Crag and tail

A crag (sometimes spelled cragg, or in Scotland craig) is a rocky hill or mountain, generally isolated from other high ground.

The Abbey Craig, a crag with tail near the University of Stirling. The Wallace Monument stands on the crag at the right, and the long tail slopes down leftward
Salisbury Crags to the left and Arthur's Seat to the right, with their tails sloping east to the right.

Origin

Crags are formed when a glacier or ice sheet passes over an area that contains a particularly resistant rock formation (often granite, a volcanic plug or some other volcanic structure). The force of the glacier erodes the surrounding softer material, leaving the rocky block protruding from the surrounding terrain. Frequently the crag serves as a partial shelter to softer material in the wake of the glacier, which remains as a gradual fan or ridge forming a tapered ramp (called the tail) up the leeward side of the crag.[1]

In older examples, or those latterly surrounded by the sea, the tail is often missing, having been removed by post-glacial erosion.

Examples

Examples of crag and tail formations include:

See also

References
  1. Chamber's Encyclopædia: A Dictionary of Universal Knowledge. Vol. 3. W.R.Chambers. 1897. p. 541. Retrieved 2019-11-03.
  2. Nitsche, F. O.; Larter, R. D.; Gohl, K.; Graham, A. G. C.; Kuhn, G. (2016). "Crag-and-tail features on the Amundsen Sea continental shelf, West Antarctica" (PDF). Geological Society, London, Memoirs. Geological Society of London. 46 (1): 199–200. doi:10.1144/m46.2. ISSN 0435-4052. S2CID 133161379.
  • Holmes, Arthur, Principles of Physical Geology, Halsted, 1978, 3rd ed., pp 421 – 422 ISBN 0-471-07251-6
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