arête

A steep-sided arête in the Alps. The Alps were formed when the sea-bed was lifted up by the movement of tectonic plates, and were shaped by the movement of glaciers during the Ice Age.

An arête is a steep-sided ridge between two glacially-formed valleys, or corries. If three corries all erode towards the same point, a triangular arête may be formed.

The Llanberis Pass in Snowdonia National Park, north Wales, is typical of a U-shaped valley formed by glacial erosion. It runs for six miles southeast-northwest, from Pen-y-Pass down to the village of Llanberis at the head of Lake Padarn. Steep-sided corries hang above it, leading to the Snowdon arêtes, and in the valley bottom huge slabs of exposed rock show signs of glacial striation.

Sharp narrow ridge separating two glacial troughs (U-shaped valleys), or corries. They are formed by intense freeze–thaw weathering on the sides of mountains. The typical U-shaped cross-sections of glacial troughs give arêtes very steep sides. Arêtes are common in glaciated mountain regions such as the Rockies, the Himalayas, and the Alps. There are also several in the UK, for example Striding Edge and Swirral Edge in the English Lake District.