Section 15.2 Glacial Movements and Erosion. How do glaciers move? What are some reasons why glaciers move? Heavy snow fall Steep slopes Temperature increase/summer.
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Section 15.2Glacial Movements and Erosion
How do glaciers move?
What are some reasons why glaciers move?
• Heavy snow fall
• Steep slopes
• Temperature increase/summer
What slows glaciers down?
• Friction
Slip and slide on a layer of water (friction)
2 main types of glacial movement
1. Basal slip
2. Plastic flow
1. Basal slip
• Basal slip = immense weight of the glacier puts pressure on the bottom causing grains of ice to partially melt
– creates a slushy layer– glacier “slips and slides” on the slush
2. Plastic Flow
• Due to pressure (weight) of snow above
• Grains of ice actually deform and flatten
• Ice in the interior of the glacier moves forward like a plastic putty
As a glacier moves…Crevasses form
• cracks in the glacier due to increased speed often associated with a steep incline
What happens at the end of a glacier?
If the glacier is below the snowline…
ice front -the ice starts to melt, signifying the end of the glacier
What happens at the end of a glacier?
If the snowline is at sea level…
calving -large pieces of glacier break off of the front (icebergs!)
How do glaciers cause erosion?
Till -breaking down boulders, rocks, pebbles, and small grains into smaller pieces
Moraine -the accumulation of till
The Ransom Moraine is a
large moraine that
cuts diagonally
across Kendall County
Aftermath of glaciers
Striations -occur when the glacial load scratches parallel groves in the underlying bedrock
Roches mountonnees
a distinct pattern of rocks that are often exposed that bare a resemblance to a flock of sheep. “sheep rocks”
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