Which glacial process creates tarns within cirques after glacial retreat?

💡 Explanation

When glacial ice retreats from a cirque, differential erosion occurs because the base of the cirque is eroded at a faster rate through abrasion, undercutting and ice plucking, creating a depression in underlying bedrock that later fills with meltwater to form a tarn. Therefore differential erosion creates the tarn, rather than isostatic rebound, or moraine damming, or simply sediment compaction, which form landforms in different environments from those associated with cirques.

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