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Glaciers
Changing Earth’s Surface
5 Agents of Erosion
Gravity Running Water Glaciers Waves Wind
Glaciers
Glacier – any large mass of ice that moves slowly over land.
Two Types• Continental
• Valley
Continental Glaciers
A glacier that covers much of a continent or large island.
Ice Age
Continental glaciers have covered larger parts of Earth’s surface.
Valley Glaciers
A long, narrow glacier that forms when snow and ice build up high in a mountain valley.
Valley Glaciers
Once the depth of the snow and ice reaches more than 30-40 meters, gravity begins to pull the glacier downhill.
Valley Glaciers
Rate – a few centimeters to a few meters per day.
Glaciers Shape the Land
Erosion Deposition
Glacial Erosion
Plucking – the process by which a glacier picks up rocks as it flows over the land.
Glacial Deposition
When a glacier melts, it deposits the sediment it eroded from the land, creating various landforms.
Till
The mixture of sediment that a glacier deposits directly on the surface.
Clay, silt, sand, gravel, and boulders
Deposition Landforms
Moraine• The till deposited at the edges of a glacier
forms a ridge.
Terminal Moraine• The ridge of till at the farthest point reached
by a glacier
• Long Island NY is a terminal moraine from the last ice age.
Deposition Landforms
Kettle• A small depression that forms when a chunk
of ice is left in glacial till.
• Kettles often fill with water. Many found in Minnesota
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