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L_0226 | maps | T_1401 | A geologic map shows the geological features of a region (see Figure 1.3 for an example). Rock units are color- coded and identified in a key. Faults and folds are also shown on geologic maps. The geology is superimposed on a topographic map to give a more complete view of the geology of the region. Click image to the left or use the URL below. URL: | text | null |
L_0227 | mars | T_1402 | Mars is the fourth planet from the Sun, and the first planet beyond Earths orbit (Figure 1.1). Mars is a quite different from Earth and yet more similar than any other planet. Mars is smaller, colder, drier, and appears to have no life, but volcanoes are common to both planets and Mars has many. Mars is easy to observe, so Mars has been studied more thoroughly than any other extraterrestrial planet. Space probes, rovers, and orbiting satellites have all yielded information to planetary geologists. Although no humans have ever set foot on Mars, both NASA and the European Space Agency have set goals of sending people to Mars sometime between 2030 and 2040. This image of Mars, taken by the Hubble Space Telescope in October, 2005, shows the planets red color, a small ice cap on the south pole, and a dust storm. | text | null |
L_0227 | mars | T_1403 | Viewed from Earth, Mars is reddish in color. The ancient Greeks and Romans named the planet after the god of war. The surface is not red from blood but from large amounts of iron oxide in the soil. The Martian atmosphere is very thin relative to Earths and has much lower atmospheric pressure. Although the atmosphere is made up mostly of carbon dioxide, the planet has only a weak greenhouse effect, so temperatures are only slightly higher than if the planet had no atmosphere. | text | null |
L_0227 | mars | T_1404 | Mars has mountains, canyons, and other features similar to Earth. Some of these surface features are amazing for their size! Olympus Mons is a shield volcano, similar to the volcanoes that make up the Hawaiian Islands. But Olympus Mons is also the largest mountain in the solar system (Figure 1.2). Mars also has the largest canyon in the solar system, Valles Marineris (Figure 1.3). | text | null |
L_0227 | mars | T_1405 | It was previously believed that water cannot stay in liquid form on Mars because the atmospheric pressure is too low. However, there is a lot of water in the form of ice and even prominent ice caps (Figure 1.4). Scientists also think Olympus Mons is about 27 km (16.7 miles/88,580 ft) above the Martian sur- face, more than three times taller than Mount Everest. The volcanos base is about the size of the state of Arizona. Valles Marineris is 4,000 km (2,500 mi) long, as long as Europe is wide, and one-fifth the circumference of Mars. The canyon is 7 km (4.3 mi) deep. By comparison, the Grand Canyon on Earth is only 446 km (277 mi) long and about 2 km (1.2 mi) deep. that there is a lot of ice present just under the Martian surface. This ice can melt when volcanoes erupt, and water can flow across the surface. In late 2015, NASA confirmed the presence of water on Mars. Scientists think that water once flowed over the Martian surface because there are surface features that look like water-eroded canyons. The presence of water on Mars suggests that it might have been possible for life to exist on Mars in the past. | text | null |
L_0227 | mars | T_1405 | It was previously believed that water cannot stay in liquid form on Mars because the atmospheric pressure is too low. However, there is a lot of water in the form of ice and even prominent ice caps (Figure 1.4). Scientists also think Olympus Mons is about 27 km (16.7 miles/88,580 ft) above the Martian sur- face, more than three times taller than Mount Everest. The volcanos base is about the size of the state of Arizona. Valles Marineris is 4,000 km (2,500 mi) long, as long as Europe is wide, and one-fifth the circumference of Mars. The canyon is 7 km (4.3 mi) deep. By comparison, the Grand Canyon on Earth is only 446 km (277 mi) long and about 2 km (1.2 mi) deep. that there is a lot of ice present just under the Martian surface. This ice can melt when volcanoes erupt, and water can flow across the surface. In late 2015, NASA confirmed the presence of water on Mars. Scientists think that water once flowed over the Martian surface because there are surface features that look like water-eroded canyons. The presence of water on Mars suggests that it might have been possible for life to exist on Mars in the past. | text | null |
L_0227 | mars | T_1405 | It was previously believed that water cannot stay in liquid form on Mars because the atmospheric pressure is too low. However, there is a lot of water in the form of ice and even prominent ice caps (Figure 1.4). Scientists also think Olympus Mons is about 27 km (16.7 miles/88,580 ft) above the Martian sur- face, more than three times taller than Mount Everest. The volcanos base is about the size of the state of Arizona. Valles Marineris is 4,000 km (2,500 mi) long, as long as Europe is wide, and one-fifth the circumference of Mars. The canyon is 7 km (4.3 mi) deep. By comparison, the Grand Canyon on Earth is only 446 km (277 mi) long and about 2 km (1.2 mi) deep. that there is a lot of ice present just under the Martian surface. This ice can melt when volcanoes erupt, and water can flow across the surface. In late 2015, NASA confirmed the presence of water on Mars. Scientists think that water once flowed over the Martian surface because there are surface features that look like water-eroded canyons. The presence of water on Mars suggests that it might have been possible for life to exist on Mars in the past. | text | null |
L_0227 | mars | T_1406 | Mars has two very small moons that are irregular rocky bodies (Figure 1.5). Phobos and Deimos are named after characters in Greek mythology the two sons of Ares, who followed their father into war. Ares is equivalent to the Roman god Mars. Mars has two small moons, Phobos (left) and Deimos (right). Both were discovered in 1877 and are thought to be captured asteroids. Click image to the left or use the URL below. URL: Click image to the left or use the URL below. URL: | text | null |
L_0229 | measuring earthquake magnitude | T_1408 | A seismograph produces a graph-like representation of the seismic waves it receives and records them onto a seismogram (Figure 1.1). Seismograms contain information that can be used to determine how strong an earthquake was, how long it lasted, and how far away it was. Modern seismometers record ground motions using electronic motion detectors. The data are then kept digitally on a computer. If a seismogram records P-waves and surface waves but not S-waves, the seismograph was on the other side of the Earth from the earthquake. The amplitude of the waves can be used to determine the magnitude of the earthquake, which will be discussed in a later section. | text | null |
L_0229 | measuring earthquake magnitude | T_1409 | The seismogram in the introduction shows: foreshocks. the arrival of the P-waves. the arrival of the S-waves. the arrival of the surface waves (very hard to pick out). aftershocks. the times when all of these things occur. These seismograms show the arrival of P- waves and S-waves. The surface waves arrive just after the S-waves and are diffi- cult to distinguish. Time is indicated on the horizontal portion (or x-axis) of the graph. Click image to the left or use the URL below. URL: | text | null |
L_0230 | mechanical weathering | T_1410 | Mechanical weathering (also called physical weathering) breaks rock into smaller pieces. These smaller pieces are just like the bigger rock, but smaller. That means the rock has changed physically without changing its composition. The smaller pieces have the same minerals, in just the same proportions as the original rock. | text | null |
L_0230 | mechanical weathering | T_1411 | There are many ways that rocks can be broken apart into smaller pieces. Ice wedging is the main form of mechanical weathering in any climate that regularly cycles above and below the freezing point (Figure 1.1). Ice wedging works quickly, breaking apart rocks in areas with temperatures that cycle above and below freezing in the day and night, and also that cycle above and below freezing with the seasons. Ice wedging breaks apart so much rock that large piles of broken rock are seen at the base of a hillside, as rock fragments separate and tumble down. Ice wedging is common in Earths polar regions and mid latitudes, and also at higher elevations, such as in the mountains. | text | null |
L_0230 | mechanical weathering | T_1412 | Abrasion is another form of mechanical weathering. In abrasion, one rock bumps against another rock. Gravity causes abrasion as a rock tumbles down a mountainside or cliff. Moving water causes abrasion as particles in the water collide and bump against one another. Strong winds carrying pieces of sand can sandblast surfaces. Ice in glaciers carries many bits and pieces of rock. Rocks embedded at the bottom of the glacier scrape against the rocks below. Abrasion makes rocks with sharp or jagged edges smooth and round. If you have ever collected beach glass or cobbles from a stream, you have witnessed the work of abrasion (Figure 1.2). | text | null |
L_0230 | mechanical weathering | T_1413 | Now that you know what mechanical weathering is, can you think of other ways it could happen? Plants and animals can do the work of mechanical weathering (Figure 1.3). This could happen slowly as a plants roots grow into a crack or fracture in rock and gradually grow larger, wedging open the crack. Burrowing animals can also break apart rock as they dig for food or to make living spaces for themselves. | text | null |
L_0230 | mechanical weathering | T_1414 | Human activities are responsible for enormous amounts of mechanical weathering, by digging or blasting into rock to build homes, roads, and subways, or to quarry stone. (a) Humans are tremendous agents of mechanical weathering. (b) Salt weathering of building stone on the island of Gozo, Malta. | text | null |
L_0231 | mercury | T_1415 | The smallest planet, Mercury, is the planet closest to the Sun. Because Mercury is so close to the Sun, it is difficult to observe from Earth, even with a telescope. However, the Mariner 10 spacecraft, shown in Figure 1.1, visited Mercury from 1974 to 1975. The MESSENGER spacecraft has been studying Mercury in detail since 2005. The craft is currently in orbit around the planet, where it is creating detailed maps. MESSENGER stands for Mercury Surface, Space Environment, Geochemistry and Ranging. (a) Mariner 10 made three flybys of Mercury in 1974 and 1975. (b) A 2008 image of compiled from a flyby by MESSENGER. As Figure 1.2 shows, the surface of Mercury is covered with craters, like Earths Moon. Ancient impact craters means that for billions of years Mercury hasnt changed much geologically. Also, with very little atmosphere, the processes of weathering and erosion do not wear down structures on the planet. | text | null |
L_0231 | mercury | T_1416 | Mercury is named for the Roman messenger god, who could run extremely quickly, just as the planet moves very quickly in its orbit around the Sun. A year on Mercury the length of time it takes to orbit the Sun is just 88 Earth days. Despite its very short years, Mercury has very long days. A day is defined as the time it takes a planet to turn on its axis. Mercury rotates slowly on its axis, turning exactly three times for every two times it orbits the Sun. Therefore, each day on Mercury is 57 Earth days long. In other words, on Mercury, a year is only a Mercury day and a half long! | text | null |
L_0231 | mercury | T_1417 | Mercury is close to the Sun, so it can get very hot. However, Mercury has virtually no atmosphere, no water to insulate the surface, and it rotates very slowly. For these reasons, temperatures on the surface of Mercury vary widely. In direct sunlight, the surface can be as hot as 427 C (801 F). On the dark side, or in the shadows inside craters, the surface can be as cold as -183 C (-297 F)! Although most of Mercury is extremely dry, scientists think Mercury is covered with craters, like Earths Moon. MESSENGER has taken extremely detailed pictures of the planets surface. there may be a small amount of water in the form of ice at the poles of Mercury, in areas that never receive direct sunlight. | text | null |
L_0231 | mercury | T_1418 | Figure 1.3 shows a diagram of Mercurys interior. Mercury is one of the densest planets. Its relatively large, liquid core, made mostly of melted iron, takes up about 42% of the planets volume. | text | null |
L_0232 | mercury pollution | T_1419 | Mercury is released into the atmosphere when coal is burned (Figure 1.1). But breathing the mercury is not harmful. In the atmosphere, the mercury forms small droplets that are deposited in water or sediments. | text | null |
L_0232 | mercury pollution | T_1420 | Do you know why you are supposed to eat large predatory fish like tuna infrequently? It is because of the bioaccu- mulation of mercury in those species. Some pollutants remain in an organism throughout its life, a phenomenon called bioaccumulation. In this process, an organism accumulates the entire amount of a toxic compound that it consumes over its lifetime. Not all substances bioaccumulate. Can you name one that does not? Aspirin does not bioaccumulate; if it did, a person would quickly accumulate a toxic amount in her body. Compounds that bioaccumulate are usually stored in the organisms fat. In the sediments, bacteria convert the droplets to the hazardous compound methyl mercury. Bacteria and plankton store all of the mercury from all of the seawater they ingest (Figure 1.2). A small fish that eats bacteria and plankton accumulates all of the mercury from all of the tiny creatures it eats over its lifetime. A big fish accumulates all of the mercury from all of the small fish it eats over its lifetime. For a tuna at the top of the food chain, thats a lot of mercury. Historic increases of mercury in the atmo- sphere: blue is volcanic eruptions; brown, purple, and pink are human-caused. The red region shows the effect of industrial- ization on atmospheric mercury. So tuna pose a health hazard to anything that eats them because their bodies are so high in mercury. This is why the government recommends limits on the amount of tuna that people eat. Limiting intake of large predatory fish is especially important for children and pregnant women. If the mercury just stayed in a persons fat, it would not be harmful, but that fat is used when a woman is pregnant or nursing a baby. A person will also get the mercury into her system when she (or he) burns the fat while losing weight. | text | null |
L_0232 | mercury pollution | T_1421 | Methyl mercury poisoning can cause nervous system or brain damage, especially in infants and children. Children may experience brain damage or developmental delays. The phrase mad as a hatter was common when Lewis Carroll wrote his Alice in Wonderland stories. It was based on symptoms suffered by hatters who were exposed to mercury and experienced mercury poisoning while using the metal to make hats (Figure 1.3). Like mercury, other metals and VOCS can bioaccumulate, causing harm to animals and people high on the food chain. Mercury, a potent neurotoxin, has been flowing into the San Francisco Bay since the Gold Rush Era. It has settled in the bays mud and made its way up the food chain, endangering wildlife and making many fish unsafe to eat. Now a multi-billion-dollar plan aims to clean it up. Click image to the left or use the URL below. URL: | text | null |
L_0233 | mesosphere | T_1422 | Above the stratosphere is the mesosphere. Temperatures in the mesosphere decrease with altitude. Because there are few gas molecules in the mesosphere to absorb the Suns radiation, the heat source is the stratosphere below. The mesosphere is extremely cold, especially at its top, about -90o C (-130o F). | text | null |
L_0233 | mesosphere | T_1423 | The air in the mesosphere has extremely low density: 99.9% of the mass of the atmosphere is below the mesosphere. As a result, air pressure is very low (Figure 1.1). A person traveling through the mesosphere would experience severe burns from ultraviolet light since the ozone layer, which provides UV protection, is in the stratosphere below. There would be almost no oxygen for breathing. And, of course, your blood would boil at normal body temperature. Click image to the left or use the URL below. URL: | text | null |
L_0236 | metamorphic rock classification | T_1430 | Table 1.1 shows some common metamorphic rocks and their original parent rock. Picture Rock Name Slate Type of Rock Foliated Metamorphic Comments Phyllite Foliated Metamorphism of slate, but under greater heat and pressure than slate Schist Foliated Often derived from meta- morphism of claystone or shale; metamorphosed under more heat and pres- sure than phyllite Gneiss Foliated Metamorphism of various different rocks, under ex- treme conditions of heat and pressure Hornfels Non-foliated Contact metamorphism of various different rock types Metamorphism of shale Picture Rock Name Comments Quartzite Type of Metamorphic Rock Non-foliated Marble Non-foliated Metamorphism of lime- stone Metaconglomerate Non-foliated Metamorphism of con- glomerate Metamorphism of quartz sandstone Click image to the left or use the URL below. URL: | text | null |
L_0237 | metamorphic rocks | T_1431 | Any type of rock - igneous, sedimentary, or metamorphic can become a metamorphic rock. All that is needed is enough heat and/or pressure to alter the existing rocks physical or chemical makeup without melting the rock entirely. Rocks change during metamorphism because the minerals need to be stable under the new temperature and pressure conditions. The need for stability may cause the structure of minerals to rearrange and form new minerals. Ions may move between minerals to create minerals of different chemical composition. Hornfels, with its alternating bands of dark and light crystals, is a good example of how minerals rearrange themselves during metamorphism. Hornfels is shown in the table for the "Metamorphic Rock Classification" concept. | text | null |
L_0237 | metamorphic rocks | T_1432 | Extreme pressure may also lead to foliation, the flat layers that form in rocks as the rocks are squeezed by pressure (Figure 1.1). Foliation normally forms when pressure is exerted in only one direction. Metamorphic rocks may also be non-foliated. Quartzite and marble, shown in the concept "Metamorphic Rock Classification," are non-foliated. A foliated metamorphic rock. | text | null |
L_0237 | metamorphic rocks | T_1433 | The two main types of metamorphism are both related to heat within Earth: 1. Regional metamorphism: Changes in enormous quantities of rock over a wide area caused by the extreme pressure from overlying rock or from compression caused by geologic processes. Deep burial exposes the rock to high temperatures. 2. Contact metamorphism: Changes in a rock that is in contact with magma. The changes occur because of the magmas extreme heat. Click image to the left or use the URL below. URL: | text | null |
L_0238 | meteors | T_1434 | A meteor, such as in Figure 1.1, is a streak of light across the sky. People call them shooting stars but they are actually small pieces of matter burning up as they enter Earths atmosphere from space. Meteors are called meteoroids before they reach Earths atmosphere. Meteoroids are smaller than asteroids and range from the size of boulders down to the size of tiny sand grains. Still smaller objects are called interplanetary dust. When Earth passes through a cluster of meteoroids, there is a meteor shower. These clusters are often remnants left behind by comet tails. | text | null |
L_0238 | meteors | T_1435 | Although most meteors burn up in the atmosphere, larger meteoroids may strike the Earths surface to create a meteorite. Meteorites are valuable to scientists because they provide clues about our solar system. Many meteorites are from asteroids that formed when the solar system formed (Figure 1.2). A few meteorites are made of rocky material that is thought to have come from Mars when an asteroid impact shot material off the Martian surface and into space. Click image to the left or use the URL below. URL: | text | null |
L_0238 | meteors | T_1435 | Although most meteors burn up in the atmosphere, larger meteoroids may strike the Earths surface to create a meteorite. Meteorites are valuable to scientists because they provide clues about our solar system. Many meteorites are from asteroids that formed when the solar system formed (Figure 1.2). A few meteorites are made of rocky material that is thought to have come from Mars when an asteroid impact shot material off the Martian surface and into space. Click image to the left or use the URL below. URL: | text | null |
L_0240 | milky way | T_1438 | The Milky Way Galaxy, which is our galaxy. The Milky Way is made of millions of stars along with a lot of gas and dust. It looks different from other galaxies because we are looking at the main disk from within the galaxy. Astronomers estimate that the Milky Way contains 200 to 400 billion stars. | text | null |
L_0240 | milky way | T_1439 | Although it is difficult to know what the shape of the Milky Way Galaxy is because we are inside of it, astronomers have identified it as a typical spiral galaxy containing about 200 billion to 400 billion stars (Figure 1.1). An artists rendition of what astronomers think the Milky Way Galaxy would look like seen from above. The Sun is located approximately where the arrow points. Like other spiral galaxies, our galaxy has a disk, a central bulge, and spiral arms. The disk is about 100,000 light- years across and 3,000 light-years thick. Most of the Galaxys gas, dust, young stars, and open clusters are in the disk. What evidence do astronomers find that lets them know that the Milky Way is a spiral galaxy? 1. The shape of the galaxy as we see it (Figure 1.2). 2. The velocities of stars and gas in the galaxy show a rotational motion. 3. The gases, color, and dust are typical of spiral galaxies. The central bulge is about 12,000 to 16,000 light-years wide and 6,000 to 10,000 light-years thick. The central bulge contains mostly older stars and globular clusters. Some recent evidence suggests the bulge might not be spherical, but is instead shaped like a bar. The bar might be as long as 27,000 light-years long. The disk and bulge are surrounded by a faint, spherical halo, which also contains old stars and globular clusters. Astronomers have discovered that there is a gigantic black hole at the center of the galaxy. The Milky Way Galaxy is a big place. If our solar system were the size of your fist, the Galaxys disk would still be An infrared image of the Milky Way shows the long thin line of stars and the central bulge typical of spiral galaxies. wider than the entire United States! | text | null |
L_0240 | milky way | T_1439 | Although it is difficult to know what the shape of the Milky Way Galaxy is because we are inside of it, astronomers have identified it as a typical spiral galaxy containing about 200 billion to 400 billion stars (Figure 1.1). An artists rendition of what astronomers think the Milky Way Galaxy would look like seen from above. The Sun is located approximately where the arrow points. Like other spiral galaxies, our galaxy has a disk, a central bulge, and spiral arms. The disk is about 100,000 light- years across and 3,000 light-years thick. Most of the Galaxys gas, dust, young stars, and open clusters are in the disk. What evidence do astronomers find that lets them know that the Milky Way is a spiral galaxy? 1. The shape of the galaxy as we see it (Figure 1.2). 2. The velocities of stars and gas in the galaxy show a rotational motion. 3. The gases, color, and dust are typical of spiral galaxies. The central bulge is about 12,000 to 16,000 light-years wide and 6,000 to 10,000 light-years thick. The central bulge contains mostly older stars and globular clusters. Some recent evidence suggests the bulge might not be spherical, but is instead shaped like a bar. The bar might be as long as 27,000 light-years long. The disk and bulge are surrounded by a faint, spherical halo, which also contains old stars and globular clusters. Astronomers have discovered that there is a gigantic black hole at the center of the galaxy. The Milky Way Galaxy is a big place. If our solar system were the size of your fist, the Galaxys disk would still be An infrared image of the Milky Way shows the long thin line of stars and the central bulge typical of spiral galaxies. wider than the entire United States! | text | null |
L_0240 | milky way | T_1440 | Our solar system, including the Sun, Earth, and all the other planets, is within one of the spiral arms in the disk of the Milky Way Galaxy. Most of the stars we see in the sky are relatively nearby stars that are also in this spiral arm. We are about 26,000 light-years from the center of the galaxy, a little more than halfway out from the center of the galaxy to the edge. Just as Earth orbits the Sun, the Sun and solar system orbit the center of the Galaxy. One orbit of the solar system takes about 225 to 250 million years. The solar system has orbited 20 to 25 times since it formed 4.6 billion years ago. Astronomers have recently discovered that at the center of the Milky Way, and most other galaxies, is a supermassive black hole, although a black hole cannot be seen. This video describes the solar system in which we live. It is located in an outer edge of the Milky Way galaxy, which spans 100,000 light years. Click image to the left or use the URL below. URL: The Universe contains many billions of stars and there are many billions of galaxies. Our home, the Milky Way galaxy, is only one. Click image to the left or use the URL below. URL: | text | null |
L_0246 | moon | T_1473 | The Moon is Earths only natural satellite, a body that moves around a larger body in space. The Moon orbits Earth for the same reason Earth orbits the Sun gravity. The Moon is 3,476 km in diameter, about one-fourth the size of Earth. The satellite is also not as dense as the Earth; gravity on the Moon is only one-sixth as strong as it is on Earth. An astronaut can jump six times as high on the Moon as on Earth! The Moon makes one complete orbit around the Earth every 27.3 days. The Moon also rotates on its axis once every 27.3 days. Do you know what this means? The same side of the Moon always faces Earth, so that side of the Moon is what we always see in the night sky (Figure 1.1). The Moon makes no light of its own, but instead only reflects light from the Sun. (a) The near side of the Moon faces Earth continually. It has a thinner crust with many more maria (flat areas of basaltic rock). (b) The far side of the Moon has only been seen by spacecraft. It has a thicker crust and far fewer maria (flat areas of basaltic rock). | text | null |
L_0246 | moon | T_1474 | The Moon has no atmosphere. Since an atmosphere moderates temperature, the Moons average surface temperature during the day is approximately 225 F, but drops to -243 F at night. The coldest temperatures, around -397 F, occur in craters in the permanently shaded south polar basin. These are among the coldest temperatures recorded in the entire solar system. Earths landscape is extremely varied, with mountains, valleys, plains and hills. This landscape is always changing as plate tectonics builds new features and weathering and erosion destroys them. The landscape of the Moon is very different. With no plate tectonics, features are not built. With no atmosphere, features are not destroyed. Still, the Moon has a unique surface. Lunar surface features include the bowl-shaped craters that are caused by meteorite impacts (Figure 1.2). If Earth did not have plate tectonics or erosion, its surface would also be covered with meteorite craters. Even from Earth, the Moon has visible dark areas and light areas. The dark areas are called maria, which means seas because thats what the ancients thought they were. In fact, the maria are not water but solid, flat areas of basaltic lava. From about 3.0 to 3.5 billion years ago the Moon was continually bombarded by meteorites. Some of these meteorites were so large that they broke through the Moons newly formed surface. Then, magma flowed out and filled the craters. Scientists estimate this meteorite-caused volcanic activity on the Moon ceased about 1.2 billion years ago, but most occurred long before that. The lighter parts of the Moon are called terrae or highlands (Figure 1.3). The terrae are higher than the maria and A crater on the surface of the Moon. include several high mountain ranges. The terrae are the light silicate minerals that precipitated out of the ancient magma ocean and formed the early lunar crust. There are no lakes, rivers, or even small puddles anywhere to be found on the Moons surface, but water in the form of ice has been found in the extremely cold craters and bound up in the lunar soil. Despite the possible presence of water, the lack of an atmosphere and the extreme temperatures make it no surprise to scientists that the Moon has absolutely no evidence of life. Life from Earth has visited the Moon and there are footprints of astronauts on the lunar surface. With no wind, rain, or living thing to disturb them, these footprints will remain as long as the Moon exists. Only an impact with a meteorite could destroy them. | text | null |
L_0246 | moon | T_1475 | Like Earth, the Moon has a distinct crust, mantle, and core. What is known about the Moons interior was determined from the analysis of rock samples gathered by astronauts and from unmanned spacecraft sent to the Moon (Figure The Moons small core, 600 to 800 kilometers in diameter, is mostly iron with some sulfur and nickel. The mantle is composed of the minerals olivine and orthopyroxene. Analysis of Moon rocks indicates that there may also be high levels of iron and titanium in the lunar mantle. A close-up of the Moon, showing maria (the dark areas) and terrae (the light areas); maria covers around 16% of the Moons surface, mostly on the side of the Moon we see. LCROSS crashed into the Moon in May 2009. This QUEST video describes the mission. After watching, look up the mission to see what they found! Click image to the left or use the URL below. URL: Click image to the left or use the URL below. URL: | text | null |
L_0246 | moon | T_1475 | Like Earth, the Moon has a distinct crust, mantle, and core. What is known about the Moons interior was determined from the analysis of rock samples gathered by astronauts and from unmanned spacecraft sent to the Moon (Figure The Moons small core, 600 to 800 kilometers in diameter, is mostly iron with some sulfur and nickel. The mantle is composed of the minerals olivine and orthopyroxene. Analysis of Moon rocks indicates that there may also be high levels of iron and titanium in the lunar mantle. A close-up of the Moon, showing maria (the dark areas) and terrae (the light areas); maria covers around 16% of the Moons surface, mostly on the side of the Moon we see. LCROSS crashed into the Moon in May 2009. This QUEST video describes the mission. After watching, look up the mission to see what they found! Click image to the left or use the URL below. URL: Click image to the left or use the URL below. URL: | text | null |
L_0248 | natural gas power | T_1480 | Natural gas, often known simply as gas, is composed mostly of the hydrocarbon methane. The amount of natural gas being extracted and used in the Untied States is increasing rapidly. | text | null |
L_0248 | natural gas power | T_1481 | Natural gas forms under the same conditions that create oil. Organic material buried in the sediments harden to become a shale formation that is the source of the gas. Although natural gas forms at higher temperatures than crude oil, the two are often found together. The largest natural gas reserves in the United States are in the Appalachian Basin, North Dakota and Montana, Texas, and the Gulf of Mexico region (Figure 1.1). California also has natural gas, found mostly in the Central Valley. In the northern Sacramento Valley and the Sacramento Delta, a sediment-filled trough formed along a location where crust was pushed together (an ancient convergent margin). Gas production in the lower 48 United States. | text | null |
L_0248 | natural gas power | T_1482 | Like crude oil, natural gas must be processed before it can be used as a fuel. Some of the chemicals in unprocessed natural gas are poisonous to humans. Other chemicals, such as water, make the gas less useful as a fuel. Processing natural gas removes almost everything except the methane. Once the gas is processed, it is ready to be delivered and used. Natural gas is delivered to homes for uses such as cooking and heating. Like coal and oil, natural gas is also burned to generate heat for powering turbines. The spinning turbines turn generators, and the generators create electricity. Click image to the left or use the URL below. URL: | text | null |
L_0248 | natural gas power | T_1483 | Natural gas burns much cleaner than other fossil fuels, meaning that it causes less air pollution. Natural gas also produces less carbon dioxide than other fossil fuels do for the same amount of energy, so its global warming effects are less (Figure 1.2). Unfortunately, drilling for natural gas can be environmentally destructive. One technique used is hydraulic fractur- ing, also called fracking, which increases the rate of recovery of natural gas. Fluids are pumped through a borehole to create fractures in the reservoir rock that contains the natural gas. Material is added to the fluid to prevent the fractures from closing. The damage comes primarily from chemicals in the fracturing fluids. Chemicals that have been found in the fluids may be carcinogens (cancer-causing), radioactive materials, or endocrine disruptors, which interrupt hormones in the bodies of humans and animals. The fluids may get into groundwater or may runoff into streams and other surface waters. As noted above, fracking may cause earthquakes. Click image to the left or use the URL below. URL: | text | null |
L_0249 | natural resource conservation | T_1484 | So that people in developed nations maintain a good lifestyle and people in developing nations have the ability to improve their lifestyles, natural resources must be conserved and protected (Figure 1.1). People are researching ways to find renewable alternatives to non-renewable resources. Here is a checklist of ways to conserve resources: Buy less stuff (use items as long as you can, and ask yourself if you really need something new). Reduce excess packaging (drink tap water instead of water from plastic bottles). Recycle materials such as metal cans, old cell phones, and plastic bottles. Purchase products made from recycled materials. Reduce pollution so that resources are maintained. Prevent soil erosion. Plant new trees to replace those that are cut down. Drive cars less, take public transportation, bicycle, or walk. Conserve energy at home (turn out lights when they are not needed). Click image to the left or use the URL below. URL: Click image to the left or use the URL below. URL: | text | null |
L_0250 | neptune | T_1485 | Neptune, shown in Figure 1.1, is the only major planet that cant be seen from Earth without a telescope. Scientists predicted the existence of Neptune before it was discovered because Uranus did not always appear exactly where it should appear. They knew that the gravitational pull of another planet beyond Uranus must be affecting Uranus orbit. Neptune was discovered in 1846, in the position that had been predicted, and it was named Neptune for the Roman god of the sea because of its bluish color. This image of Neptune was taken by Voy- ager 2 in 1989. The Great Dark Spot seen on the left center in the picture has since disappeared, but a similar dark spot has appeared on another part of the planet. In many respects, Neptune is similar to Uranus (Figure 1.2). Neptune has slightly more mass than Uranus, but it is slightly smaller in size. Neptune is much farther from the Sun, at nearly 4.5 billion km (2.8 billion mi). The planets slow orbit means that it takes 165 Earth years to go once around the Sun. | text | null |
L_0250 | neptune | T_1486 | Neptunes blue color is mostly because of frozen methane (CH4 ). When Voyager 2 visited Neptune in 1986, there was a large dark-blue spot, which scientists named the Great Dark Spot, south of the equator. When the Hubble Space Telescope took pictures of Neptune in 1994, the Great Dark Spot had disappeared, but another dark spot had appeared north of the equator. Astronomers think that both of these spots represent gaps in the methane clouds on Neptune. The changing appearance of Neptune is caused by its turbulent atmosphere. The winds on Neptune are stronger than on any other planet in the solar system, reaching speeds of 1,100 km/h (700 mi/h), close to the speed of sound. This extreme weather surprised astronomers, since the planet receives little energy from the Sun to power weather systems. Neptunes core is 7000 C (12,632 C) which means that it produces more energy than it receives from the Sun. Neptune is also one of the coldest places in the solar system. Temperatures at the top of the clouds are about -218 C (-360 F). Neptunes composition is that of a gas giant: (1) upper atmosphere, (2) atmo- sphere composed of hydrogen, helium and methane gas, (3) mantle of water, ammonia and methane ice, (4) core of rock and ice. | text | null |
L_0250 | neptune | T_1487 | Neptune has faint rings of ice and dust that may change or disappear in fairly short time frames. Neptune has 13 known moons. Triton, shown in Figure 1.3, is the only one of them that has enough mass to be spherical in shape. Triton orbits in the direction opposite to the orbit of Neptune. Scientists think Triton did not form around Neptune, but instead was captured by Neptunes gravity as it passed by. This image of Triton, Neptunes largest moon, was taken by Voyager 2 in 1989. | text | null |
L_0251 | nitrogen cycle in ecosystems | T_1488 | Nitrogen (N2 ) is vital for life on Earth as an essential component of organic materials, such as amino acids, chloro- phyll, and nucleic acids such as DNA and RNA (Figure 1.1). Chlorophyll molecules, essential for photosynthesis, contain nitrogen. | text | null |
L_0251 | nitrogen cycle in ecosystems | T_1489 | Although nitrogen is the most abundant gas in the atmosphere, it is not in a form that plants can use. To be useful, nitrogen must be fixed, or converted into a more useful form. Although some nitrogen is fixed by lightning or blue-green algae, much is modified by bacteria in the soil. These bacteria combine the nitrogen with oxygen or hydrogen to create nitrates or ammonia (Figure 1.2). (a) Nucleic acids contain nitrogen (b) Chlorophyll molecules contain nitrogen | text | null |
L_0251 | nitrogen cycle in ecosystems | T_1489 | Although nitrogen is the most abundant gas in the atmosphere, it is not in a form that plants can use. To be useful, nitrogen must be fixed, or converted into a more useful form. Although some nitrogen is fixed by lightning or blue-green algae, much is modified by bacteria in the soil. These bacteria combine the nitrogen with oxygen or hydrogen to create nitrates or ammonia (Figure 1.2). (a) Nucleic acids contain nitrogen (b) Chlorophyll molecules contain nitrogen | text | null |
L_0251 | nitrogen cycle in ecosystems | T_1490 | Animals eat plant tissue and create animal tissue. After a plant or animal dies or an animal excretes waste, bacteria and some fungi in the soil fix the organic nitrogen and return it to the soil as ammonia. Nitrifying bacteria oxidize the ammonia to nitrites, while other bacteria oxidize the nitrites to nitrates, which can be used by the next generation of plants. In this way, nitrogen does not need to return to a gas. Under conditions when there is no oxygen, some bacteria can reduce nitrates to molecular nitrogen. Click image to the left or use the URL below. URL: | text | null |
L_0252 | non renewable energy resources | T_1491 | Nonrenewable resources are natural resources that are limited in supply and cannot be replaced as quickly as they are used up. A natural resource is anything people can use that comes from nature. Energy resources are some of the most important natural resources because everything we do requires energy. Nonrenewable energy resources include fossil fuels such as oil and the radioactive element uranium. | text | null |
L_0252 | non renewable energy resources | T_1492 | Oil, or petroleum, is one of several fossil fuels. Fossil fuels are mixtures of hydrocarbons (compounds containing only hydrogen and carbon) that formed over millions of years from the remains of dead organisms. In addition to oil, they include coal and natural gas. Fossil fuels provide most of the energy used in the world today. They are burned in power plants to produce electrical energy, and they also fuel cars, heat homes, and supply energy for many other purposes. You can see some ways they are used in the Figure 1.1. Q: Why do fossil fuels have energy? A: Fossil fuels contain stored chemical energy that came originally from the sun. | text | null |
L_0252 | non renewable energy resources | T_1493 | When ancient plants underwent photosynthesis, they changed energy in sunlight to stored chemical energy in food. The plants used the food and so did the organisms that ate the plants. After the plants and other organisms died, their remains gradually changed to fossil fuels as they were covered and compressed by layers of sediments. Petroleum and natural gas formed from ocean organisms and are found together. Coal formed from giant tree ferns and other swamp plants. | text | null |
L_0252 | non renewable energy resources | T_1494 | When fossil fuels burn, they release thermal energy, water vapor, and carbon dioxide. The thermal energy can be used to generate electricity or do other work. The carbon dioxide is released into the atmosphere and is a major cause of global climate change. The burning of fossil fuels also releases many pollutants into the air. Pollutants such as sulfur dioxide form acid rain, which kills living things and damages metals, stonework, and other materials. Pollutants such as nitrogen oxides cause smog, which is harmful to human health. Tiny particles, or particulates, released when fossil fuels burn also harm human health. The Figure 1.2 shows the amounts of pollutants released by different fossil fuels. Natural gas releases the least pollution; coal releases the most. Petroleum has the additional risk of oil spills, which may seriously damage ecosystems. Q: Some newer models of cars and other motor vehicles can run on natural gas. Why would a natural gas vehicle be better for the environment than a vehicle that burns gasoline, which is made from oil? A: Natural gas produces much less pollution and carbon dioxide when it burns than gasoline does. So a natural gas vehicle would contribute less to global climate change, acid rain, and air pollution that harms health. Besides being better for the environment, burning natural gas instead of gasoline results in less engine wear and provides more energy for a given amount of fuel. | text | null |
L_0252 | non renewable energy resources | T_1495 | Like fossil fuels, the radioactive element uranium can be used to generate electrical energy in power plants. This source of energy is known as nuclear energy. In a nuclear power plant, the nuclei of uranium atoms are split apart into smaller nuclei in the process of nuclear fission. This process releases a tremendous amount of energy from just a small amount of uranium. The total supply of uranium in the world is quite limited, however, and cannot be replaced once it is used up. Thats why nuclear energy is a nonrenewable resource. The use of nuclear energy also produces dangerous radioactive wastes. In addition, accidents at nuclear power plants have the potential to release large amounts of harmful radiation into the environment. Q: Why is nuclear energy often considered to be greener than energy from fossil fuels? A: Unlike energy from fossil fuels, nuclear energy doesnt produce air pollution or carbon dioxide that contributes to global climate change. | text | null |
L_0253 | nuclear power | T_1496 | When the nucleus of an atom is split, it releases a huge amount of energy called nuclear energy. For nuclear energy to be used as a power source, scientists and engineers have learned to split nuclei and to control the release of energy (Figure 1.1). | text | null |
L_0253 | nuclear power | T_1497 | Nuclear power plants, such as the one seen in Figure 1.2, use uranium, which is mined, processed, and then concentrated into fuel rods. When the uranium atoms in the fuel rods are hit by other extremely tiny particles, they split apart. The number of tiny particles allowed to hit the fuel rods needs to be controlled, or they would cause a dangerous explosion. The energy from a nuclear power plant heats water, which creates steam and causes a turbine to spin. The spinning turbine turns a generator, which in turn produces electricity. Many countries around the world use nuclear energy as a source of electricity. In the United States, a little less than 20% of electricity comes from nuclear energy. | text | null |
L_0253 | nuclear power | T_1497 | Nuclear power plants, such as the one seen in Figure 1.2, use uranium, which is mined, processed, and then concentrated into fuel rods. When the uranium atoms in the fuel rods are hit by other extremely tiny particles, they split apart. The number of tiny particles allowed to hit the fuel rods needs to be controlled, or they would cause a dangerous explosion. The energy from a nuclear power plant heats water, which creates steam and causes a turbine to spin. The spinning turbine turns a generator, which in turn produces electricity. Many countries around the world use nuclear energy as a source of electricity. In the United States, a little less than 20% of electricity comes from nuclear energy. | text | null |
L_0253 | nuclear power | T_1498 | Nuclear power is clean. It does not pollute the air. However, the use of nuclear energy does create other environ- mental problems. Uranium must be mined (Figure 1.3). The process of splitting atoms creates radioactive waste, which remains dangerous for thousands or hundreds of thousands of years. As yet, there is no long-term solution for storing this waste. The development of nuclear power plants has been on hold for three decades. Accidents at Three Mile Island and Chernobyl, Ukraine verified peoples worst fears about the dangers of harnessing nuclear power (Figure 1.4). Recently, nuclear power appeared to be making a comeback as society looked for alternatives to fossil fuels. After all, nuclear power emits no pollutants, including no greenhouse gases. But the 2011 disaster at the Fukushima Daiichi Nuclear Power Plant in Japan may have resulted in a new fear of nuclear power. The cause of the disaster was a 9.0 magnitude earthquake and subsequent tsunami, which compromised the plant. Although a total meltdown was averted, the plant experienced multiple partial meltdowns, core breaches, radiation releases, and cooling failures. The plant is scheduled for a complete cold shutdown before the end of 2011. Damaged building near the site of the Chernobyl disaster. Nuclear power is a controversial subject in California and most other places. Nuclear power has no pollutants including carbon emissions, but power plants are not always safe and the long-term disposal of wastes is a problem that has not yet been solved. The future of nuclear power is murky. | text | null |
L_0253 | nuclear power | T_1498 | Nuclear power is clean. It does not pollute the air. However, the use of nuclear energy does create other environ- mental problems. Uranium must be mined (Figure 1.3). The process of splitting atoms creates radioactive waste, which remains dangerous for thousands or hundreds of thousands of years. As yet, there is no long-term solution for storing this waste. The development of nuclear power plants has been on hold for three decades. Accidents at Three Mile Island and Chernobyl, Ukraine verified peoples worst fears about the dangers of harnessing nuclear power (Figure 1.4). Recently, nuclear power appeared to be making a comeback as society looked for alternatives to fossil fuels. After all, nuclear power emits no pollutants, including no greenhouse gases. But the 2011 disaster at the Fukushima Daiichi Nuclear Power Plant in Japan may have resulted in a new fear of nuclear power. The cause of the disaster was a 9.0 magnitude earthquake and subsequent tsunami, which compromised the plant. Although a total meltdown was averted, the plant experienced multiple partial meltdowns, core breaches, radiation releases, and cooling failures. The plant is scheduled for a complete cold shutdown before the end of 2011. Damaged building near the site of the Chernobyl disaster. Nuclear power is a controversial subject in California and most other places. Nuclear power has no pollutants including carbon emissions, but power plants are not always safe and the long-term disposal of wastes is a problem that has not yet been solved. The future of nuclear power is murky. | text | null |
L_0255 | obtaining energy resources | T_1503 | Net energy is the amount of useable energy available from a resource after subtracting the amount of energy needed to make the energy from that resource available. For example, every 5 barrels of oil that are made available for use require 1 barrel for extracting and refining the petroleum. What is the net energy from this process? About 4 barrels (5 barrels minus 1 barrel). What happens if the energy needed to extract and refine oil increases? Why might that happen? The energy cost of an energy resource increases when the easy deposits of that resource have already been consumed. For example, if all the nearshore petroleum in a region has been extracted, more costly drilling must take place further offshore (Figure 1.1). If the energy cost of obtaining energy increases, the resource will be used even faster. Offshore drilling is taking place in deeper water than before. It takes a lot of energy to build a deep drilling platform and to run it. | text | null |
L_0255 | obtaining energy resources | T_1504 | The net-energy ratio demonstrates the difference between the amount of energy available in a resource and the amount of energy used to get it. If it takes 8 units of energy to make available 10 units of energy, then the net-energy ratio is 10/8 or 1.25. What does a net-energy ratio larger than 1 mean? What if the net-energy ratio is less than 1? A net-energy ratio larger than 1 means that there is a net gain in usable energy; a net-energy ratio smaller than one means there is an overall energy loss. Table 1.1 shows the net-energy ratios for some common energy sources. Energy Source Solar Energy Natural Gas Petroleum Coal-fired Electricity Net-energy Ratio 5.8 4.9 4.5 2.5-5.1 Notice from the table that solar energy yields much more net energy than other sources. This is because it takes very little energy to get usable solar energy. Sunshine is abundant and does not need to be found, extracted, or transported very far. The range for coal-fired electricity is because of the differing costs of transporting the coal. What does this suggest about using coal to generate electricity? The efficiency is greater in areas where the coal is locally mined and does not have to be transported great distances (Figure 1.2). Obtaining coal for energy takes a lot of energy. The coal must be located, extracted, refined, and transported. Because so much of the energy we use is from fossil fuels, we need to be especially concerned about using them efficiently. Sometimes our choices affect energy efficiency. For example, transportation by cars and airplanes is less energy-efficient than transportation by boats and trains. | text | null |
L_0256 | ocean ecosystems | T_1505 | Conditions in the intertidal zone change rapidly as water covers and uncovers the region and waves pound on the rocks. A great abundance of life is found in the intertidal zone (Figure 1.1). High energy waves hit the organisms that live in this zone, so they must be adapted to pounding waves and exposure to air during low tides. Hard shells protect from waves and also protect against drying out when the animal is above water. Strong attachments keep the animals anchored to the rock. In a tide pool, as in the photo, what organisms are found where and what specific adaptations do they have to that zone? The mussels on the top left have hard shells for protection and to prevent drying because they are often not covered by water. The sea anemones in the lower right are more often submerged and have strong attachments but can close during low tides. Many young organisms get their start in estuaries and so they must be adapted to rapid shifts in salinity. Organisms in a tide pool include sea stars and sea urchins. Click image to the left or use the URL below. URL: | text | null |
L_0256 | ocean ecosystems | T_1506 | Corals and other animals deposit calcium carbonate to create rock reefs near the shore. Coral reefs are the rain- forests of the oceans, with a tremendous amount of species diversity (Figure 1.2). Reefs can form interesting shapes in the oceans. Remember that hot spots create volcanoes on the seafloor. If these volcanoes rise above sea level to become islands, and if they occur in tropical waters, coral reefs will form on them. Since the volcanoes are cones, the reef forms in a circle around the volcano. As the volcano comes off the hot spot, the crust cools. The volcano subsides and then begins to erode away (Figure 1.3). Eventually, all that is left is a reef island called an atoll. A lagoon is found inside the reef. | text | null |
L_0256 | ocean ecosystems | T_1507 | The open ocean is a vast area. Food either washes down from the land or is created by photosynthesizing plankton. Zooplankton and larger animals feed on the phytoplankton and on each other. Larger animals such as whales and giant groupers may live their entire lives in the open water. How do fish survive in the deepest ocean? The few species that live in the greatest depths are very specialized (Figure 1.4). Since its rare to find a meal, the fish use very little energy; they move very little, breathe slowly, have minimal bone structure and a slow metabolism. These fish are very small. To maximize the chance of getting a meal, some species may have jaws that unhinge to accept a larger fish or backward-folding teeth to keep prey from escaping. Coral reefs are among the most densely inhabited and diverse areas on the globe. In this image of Maupiti Island in the South Pacific, the remnants of the volcano are surrounded by the circular reef. An 1896 drawing of a deep sea angler fish with a bioluminescent lure to attract prey. | text | null |
L_0256 | ocean ecosystems | T_1507 | The open ocean is a vast area. Food either washes down from the land or is created by photosynthesizing plankton. Zooplankton and larger animals feed on the phytoplankton and on each other. Larger animals such as whales and giant groupers may live their entire lives in the open water. How do fish survive in the deepest ocean? The few species that live in the greatest depths are very specialized (Figure 1.4). Since its rare to find a meal, the fish use very little energy; they move very little, breathe slowly, have minimal bone structure and a slow metabolism. These fish are very small. To maximize the chance of getting a meal, some species may have jaws that unhinge to accept a larger fish or backward-folding teeth to keep prey from escaping. Coral reefs are among the most densely inhabited and diverse areas on the globe. In this image of Maupiti Island in the South Pacific, the remnants of the volcano are surrounded by the circular reef. An 1896 drawing of a deep sea angler fish with a bioluminescent lure to attract prey. | text | null |
L_0256 | ocean ecosystems | T_1507 | The open ocean is a vast area. Food either washes down from the land or is created by photosynthesizing plankton. Zooplankton and larger animals feed on the phytoplankton and on each other. Larger animals such as whales and giant groupers may live their entire lives in the open water. How do fish survive in the deepest ocean? The few species that live in the greatest depths are very specialized (Figure 1.4). Since its rare to find a meal, the fish use very little energy; they move very little, breathe slowly, have minimal bone structure and a slow metabolism. These fish are very small. To maximize the chance of getting a meal, some species may have jaws that unhinge to accept a larger fish or backward-folding teeth to keep prey from escaping. Coral reefs are among the most densely inhabited and diverse areas on the globe. In this image of Maupiti Island in the South Pacific, the remnants of the volcano are surrounded by the circular reef. An 1896 drawing of a deep sea angler fish with a bioluminescent lure to attract prey. | text | null |
L_0256 | ocean ecosystems | T_1508 | Hydrothermal vents are among the most unusual ecosystems on Earth since they are dependent on chemosynthetic organisms at the base of the food web. At mid-ocean ridges at hydrothermal vents, bacteria that use chemosyn- thesis for food energy are the base of a unique ecosystem (Figure 1.5). This ecosystem is entirely separate from the photosynthesis at the surface. Shrimp, clams, fish, and giant tube worms have been found in these extreme places. Giant tube worms found at hydrothermal vents get food from the chemosynthetic bacteria that live within them. The bacte- ria provide food; the worms provide shel- ter. A video explaining hydrothermal vents with good footage is seen here: | text | null |
L_0257 | ocean garbage patch | T_1509 | Trash from land may end up as trash in the ocean, sometimes extremely far from land. Some of it will eventually wash ashore, possibly far from where it originated (Figure 1.1). | text | null |
L_0257 | ocean garbage patch | T_1510 | Although people had once thought that the trash found everywhere at sea was from ships, it turns out that 80% is from land. Some of that is from runoff, some is blown from nearshore landfills, and some is dumped directly into the sea. The 20% that comes from ships at sea includes trash thrown overboard by large cruise ships and many other vessels. It also includes lines and nets from fishing vessels. Ghost nets, nets abandoned by fishermen intentionally or not, float the seas and entangle animals so that they cannot escape. Containers sometimes go overboard in storms. Some noteworthy events, like a container of rubber ducks that entered the sea in 1992, are used to better understand ocean currents. The ducks went everywhere! | text | null |
L_0257 | ocean garbage patch | T_1511 | About 80% of the trash that ends up in the oceans is plastic. This is because a large amount of the trash produced since World War II is plastic. Also many types of plastic do not biodegrade, so they simply accumulate. While many types of plastic photodegrade that is, they break up in sunlight this process only works when the plastics are dry. Plastic trash in the water does break down into smaller pieces, eventually becoming molecule-sized polymers. Other trash in the oceans includes chemical sludge and materials that do biodegrade, like wood. | text | null |
L_0257 | ocean garbage patch | T_1512 | Some plastics contain toxic chemicals, such as bisphenol A. Plastics can also absorb organic pollutants that may be floating in the water, such as the pesticide DDT (which is banned in the U.S. but not in other nations) and some endocrine disruptors. | text | null |
L_0257 | ocean garbage patch | T_1513 | Trash from the lands all around the North Pacific is caught up in currents. The currents bring the trash into the center of the North Pacific Gyre. Scientists estimate that it takes about six years for trash to move from west coast of North America to the center of the gyre. The concentration of trash increases toward the center of the gyre. While recognizable pieces of garbage are visible, much of the trash is tiny plastic polymers that are invisible but can be detected in water samples. The particles are at or just below the surface within the gyre. Plastic confetti-like pieces are visible beneath the surface at the gyres center. This albatross likely died from the plastic it had ingested. The size of the garbage patch is unknown, since it cant be seen from above. Some people estimate that its twice the size of continental U.S, with a mass of 100 million tons. | text | null |
L_0257 | ocean garbage patch | T_1513 | Trash from the lands all around the North Pacific is caught up in currents. The currents bring the trash into the center of the North Pacific Gyre. Scientists estimate that it takes about six years for trash to move from west coast of North America to the center of the gyre. The concentration of trash increases toward the center of the gyre. While recognizable pieces of garbage are visible, much of the trash is tiny plastic polymers that are invisible but can be detected in water samples. The particles are at or just below the surface within the gyre. Plastic confetti-like pieces are visible beneath the surface at the gyres center. This albatross likely died from the plastic it had ingested. The size of the garbage patch is unknown, since it cant be seen from above. Some people estimate that its twice the size of continental U.S, with a mass of 100 million tons. | text | null |
L_0257 | ocean garbage patch | T_1514 | Marine birds, such as albatross, or animals like sea turtles, live most of their lives at sea and just come ashore to mate. These organisms cant break down the plastic and they may eventually die (Figure 1.2). Boats may be affected. Plastic waste is estimated to kill 100,000 sea turtles and marine mammals annually, but exact numbers are unknown. Plastic shopping bags are extremely abundant in the oceans. If an organism accidentally ingests one, it may clog digestion and cause starvation by stopping food from moving through or making the animal not feel hungry. In some areas, plastics have seven times the concentration of zooplankton. This means that filter feeders are ingesting a lot of plastics. This may kill the organisms or the plastics may remain in their bodies. They are then eaten by larger organisms that store the plastics and may eventually die. Fish may eat organisms that have eaten plastic and then be eaten by people. This also exposes humans to toxic chemicals that the fish may have ingested with the plastic. There are similar patches of trash in the gyres of the North Atlantic and Indian oceans. The Southern Hemisphere has less trash buildup because less of the region is continent. | text | null |
L_0258 | ocean zones | T_1515 | Oceanographers divide the ocean into zones both vertically and horizontally. | text | null |
L_0258 | ocean zones | T_1516 | To better understand regions of the ocean, scientists define the water column by depth. They divide the entire ocean into two zones vertically, based on light level. Large lakes are divided into similar regions. Sunlight only penetrates the sea surface to a depth of about 200 m, creating the photic zone ("photic" means light). Organisms that photosynthesize depend on sunlight for food and so are restricted to the photic zone. Since tiny photosynthetic organisms, known as phytoplankton, supply nearly all of the energy and nutrients to the rest of the marine food web, most other marine organisms live in or at least visit the photic zone. In the aphotic zone there is not enough light for photosynthesis. The aphotic zone makes up the majority of the ocean, but has a relatively small amount of its life, both in diversity of type and in numbers. The aphotic zone is subdivided based on depth (Figure 1.1). The average depth of the ocean is 3,790 m, a lot more shallow than the deep trenches but still an incredible depth for sea creatures to live in. What makes it so hard to live at the bottom of the ocean? The three major factors that make the deep ocean hard to inhabit are the absence of light, low temperature, and extremely high pressure. | text | null |
L_0258 | ocean zones | T_1517 | The seabed is divided into the zones described above, but ocean itself is also divided horizontally by distance from the shore. Nearest to the shore lies the intertidal zone (also called the littoral zone), the region between the high and low tidal marks. The hallmark of the intertidal is change: water is in constant motion in the form of waves, tides, and currents. The land is sometimes under water and sometimes exposed. The neritic zone is from low tide mark and slopes gradually downward to the edge of the seaward side of the continental shelf. Some sunlight penetrates to the seabed here. The oceanic zone is the entire rest of the ocean from the bottom edge of the neritic zone, where sunlight does not reach the bottom. The sea bed and water column are subdivided further, as seen in the Figure 1.1. Click image to the left or use the URL below. URL: | text | null |
L_0259 | oil spills | T_1518 | Large oil spills, like the Exxon Valdez in Alaska in 1989, get a lot of attention, as they should. Besides these large spills, though, much more oil enters the oceans from small leaks that are only a problem locally. In this concept, well take a look at a large recent oil spill in the Gulf of Mexico. | text | null |
L_0259 | oil spills | T_1519 | New drilling techniques have allowed oil companies to drill in deeper waters than ever before. This allows us to access oil deposits that were never before accessible, but only with great technological difficulty. The risks from deepwater drilling and the consequences when something goes wrong are greater than those associated with shallower wells. | text | null |
L_0259 | oil spills | T_1520 | Working on oil platforms is dangerous. Workers are exposed to harsh ocean conditions and gas explosions. The danger was never more obvious than on April 20, 2010, when 11 workers were killed and 17 injured in an explosion on a deepwater oil rig in the Gulf of Mexico (Figure 1.1). The drilling rig, operated by BP, was 77 km (48 miles) offshore and the depth to the well was more than 5,000 feet. The U.S. Coast Guard tries to put out the fire and search for missing workers after the explosion on the Deepwater Horizon drilling rig. Eleven workers were killed. | text | null |
L_0259 | oil spills | T_1521 | Two days after the explosion, the drill rig sank. The 5,000-foot pipe that connected the wellhead to the drilling platform bent. Oil was free to gush into the Gulf of Mexico from nearly a mile deep (Figure 1.2). Initial efforts to cap or contain the spill at or near its source all failed to stop the vast oil spill. It was not until July 15, nearly three months after the accident, that the well was successfully capped. Estimating the flow of oil into the Gulf from the well was extremely difficult because the leak was so far below the surface. The U.S. government estimates that about 4.9 million barrels entered the Gulf at a rate of 35,000 to 60,000 barrels a day. The largest previous oil spill in the United States was of 300,000 barrels by the Exxon Valdez in 1989 in Prince William Sound, Alaska. | text | null |
L_0259 | oil spills | T_1522 | Once the oil is in the water, there are three types of methods for dealing with it: 1. Removal: Oil is corralled and then burned; natural gas is flared off (Figure 1.3). Machines that can separate oil from the water are placed aboard ships stationed in the area. These ships cleaned tens of thousands of barrels of contaminated seawater each day. 2. Containment: Floating containment booms are placed on the surface offshore of the most sensitive coastal areas in an attempt to attempt to trap the oil. But the seas must be calm for the booms to be effective, and so were not very useful in the Gulf (Figure 1.4). Sand berms have been constructed off of the Louisiana coast to keep the oil from reaching shore. (a) On May 17, 2010, oil had been leaking into the Gulf for nearly one month. On that date government estimates put the maximum total oil leak at 1,600,000 barrels, according to the New York Times. (b) The BP oil spill on June 19, 2010. The government estimates for total oil leaked by this date was 3,200,000 barrels. 3. Dispersal: Oil disperses naturally over time because it mixes with the water. However, such large amounts of oil will take decades to disperse. To speed the process up, BP has sprayed unprecedented amounts of chemical dispersants on the spill. That action did not receive support from the scientific community since no one knows the risks to people and the environment from such a large amount of these harmful chemicals. Some workers may have become ill from exposure to the chemicals. | text | null |
L_0259 | oil spills | T_1522 | Once the oil is in the water, there are three types of methods for dealing with it: 1. Removal: Oil is corralled and then burned; natural gas is flared off (Figure 1.3). Machines that can separate oil from the water are placed aboard ships stationed in the area. These ships cleaned tens of thousands of barrels of contaminated seawater each day. 2. Containment: Floating containment booms are placed on the surface offshore of the most sensitive coastal areas in an attempt to attempt to trap the oil. But the seas must be calm for the booms to be effective, and so were not very useful in the Gulf (Figure 1.4). Sand berms have been constructed off of the Louisiana coast to keep the oil from reaching shore. (a) On May 17, 2010, oil had been leaking into the Gulf for nearly one month. On that date government estimates put the maximum total oil leak at 1,600,000 barrels, according to the New York Times. (b) The BP oil spill on June 19, 2010. The government estimates for total oil leaked by this date was 3,200,000 barrels. 3. Dispersal: Oil disperses naturally over time because it mixes with the water. However, such large amounts of oil will take decades to disperse. To speed the process up, BP has sprayed unprecedented amounts of chemical dispersants on the spill. That action did not receive support from the scientific community since no one knows the risks to people and the environment from such a large amount of these harmful chemicals. Some workers may have become ill from exposure to the chemicals. | text | null |
L_0259 | oil spills | T_1522 | Once the oil is in the water, there are three types of methods for dealing with it: 1. Removal: Oil is corralled and then burned; natural gas is flared off (Figure 1.3). Machines that can separate oil from the water are placed aboard ships stationed in the area. These ships cleaned tens of thousands of barrels of contaminated seawater each day. 2. Containment: Floating containment booms are placed on the surface offshore of the most sensitive coastal areas in an attempt to attempt to trap the oil. But the seas must be calm for the booms to be effective, and so were not very useful in the Gulf (Figure 1.4). Sand berms have been constructed off of the Louisiana coast to keep the oil from reaching shore. (a) On May 17, 2010, oil had been leaking into the Gulf for nearly one month. On that date government estimates put the maximum total oil leak at 1,600,000 barrels, according to the New York Times. (b) The BP oil spill on June 19, 2010. The government estimates for total oil leaked by this date was 3,200,000 barrels. 3. Dispersal: Oil disperses naturally over time because it mixes with the water. However, such large amounts of oil will take decades to disperse. To speed the process up, BP has sprayed unprecedented amounts of chemical dispersants on the spill. That action did not receive support from the scientific community since no one knows the risks to people and the environment from such a large amount of these harmful chemicals. Some workers may have become ill from exposure to the chemicals. | text | null |
L_0259 | oil spills | T_1523 | BP drilled two relief wells into the original well. When the relief wells entered the original borehole, specialized liquids were pumped into the original well to stop the flow. Operation of the relief wells began in August 2010. The original well was declared effectively dead on September 19, 2010. | text | null |
L_0259 | oil spills | T_1524 | The economic and environmental impact of this spill will be felt for many years. Many people rely on the Gulf for their livelihoods or for recreation. Commercial fishing, tourism, and oil-related jobs are the economic engines of the region. Fearing contamination, NOAA imposed a fishing ban on approximately one-third of the Gulf (Figure 1.5). Tourism is down in the region as beach goers find other ways to spend their time. Real estate prices along the Gulf have declined precipitously. This was the extent of the banned area on June 21, 2010. The Gulf of Mexico is one of only two places in the world where bluefin tuna spawn and they are also already endangered. Marine mammals in the Gulf may come up into the slick as they come to the surface to breathe. Eight national parks and seashores are found along the Gulf shores. Other locations may be ecologically sensitive habitats such as mangroves or marshlands. | text | null |
L_0259 | oil spills | T_1525 | There is still oil on beaches and in sediment on the seafloor in the region. Chemicals from the oil dispersants are still in the water. In October 2011 a report was issued that showed that whales and dolphins are dying in the Gulf at twice their normal rate. The long-term effects will be with us for a long time. Click image to the left or use the URL below. URL: | text | null |
L_0260 | overpopulation and over consumption | T_1526 | The Green Revolution has brought enormous impacts to the planet. | text | null |
L_0260 | overpopulation and over consumption | T_1527 | Natural landscapes have been altered to create farmland and cities. Already, half of the ice-free lands have been converted to human uses. Estimates are that by 2030, that number will be more than 70%. Forests and other landscapes have been cleared for farming or urban areas. Rivers have been dammed and the water is transported by canals for irrigation and domestic uses. Ecologically sensitive areas have been altered: wetlands are now drained and coastlines are developed. | text | null |
L_0260 | overpopulation and over consumption | T_1528 | Modern agricultural practices produce a lot of pollution (Figure 1.1). Some pesticides are toxic. Dead zones grow as fertilizers drain off farmland and introduce nutrients into lakes and coastal areas. Farm machines and vehicles used to transport crops produce air pollutants. Pollutants enter the air, water, or are spilled onto the land. Moreover, many types of pollution easily move between air, water, and land. As a result, no location or organism not even polar bears in the remote Arctic is free from pollution. | text | null |
L_0260 | overpopulation and over consumption | T_1529 | The increased numbers of people have other impacts on the planet. Humans do not just need food. They also need clean water, secure shelter, and a safe place for their wastes. These needs are met to different degrees in different nations and among different socioeconomic classes of people. For example, about 1.2 billion of the worlds people do not have enough clean water for drinking and washing each day (Figure 1.2). | text | null |
L_0260 | overpopulation and over consumption | T_1530 | The addition of more people has not just resulted in more poor people. A large percentage of people expect much more than to have their basic needs met. For about one-quarter of people there is an abundance of food, plenty of water, and a secure home. Comfortable temperatures are made possible by heating and cooling systems, rapid trans- portation is available by motor vehicles or a well-developed public transportation system, instant communication takes place by phones and email, and many other luxuries are available that were not even dreamed of only a few The percentage of people in the world that live in abject poverty is decreasing some- what globally, but increasing in some re- gions, such as Sub-Saharan Africa. decades ago. All of these require resources in order to be produced, and fossil fuels in order to be powered (Figure Many people refer to the abundance of luxury items in these peoples lives as over-consumption. People in developed nations use 32 times more resources than people in the developing countries of the world. Click image to the left or use the URL below. URL: Click image to the left or use the URL below. URL: | text | null |
L_0261 | ozone depletion | T_1531 | At this point you might be asking yourself, Is ozone bad or is ozone good? There is no simple answer to that question: It depends on where the ozone is located (Figure 1.1). In the troposphere, ozone is a pollutant. In the ozone layer in the stratosphere, ozone screens out high energy ultraviolet radiation and makes Earth habitable. | text | null |
L_0261 | ozone depletion | T_1532 | Human-made chemicals are breaking ozone molecules in the ozone layer. Chlorofluorocarbons (CFCs) are the most common, but there are others, including halons, methyl bromide, carbon tetrachloride, and methyl chloroform. CFCs were once widely used because they are cheap, nontoxic, nonflammable, and non-reactive. They were used as spray-can propellants, refrigerants, and in many other products. Once they are released into the air, CFCs float up to the stratosphere. Air currents move them toward the poles. In the winter, they freeze onto nitric acid molecules in polar stratospheric clouds (PSC) (Figure 1.2). In the spring, (1) Solar energy breaks apart oxygen molecules into two oxygen atoms. (2) Ozone forms when oxygen atoms bond together as O3 . UV rays break apart the ozone molecules into one oxygen molecule (O2 ) and one oxygen atom (O). These processes convert UV radiation into heat, which is how the Sun heats the stratosphere. (3) Under natural cir- cumstances, the amount of ozone cre- ated equals the amount destroyed. When O3 interacts with chlorine or some other gases the O3 breaks down into O2 and O and so the ozone layer loses its ability to filter out UV. the Suns warmth starts the air moving, and ultraviolet light breaks the CFCs apart. The chlorine atom floats away and attaches to one of the oxygen atoms on an ozone molecule. The chlorine pulls the oxygen atom away, leaving behind an O2 molecule, which provides no UV protection. The chlorine then releases the oxygen atom and moves on to destroy another ozone molecule. One CFC molecule can destroy as many as 100,000 ozone molecules. PSCs form only where the stratosphere is coldest, and are most common above Antarctica in the wintertime. PSCs are needed for stratospheric ozone to be de- stroyed. | text | null |
L_0261 | ozone depletion | T_1532 | Human-made chemicals are breaking ozone molecules in the ozone layer. Chlorofluorocarbons (CFCs) are the most common, but there are others, including halons, methyl bromide, carbon tetrachloride, and methyl chloroform. CFCs were once widely used because they are cheap, nontoxic, nonflammable, and non-reactive. They were used as spray-can propellants, refrigerants, and in many other products. Once they are released into the air, CFCs float up to the stratosphere. Air currents move them toward the poles. In the winter, they freeze onto nitric acid molecules in polar stratospheric clouds (PSC) (Figure 1.2). In the spring, (1) Solar energy breaks apart oxygen molecules into two oxygen atoms. (2) Ozone forms when oxygen atoms bond together as O3 . UV rays break apart the ozone molecules into one oxygen molecule (O2 ) and one oxygen atom (O). These processes convert UV radiation into heat, which is how the Sun heats the stratosphere. (3) Under natural cir- cumstances, the amount of ozone cre- ated equals the amount destroyed. When O3 interacts with chlorine or some other gases the O3 breaks down into O2 and O and so the ozone layer loses its ability to filter out UV. the Suns warmth starts the air moving, and ultraviolet light breaks the CFCs apart. The chlorine atom floats away and attaches to one of the oxygen atoms on an ozone molecule. The chlorine pulls the oxygen atom away, leaving behind an O2 molecule, which provides no UV protection. The chlorine then releases the oxygen atom and moves on to destroy another ozone molecule. One CFC molecule can destroy as many as 100,000 ozone molecules. PSCs form only where the stratosphere is coldest, and are most common above Antarctica in the wintertime. PSCs are needed for stratospheric ozone to be de- stroyed. | text | null |
L_0261 | ozone depletion | T_1533 | Ozone destruction creates the ozone hole where the layer is dangerously thin (Figure 1.3). As air circulates over Antarctica in the spring, the ozone hole expands northward over the southern continents, including Australia, New Zealand, southern South America, and southern Africa. UV levels may rise as much as 20% beneath the ozone hole. The hole was first measured in 1981 when it was 2 million square km (900,000 square miles). The 2006 hole was the largest ever observed at 28 million square km (11.4 million square miles). The size of the ozone hole each year depends on many factors, including whether conditions are right for the formation of PSCs. The September 2006 ozone hole, the largest observed (through 2013). Blue and purple colors show particularly low levels of ozone. | text | null |
L_0261 | ozone depletion | T_1534 | Ozone loss also occurs over the North Polar Region, but it is not enough for scientists to call it a hole. Why do you think there is less ozone loss over the North Pole area? The region of low ozone levels is small because the atmosphere is not as cold and PSCs do not form as readily. Still, springtime ozone levels are relatively low. This low moves south over some of the worlds most populated areas in Europe, North America, and Asia. At 40o N, the latitude of New York City, UV-B has increased about 4% per decade since 1978. At 55o N, the approximate latitude of Moscow and Copenhagen, the increase has been 6.8% per decade since 1978. Click image to the left or use the URL below. URL: | text | null |
L_0261 | ozone depletion | T_1535 | Ozone losses on human health and environment include: Increases in sunburns, cataracts (clouding of the lens of the eye), and skin cancers. A loss of ozone of only 1% is estimated to increase skin cancer cases by 5% to 6%. Decreases in the human immune systems ability to fight off infectious diseases. Reduction in crop yields because many plants are sensitive to ultraviolet light. Decreases in phytoplankton productivity. A decrease of 6% to 12% has been measured around Antarctica, which may be at least partly related to the ozone hole. The effects of excess UV on other organisms is not known. Whales in the Gulf of California have been found to have sunburned cells in their lowest skin layers, indicating very severe sunburns. The problem is greatest with light colored species or species that spend more time near the sea surface. When the problem with ozone depletion was recognized, world leaders took action. CFCs were banned in spray cans in some nations in 1978. The greatest production of CFCs was in 1986, but it has declined since then. This will be discussed more in the next concept. | text | null |
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