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Plucking melt water at the base, back or sides of the glacier freezes onto rock. Glacier moves
forwards and pulls pieces of rock out
Abrasion bits of rock stuck in the ice grind against the rock below the glacier, wearing it away (like
Top of glacier ice does not move in a straight line, it moves in a circular motion (rotational slip.)
Freeze-thaw weathering water gets into cracks of rock. Freezes and expands, putting pressure on
the rock. Ice thaws, releasing pressure.
Arête Formed when two glaciers flow in parallel valleys. Glaciers erode the side of the valleys
which sharpens the ridge
Pyramidal Peak Three of more glaciers are back to back and erode the mountain
Corries Ice moves by rotational slip, erodes the hollow into a steep sided arm chair shape with a lip
at the bottom end. Ice melts leaving small lake called a tarn
Truncated spurs Ridges of land stick out into the main valley and are cut off as the glacier moves
Ribbon Lakes Form after a glacier retreats. They form in hollows where softer rock is eroded more
than the surrounding harder rock
Hanging valleys Smaller glaciers flow into the main glacier. The glacial trough is eroded much more
deeply by the larger glacier
Glacial troughs (U shaped valley) - Start off as V-shaped but turn into U shaped as the glacier erodes
the sides and the bottom making it deeper and wider
Formation of moraine
Moraine contains material of different shapes and sizes due to the way ice transports. It results from
deposition and is produced by freeze-thaw weathering, plucking and abrasion.
There are 4 types of moraine:
Lateral moraine side of the glacier
Medial moraine centre of the valley where two glaciers meet (two lateral moraines join
Terminal moraine builds up at the snout of the glacier.
Ground moraine thin layer of material deposited over a large area as the glacier melts
Drumlins Elongated hills of glacial deposited. Round, blunt and steep at the upstream end.