Ice movement in glaciers

  • Created by: darcie_cl
  • Created on: 25-02-14 12:55
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  • Ice movement in glaciers
      • Normal stresses = weight down to the ground
      • Sheer stress = due to angle of slope
      • Movement is driven by gravity and resisted by friction
      • More movement with greater accumulation as there is greater weight
    • INTERNAL DEFORMATION (ice creep)
      • Slow creep of ice due to slippage within and between ice crystals - greatest at base where pressure is at its maximum
      • Often creates crevasses within the glacier or at ice surface
      • Type 1; INTERGRANULAR = grains slip over one another (lead shot pile)
      • Type 2; INTRAGRANULAR = within a single grain of ice, stresses causes deformation along parallel lines
      • The sliding of a glacier over its rocky base
      • Sliding is accomplished in 3 ways
        • BASAL SLIP = thin layer of water builds up at ice-rock interface and the reduction in friction enables ice to slide forward
        • ENHANCED BASAL CREEP = ice squeezes up against a wide bedrock obstacle, the increased pressure causes the ie to deform around the feature
        • REGULATION SLIP = ice presses up to a small bedrock obstacle - ice melts and refreezes on the lee side where pressure is less
      • A glacier moves over weak or unconsolidated sediment instead of hard rock
      • Sediment itself can deform, moving the ice along with it
      • Sediment is like jelly being forced into another area by the pressure and weight of the sliding ice
      • Thickness of ice - thick glaciers flow slower
      • Temperature of ice - warmer glaciers flow faster because they are more able to deform
      • Bedrock - more rapid movement over easily deformable rocks (clay, shale)
      • Gradient - steep gradients flow faster


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