Glacial erosional landforms

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A-Levels Glaciation Mind Map on Glacial erosional landforms, created by EmmaSmile on 06/05/2013.
EmmaSmile
Mind Map by EmmaSmile, updated more than 1 year ago
EmmaSmile
Created by EmmaSmile over 11 years ago
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Resource summary

Glacial erosional landforms
  1. Cirques
    1. Armchair shaped hollow, steep back wall of angle 60 degrees.
      1. Hollow itself is often overdeepened, characterised by rock lip. Hollow may contain a tarn.
        1. Red Tarn, Lake District
        2. Examples: Cwm Idwal, Snowdonia.
          1. Formation
            1. Early stages of glaciation
              1. Corrie formation begins with enlargement of small hollow on hillside. Where snow accumulates year on year in small hollow, nivation processes operate, enlarging hollow and creating embryo corrie. As snow continues to accumulate, firn ice created. Eventually compressed to form true glacial ice.
                1. During glaciation
                  1. Once critical depth of ice reached, ice moves through hollow in rotational manner, enlarging the hollow. Back wall is steepened through plucking and frost-shattering and base of corrie overdeepened by abrasion.
                    1. Abrasion is facilitated by frost shattered material from back wall falling down Bergschrund crevasse at back. The thinner ice at front has less erosive power and rock lip develops at threshold of corrie.
                      1. Lip of corrie may be heightened further by deposition of moraine as ice moves out of the glacier.
                        1. Post glacial
                          1. Once ice retreated, corrie basin may become filled with water creating a tarn lake.
          2. Arete
            1. Steep knife-edged ridge which separates two corries or troughs.
              1. Example - Striding Edge, Lake District
                1. As two corries erode back to back, erosion of headwalls due to plucking and abasion results in formation of knife-shaped ridge between the two corries.
                2. Pyramidal peak
                  1. An angular glaciated mountain peak with three or more steep sides - usually back of corries.
                    1. Each side is separated by a sharp knife-edged ridge known as an arete
                    2. The Matterhorn (Swiss Alps)
                      1. Form when three or more cores around a mountain top have eroded. Their headwalls have retreated towards each other. The remaining mass between the cores is steepened, forming a pyramidal peak
                        1. The peak may be very sharp looking due to the action of frost shattering
                      2. Diffluence Col
                        1. A lower area of an arete or pass which breaches the watershed
                          1. This is where a large accumulation of ice, overspills into adjacent corrie, eroding a ''col' in the headwall, lowest part of arete
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