Question Constellation Sign up for free AQA · GCSE · Geography · Higher
Glacial erosion and corrie formation
Explain how corries form as a result of glacial erosion.
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Marking points
- 1 Explains the initial snow/ice accumulation and movement sequence.
- 2 Explains glacial erosion processes such as plucking and abrasion.
- 3 Links processes to corrie features such as steep back wall, rock basin, rock lip or tarn.
Full-mark answer
Snow collects in a hollow on a mountainside and is compressed into glacier ice. The ice moves by rotational slip. Freeze-thaw weathering and plucking loosen rock from the back wall, making it steep, while debris in the ice abrades and deepens the hollow into a rock basin. Less erosion at the front leaves a rock lip, and when the ice melts a tarn may form behind it.
Why this answer loses marks
Abrasion, plucking and rotational slip.
Listing processes does not show the sequence from snow hollow to corrie basin.