arete

Arete is a geomorphological term describing a narrow, knife-edged crest that separates two or more glacial valleys or cirques. It is typically a long, slender ridge with a sharp crest and steep slopes on either side, formed by the differential erosion of rock between adjacent glacial valleys.

Formation and characteristics: An arete forms as glaciers erode parallel valleys or as frost wedging and plucking undermine opposite sides of a ridge. Through abrasion, weathering, and rock removal, the rock between the valleys is narrowed, leaving a narrow crest that can range from a few meters to tens of meters in width and rises hundreds of meters above the valley floors. The ridge is often highly rugged and prone to rockfalls due to its steep faces and exposed crest.

Association with other landforms: Aretes commonly flank cirques at the heads of glacial valleys. When three or more cirques erode a mountain from different sides, the remaining peak may become a horn, and a series of aretes can form a serrated ridgeline around a basin or saddle.

Etymology and usage: The term derives from the French arête, meaning edge or ridge. In other fields, arête (areté) refers to virtue or excellence in ancient Greek philosophy; this sense is separate from the geographic usage but shares the same linguistic root.

See also: cirque, horn, glaciation, ridges.