What landforms result from glacial erosion?
As the glaciers expand, due to their accumulating weight of snow and ice they crush and abrade and scour surfaces such as rocks and bedrock. The resulting erosional landforms include striations, cirques, glacial horns, arêtes, trim lines, U-shaped valleys, roches moutonnées, overdeepenings and hanging valleys.
How are glacial sediments sorted?
Glaciers are flowing streams of ice. They may be huge continental ice sheets or small alpine (mountain) glaciers. All glaciers scrape up sediments and incorporate them into the base of the ice sheet. Sorted sediments carried by networks of braided streams out from the terminal moraine form an outwash plain.
What type of sediment do glaciers leave behind?
Sediments transported and deposited by glacial ice are known as till. Subglacial sediment (e.g., lodgement till) is material that has been eroded from the underlying rock by the ice, and is moved by the ice. It has a wide range of grain sizes, including a relatively high proportion of silt and clay.
How are well-sorted sediments produced?
Well-sorted sediments have grains of similar size, and are the result of much sediment transport and earth processes which segregated the sediment by depositing different size fractions in different places. Other examples of angular, poorly-sorted rocks are breccia and arkose sandstone.
Where are well-sorted sediments found?
Beach sediments that have been transported great distances will be sorted according to grain size. For example, Gulf coast sediments may have traveled the length of the Mississippi River. Winnowing of more uniform sediment shapes and sizes results in a beach with well-sorted sediments.
How do glaciers cause erosion?
As glaciers spread out over the surface of the land, (grow), they can change the shape of the land. They scrape away at the surface of the land, erode rock and sediment, carry it from one place to another, and leave it somewhere else. Thus, glaciers cause both erosional and depositional landforms.
How are glaciers an example of erosion and deposition?
Thus, evidence of glacial erosion and deposition are still present. Since glaciers move, they can pick up and transport rocks and thus erode. Since they transport material and can melt, they can also deposit material.
How are waterfalls related to glaciers and glaciation?
Glacial Erosion – Glaciers erode in several ways.: Thus, when the glacial ice melts the floor of the tributary valley hangs above the floor of the main valley and is called a hanging valley. Waterfalls generally occur where the hanging valley meets the main valley.
What are the conditions needed for a glacier to form?
Polar glaciers – Ice in a polar glacier always maintains a temperature well below its melting point. The Formation of Glacial Ice Three conditions are necessary to form a glacier: (1) Cold local climate (polar latitudes or high elevation).
What are the striations at the bottom of a glacier?
Glacial striations – long parallel scratches and grooves that are produced at the bottom of temperate glaciers by rocks embedded in the ice scraping against the rock underlying the glacier (see figure 22.12 in your text).