Glaciers
A glacier is a large mass of ice that moves slowly over land. There are two types of glaciers, continental glaciers and valley glaciers. Glaciers are a major force of erosion. They erode the land in two processes which are plucking and abrasion. Plucking is when a glacier flows over the land it pick up rocks. Plucking can move huge boulders. Glaciers can form only in an area where more snow falls then melts. Once the depth of snow and ice gets to more than 30 to 40 meters, gravity begins to pull the glacier downhill. When a glaciers melts, it deposits the sediment it eroded from the land, creating various landforms. Till is the mixture of sediments that a glacier deposits directly on the surface. Clay, silt, sand, gravel, and boulders can be found in till. The till deposited at the edges of a glacier forms a ridge called moraine. A small depression that forms when a chunk of ice is left in a glacial till called a kettle.
Continental GlacierA continental glacier is a glacier that covers much of a continent or large island. In the past continental glaciers covered parts of land called ice ages.Continental glaciers can flow in all directions as they move. Continental glaciers cover 10% of Earth's land today.
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Valley GlacierA valley glacier is a long, narrow glacier that forms when snow and ice build up high in a mountain valley. Sides of mountains keep these glaciers from spreading in all directions. Valley glacier usually move down valleys that have already been cut by rivers. Valley glaciers are found on many high mountains.
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