Glaciation

• What is a glacier

  a large mass of long-lasting ice formed by the recrystallization of snow
• Glacier as systems


  inputs ( precipitation, snow)

  stores (ice)

  flow (transfer)

  ouputs (evaporation, meltwater)
• accumulation zone


  input is greater than the output, more snow and ice entering than water leaving
• ablation zone


  output is greater than the input, more ice is lost in melting than snow falling
• freeze-thaw weathering

  • water fills crack in a rock
  • water freezes and the crack is made wider as the ice expands
  • the rock breaks into several pieces
  • the ice melts into water
  • this process repeats
• plucking

  • glacier sliding down valley creating pressure on sides and bottom
  • the heat melts small amounts of ice which creates water
  • water enters cracks in rock and freezes around loose particles
  • they are frozen onto the ice mass
  • glacier pulls it out the bedrock or the valley and is carried in the glacier
• abrasion

  • material being carried by the glacier rubs against the valley sides and bottom as glacier moves
  • this wears the rock away
  • similar to sandpaper