Wednesday 16 April 2008

Glaciation


Definitions:
Abrasion - A glacial erosion process. When blocks of rock debris are trapped on the underside of a glacier and then, as the glacier moves, this has a sand paper effectwearing away the base and sides of the valley.
Arete - a knife edge ridge that separates two corries e.g. Striding Edge
Corrie - an arm chair shaped depression formed on the side of a mountain e.g. Red Tarn
Frost shattering - a weathering process. Water gets into cracks in the rock. When the tempreature drops beloow zero, the water freezes and expands exerting pressure on the sides of the crack. Eventually the crack is widened and the rock disintegrates.
Glacial trough - U - shaped valley which has been widened and deepened by a valley glacier e.g. Patterdale
Glacier - a mass of moving ice
Plucking - A glacial erosion process. Water enters cracks in the rock and freezes so that it is attached to both the rock and the glacier. When the glacier moves, the block of rock is pulled out of the ground.
Ribbon Lake - a long thin, deep lake on the floor of a glacial trough e.g. Thirlmere

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