glacial erosional landforms

• Ice moves downhill due to gravity 

  • Rock beneath glacier moves with it 
• Rheid is a solid that can flow, glaciers move like a rheid. 

  • Stress applied quickly - ice fractures and forms crevasses 
  • Stress applied slowly due to weight of upper glacier - ice flows 
• To melt ice:

  • Increase temperature above 0 dc - affects surface 
  • Or increase pressure - called melting due to regelation 
  • Regelation creates a layer of meltwater at the base of the glacier 
• Glacier will move faster if:

  • Steeper valley floor 
  • Warmer air temperatures 
  • Lots of upstream ice 
  • Valley floor is smoothed by previous erosion 
  • Centre of glacier moves faster than edges 
• Valley sides subject to freeze-thaw weathering. 

  • Debris is poorly sorted, angular and coarse 
  • Scree slopes form 
  • Falls into sides of glacier - lateral moraine 
  • Incorporated into glacier by falling into crevasses, washing into channels made by meltwater or covered with snow that freezes into ice 
• Roche moutonees - plucking and striations from movement of glacier 
• Striations found in valley floors within polished rock. 
• Rocks at the base are abraded and turn into fine grained rock flour.
• U shaped valleys are steep sided and wide. 
• Truncated spurs - glacier erodes the interlocking spurs of a former fluvial landscape. 
• Hanging valleys are tributaries that are left behind as the glacier erodes the main river channel. 
• Lakes within u shaped valleys, depression in the landscape carved by a glacier. When the ice retreats the melt water cannot escape so is left as a lake. 
• Corries can also be called cwm or cirques. 

  • Armchair shaped hollows with steep headwall and a gentle or over deepened valley floor. 
  • Form from growth of mountainside hollow associated with earlier fluvial or mass movement. 
  • Snow accumulates in hollow and turns to ice 
  • Abrasion deepens hollow 
  • Material plucked away from headwall by ice or freeze thaw 
• Lake found in a corrie is called a tarn. 
• Most corries face towards the north or east. 

  • The northern sides of mountains receives less sun so snow builds up 
  • Western winds so snow blows into east facing hollows. 
• Aretes are the ridges separating two quarries where two headwalls meet. 

  • If three corries meet then it gets a horn peak 
• Crag and tail:

  • When glacier meets resistant rock it moves around it 
  • Softer rock protected by crag from main force of erosion 
• Glacial processes, especially erosional are not well understood, unlike fluvial, we cannot see it happening