(5) erosional landforms

• explain the features of a corrie

  • confined to a armchair or bowl shaped depression, with a steep back wall, over-deepened basin and rock lip
  • high altitude and sheltered location, most favourable for snow accumulation
  • can become a source of glacier ice
  • vary in size and shape
• explain the formation of a corrie

  • snow accumulated
  • as layers of snow build up, lower levels are compressed into the ice and the mass begins to move downhill
  • freeze-thaw weathering makes the peak jagged
  • rotational movement means base of the corrie is eroded by abrasion
  • plucking steepens back wall
  • freeze-thaw weathering and plucking leave a pyramidal peak
  • over-deepening of the corrie base leaves a depression that fills with water called a tarn
  • upward movement of the ice at the corrie exit reduces abrasion to leave behind a lip, made bigger by moraine as the glacier disappears
• what is a tarn


  a roughly circular lake formed in a corrie after a glacier has retreated
• explain the features of aretes


  a steep, knife-edges ridge produced from the intersection of two corries on either side of a slope divide
• explain the formation of aretes


  when two neighbouring corries run back to back. As each glacier erodes either side of the ridge, the edge becomes steeper and the ridge becomes narrower.
• explain the formation of pyramidal peaks


  if three or more corries intersect back to back around the sides of a mountain, a steep, narrow peak is produced between them. weathering may further sharpen the peak.
• glacial trough

  • steep sided valley with flat bottom
  • formed by the erosion of a former v-shaped river valley
  • glacier movement makes the v-shaped valley deeper and wider
• rock steps

  • steps in the glacial trough
  • formed when the glacier erodes the valley floor more deeply
  • happens when another glacier joins it or when theres less resistant rock
  • also formed by extending and compressing flow
• truncated spurs formation

  form when ridges of land that stick out into the main valley are chopped off as the glacier bulldozes through
• hanging valley formation

  valleys formed by tributary glaciers - they erode the valley floor much less deeply because they are smaller than the main glacier. when glaciers melt, the valleys get left at a higher level than the glacial trough formed by the main glacier. waterfalls may also be from from hanging valleys in the glacial trough
• ribbon lake formation

  long, thin lakes that form as a glacier retreats. they form in dips caused by erosion of bands of less resistant rock or behind dams of debris left by the glacier
• fjord formation

  long, deep inlets that form when a valley that's been eroded by a glacier is flooded by sea level rise after the ice has melted
• roche moutonee formation

  on the stoss (upward) slope, abrasion from the moving glacier occurs, leaving striations, grooves and polishing effects

  on the lee (downward) side, plucking and freeze-thaw weathering creates a jagged, uneven surface.
• what are striations

  scratches or gouges cut into bedrock by glacial abrasion. they represent the movement of the glacier using rock fragments or sand grains embedded in the base of the glacier by plucking.
• misfit stream formation

  glaciation creates a glacial trough. after glaciation, the rivers that occupy such valleys after the ice has retreated are not in proportion with the size of the valley
• ellipsoidal basin formation

  a former river valley which has been both widened and deepened from subglacial activity beneath an ice sheet.