Arete Formation

Arete formation is the glacial process that leaves behind a narrow, knife-edged mountain ridge where two cirques or glacial valleys erode headward from opposite sides of the same mountain mass, each steepening its own headwall until the intervening rock is reduced to a thin, jagged divide. Continued frost weathering on the exposed ridge crest sharpens it further after the ice retreats, producing the serrated skylines typical of heavily glaciated mountain ranges such as the Alps and the Rockies. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/