Cirque Formation

Cirque formation is the glacial erosional process that carves an amphitheatre-shaped hollow into a mountainside at the head of a valley, beginning where snow accumulates in a preexisting hollow and compacts into a small cirque glacier. Freeze-thaw weathering on the headwall feeds rock debris into the ice through bergschrund crevasses, and the glacier rotational movement over a rock basin deepens the floor by abrasion and plucking, steepens the headwall, and leaves behind a characteristic bowl with a raised lip once the ice retreats, often occupied afterward by a small tarn lake. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/