Four examples of glacial sediments are shown here. Describe the important characteristics e. What types of glacial sediments are likely to be sufficiently permeable to make good aquifers? Skip to content Chapter 16 Glaciation.
When and where was the first glaciation of the Cenozoic? What does the equilibrium line represent in a glacier? What condition is necessary for basal sliding to take place? Why do glaciers carve U-shaped valleys, and how does a hanging valley form? What are drop stones, and under what circumstances are they likely to form? Previous: Next: Chapter 17 Shorelines. Share This Book Share on Twitter. The current glacial period is known as the Pleistocene Glaciation, and while it was much more intense 20, years ago than it is now, we are still in the middle of it.
The rocks in the foreground were dropped by a retreating glacier, and the mountains in the background have been carved by glacial action. Reed Glaciers can sculpt and carve landscapes by eroding the land beneath them and by depositing rocks and sediment. This diagram shows how glaciers can erode bedrock. Abrasion involves scratching the bedrock with debris in the basal ice. Plucking is removal of entire chunks of rock.
Courtesy of Rocky Mountain National Park Glaciers can shape landscapes through erosion, or the removal of rock and sediment. They can erode bedrock by two different processes: Abrasion : The ice at the bottom of a glacier is not clean but usually has bits of rock, sediment, and debris. It is rough, like sandpaper.
As a glacier flows downslope, it drags the rock, sediment, and debris in its basal ice over the bedrock beneath it, grinding it. A broad area of stratified drift from meltwater over broad region is an outwash plain. Several types of stratified deposits form in glacial regions but are not formed directly by the ice.
Varves form where lakes are covered by ice in the winter. Dark, fine-grained clays sink to the bottom in winter but melting ice in spring brings running water that deposits lighter colored sands. If during a year, a glacier accumulates more ice than melts away, the glacier advances downhill. If a glacier melts more than it accumulates over a year, it is retreating Figure below.
Skip to main content. Search for:. Glacial Erosion and Deposition Lesson Objectives Discuss the different erosional features formed by alpine glaciers. Describe the processes by which glaciers change the underlying rocks. Discuss the particles deposited by glaciers as they advance and recede. Describe the landforms created by glacial deposits. Formation and Movement of Glaciers Glaciers are solid ice that move extremely slowly along the land surface Figure below.
The two types of glaciers are: Continental glaciers are large ice sheets that cover relatively flat ground. These glaciers flow outward from where the greatest amount of snow and ice accumulate. Alpine or valley glaciers flow downhill through mountains along existing valleys.
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