A corrie on Ben Lui in Scotland

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Robert Cunnings



Upland Glacial Features


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. It is known in Welsh as a cwm (often Anglicized as coomb, or coombe), and the French word cirque is used to denote a very similar geographical feature.

Corries begin as small hollows on a relatively smooth slope. During the ice ages, snow and ice would gather in these hollows, eroding the floor and walls of the hollow, causing them to get larger and deeper. As the hollows grew, so would it gather more snow and ice which would compact into a small glacier. Eventually, the newly formed glacier cut through the lowest edge of the hollow and continue down the hillside.

A corrie on  in Scotland

U shaped valley or glacial trough

They are generally found in glaciated uplands. They are characteristically steep-sided and flat-floored. Over-deepening of glacial troughs causes tributary valleys to hang above the main valley. Spurs are truncated, and the head of the valley often ends abruptly in a steep rock wall or trough head, for example the Lauterbrunnen Valley, Switzerland.

Glacial troughs are occupied by small valley glaciers in high mountain ranges such as the Alps and Himalayas today. However, it is unlikely that these glaciers were responsible for excavating glacial troughs. Most were probably cut by fast-flowing ice streams during periods of continental glaciation.

Pyramidal peaks

A pyramidal peak is a horn-shaped mountain summit. This horn is created by the deepening and expansive erosion of corries on three sides of the peak. Frost shattering creates a pyramidal peak’s jagged summit.

Ribbon lake

This is a long narrow lake occupying the floor of a glacial trough. Some ribbon lakes occupy depressions where intense glacial erosion has scoured the valley floor. Others have formed where recessional moraines have created a natural dam across the valley floor.


A nunatak is a mountain top that never has been covered by land ice (glaciation, ice age), of a mountain that is otherwise covered in ice. The wildlife on a nunatak can be isolated by the surrounding glacier, just like an island is in the ocean.

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An Arete is a thin, almost knife-like, ridge of . Aretes are typically formed when two  erode parallel U-shaped valleys. An arete is the thin ridge of rock that is left separating the two valleys. Aretes can also form when two glacial  erode towards one another, although frequently this results in a saddle-shaped pass, called a .


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