name the agent of erosion that produce hanging valley
glacier
title: Valley text: at the same point. Glaciated terrain is not the only site of hanging streams and valleys. Hanging valleys are also simply the product of varying rates of erosion of the main valley and the tributary valleys. The varying rates of erosion are associated with the composition of the adjacent rocks in the different valley locations. The tributary valleys are eroded and deepened by glaciers or erosion at a slower rate than that of the main valley floor, thus the difference in the two valleys' depth increases over time. The tributary valley composed of more resistant rock then hangs over the title: Hanging Hills text: by the rifting apart of North America from Eurasia and Africa. These basalt floods of lava happened over a period of 20 million years. Erosion occurring between the eruptions deposited deep layers of sediment between the lava flows, which eventually lithified into sedimentary rock. The resulting "layer cake" of basalt and sedimentary sheets eventually faulted and tilted upward. Subsequent erosion wore away the weaker sedimentary layers a faster rate than the basalt layers, leaving the abruptly tilted edges of the basalt sheets exposed, creating the distinct linear ridge and dramatic cliff faces visible today. The best way to imagine this title: Knickpoint text: a channel, known as a "knickzone". Glaciation resulting in a hanging valley are often prime spots for knickpoints. If lithology of the rock varies, such as shale amongst igneous rock, erosion will occur more steadily in the softer rock than the surrounding, tougher rock. Base level is the elevation of the surface of the water body into which a river ultimately drains, usually the ocean. A drop in base level causes a response by the river system to carve into the landscape. This incision begins at the formation of a knickpoint, and its upstream migration depends heavily upon the drainage title: Hanging Hills text: is to picture a layer cake tilted slightly up with some of the frosting (the sedimentary layer) removed in between. Subsequent scour by moving glacial ice plucked away the basalt from the steep southern end of the crest of the broken ridge, creating overhanging cliffs. In the Meriden region, numerous northeast-trending normal faults offset the volcanic flows and intervening sedimentary rocks. Several of these faults break the Metacomet Ridge north of Meriden. Stream erosion and glacial ice carved canyons along these faults, dividing the ridge into the finger-like promontories of the Hanging Hills. Merimere Reservoir was built in the fault-controlled title: Death Valley National Park text: the lateral movement. Igneous activity associated with this stretching occurred from 12 million to 4 million years ago. Sedimentation is concentrated in valleys (basins) from material eroded from adjacent ranges. The amount of sediment deposited has roughly kept up with this subsidence, resulting in retention of more or less the same valley floor elevation over time. Pleistocene ice ages started 2 million years ago, and melt from alpine glaciers on the nearby Sierra Nevada Mountains fed a series of lakes that filled Death and Panamint valleys and surrounding basins (see the top of the ). The lake that filled Death