Arête

An arête (/əˈrɛt/ ə-RET; French: [aʁɛt])[1] is a narrow ridge of rock that separates two valleys.

Arêtes can also form when two glacial cirques erode headwards towards one another, although frequently this results in a saddle-shaped pass, called a col.[2] The edge is then sharpened by freeze-thaw weathering, and the slope on either side of the arête steepened through mass wasting events and the erosion of exposed, unstable rock.

[3] The word arête is French for "edge" or "ridge"; similar features in the Alps are often described with the German equivalent term Grat.

A cleaver is a type of arête that separates a unified flow of glacial ice from its uphill side into two glaciers flanking, and flowing parallel to, the ridge, analogous to an exposed mid-channel bar in a braided river.

For example, following a cleaver up or down a mountain may avoid travelling on or under an unstable glacial, snow, or rock area.