glaciers

• What is a glacier

  Layer of ice covering extensive track of land for a long period of time
• What is a glacial period

  A time when average temperatures drop to below 11
• When did the last galcial period peak

  22000 year ago
• What is an interglacial period

  Warmer temperature and a retreat of ice
• abrasion is glaciation

  1. held at bottom of glacier
  2. rocks and boulders held at base of glacier dragged over landscape to cause strikes
• plucking 


  melt water in the glacier freezes around rocks and as the ice moves it pulls up large large pieces of rock from valley wall or sides
• Glacial formation

  1. snow remains on the same area and compresses into ice
  2. Layers build up and compress
  3. compression forces the snow to recrystallise into grains size of sugar
  4. grains grow larger as air pockets between so the snow compacts and increases density
  5. After 2 winters snow turns to firn
• Accumulation


  Glacier ice forms as snow builds up layer upon layer
• Rotational slip 


  The weight causes snow to go downhill which rotates around and out of hollows
• basal flow 


  Meltwater at bottom helps ice move
• Ablation 


  At low land it’s warmer and glacier melts
• a corrie is an arm chair shaped hollow
• formation of corrie 


  snow accumulates in a nivitation hollow layers build up and it compresses into ice. Nivitation enlarges the hollow enabling more snow to collect which turns to ice. through rotational slip the glacier attract over snow leaving an over deepened hollow. Erosion is reduced at the front of the corrie due to ice being there so moraine is deposited and a lip forms
• arete - narrow knife edged ridge
• pyramidal peak - 3+ corries back to back
• arete e.g. crib goch in snowdonia and striding edge in cumbria
• pyramidal peak e.g. ben nevis in scotland
• glacial trough is a river valley widened by glacial erosion
• hanging valley is where a tributary river to a main glacier is too cold or too high up for ice to easily move so it wasnt eroded as much
• hanging valley generally form when glacier ice deeply erodes a main or trunk valley, leaving tributary valleys literally hanging far above the main valley floor.
• a ribbon lake is a long narrow lake where the glacier had more power to erode soft rock
• truncated spur is an old river valley spur thats being sliced off
• formation of a glacial trough

  1. river erodes down into its river bed
  2. a v shaped valley is formed
  3. snow accumulates for 1000s years
  4. plucking and abrasion deepen and widened the valley
  5. a wide flat bottomed valley is formed
• lateral moraine forms at the edge of the glacier it mostly consists of scree resulting from freeze thaw
• medial moraine forms when a tributary glacier join a main glacier and 2 lateral moraine merge they are ridges down the centre of the valley
• ground moraine is material deposited below a glacier and left behind when it melts
• terminal moraine forms when material piles up at the snout of the glacier and forms a ridge across the valley