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Flashcards in How a glacier moves Deck (11)
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1
Q

Ice moving downhill

A
  • Doesn’t all behave the same way
  • Great rigidity and strength = pressure causes it to behave as a plastic body - mouldable
  • Sudden compression or tension = shear apart
2
Q

Pressure melting point

A

Temperature at which the ice is on the verge of melting

3
Q

PMP of a glacier

A
  • Slight increase in pressure = melting
  • 0 degrees on surface
  • Lower within glacier = increase in pressure by weight or movement of ice
4
Q

Warm ice (temperate)

A
  • 0 degrees throughout
  • Releases large amounts of meltwater = movement
  • Faster movement due to reduced friction
  • Basal flow, creep, extending/compressing flow or surge
  • Moraine produced by erosion of bed and deposition
5
Q

Cold ice (polar)

A
  • Permanently below 0 degrees
  • No meltwater
  • Moves slowly = frozen to bed
  • Internal flow
6
Q

Internal flow

A

Ice crystals orientate themselves in the direction of the glacier’s movement and slide past each other

  1. Jumbler of ice crystals
  2. Under pressure = ice crystals align
  3. Ice crystals can now slide past each other
7
Q

Where do glaciers move more rapidly?

A
  • Surface
  • Away from valley sides
  • Centre
8
Q

Influences on the rate of glacier movement

A
  • Temperate/polar
  • Gradient of valley floor
  • Time of year
  • Thickness of ice - thicker = faster
  • Geology - smooth rock = faster
  • Friction - more = slower
9
Q

Extending flow

A
  • Valley gradient is steeper
  • Ice accelerates = thinner
  • Reduced erosion
  • Occurs in zone of accumulation
10
Q

Compressing flow

A
  • Glacier moves downhill
  • Ice builds up = thicker = compresses
  • Occurs in zone of ablation
11
Q

Movement of ice is greatest when…?

A
  • At the point of equilibrium = greatest volume of ice passes and consequently where there is most energy available.
  • Areas with high precipitation and ablation
  • Small glaciers, which respond more readily to short-term climatic fluctuations
  • Temperate glaciers = more meltwater available
  • In areas with steep gradients