Glacial Processes

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  • Created by: Junior
  • Created on: 04-05-13 09:47
what's the main way warm based glaciers move?
Basal sliding, meltwater underneath glacier reduces friction.
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What's the main way cold based glaciers move?
internal deformation, ice crystals shift past each other so ice bends and wraps to flow downhill
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What is extension flow?
strong gravitational force pulling ice downwards creates tension causing ice to fracture into thick layers slips downwards as ice expands.
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what is compressional flow?
high pressure causes ice to compress on shallow slope fracturing into layers which slop over one another.
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What three things determine the speed of a glacier?
The gradient - steeper valley faster flow, thickness - warm based think ice more pressure cold more internal deformation and the temperature - more meltwater.
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where are the fastest and slowest flows on a glacier and why?
Fastest: surface and middle of glacier. slowest: bottom and side of glacier, friction between ice and valley sides.
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What is a crevasse?
Deep cracks on top of glacier caused by stresses and strains (caused by extensional/compressional flow or tension between back wall and valley sides. deep as 45m, wide as 20m, several hundred meters long.
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What is a bergschrund?
large crevasse formed by tension as glacier pulls away from ice attached to back wall. (semicircular crevasse), over 100m deep, Lhotse face Mt Everest between camps 1 & 2, main source of meltwater.
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What is plucking?
ice contact with valley causes meltwater, refreezes around rocks and plucks rock away when valley moves forward. creates steep back wall
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What is Abrasion?
Subglacial debris grinds against valley floor and walls.
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What is weathering? (frost shattering)
AKA-freezethaw, meltwater gets in cracks in valley walls and expands as it freezes, exerts pressure on rocks, eventually breaks off.
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What three ways do glaciers transport debris?
supraglacial - on top, englacial - within the glacier - subglacial - along the base.
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what is the name of unsorted material deposited by a galcier?
Till or boulder clay, lodgement till spread beneath ice by moving glaciers. ablation till deposited mainly by snout as it melts b/c most ablation happens here.till points in flow direction, landforms called moraines.
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Card 2

Front

What's the main way cold based glaciers move?

Back

internal deformation, ice crystals shift past each other so ice bends and wraps to flow downhill

Card 3

Front

What is extension flow?

Back

Preview of the front of card 3

Card 4

Front

what is compressional flow?

Back

Preview of the front of card 4

Card 5

Front

What three things determine the speed of a glacier?

Back

Preview of the front of card 5
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