An arête is a sharp, narrow ridge formed between two glacial valleys or cirques. It is typically created by the erosion of glaciers that carve out the sides of a mountain, leaving a steep, knife-edge ridge. Arêtes are common in alpine regions and are significant in understanding the processes of glacial erosion and mountain geomorphology.
Reference: Benn, D. I., & Evans, D. J. A. (2010). Glaciers and Glaciation. Routledge.