslie
Spatial and temporal variability of meiobenthic density in the Blanes submarine canyon (NW Mediterranean)
NASA Astrophysics Data System (ADS)
Meiofaunal density distribution was studied from 400 m to 1500 m depth inside Blanes submarine canyon (NW Mediterranean), and on the eastern open slope in autumn 2003 and spring 2004. Our multidisciplinary approach allowed to study the hydrodynamics and sedimentary processes in the Blanes Canyon that characterize it as highly heterogeneous environment. Inside the canyon area, particle fluxes were higher than on the slope area, increased from autumn to spring and mostly consisted of lithogenic material. Moreover the canyon�s locations experienced more intense bottoms� currents and sediment disturbance, being reflected in a greater variability of meiobenthic densities, both between stations and sampling times than on the open slope. No clear trends (e.g. declining densities) associated with increasing depths were observed. Contrary in the open slope, current velocities were relatively lower compared with the canyon area and showed lower temporal variability. At the same time, the nutritional quality of the particle fluxes at deeper grounds were higher, probably allowing the meiofaunal densities not to change over time. In conclusion, the meiobenthos in our system apparently showed a higher temporal variability, inside the canyon area, strongly affected by particle fluxes or erosive and sediment-mixing processes linked to current modifications induced by the canyon topography.
Romano, C.; Coenjaerts, J.; Flexas, M. M.; Z��iga, D.; Vanreusel, A.; Company, J. B.; Martin, D.
75 FR 10838 - Pacific Gas and Electric Company; Diablo Canyon Power Plant; Exemption
Federal Register 2010, 2011, 2012, 2013
...50-323; NRC-2010-0059] Pacific Gas and Electric Company; Diablo Canyon Power Plant; Exemption 1.0 Background Pacific Gas...Nos. DPR-80 and DPR-82, which authorize operation of the Diablo Canyon Power Plant, Units Nos. 1 and 2 (DCPP). The...
77 FR 7211 - Pacific Gas and Electric Company, Diablo Canyon Independent Spent Fuel Storage Installation...
Federal Register 2010, 2011, 2012, 2013
...72-26; NRC-2011-0110] Pacific Gas and Electric Company, Diablo Canyon Independent Spent Fuel Storage Installation; Notice...SNM-2511 to the Pacific Gas and Electric Company (PG&E) for the Diablo Canyon (DC) Independent Spent Fuel Storage...
75 FR 8152 - Pacific Gas and Electric Company; Diablo Canyon Power Plant Environmental Assessment and Finding...
Federal Register 2010, 2011, 2012, 2013
...50-323; NRC-2010-0059] Pacific Gas and Electric Company; Diablo Canyon Power Plant Environmental Assessment and Finding of No...Electric Company (PG&E, the licensee), for operation of the Diablo Canyon Power Plant, Unit Nos. 1 and 2 (DCPP), located...
Combined optic-flow and stereo-based navigation of urban canyons for a UAV
We present a novel vision-based technique for navigating an unmanned aerial vehicle (UAV) through urban canyons. Our technique relies on both optic flow and stereo vision information. We show that the combination of stereo and optic flow (stereo flow) is more effective at navigating urban canyons than either technique alone. Optic flow from a pair of sideways looking cameras is
Stefan Hrabar; Gaurav S. Sukhatme; Peter Corke; Kane Usher; Jonathan Roberts
Amphitheater-headed canyons formed by megaflooding at Malad Gorge, Idaho
Many bedrock canyons on Earth and Mars were eroded by upstream propagating headwalls, and a prominent goal in geomorphology and planetary science is to determine formation processes from canyon morphology. A diagnostic link between process and form remains highly controversial, however, and field investigations that isolate controls on canyon morphology are needed. Here we investigate the origin of Malad Gorge, Idaho, a canyon system cut into basalt with three remarkably distinct heads: two with amphitheater headwalls and the third housing the active Wood River and ending in a 7% grade knickzone. Scoured rims of the headwalls, relict plunge pools, sediment-transport constraints, and cosmogenic (3He) exposure ages indicate formation of the amphitheater-headed canyons by large-scale flooding ?46 ka, coeval with formation of Box Canyon 18 km to the south as well as the eruption of McKinney Butte Basalt, suggesting widespread canyon formation following lava-flow diversion of the paleo-Wood River. Exposure ages within the knickzone-headed canyon indicate progressive upstream younging of strath terraces and a knickzone propagation rate of 2.5 cm/y over at least the past 33 ka. Results point to a potential diagnostic link between vertical amphitheater headwalls in basalt and rapid erosion during megaflooding due to the onset of block toppling, rather than previous interpretations of seepage erosion, with implications for quantifying the early hydrosphere of Mars.
Lamb, Michael P.; Mackey, Benjamin H.; Farley, Kenneth A.
Amphitheater-headed canyons formed by megaflooding at Malad Gorge, Idaho.
Many bedrock canyons on Earth and Mars were eroded by upstream propagating headwalls, and a prominent goal in geomorphology and planetary science is to determine formation processes from canyon morphology. A diagnostic link between process and form remains highly controversial, however, and field investigations that isolate controls on canyon morphology are needed. Here we investigate the origin of Malad Gorge, Idaho, a canyon system cut into basalt with three remarkably distinct heads: two with amphitheater headwalls and the third housing the active Wood River and ending in a 7% grade knickzone. Scoured rims of the headwalls, relict plunge pools, sediment-transport constraints, and cosmogenic ((3)He) exposure ages indicate formation of the amphitheater-headed canyons by large-scale flooding ?46 ka, coeval with formation of Box Canyon 18 km to the south as well as the eruption of McKinney Butte Basalt, suggesting widespread canyon formation following lava-flow diversion of the paleo-Wood River. Exposure ages within the knickzone-headed canyon indicate progressive upstream younging of strath terraces and a knickzone propagation rate of 2.5 cm/y over at least the past 33 ka. Results point to a potential diagnostic link between vertical amphitheater headwalls in basalt and rapid erosion during megaflooding due to the onset of block toppling, rather than previous interpretations of seepage erosion, with implications for quantifying the early hydrosphere of Mars. PMID:24344293
Lamb, Michael P; Mackey, Benjamin H; Farley, Kenneth A
Effects of building-roof cooling on flow and air temperature in urban street canyons
NASA Astrophysics Data System (ADS)
The effects of building-roof cooling on flow and air temperature in 3D urban street canyons are numerically investigated using a computational fluid dynamics (CFD) model. The aspect ratios of the building and street canyon considered are unity. For investigating the building-roof cooling effects, the building-roof temperatures are systematically changed. The traditional flow pattern including a portal vortex appears in the spanwise canyon. Compared with the case of the control run, there are minimal differences in flow pattern in the cases in which maximum building-roof cooling is considered. However, as the building roof becomes cooler, the mean kinetic energy increases and the air temperature decreases in the spanwise canyon. Building-roof cooling suppresses the upward and inward motions above the building roof, resultantly increasing the horizontal velocity near the roof level. The increase in wind velocity above the roof level intensifies the secondarily driven vortex circulation as well as the inward (outward) motion into (out of) the spanwise canyon. Finally, building-roof cooling reduces the air temperature in the spanwise canyon, supplying much relatively cool air from the streamwise canyon into the spanwise canyon.
Kim, Jae-Jin; Pardyjak, Eric; Kim, Do-Yong; Han, Kyoung-Soo; Kwon, Byung-Hyuk
Effects of building-roof cooling on flow and air temperature in urban street canyons
NASA Astrophysics Data System (ADS)
The effects of building-roof cooling on flow and air temperature in 3D urban street canyons are numerically investigated using a computational fluid dynamics (CFD) model. The aspect ratios of the building and street canyon considered are unity. For investigating the building-roof cooling effects, the building-roof temperatures are systematically changed. The traditional flow pattern including a portal vortex appears in the spanwise canyon. Compared with the case of the control run, there are minimal differences in flow pattern in the cases in which maximum building-roof cooling is considered. However, as the building roof becomes cooler, the mean kinetic energy increases and the air temperature decreases in the spanwise canyon. Building-roof cooling suppresses the upward and inward motions above the building roof, resultantly increasing the horizontal velocity near the roof level. The increase in wind velocity above the roof level intensifies the secondarily driven vortex circulation as well as the inward (outward) motion into (out of) the spanwise canyon. Finally, building-roof cooling reduces the air temperature in the spanwise canyon, supplying much relatively cool air from the streamwise canyon into the spanwise canyon.
Kim, Jae-Jin; Pardyjak, Eric; Kim, Do-Yong; Han, Kyoung-Soo; Kwon, Byung-Hyuk
Dispersal of natural and anthropogenic lead through submarine canyons at the Portuguese margin
Submarine canyons represent natural conduits for preferential transport of particulate material, including anthropogenic contaminants, from coastal zones directly to the deep sea. To assess related dispersal of natural and anthropogenic lead (Pb), we analyzed Pb concentrations and stable isotope ratios in surface sediments and sediment trap particulate material from the Portuguese margin Nazar� and Set�bal\\/Lisbon canyons. Geochemical data are integrated
T. O. Richter; H. C. de Stigter; W. Boer; C. C. Jesus; T. C. E. van Weering
The Grand Canyon and Other Holes in the Ground. Natural Wonder Notebook.
ERIC Educational Resources Information Center
The Grand Canyon, the natural wonder visited most often in the United States, is explored on foot, on burro, and by boat in this article. Learn about the canyon's different rock layers as well as its erosion, plant life, animal life, and water flow. (JM)
Markle, Sandra
Delaware River: Evidence for its former extension to Wilmington Submarine Canyon
Seismic-reflection profiles indicate that during the Pleistocene the Delaware River flowed across the continental shelf east of Delaware Bay and emptied into Wilmington Submarine Canyon. The ancestral valley (width, 3 to 8 kilometers; relief, 10 to 30 meters) is buried, is not reflected in the surface topography, and probably predates the formation of the present canyon head.
Twichell, D. C.; Knebel, H. J.; Folger, D. W.
Habitat-specific distribution of Pacific ocean perch ( Sebastes alutus) in Pribilof Canyon, Bering Sea
Shelf edge canyons are well-known sites of enhanced biomass due to on-shore transport and concentration of zooplankton along their axes, both of which contribute to the high densities of nekton frequently found in these canyons. Using a combination of acoustics, trawling, and in situ observations with a remotely operated vehicle (ROV), the distribution of pelagic and demersal biota within Pribilof
Richard D. Brodeur
Deposition and early hydrologic evolution of Westwater Canyon wet alluvial-fan system
The Westwater Canyon Member is one of several large, low-gradient alluvial fans that compose the Morrison Formation in the Four Corners area. Morrison fans were deposited by major laterally migrating streams entering a broad basin bounded by highlands to the west and south. The Westwater Canyon sand framework consists of a downfan succession of 1) proximal braided channel, 2) straight
Captured in Stone: Women in the Rock Art of Canyon de Chelly.
ERIC Educational Resources Information Center
Describes the pictographs (painted images on stone) and petroglyphs (pecked images on stone) found in the Canyon de Chelly National Monument in Arizona. Canyon de Chelly includes one of the largest concentrations of American Indian rock art in the southwest. Discusses the depiction of women in these images. (MJP)
Travis, Tara
78 FR 3879 - Ochoco National Forest, Paulina Ranger District; Oregon; Fox Canyon Cluster Allotment Management...
Federal Register 2010, 2011, 2012, 2013
...include head-cut repair, in-stream placement of wood and/or rock...riparian exclosure on .5 miles of South Fork Fox Canyon Creek. In-stream placement of wood and/or rock...take place on 1.5 miles of South Fork Fox Canyon Creek....
20140501-0531_Green Machine Florida Canyon Hourly Data
Employing innovative product developments to demonstrate financial and technical viability of producing electricity from low temperature geothermal fluids, coproduced in a mining operation, by employing ElectraTherm's modular and mobile heat-to-power "micro geothermal" power plant with output capacity expected in the 30-70kWe range. The Green Machine is an Organic Rankine Cycle power plant. The Florida Canyon machine is powered by geothermal brine with air cooled condensing. The data provided is an hourly summary from 01 May to 31 May 2014.
Joe Thibedeau
An exhumed Late Paleozoic canyon in the rocky mountains
Landscapes are thought to be youthful, particularly those of active orogenic belts. Unaweep Canyon in the Colorado Rocky Mountains, a large gorge drained by two opposite-flowing creeks, is an exception. Its origin has long been enigmatic, but new data indicate that it is an exhumed late Paleozoic landform. Its survival within a region of profound late Paleozoic orogenesis demands a reassessment of tectonic models for the Ancestral Rocky Mountains, and its form and genesis have significant implications for understanding late Paleozoic equatorial climate. This discovery highlights the utility of paleogeomorphology as a tectonic and climatic indicator. ?? 2007 by The University of Chicago. All rights reserved.
Soreghan, G. S.; Sweet, D. E.; Marra, K. R.; Eble, C. F.; Soreghan, M. J.; Elmore, R. D.; Kaplan, S. A.; Blum, M. D.
20140301-0331_Green Machine Florida Canyon Hourly Data
Employing innovative product developments to demonstrate financial and technical viability of producing electricity from low temperature geothermal fluids, coproduced in a mining operation, by employing ElectraTherm's modular and mobile heat-to-power "micro geothermal" power plant with output capacity expected in the 30-70kWe range. The Green Machine is an Organic Rankine Cycle power plant. The Florida Canyon machine is powered by geothermal brine with air cooled condensing. The data provided is an hourly summary from 01 Mar to 31 Mar 2014.
Joe Thibedeau
Ordering Geologic Events and Interpreting Geologic History: The Grand Canyon
NSDL National Science Digital Library
This activity is designed to help students recognize the connections among things like rock identification and map reading with the "story" that these things can tell us in terms of geologic history. Students have already learned about using observation to identify rocks and the principles of interpreting geologic cross-sections. The activity gives students practice in rock ID, topo map reading, geologic map reading and the aspects of geologic time. Students work with rock samples and a geologic map of the Grand Canyon to interpret a history for the area.
Wenner, Jennifer
Air pollutant retention within a complex of urban street canyons
NASA Astrophysics Data System (ADS)
Epidemiological studies of health effects associated with ambient air pollution are subject to uncertainty in the effects estimates related to the spatial and temporal variability of ambient air pollution. This study examines meteorological and concentration decay data for an urban canopy in Oklahoma City, OK to develop a modeling approach that can be used to estimate spatiotemporal variability in contaminant retention that could add bias or uncertainty to epidemiological results. Concentration and microscale turbulent wind data from the Joint Urban 2003 study were reanalyzed to examine scaling relationships between contaminant residence time in urban street canyons, urban boundary layer winds, and urban topography. Street-level sulfur hexafluoride (SF 6) concentration time series were reviewed to find time periods that included a peak and decay. Exponential decay curves were fitted to each period, and a characteristic residence time was derived from each model slope. That residence time was nondimensionalized by the ratio of mean urban boundary layer wind speed to height of the building just upwind of the street canyon in which the concentration was measured. Sonic detection and ranging (SODAR) data were used to assess atmospheric turbulence conditions at times concurrent with the concentration decay measurements. Reynolds number ( Re) was calculated from the 15-min average wind velocity and ranged from 2.1 � 10 6 to 7.6 � 10 7. Nondimensional residence time ( H) ranged from 3.7 to 996 with a median of 13.3. Inverse relationships were validated between H and Re and between H and the street canyon aspect ratio. These relationships provided a mechanism to understand time-varying ventilation within a street canyon. The results shown here were intended to demonstrate how scaling relationships derived from the transport equation can be used to provide rapid estimates of characteristic decay times for the purpose of estimating variability in the concentrations encountered in an urban environment. This could be a useful tool to reduce uncertainty in air pollution epidemiological study results related to spatial and temporal variability in urban concentrations.
Richmond-Bryant, J.; Isukapalli, S. S.; Vallero, D. A.
Incision History of the Black Canyon of the Gunnison
NASA Astrophysics Data System (ADS)
The Gunnison River is the major tributary of the Colorado River that drains some of the highest topography of the Colorado Rocky Mountains. Paleo river profiles at 640ka, 10Ma, and ~35Ma provide benchmarks to understand the long-term incision history of the Black Canyon. Reconstruction of these paleo profiles is based on elevated bedrock straths and alluvial deposits that can be dated using the Lava Creek B ash (640 ka), Grand Mesa and associated basalts (10 Ma), and Oligocene ash flow tuffs (~35 Ma). Comparison of these to the modern profile offers insight into incision history. The modern long profile displays a distinct knickpoint located near the Painted Wall in the Black Canyon of the Gunnison National Park. This high-gradient reach (10-km-long) is partly explained by the Vernal Mesa Granite, but it traverses basement lithologies present above and below the knickpoint, suggesting that increased river gradient is not explained entirely by hard bedrock. Incision rates downstream of the knickpoint are higher (250-300 m/Ma over 640 ka and ~ 150 m/Ma over 10 Ma) in comparison to upstream rates (140 m/Ma over 640 ka and ~ 150 m/Ma over 10 Ma). The difference in incision rates across the knickpoint argue that this feature reflects transient adjustment of the fluvial system to baselevel lowering associated with downstream drainage reorganization. Incision rates in the nearby reaches of the Colorado River since 1-3 Ma are distinctly higher than those in the time periods of ~30 Ma- present and 10 Ma-present. This leads us to infer that rapid incision was not established in the Gunnison region until post ca. 3 Ma. A knickpoint similar to that seen in the modern profile is present in the reconstructed 640ka profile, reinforcing the transient character and implying upstream migration of the knickpoint of 25km in the past 640 ka. Projection of the ~ 640 ka river gravels in the abandoned Shinn- Bostwick tributary to its intersection with the Gunnison at Red Canyon is presently the best constraint on the age of incision; here, ~400m of its ~700m total depth in the Black Canyon has been incised in the last 640 ka. To refine these profiles and incision rates, new mapping and sampling for cosmogenic burial dating have been conducted on major terraces at the North Fork Gunnison-Gunnison River confluence, the Shinn-Bostwick Park, and Grizzley Creek. These will provide new dates, confirm tephrochronolgic associations, and refine preexisting data to further constrain incision history.
Sandoval, M.; Karlstrom, K. E.; Aslan, A.; Kirby, E.; Granger, D.
Health Hazard Evaluation Report: HETA 99-0321-2873, U.S. Department of the Interior, Grand Canyon National Park, Grand Canyon, Arizona.
National Technical Information Service (NTIS)
The National Institute for Occupational Safety and Health (NIOSH) received a health hazard evaluation (HHE) request from the management of the Grand Canyon National Park in Arizona. The request indicated that many employees, especially park rangers assign...
Morpho-sedimentary features and sediment dispersal of the Fangliao Submarine Canyon in the active margin offshore SW Taiwan
NASA Astrophysics Data System (ADS)
Using newly collected multi-channel seismic profiles and bathymetric data this paper characterizes morphology and relates it to structural and sedimentary processes in the Fangliao Submarine Canyon and contrasts with the nearby Kaoping Canyon about 20 km in distance by the sediment dispersal in terms of source to sink. The Fangliao Canyon consists of three distinct morphologic parts: an upper canyon, a lower canyon and a distal submarine fan. The upper canyon indents into and begins at the shelf edge and extends downsope in a relatively straight course for a distance of about 22 km and ends at water depth of about 600 where the canyon turns sharply to the southwest. The deflection of canyon course is caused by the presence of a structural high of diapiric mud ridge. The lower canyon runs southwestwards along the western edge of the elongate ridge for a distance of about 45 km and is in water depth of about of 900 m where the canyon mouth opens and sediments disperse laterally and downslope, forming a relatively small submarine fan of about 400 square kilometers. The upper canyon is represented by a relatively narrow (3-4.5 km), V-shaped valley with canyon relief less than 300 m. Seismic profiles reveal terminations of parallel reflectors against steep canyon walls and slumping and sliding features, suggesting erosional canyon down-cutting. In the lower canyon, the canyon width increases to 12 km wide and canyon relief greater than 400 meters, indicating intense down-cutting of canyon floor and lateral erosion of canyon walls. However, the cross-sectional morphology is characterized by varying V-and U-shaped valleys. Relatively flat reflectors onlap the canyon floor and result in U-shaped cross sections, indicating combined effects of erosion and deposition. The distal submarine fan is a low-relief depositional feature probably resulting from channelized and overbank deposition. Although under the same conditions of climate, sea-level changes and tectonics of the SW Taiwan margin the Fangliao Canyon differs greatly from the nearby Kaoping Canyon in terms of sediment dispersal. The sediment source of the Fangliao Canyon is mainly derived from the canyon head indenting the shelf edge where neither major rivers nor deltas are close to or present, resulting in limited sediment supply from the shelf to the canyon head. Therefore, the Fangliao Canyon serves as a sediment pathway fed by limited sediments from the shelf edge, allowing to transport sediments for a relatively short distance of about 70 km and depositing them at the upper continental slope in water depth of about 1000 m, forming a small fan, the ultimate sediment sink. In contrast, the head of Kaoping canyon is connected to the Kaoping River, a small mountainous river with a high sediment yield. Recurrent hyperpycnal flows during the flood seasons are transporting great amounts of sediments to the Kaoping canyon head to generate powerful down-slope sediment flows, transporting sediments for a long distance of about 260 km across the entire continental slope and reaching the deep-sea Manila Trench, the ultimate sediment sink. Without continuous and large supply of sediments to the canyon head the Fangliao Canyon can be considered as a sediment pathway with limited capacity for transporting shallow marine sediments to the deep sea. Key words: submarine canyon, morphology, sediment dispersal, seismics,Taiwan
Chang, Y. H.; Chiang, C. S.; Yu, H. S.
Experience the magic of light and color: outreach activity by Universidad del Valle student chapter
NASA Astrophysics Data System (ADS)
During 2007, the Universidad del Valle Student Chapter presented a proposal for developing an educational outreach activity for children from an underprivileged zone to the Optical Society of America Foundation (OSAF) and to SPIE. The activity was carried out jointly by OSA and SPIE Universidad del Valle Student Chapters in the hillsides of Santiago de Cali, in a zone known as "Pueblo Joven" during 2008. It was aimed to boys and girls with ages between 8 and 13 years and was called "Experience the magic of light and color". The main purpose was to bring the children some basic concepts on optics and to encourage them to explore science through optics. The Universidad del Valle Student Chapters designed a series of talks and practical workshops where children participated in hands-on experiments that easily explain the fundamental concepts of light phenomena. Afterwards the children presented their achievements in a small science fair offered to the community and tried to explain in their own words what they learned and built. In this work, we present the most successful experimental designs and the educational standards we tried to develop with this activity.
Valdes, Claudia; Reyes, Camilo; Osorio, Alberto; Solarte, Efrain
Populating a Control Point Database: A cooperative effort between the USGS, Grand Canyon Monitoring and Research Center and the Grand Canyon Youth Organization
NASA Astrophysics Data System (ADS)
The Grand Canyon Monitoring and Research Center measures the effects of Glen Canyon Dam operations on the resources along the Colorado River from Glen Canyon Dam to Lake Mead in support of the Grand Canyon Adaptive Management Program. Control points are integral for geo-referencing the myriad of data collected in the Grand Canyon including aerial photography, topographic and bathymetric data used for classification and change-detection analysis of physical, biologic and cultural resources. The survey department has compiled a list of 870 control points installed by various organizations needing to establish a consistent reference for data collected at field sites along the 240 mile stretch of Colorado River in the Grand Canyon. This list is the foundation for the Control Point Database established primarily for researchers, to locate control points and independently geo-reference collected field data. The database has the potential to be a valuable mapping tool for assisting researchers to easily locate a control point and reduce the occurrance of unknowingly installing new control points within close proximity of an existing control point. The database is missing photographs and accurate site description information. Current site descriptions do not accurately define the location of the point but refer to the project that used the point, or some other interesting fact associated with the point. The Grand Canyon Monitoring and Research Center (GCMRC) resolved this problem by turning the data collection effort into an educational exercise for the participants of the Grand Canyon Youth organization. Grand Canyon Youth is a non-profit organization providing experiential education for middle and high school aged youth. GCMRC and the Grand Canyon Youth formed a partnership where GCMRC provided the logistical support, equipment, and training to conduct the field work, and the Grand Canyon Youth provided the time and personnel to complete the field work. Two data collection efforts were conducted during the 2004 summer allowing 40 youth the opportunity to contribute valuable information to the Control Point Database. This information included: verification of point existence, photographs, accurate site descriptions concisely describing the location of the point, how to reach the point, the specific point location and detailed bearings to visible and obvious land marks. The youth learned to locate themselves and find the points using 1:1000 airphotos, write detailed site descriptions, take bearings with a compass, measure vertical and horizontal distances, and use a digital camera. The youth found information for 252 control points (29% of the total points).
Brown, K. M.; Fritzinger, C.; Wharton, E.
Applications of Physical Modeling to the Evolution of Slot Canyon Morphology
NASA Astrophysics Data System (ADS)
Abrasion-dominated fluvial erosion generates slot canyons with intricately undulating wall morphology. Flows in slot canyons are unique in that the walls comprise a significant portion of the wetted perimeter of the flow. Wire Pass, UT incises through massive cross-bedded Navajo Sandstone. The canyon ranges in width from <1 m to �5 m in the slotted sections, and in depth from �5 m to �25 m. Incision in Wire Pass and related slots is limited to ephemeral flash floods; paleoflood debris indicates that the depth-to-width ratios of these flows are at least 1:1. Sub-meter resolution field mapping of a 20 m length of Wire Pass shows that the wall morphology is a complicated combination of both in-phase (meander-like), and out-of-phase (pinch and swell) type undulations. In order to understand the evolution of slot canyon wallforms, and the influence of these shapes on flow dynamics, we recorded the evolution of four distinct canyon wall morphologies in a 2.4 m flume box at the St. Anthony Falls Laboratory. In a substrate consisting of approximately 3:2 mixtures of F110 sand and plaster of Paris, we molded in-phase and out-of-phase undulations, and wide (6.5 cm) and narrow (4 cm) straight initial wall profiles. Sediment-laden water flowed through each canyon at discharges ranging from 2.6 L/s to 4.2 L/s. We made velocity measurements in three dimensions in sections of each canyon. At 5 hr intervals we documented wall and bed morphology at 0.5 cm resolution using a Keyance LK-500 laser mounted on a moving cart. Initial results show that wall faces in both undulating canyons evolve at different rates, and their flow fields are strongly asymmetric. Upstream-facing walls in undulating canyons eroded most rapidly. In the straight-walled canyons, small perturbations developed in the walls. Each canyon incised downward and headward from a knickpoint generated by a consistent lower boundary. Incision depths averaged �6 cm. Incision generally propagated around small cracks in the substrate and in potholes formed around small pebbles. The location and shape of scallops on the bed of each canyon was strongly controlled by wall morphology. Continued analysis of slot canyon dynamics in the field and laboratory should further the understanding of bedrock canyons dominated by abrasion.
Carter, C. L.; Anderson, R. S.
Study of drill core from the East Chaco Canyon area, San Juan Basin. Part I. Geochemical studies
The East Chaco Canyon (ECC) drilling program was undertaken by the US Department of Energy (DOE) to compare the Westwater Canyon Member of the Morrison Formation from the ECC part of the San Juan Basin with the highly uranium mineralized Westwater Canyon Member of the Grants Mineral Belt (GMB). Core from fifteen DOE drill holes was made available in part
75 FR 54920 - In the Matter of Pacific Gas & Electric Company (Diablo Canyon Nuclear Power Plant, Units 1 and 2...
Federal Register 2010, 2011, 2012, 2013
...Matter of Pacific Gas & Electric Company (Diablo Canyon Nuclear Power Plant, Units 1 and...License Nos. DPR-80 and DPR-82 for the Diablo Canyon Nuclear Power Plant, Units 1 and...understanding of seismic risks to the Diablo Canyon nuclear power plant....
75 FR 26788 - Public Land Order No. 7742; Withdrawal of Public Land for the Manning Canyon Tailings Repository; UT
Federal Register 2010, 2011, 2012, 2013
...of Public Land for the Manning Canyon Tailings Repository; UT AGENCY: Bureau of Land...protect the integrity of the Manning Canyon Tailings Repository and surrounding drainage structures...Federal investment in the Manning Canyon Tailings Repository. The Bureau of Land...
F-Canyon Suspension and Deactivation Safety Analysis Reports
This paper describes Savannah River Site's compliance with the Department of Energy (DOE) direction to suspend current operations, transition to accommodate revised facility missions, and initiate operations to deactivate F-Canyon using a suspension and deactivation safety basis. This paper integrates multiple Workshop theme topics - Lessons Learned from the Safety Analysis Process, Improvements in Documenting Hazard and Accident Analysis, and Closure Issues - Decontamination and Decommissioning. The paper describes the process used to develop safety documentation to support suspension and deactivation activities for F-Canyon. Embodied are descriptive efforts that include development of intermediate and final ''end states'' (e.g., transitional operations), preparation of safety bases documents to support transition, performance of suspension and deactivation activities (e.g. solvent washing, tank/sump flushing, and laboratory waste processing), and downgrade of Safety Class and Safety Significant equipment. The reduction and/or removal of hazards in the facility result in significant risk (frequency times consequence) reduction to the public, site workers, and the environment. Risk reduction then allows the downgrade of safety class and safety significant systems (e.g., ventilation system) and elimination of associated surveillances. The downgrade of safety systems results in significant cost savings.
Outage differences between Diablo Canyon and Unterweser power plants
Diablo Canyon (DCPP) of Pacific Gas and Electric Company and Unterweser (KKU) of PreussenElektra have had an ongoing exchange program since 1989, which includes mutual visits by their employees at the optimum time for observing outages. Both DCPP and Unterweser use four-loop pressurized water reactors (PWRs), DCPP with two 1,100-MW units and KKU with a single 1,300-MW unit. Unterweser finished its 11th outage in 1990; DCPP units 1 and 2 will have their fourth outages in 1991. The scope of the maintenance and refueling work is quite similar in both plants and offers, therefore, a good basis for comparison. Outage durations at European Kraftwerk Union KWU-PWR plants average {approximately}30 days as compared to the 60 to 80 days for PWRs in the US. Diablo Canyon has reduced outage durations from > 100 days to < 60. The key areas that contribute to the differences in outage duration are plant design and layout and outage execution.
Mehrens, H. (PreussenElektra, Stadland (West Germany))
Geologic map of the Paintbrush Canyon Area, Yucca Mountain, Nevada
This geologic map is produced to support site characterization studies of Yucca Mountain, Nevada, site of a potential nuclear waste storage facility. The area encompassed by this map lies between Yucca Wash and Fortymile Canyon, northeast of Yucca Mountain. It is on the southern flank of the Timber Mountain caldera complex within the southwest Nevada volcanic field. Miocene tuffs and lavas of the Calico Hills Formation, the Paintbrush Group, and the Timber Mountain Group crop out in the area of this map. The source vents of the tuff cones and lava domes commonly are located beneath the thickest deposits of pyroclastic ejecta and lava flows. The rocks within the mapped area have been deformed by north- and northwest-striking, dominantly west-dipping normal faults and a few east-dipping normal faults. Faults commonly are characterized by well developed fault scarps, thick breccia zones, and hanging-wall grabens. Latest movement as preserved by slickensides on west-dipping fault scarps is oblique down towards the southwest. Two of these faults, the Paintbrush Canyon fault and the Bow Ridge fault, are major block-bounding faults here and to the south at Yucca Mountain. Offset of stratigraphic units across faults indicates that faulting occurred throughout the time these volcanic units were deposited.
Dickerson, R.P. [Geological Survey, Denver, CO (United States); Drake, R.M. II [Pacific Western Technologies, Ltd., Lakewood, CO (United States)
Geologic Map of MTM -20012 and -25012 Quadrangles, Margaritifer Terra Region of Mars
Mars Transverse Mercator (MTM) -20012 and -25012 quadrangles (lat 17.5 deg - 27.5 deg S., long 345 deg - 350 deg E.) cover a portion of Margaritifer Terra near the east end of Valles Marineris. The map area consists of a diverse assemblage of geologic surfaces including isolated knobs of rugged mountainous material, heavily cratered and dissected ancient highland material, a variety of plains materials, chaotic terrain materials, and one of the highest densities of preserved valleys and their associated deposits on the planet (Saunders, 1979; Baker, 1982; Phillips and others, 2000, 2001). The map area is centered on a degraded, partially filled, ~200-km-diameter impact structure (lat 22 deg S., long 347.5 deg E.), informally referred to as Parana basin, located between Parana Valles to the east and Loire Valles to the west. Parana Valles is a network of multidigitate, mostly east-west-oriented valleys that flowed west and discharged into Parana basin (Grant, 1987, 2000; Grant and Parker, 2002). Loire Valles, broadly comparable in length to the Grand Canyon on Earth, has a deeply incised channel within the map area that originates at the west-northwest edge of Erythraeum Chaos within Parana basin (Grant, 1987, 2000; Grant and Parker, 2002; Strom and others, 2000). Parana and Loire Valles, combined with Samara Valles to the west, form one of the most laterally extensive, well-integrated valley networks on Mars (Grant, 2000) and record a long history of modification by fluvial processes. The origin and morphology of the valley networks, therefore, provide insight into past environmental conditions, whereas their relation with other landforms helps constrain the timing and role of fluvial processes in the evolution and modification of the Margaritifer Terra region.
Grant, J. A.; Wilson, S. A.; Fortezzo, C. M.; Clark, D. A.
Megafauna of vulnerable marine ecosystems in French mediterranean submarine canyons: Spatial distribution and anthropogenic impacts
NASA Astrophysics Data System (ADS)
Vulnerable Marine Ecosystems (VME) in the deep Mediterranean Sea have been identified by the General Fisheries Commission for the Mediterranean as consisting of communities of Scleractinia (Lophelia pertusa and Madrepora oculata), Pennatulacea (Funiculina quadrangularis) and Alcyonacea (Isidella elongata). This paper deals with video data recorded in the heads of French Mediterranean canyons. Quantitative observations were extracted from 101 video films recorded during the MEDSEACAN cruise in 2009 (Aamp/Comex). Qualitative information was extracted from four other cruises (two Marum/Comex cruises in 2009 and 2011 and two Ifremer cruises in 1995 and 2010) to support the previous observations in the Cassidaigne and Lacaze-Duthiers canyons. All the species, fishing impacts and litter recognized in the video films recorded from 180 to 700 m depth were mapped using GIS. The abundances and distributions of benthic fishing resources (marketable fishes, Aristeidae, Octopodidae), Vulnerable Marine Species, trawling scars and litter of 17 canyons were calculated and compared, as was the open slope between the Stoechades and Toulon canyons. Funiculina quadrangularis was rarely observed, being confined for the most part to the Marti canyon and, I. elongata was abundant in three canyons (Bourcart, Marti, Petit-Rh�ne). These two cnidarians were encountered in relatively low abundances, and it may be that they have been swept away by repeated trawling. The Lacaze-Duthiers and Cassidaigne canyons comprised the highest densities and largest colony sizes of scleractinian cold-water corals, whose distribution was mapped in detail. These colonies were often seen to be entangled in fishing lines. The alcyonacean Callogorgia verticillata was observed to be highly abundant in the Bourcart canyon and less abundant in several other canyons. This alcyonacean was also severely affected by bottom fishing gears and is proposed as a Vulnerable Marine Species. Our studies on anthropogenic impacts show that seafloor disturbance by benthic fishing is mainly attributable to trawling in the Gulf of Lion and to long lines where rocky substrates are present. The bauxite residue (red mud) expelled in the Cassidaigne canyon was seen to prevent fauna from settling at the bottom of the canyon and it covered much of the flanks. Litter was present in all of the canyons and especially in considerable quantities in the Ligurian Sea, where the heads of the canyons are closer to the coast. Three Marine Protected Areas and one fishing area with restricted access have recently been established and should permit the preservation of these deep ecosystems.
Fabri, M.-C.; Pedel, L.; Beuck, L.; Galgani, F.; Hebbeln, D.; Freiwald, A.
Dispersal of natural and anthropogenic lead through submarine canyons at the Portuguese margin
NASA Astrophysics Data System (ADS)
Submarine canyons represent natural conduits for preferential transport of particulate material, including anthropogenic contaminants, from coastal zones directly to the deep sea. To assess related dispersal of natural and anthropogenic lead (Pb), we analyzed Pb concentrations and stable isotope ratios in surface sediments and sediment trap particulate material from the Portuguese margin Nazar� and Set�bal/Lisbon canyons. Geochemical data are integrated with previously obtained data on near-bottom hydrodynamics and processes and pathways of sediment transport. The two canyon systems are located in close geographic proximity to each other, but represent contrasting settings in terms of sediment input and down-canyon sediment transport processes. Concentration-isotope diagrams and three-isotope plots ( 206Pb/ 207Pb vs. 208Pb/ 206Pb) suggest binary mixing between natural and anthropogenic end members. The inferred isotopic signature of pollutant Pb ( 206Pb/ 207Pb=1.143 [1.134-1.149, 95% confidence interval]) is most consistent with industrial Pb; ongoing influence from gasoline Pb additives is at most of minor importance. Two proposed natural end members most likely bracket the isotopic signature of natural Pb. Accordingly, binary mixing calculations indicate that on average 20-45% vs. 35-55% of total Pb is derived from anthropogenic sources in the Nazar� and Set�bal-Lisbon canyon systems, respectively. Enhanced anthropogenic influence in the latter area is consistent with its proximity to heavily populated and industrialized areas and with sediment input from the Tagus and Sado rivers, potential major carriers of pollutant particles. In both canyon systems, the anthropogenic component generally decreases with increasing water depth. Isotopic signatures of sediment trap particulate material are generally consistent with surface sediment data at similar water depth, but show large variability in the upper Nazar� canyon and major deviations from surface sediments in the lower canyon. In the lower canyon, Pb isotopic ratios of sediment trap particulate material mostly reflect low pelagic fluxes from the overlying water column, whereas surface sediment signatures are dominated by episodic down-canyon mass transport events. Such gravity flows appear to incorporate older (pre-industrial) material masking the isotopic signature of pollutant Pb. Large variability in the upper canyon reflects continuous sediment resuspension by bottom currents. Stronger average bottom currents are associated with higher 206Pb/ 207Pb ratios of sediment trap particulate material and hence decreased influence of pollutant Pb. This may reflect preferential resuspension of natural Pb at the canyon floor and/or additional remobilization of older, less-polluted sediment in adjacent areas such as the canyon walls.
Richter, T. O.; de Stigter, H. C.; Boer, W.; Jesus, C. C.; van Weering, T. C. E.
A sand budget for Marble Canyon, Arizona: implications for long-term monitoring of sand storage change
Recent U.S. Geological Survey research is providing important insights into how best to monitor changes in the amount of tributary-derived sand stored on the bed of the Colorado River and in eddies in Marble Canyon, Arizona. Before the construction of Glen Canyon Dam and other dams upstream, sandbars in Glen, Marble, and Grand Canyons were replenished each year by sediment-rich floods. Sand input into the Colorado River is crucial to protecting endangered native fish, animals, and plants and cultural and recreational resources along the river in Glen Canyon National Recreation Area and Grand Canyon National Park.
Grams, Paul E.
Comment on �Apatite 4He/3He and (U-Th)/He Evidence for an Ancient Grand Canyon�
NASA Astrophysics Data System (ADS)
Flowers and Farley (Reports, 21 December 2012, p. 1616; published online 29 November 2012) propose that the Grand Canyon is 70 million years old. Starkly contrasting models for the age of the Grand Canyon�70 versus 6 million years�can be reconciled by a shallow paleocanyon that was carved in the eastern Grand Canyon 25 to 15 million years ago (Ma), negating the proposed 70 Ma and 55 Ma paleocanyons. Cooling models and geologic data are most consistent with a 5 to 6 Ma age for western Grand Canyon and Marble Canyon.
Karlstrom, Karl E.; Lee, John; Kelley, Shari; Crow, Ryan; Young, Richard A.; Lucchitta, Ivo; Beard, L. Sue; Dorsey, Rebecca; Ricketts, Jason W.; Dickinson, William R.; Crossey, Laura
Fluctuating Helical Asymmetry and Morphology of Snails (Gastropoda) in Divergent Microhabitats at 'Evolution Canyons I and II,' Israel
Background Developmental instability of shelled gastropods is measured as deviations from a perfect equiangular (logarithmic) spiral. We studied six species of gastropods at �Evolution Canyons I and II� in Carmel and the Galilee Mountains, Israel, respectively. The xeric, south-facing, �African� slopes and the mesic, north-facing, �European� slopes have dramatically different microclimates and plant communities. Moreover, �Evolution Canyon II� receives more rainfall than �Evolution Canyon I.� Methodology/Principal Findings We examined fluctuating asymmetry, rate of whorl expansion, shell height, and number of rotations of the body suture in six species of terrestrial snails from the two �Evolution Canyons.� The xeric �African� slope should be more stressful to land snails than the �European� slope, and �Evolution Canyon I� should be more stressful than �Evolution Canyon II.� Only Eopolita protensa jebusitica showed marginally significant differences in fluctuating helical asymmetry between the two slopes. Contrary to expectations, asymmetry was marginally greater on the �European� slope. Shells of Levantina spiriplana caesareana at �Evolution Canyon I,� were smaller and more asymmetric than those at �Evolution Canyon II.� Moreover, shell height and number of rotations of the suture were greater on the north-facing slopes of both canyons. Conclusions/Significance Our data is consistent with a trade-off between drought resistance and thermoregulation in snails; Levantina was significantly smaller on the �African� slope, for increasing surface area and thermoregulation, while Eopolita was larger on the �African� slope, for reducing water evaporation. In addition, �Evolution Canyon I� was more stressful than Evolution Canyon II� for Levantina.
Raz, Shmuel; Schwartz, Nathan P.; Mienis, Hendrik K.; Nevo, Eviatar; Graham, John H.
Impact of the continental shelf slope on upwelling through submarine canyons
NASA Astrophysics Data System (ADS)
Submarine canyons that cut into the continental shelf are regions of enhanced upwelling. The depth of upwelling and flux through the canyons determines their role in exchange between the shelf and the open ocean. Scaling analyses that relate these quantities to the strength of the flow, stratification, Coriolis parameter, and topographic shape parameters allow their estimation in the absence of a full numerical simulation or a detailed field study. Here we add the effect of the continental shelf slope to the scaling of the depth of upwelling, upwelling flux, and deep water stretching. The scaling is then tested using a three-dimensional primitive equation model over 18 distinct geometries. The impact of the continental shelf is significant for real canyons with changes in the depth of upwelling of up to 11% and of the flux of upwelling of up to 70%. The numerical simulations clearly show three types of canyon upwelling, a symmetric time-dependent flux, the dominant advection-driven flux, and a new flux that appears to be related to internal waves. They also suggest that the canyon width is more important than the upstream canyon shape in determining the strength of the flow across the canyon.
Howatt, T. M.; Allen, S. E.
Modelling dispersion of traffic pollution in a deep street canyon: Application of CFD and operational models
NASA Astrophysics Data System (ADS)
In this study, numerical modelling of the flow and concentration fields has been undertaken for a deep street canyon in Naples (Italy), having aspect ratio (i.e. ratio of the building height H to the street width W) H/ W = 5.7. Two different modelling techniques have been employed: computational fluid dynamics (CFD) and operational dispersion modelling. The CFD simulations have been carried out by using the RNG k- ? turbulence model included in the commercial suite FLUENT, while operational modelling has been conducted by means of the WinOSPM model. Concentration fields obtained from model simulations have been compared with experimental data of CO concentrations measured at two vertical locations within the canyon. The CFD results are in good agreement with the experimental data, while poor agreement is observed for the WinOSPM results. This is because WinOSPM was originally developed and tested for street canyons with aspect ratio H/ W ? 1. Large discrepancies in wind profiles simulated within the canyon are observed between CFD and OSPM models. Therefore, a modification of the wind profile within the canyon is introduced in WinOSPM for extending its applicability to deeper canyons, leading to an improved agreement between modelled and experimental data. Further development of the operational dispersion model is required in order to reproduce the distinct air circulation patterns within deep street canyons.
Murena, Fabio; Favale, Giuseppe; Vardoulakis, Sotiris; Solazzo, Efisio
Science Activities Associated with Proposed 2008 High-Flow Experiment at Glen Canyon Dam
Grand Canyon National Park lies approximately 15 miles downriver from Glen Canyon Dam, which was built on the Colorado River just south of the Arizona-Utah border. Because the dam stops most sediment moving downstream, its presence has resulted in erosion and shrinkage of river sandbars in Grand Canyon. Fewer and smaller sandbars mean smaller camping beaches for visitors to use, continued erosion of cultural sites, and possibly less habitat for native fish, including the endangered humpback chub. In an effort to restore sandbars and related habitat and to comply with its responsibilities under the Grand Canyon Protection Act, the Department of the Interior has proposed a high-flow release of water from Glen Canyon Dam in March 2008. The U.S. Geological Survey?s (USGS) Grand Canyon Monitoring and Research Center is responsible for coordinating research associated with the proposed experiment. The proposed studies are designed to evaluate the feasibility of using such high flows to improve a range of Grand Canyon resources.
Hamill, John
Water-quality data for Walnut Canyon and Wupatki National Monuments, Arizona, 2001-02
Water-quality data are provided for four sites in Walnut Canyon and Wupatki National Monuments in north-central Arizona. These data describe the current water quality and provide baseline water-quality information for monitoring future trends. Water samples were collected from a ground-water seep and well in Walnut Canyon and from a spring and a river in Wupatki during September 2001 to September 2002. Water from the four sites is from four different sources. In Walnut Canyon, Cherry Canyon seep is in a shallow local aquifer, and the Little Colorado River contains ground-water discharge from several aquifers and runoff from a 22,000 square-mile drainage area. Concentrations of dissolved solids were similar within the two monuments; the range for water samples from Walnut Canyon was 203 to 248 milligrams per liter, and the range for water samples from Wupatki was 503 to 614 milligrams per liter. Concentrations of trace elements were generally low in water samples from the three ground-water sites--Cherry Canyon seep, Walnut Canyon headquarters well, and Heiser Spring. The water sample collected from the Little Colorado River, however, had high concentrations of aluminum (4,020 micrograms per liter), antimony (54 micrograms per liter), arsenic (14.3 micrograms per liter), and iron (749 micrograms per liter) relative to U.S. Environmental Protection Agency Primary and Secondary Maximum Contaminant Levels. Concentrations of nitrate (as nitrogen) in water samples from the four sites were generally low (0.11 to 1.8 milligrams per liter) and are within the upper 25 percent of nitrate concentrations measured in the regional aquifer near Flagstaff in 1996 and 1997. Water samples from Cherry Canyon seep, Heiser Spring, and the Little Colorado River contained total coliform bacteria. Fecal coliform and Escherichia coli bacteria were found in water samples from Cherry Canyon seep and the Little Colorado River.
Thomas, Blakemore E.
Fish Passage Assessment: Big Canyon Creek Watershed, Technical Report 2004.
This report presents the results of the fish passage assessment as outlined as part of the Protect and Restore the Big Canyon Creek Watershed project as detailed in the CY2003 Statement of Work (SOW). As part of the Northwest Power Planning Council's Columbia Basin Fish and Wildlife Program (FWP), this project is one of Bonneville Power Administration's (BPA) many efforts at off-site mitigation for damage to salmon and steelhead runs, their migration, and wildlife habitat caused by the construction and operation of federal hydroelectric dams on the Columbia River and its tributaries. The proposed restoration activities within the Big Canyon Creek watershed follow the watershed restoration approach mandated by the Fisheries and Watershed Program. Nez Perce Tribal Fisheries/Watershed Program vision focuses on protecting, restoring, and enhancing watersheds and treaty resources within the ceded territory of the Nez Perce Tribe under the Treaty of 1855 with the United States Federal Government. The program uses a holistic approach, which encompasses entire watersheds, ridge top to ridge top, emphasizing all cultural aspects. We strive toward maximizing historic ecosystem productive health, for the restoration of anadromous and resident fish populations. The Nez Perce Tribal Fisheries/Watershed Program (NPTFWP) sponsors the Protect and Restore the Big Canyon Creek Watershed project. The NPTFWP has the authority to allocate funds under the provisions set forth in their contract with BPA. In the state of Idaho vast numbers of relatively small obstructions, such as road culverts, block thousands of miles of habitat suitable for a variety of fish species. To date, most agencies and land managers have not had sufficient, quantifiable data to adequately address these barrier sites. The ultimate objective of this comprehensive inventory and assessment was to identify all barrier crossings within the watershed. The barriers were then prioritized according to the amount of habitat blocked at each site and the fish life history stages impacted. This assessment protocol will hopefully prove useful to other agencies and become a model for use in other watersheds.
Christian, Richard
Photomosaics and logs of trenches on the San Andreas Fault at Mill Canyon near Watsonville, California
We present photomosaics and logs of the walls of trenches excavated for a paleoseismic study at Mill Canyon, one of two sites along the San Andreas fault in the Santa Cruz Mtns. on the Kelley-Thompson Ranch. This site was a part of Rancho Salsipuedes begining in 1834. It was purchased by the present owner�s family in 1851. Remnants of a cabin/mill operations still exist up the canyon dating from 1908 when the area was logged. At this location, faulting has moved a shutter ridge across the mouth of Mill Canyon ponding Holocene sediment. Recent faulting is confined to a narrow zone near the break in slope.
Fumal, Thomas E.; Dawson, Timothy E.; Flowers, Rebecca; Hamilton, John C.; Heingartner, Gordon F.; Kessler, James; Samrad, Laura
Nearshore temperature findings for the Colorado River in Grand Canyon, Arizona: possible implications for native fish
Since the completion of Glen Canyon Dam, Arizona, in 1963, downstream water temperatures in the main channel of the Colorado River in Glen, Marble, and Grand Canyons are much colder in summer. This has negatively affected humpback chub (Gila cypha) and other native fish adapted to seasonally warm water, reducing main-channel spawning activity and impeding the growth and development of larval and juvenile fish. Recently published studies by U.S. Geological Survey scientists found that under certain conditions some isolated nearshore environments in Grand Canyon allow water to become separated from the main-channel current and to warm, providing refuge areas for the development of larval and juvenile fish.
Ross, Robert P.; Vernieu, William S.
Elastomechanical methods in the exploration of the Valles Caldera, New Mexico. Final report, June 8, 1981-October 8, 1981
The Valles caldera in the Jemez Mountains of New Mexico is a case of an active caldera that is an object for a comprehensive ground tilt field program to map both elastic and rheic discontinuities. Based on a rather comprehensive theoretical development that is outlined in five separate Essays, estimates of the amplitudes of some of the possible ground tilt signals were obtained. Based on the results, the strongest signals of the order of 100 to 200 nanoradians would appear to result from the purely elastic response of the caldera fill to a barometric forcing. Moreover, assuming a magmatic underplate below the Valles, barometric forcing may lead to a flexure of the upper crust that could generate tilt signals of a similar magnitude. Present data material is insufficient to allow a useful estimate to be made of the possible tilt signals due to the rheic properties of a Valles pluton that may be in the state of partial fusion.
Bodvarsson, G.