glacial erosion and depositional features
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Glacial Erosion and Depositional Features. How Do Glaciers Affect the Landscape?. Glacial Erosion. Glaciers remove loose rock from the valleys The flowing glacier pries rocks loose and incorporates them into the ice. Glacial Striations. Rocks scrape the underlying bedrock - PowerPoint PPT PresentationTRANSCRIPT
Glacial Erosion and Depositional Features
How Do Glaciers Affect the Landscape?
Glacial Erosion
• Glaciers remove loose rock from the valleys• The flowing glacier pries rocks loose and
incorporates them into the ice
Glacial Striations
• Rocks scrape the underlying bedrock• This picture was taken near Squamish 1997
Valley Shape
• Glaciers will carve out a U shaped valley
• A fjord is a U shaped valley filled in with water. It’s also called an inlet.
Fjords and InletsSognefjord, Norway
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
The glacier erodes
After the glacier melts
The Matterhorn
In the Swiss alps
• A Swiss glacier is eroding the mountain.
Glacier at work
Swiss Alps are glacially sculpted
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.
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.
Glacial Erratics
Estonia, Gulf of Finland. These rocks were carried and deposited by glaciers from Finland to Estonia
• Burnaby Mountain ParkGlacial Erratics
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
CL
Moraine dams the lake
• Banff National Park• The haze is from the
forest fires of 2003
Moraine Lake
• Bluest lake in the Rockies. The glacial till causes the light to be scattered leaving the lake very blue.
Peyto Lake
• End moraine of the Matanuska Glacier, Alaska. • Note the poorly sorted sediment; The boulders are
several meters in diameter.
End Moraine
• 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
Retreating Glacier
End moraine
The retreating Athabasca GlacierJasper National Park, Alberta
On the Athabasca GlacierGlaciers are full of dirt, and there are crevasses.
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.
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.
Kennicott Glacier, Alaska.
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