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Valley
glaciers erode
in two different ways, by plucking
and abrasion.
Plucking happens when materials are picked up by the moving
glacier and moved from the place that it has been for centuries.
The materials that are picked up by plucking are either laying
on the ground, or they are broken or fractured
off of the side of a mountain. These materials are pushed
along by the glacier and scrape big gouges and grooves on
the bedrock
that is below the soil. This is called abrasion. During abrasion
smaller particles act like large pieces of sand paper and
cause grooves to be carved into the land. The surfaces of
rocks are polished as the glacier moves across it.
Water
and glacial ice affect land in different ways. Rivers run
across the land and carve a valley in the shape of a deep
V. Valley glaciers follow the river bed and cut the deep V
into a smoother but larger U-shape as they move down the mountain.
The sides of the U-shaped valleys are much steeper and rugged
than when they were shaped by a river. The ice in a glacier
is much more destructive to the land than the running water
in rivers. |
