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glaciation (Formation of a corrie (Corrie is a bowl shaped depression on…
glaciation
Formation of a corrie
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Glacier moves downslope, making the hole deeper.
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Some rocks are deposited to form a rock lip and this acts a dam when the glacier melts and rainwater collects to form a tarn.
Glacial Trough
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The glacier erodes the rock and produces truncated spurs where the interlocking spurs have broken away.
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Ribbon lakes – long thin, glacial lakes. Found at the base of U shaped valleys. Areas of softer rock at the base of the valley are eroded more and produce lakes. Material is deposited at the end of the valley and dams to hold water in place.
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Glacial Deposition
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A glacier will drop its load when it loses energy: either moves to a flatter slope and so is not moving as quickly, or starts melting.
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Freeze Thaw Weathering – Link to erosion, rock fall and mass movement
Freeze thaw – water enters cracks in the rock, freezes, expands by 9% of its volume and puts pressure on the rock. Many repeats and rock will break.
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This process tends to happen at the sides of valleys. Rock may fall off and go underneath the glacier. Here, these rocks get dragged along by the glacier and are used as a ‘tool of abrasion’.
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Erratics
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When the glacier melts, they are dropped. An erratic will be placed on top of an area of rock that is not the same rock as the erratic.
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Drumlin Formation
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As the glacier loses energy, it drops till. This is because the friction with the ground and till becomes greater than with the ice and the till.
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Ice Sheet/Valley Glacier
Ice sheet is a very large glacier that covers a vast area. The key feature is that these ice sheets cover the top of the mountains. E.g. Antarctica.
Valley glaciers – These fill valleys that were at one time carved out by rivers. Places like Snowdonia and the Lake District were carved out by them. Still found in the Alps. Key is that they are held in place by the sides of the mountains.
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