Corrie
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- This article is about the geographical feature. For other uses, see Corrie (disambiguation).
In geography, a corrie is a terrain feature created by glaciation in high mountains. The word is an anglicisation of the Gaelic word coire meaning hollow. In Wales it is often known as a cwm (from Welsh, but with anglicised plural cwms, and often anglicised as coomb or coombe). The French word cirque is also used to denote a very similar geographical feature, though a difference is described below.
The formation of a corrie
Corries begin as small hollows on a relatively smooth slope.Snow accumulates in the north- and east-facing hollows. The snow is compacted into ice as air is compressed out, causing it to move downhill. Freeze-thaw weathering and plucking create a steep backwall. Rocks carried at the bottom of the ice erode the base of the hollow by abrasion to form a rock basin. Since the ice exerts a larger pressure over the deepest part of the hollow, rotational slip movement will occur, creating a more gently sloping rock lip, since the rate of erosion here is decreased. Over time, the height of the lip is increased by the deposition of moraine. The rock lip and moraine act as a dam behind which rain water may accumulate after the Ice Age, creating a corrie lake or tarn.
The difference between corrie and cirque
The corrie is geologically similar to the French cirque. However, where a corrie is an almost complete bowl beyond which the hill generally slopes quite steeply away, a cirque can also be found at the head of a deep, wide U-shaped valley with a relatively flat floor.Related glacial features
Two corries formed close to each other can erode the separating rock until it forms a knife-edged ridge known as an arête.When three or more corries are formed around the summit of a mountain, they can form a horn or pyramidal peak. In some cases, this peak will be made accessible by one or more arêtes. The Matterhorn in the European Alps is a fine example.
See also
- The Corries, a Scottish folk band named after the geographical feature
External links
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