Action of Glacier Erosion
The action of glacier is an important agent of erosion, transportation and deposition of materials that is confined on mountainous and temperate regions of the world.
Ways of carrying out action of Glacier
The action of glacier is carried out in the following ways:
- Sapping: It is the breaking up of rocks of alternate freezing and thawing of water at the bottom of cracks between a mass of ice and ides and floor of a valley or the sides of a mountain
- Plucking: It is the tearing away of blocks of rocks which have become frozen on the sides or bottom of a glacier
- Abrasion: is the wearing away of rocks beneath a glacier by the scouring action of the rocks embedded in the glacier
Features of Glacier Erosion in the Highland Areas:
Striations: are scratches or marks left on rock over which glacier passes. Rock fragments or mountain embedded in the glacier affect the striation of rocks
Corries or Cirque: is a deep and rounded hollow or depression with steep sides, formed through erosion by ice. They are arm – chair shaped hollows, resulting from plucking of rock materials down the slope. After the ice has moved, it later forms corrie lake
Arete: occur when two corries cut back opposite side of the same mountain. Resulting in a knife edge ridge called arête. Arête is therefore a wall ridge like structure separating two corries
Pyramidal peak: occurs where three or more corrie cut back on the same mountain. A pinnacle shaped like like pyramid, develops and is called pyramidal peak
Bergshrund: is formed at or near head of glacier. It is a deep and vertical crack separating the lower part of a glacier that has started to move down its valley and the upper part which is static.
U- Shaped Valley or Trough: is a wide flat floor with very steep side which has been eroded by glacier. All the sides and floor including all debris are washed away by glacier. This results in the formation of a U- shaped valley which forms the main valley
Hanging Valley: results when glacier action from tributaries eroded materials into the main or U shaped Valley.
Rock Basin and Rock Step: when two tributaries join a main valley, the additional weight of ice in the main valley cuts deeper into the valley floor at the point of convergence, thus forming a rock step. It can also be formed due to the difficulties in resistance to frost action. Rock basin is formed when glacier erodes and excavates the valley floor so deep to form rock basin
Moraines: are made up of rocks that are shattered by frost action, embedded in the glacier and brought down the valley. Moraines exist in lateral, medial ground and in terminal forms
For more notes; see: https://passnownow.com/classwork-support/
