Glacial Erosion and Depositional Features
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Transcript of Glacial Erosion and Depositional Features
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Glacial Erosion and Depositional Features
How Do Glaciers Affect the Landscape?
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Glacial Erosion
• Glaciers remove loose rock from the valleys• The flowing glacier pries rocks loose and
incorporates them into the ice
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Glacial Striations
• Rocks scrape the underlying bedrock• This picture was taken near Squamish 1997
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Valley Shape
• Glaciers will carve out a U shaped valley
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• A fjord is a U shaped valley filled in with water. It’s also called an inlet.
Fjords and InletsSognefjord, Norway
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Erosional Features
• At the top of an alpine glacier a semicircular basin is carved out called a cirque
• When two cirques form on a peak the ridge separating them is called an arête
• Three or more cirques on a mountain can carve out a horn
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The glacier erodes
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After the glacier melts
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The Matterhorn
In the Swiss alps
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• A Swiss glacier is eroding the mountain.
Glacier at work
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Swiss Alps are glacially sculpted
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Glacial Deposits
• Glaciers pick up everything in its path, even the largest boulders.
• Large amounts of sediment can be carried large distances by glaciers.
• Glacial deposit is called till.
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Erratics
• Erratics are large boulders carried and then deposited by a glacier.
• It marks the furthest extent of the glacier.• Near 12th Avenue and 200th Street, Surrey.
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Glacial Erratics
Estonia, Gulf of Finland. These rocks were carried and deposited by glaciers from Finland to Estonia
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• Burnaby Mountain ParkGlacial Erratics
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Moraines
• A moraine is a mound or ridge of till deposited by a glacier
• The different places along a glacier’s advance will result in the different types of moraines
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CL
Moraine dams the lake
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• Banff National Park• The haze is from the
forest fires of 2003
Moraine Lake
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• Bluest lake in the Rockies. The glacial till causes the light to be scattered leaving the lake very blue.
Peyto Lake
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• End moraine of the Matanuska Glacier, Alaska. • Note the poorly sorted sediment; The boulders are
several meters in diameter.
End Moraine
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• The terminus of a glacier may remain stationary for years.• The sediment piles up in a ridge called an end moraine.• If this marks the furthest extent of the glacier it is a
terminal moraine.
Formation of end moraine
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Retreating Glacier
End moraine
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The retreating Athabasca GlacierJasper National Park, Alberta
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On the Athabasca GlacierGlaciers are full of dirt, and there are crevasses.
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Lateral Moraine
• Lateral moraines are accumulations of sediment on the margins of glaciers. • Rock slides, rock falls, snow avalanches and other forms of mass wasting are
especially efficient at loading the margins of the glacier with this material.
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Formation of a Medial Moraine
• The medial moraine forms where two tributary glaciers meet, and their adjacent lateral moraines merge to form the medial moraine.
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Kennicott Glacier, Alaska.
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Medial Moraine
At least how many tributary glaciers must there be to create this formation?
Three, because there are two medial moraines
• Switzerland, Aletsch Glacier in the Bernese Oberland