1c.Movement

Question 1

Cold based (polar) glaciers

Answer 1

• High latitude
• Low relief
• Basal temp below pressure melting point (temp at which ice is on the verge of melting). (frozen to bedrock)
• Slow movement (few metres / year)
• Move via internal deformation

-Glaciers not very active, little seasonal differences

Question 2

Warm based (temperate) glaciers

Answer 2

• High altitude
• Steep relief
• Basal temps above pressure melting point (temp at which ice is on the verge of melting)
• Mainly move by basal sliding
• Rapid movement (20-200m / year)

-Glaciers are very active with significant seasonal advance

Question 3

Basal sliding

Answer 3

-Glaciers move due to temps at base
Consist of
-Slippage: ice slides due to less friction from melt water
-Creep / regelation: ice deforms under pressure due to obstructions (ice spreads over obstacle)
-Bed deformation: ice carried by saturated bed sediments (reduce friction)

Question 4

Internal deformation

Answer 4

• Response of ice gains to pressure
• Increased thickness and angle = more deformation
• Intergranular flow (ice crystals move independently
• Laminar flow (individual layers in glacier move)
• Occur on slopes

Question 5

Crevasses

Answer 5

• Crevasses form when ice cant deform quick over steep slope

- Common in upper parts of glacier

Question 6

Extending & compressing flow

Answer 6

• Change in gradient
• Steep: velocity increases, ice becomes thinner when stretched
• Reduced gradient: velocity falls, ice rams into each other, compression, thick ice

Question 7

Surgeing

Answer 7

• Rapid movement
• Large level of inputs
• Phase of accelerated flow