ARÊTES AND MOUNTAIN GLACIERS

When I was researching my recent blog on “High Mountains Peaks,” I knew that such mountains are inherently associated with arêtes (pronounced “ah-rets), however, that glacial-geomorphic term is inexplicably seldom mentioned in any “on-line” remarks or literature.

The word arête (pleural arêtes) is a French term, meaning “fish bone,” in order to describe the sharp angular ridges with crests and divides in glaciated or formerly glaciated mountain areas. These crests and divides are jagged and look like serrations in a “saw blade.” In some cases, the crests can be spines (e.g., like the spectacular examples found in the glaciated areas of the Patagonia region in southern South America or in the Trango area of Pakistan). Arêtes are formed by the processes of erosion and freeze-thaw weathering, and they are especially evident in high-mountain glaciated areas and result from the continued backward growth of the walls of adjacent eroded valleys.

 An area that has been eroded by four coalescing mountain glaciers. All the sharp, jagged ridge lines (arêtes) associated with the glacier were caused by erosion. One of these arêtes is indicated on the figure above, which is based on (but modified) from fig. 14.11, on page 354, of  Hamblin, W.K. and E.H. Christiansen 1998. Earth’s dynamic systems. 8^th ed. Prenctice Hall, New Jersey, 740 pp.