A cirque is an amphitheatre-like valley (or valley head) of glacial origin, formed by glacial erosion at the head of the glacier. Cirques are typically partially surrounded by steep cliffs. The highest cliff is often called a headwall. They are also known as a cwm in Wales, a coomb in England and a corrie in Scotland and Ireland.

Many glacial cirques contain tarns dammed by glacial till. Cirques form in conditions which are favorable; which in the northern hemisphere includes the north-east slope being in shade and away from prevailing winds. These areas are sheltered from heat, and so, they encourage the accumulation of snow.

Formation

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Cirques form in conditions which are favorable for glacier formation - where snow can accumulate into a thick and large mass.

If the accumulation of snow increase, the snow would transform into glacial ice. The process of nivation follows (where a hollow in a slope may be enlarged by freeze-thaw weathering and glacial erosion). Eventually, this hollow would become big enough so that glacial erosion would be intensified. Debris (or till) in the ice may also abrade (glacial abrasion) the bed surface; should ice move down a slope it would have a ‘sandpaper effect’ on the bedrock beneath on which it scrapes.

If two adjacent cirques erode toward one another, an arete, or steep sided ridge, forms.
Should three or more cirques erode toward one another, a pyramidal peak or glacial horn would be created.

Notable cirques

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• Iceberg Cirque, Montana, United States
• Cirque de Navacelles, France
• Cirque of the Towers, Wyoming, United States
• Tuckerman Ravine, New Hampshire, United States
• Śnieżne Kotły, Karkonosze Mountains, Poland

Landforms | Glaciology

Kar | Kar (Talform) | Circo glaciar | Tsirkusorg | Cirque naturel | 圏谷 | Cyrk lodowcowy