how glaciers move

Question 1

basal slip

Answer 1

-temperate glaciers
- move around 2-3m a day
- pressure melting of ice at its base
-as a glacier moves, it exerts pressure, creating melting
-thin film of water between glacier and bedrock reduces friction

Question 2

regelation creep

Answer 2

-relevant in temperate glaciers where temps are above freezing
-melting and refreezing of ice due to pressure
- glacier encounters an obstacle, the pressure increases on the upstream side = melting
- pressure decreases on the downstream side = refreezing and glacier moves over the obstacle

Question 3

internal deformation

Answer 3

-polar and temperate glaciers
- moves 1-2cm a day
-inter-granular movements = indivdual ice crystals slip and slide over eachother
-intra-granular movement = individual ice crystals become deformed or fractures due to intense stresses within ice (exerted by glaciers mass under influence of gravity)
- gradually mass of ice deforms and moves downhill in response to gravity
-movement between or within individual grains of ice, slipping over each other, melting and recrystallising