How are aretês made?

Answer 1

An arête is a thin, almost knife-like, ridge of rock which is typically formed when two glaciers erode parallel U-shaped valleys. The arête is a thin ridge of rock that is left separating the two valleys. Arêtes can also form when two glacial cirques erode towards one another, although frequently this results in a saddle-shaped pass, called a col. The word "arête" is actually French for fishbone; similar features in the Alps are described with the German equivalent term Grat or Kamm (comb).

Where three or more cirques meet, then a glacial horn or a pyramidal peak is created.

Notable examples of arêtes include:

Knife Edge, on Mount Katahdin, USA
Clouds Rest, in the Sierra Nevada, USA
The Minarets, in the Sierra Nevada, USA
The Garden Wall, in Glacier National Park (US) (image to right)
Crib Goch, in Snowdonia National Park, Wales
The Catwalk, in the Olympic National Park, USA