glacial erosion landforms

glacial erosion landforms

1. corrie

   • snow falls onto the slope where it accumulates
     • nivation acts on the hollow - freeze thaw under patches of snow - enlarges the hollow
       • snow falls - increases pressure.
         • back wall becomes steeper (plucking & freeze thaw) makes it jagged
           • the material abrades the floor of the hollow & rotational flow also deepens the corrie
             • thinner ice at the edge doesn't erode as much - rock lip forms
               • ice moves down slope - forms crevasses (extending flow) near the lip
                 • bergshrund forms at the back wall - extending flow
                   • after melt water forms a tarn

2. glacial valley (glacial trough or u shaped valley)

   • river cannot erode at the upper course - not enough energy - why interlocking spurs occur
     • glacier formed by accumulation (moves by basal sliding) has more energy to erode by abrasion, plucking & freeze thaw weathering
       • sides and base become deeper - removes the inter locking spurs
         • forms truncated spurs & a u shaped valley

3. hanging valley

   • smaller glacier erodes & joins to the larger glacier
     • different rates of erosion - smaller is slower - forms a hanging valley
       • same process as a glacial valley

4. arête and pyramidal peak

   • arête
     • 2 corries lie back to back and will leave a narrow steep sided ridge
   • pyramidal peak
     • 3+ corries develop on a mountain all back to back
       • may be sharp due to frost shattering

5. ribbon lake

   • over deepened valley floor creates a depression where a lake forms
     • that part of the valley floor has been eroded more due to ...
       • softer rock - easier to abrade
       • more compression due to more mass = more erosion
       • where tributary glaciers form = increase in mass = increase in erosion - peidmont

6. Roche moutonee

   • increase in pressure caused pressure melting point - regulation
     • abrades in direction of ice movement - smoother
       • reaches edge - no pressure = freezes
         • plucks the edge because it freezes
           • makes a jagged

7. crag & tail

   • e.g. Edinburgh
     • direction of ice movement = abrasion
       • softer rock is worn away
         • resistant rock is not eroded = crag
           • softer rock beyond that is not eroded due to cover from the resistant rock
             • this forms the tail