
Upper Thornton Lake Cirque in North Cascades National Park, U.S.

A cirque (French: [siʁk]; from the Latin word circus) is an amphitheatre-like valley formed by glacial erosion. Alternative names for this landform are corrie (from Scottish Gaelic coire, meaning a pot or cauldron)[1] and cwm (Welsh for 'valley'; pronounced [kʊm]). A cirque may also be a similarly shaped landform arising from fluvial erosion.

The concave shape of a glacial cirque is open on the downhill side, while the cupped section is generally steep. Cliff-like slopes, down which ice and glaciated debris combine and converge, form the three or more higher sides. The floor of the cirque ends up bowl-shaped, as it is the complex convergence zone of combining ice flows from multiple directions and their accompanying rock burdens. Hence, it experiences somewhat greater erosion forces and is most often overdeepened below the level of the cirque's low-side outlet (stage) and its down-slope (backstage) valley. If the cirque is subject to seasonal melting, the floor of the cirque most often forms a tarn (small lake) behind a dam, which marks the downstream limit of the glacial overdeepening. The dam itself can be composed of moraine, glacial till, or a lip of the underlying bedrock.[2]

The fluvial cirque or makhtesh, found in karst landscapes, is formed by intermittent river flow cutting through layers of limestone and chalk leaving sheer cliffs. A common feature for all fluvial-erosion cirques is a terrain which includes erosion resistant upper structures overlying materials which are more easily eroded.


Formation of cirque and resulting tarn
Maritsa cirque in Rila Mountain, Bulgaria

Glacial-erosion cirque formation

Glacial cirques are found amongst mountain ranges throughout the world; 'classic' cirques are typically about one kilometer long and one kilometer wide. Situated high on a mountainside near the firn line, they are typically partially surrounded on three sides by steep cliffs. The highest cliff often is called a headwall. The fourth side forms the lip, threshold or sill,[3] the side at which the glacier flowed away from the cirque. Many glacial cirques contain tarns dammed by either till (debris) or a bedrock threshold. When enough snow accumulates it can flow out the opening of the bowl and form valley glaciers which may be several kilometers long.

Cirques form in conditions which are favorable; in the northern hemisphere the conditions include the north-east slope where they are protected from the majority of the sun's energy and from the prevailing winds. These areas are sheltered from heat, encouraging the accumulation of snow; if the accumulation of snow increases, the snow turns into glacial ice. The process of nivation follows, whereby a hollow in a slope may be enlarged by ice segregation weathering and glacial erosion. Ice segregation erodes the vertical rock face and causes it to disintegrate, which may result in an avalanche bringing down more snow and rock to add to the growing glacier.[4] Eventually, this hollow may become large enough that glacial erosion intensifies. The enlarging of this open ended concavity creates a larger leeward deposition zone, furthering the process of glaciation. Debris (or till) in the ice also may abrade the bed surface; should ice move down a slope it would have a ‘sandpaper effect’ on the bedrock beneath, on which it scrapes.



Lake Seal, Mt. Field National Park, Tasmania – a cirque formed from a glacier is visible in the walls around Lake Seal[6]


Where cirques form one behind the other, a cirque stairway results as at the Zastler Loch in the Black Forest.


Fluvial-erosion cirque formation

Although a less common usage,[nb 1] the term cirque is also used for amphitheatre-shaped, fluvial-erosion features. For example, an approximately 200 square kilometres (77 sq mi) anticlinal erosion cirque is at 30°35′N 34°45′E﻿ / ﻿30.583°N 34.750°E﻿ / 30.583; 34.750﻿ (Negev anticlinal erosion cirque) on the southern boundary of the Negev highlands. This erosional cirque or makhtesh was formed by intermittent river flow in the Makhtesh Ramon cutting through layers of limestone and chalk, resulting in cirque walls with a sheer 200 metres (660 ft) drop.[8] The Cirque du Bout du Monde is another such feature, created in karst terraine in the Burgundy region of the department of Côte-d'Or in France.



The Western Cwm with the Lhotse face of Mount Everest in the background

Notable cirques

Tuckerman Ravine cirque, headwall and spring skiers, New Hampshire

See also





  1. ^ Chisholm, Hugh, ed. (1911). "Corrie" . Encyclopædia Britannica. Vol. 7 (11th ed.). Cambridge University Press. p. 196.
  2. ^ Knight, Peter G. (2009). "Cirques". Encyclopedia of Earth Sciences Series: Encyclopedia of Paleoclimatology and Ancient Environments. Cirques. Vol. 1358. Springer Netherlands: . pp. 155–56. doi:10.1007/978-1-4020-4411-3_37. ISBN 978-1-4020-4551-6.
  3. ^ Evans, I.S. (1971). "8.11(i) The geomorphology and Morphometry of Glacial and Nival Areas". In Chorley R.J. & Carson M.A. (ed.). Introduction to fluvial processes. University paperbacks. Vol. 407. Routledge. p. 218. ISBN 978-0-416-68820-7. Retrieved 2010-01-24.
  4. ^ a b Johnny W. Sanders; Kurt M. Cuffey; Jeffrey R. Moore; Kelly R. MacGregor; Jeffrey L. Kavanaugh (2012). "Periglacial weathering and headwall erosion in cirque glacier bergschrunds". Geology. 40 (9): 779–782. Bibcode:2012Geo....40..779S. doi:10.1130/G33330.1. S2CID 128580365.
  5. ^ Rempel, A.W.; Wettlaufer, J.S.; Worster, M.G. (2001). "Interfacial Premelting and the Thermomolecular Force: Thermodynamic Buoyancy". Physical Review Letters. 87 (8): 088501. Bibcode:2001PhRvL..87h8501R. doi:10.1103/PhysRevLett.87.088501. PMID 11497990. S2CID 10308635.
  6. ^ "Mt Field National Park: Landforms, Flora and Fauna". Parks and Wildlife Service Tasmania. Archived from the original on 2011-06-09. Retrieved 2009-05-12.
  7. ^ Barr, I.D.; Spagnolo, M. (2015). "Glacial cirques as palaeoenvironmental indicators: Their potential and limitations". Earth-Science Reviews. 151: 48. Bibcode:2015ESRv..151...48B. doi:10.1016/j.earscirev.2015.10.004.
  8. ^ Distinguishing signal from noise: Long-term studies of vegetation in Makhtesh Ramon erosion cirque, Negev desert, Israel ; David Ward, David Saltz and Linda Olsvig-Whittaker; Plant Ecology, 2000, Volume 150, Numbers 1–2, pp. 27–36
  10. ^ John O'Dwyer. "Go Walk: Coumshingaun, Co Waterford". The Irish Times.

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