How a glacier moves Flashcards
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
- Jumbler of ice crystals
- Under pressure = ice crystals align
- 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
