Arete

An arete is a narrow ridge of rock that separates two valleys, typically formed when two glaciers erode parallel U shaped valleys on either side of it. An arete can also form where two glacial cirques erode headward toward each other, though that process more often produces a saddle shaped pass called a col. Once formed, the ridge is sharpened by freeze thaw weathering and steepened as unstable rock wastes away from its flanks. The name comes from the French word for edge or ridge, and the same kind of feature in the Alps is often called by its German name, Grat.