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Crevasse is also a traditional term for a levee breach.

A crevasse is a deep crack, or fracture, found in an ice sheet or glacier, as opposed to a crevice that forms in rock. Crevasses form as a result of the movement and resulting stress associated with the shear stress generated when two semi-rigid pieces above a plastic substrate have different rates of movement. The resulting intensity of the shear stress causes a breakage along the faces.

Description[edit]

Crevasses often have vertical or near-vertical walls, which can then melt and create seracs, arches, and other ice formations.[1] These walls sometimes expose layers that represent the glacier's stratigraphy. Crevasse size often depends upon the amount of liquid water present in the glacier. A crevasse may be as deep as 45 metres, as wide as 20 metres, and up to several hundred metres long.[citation needed]

A crevasse may be covered, but not necessarily filled, by a snow bridge made of the previous years' accumulation and snow drifts. The result is that crevasses are rendered invisible, and thus potentially lethal to anyone attempting to navigate their way across a glacier. Occasionally a snow bridge over an old crevasse may begin to sag, providing some landscape relief, but this cannot be relied upon. Anyone planning to travel on a glacier should be trained in crevasse rescue.[citation needed]

The presence of water in a crevasse can significantly increase its penetration. Water-filled crevasses may reach the bottom of glaciers or ice sheets and provide a direct hydrologic connection between the surface, where significant summer melting occurs, and the bed of the glacier, where additional water may moisten and lubricate the bed and accelerate ice flow.[citation needed]

Types of crevasses[edit]

  • Longitudinal crevasses form parallel to flow where the glacier width is expanding. They develop in areas of tensile stress, such as where a valley widens or bends. They are typically concave down and form an angle greater than 45° with the margin.[2]
  • Splashing crevasses result from shear stress from the margin of the glacier and longitudinal compressing stress from lateral extension. They extend from the glacier's margin and are concave up with respect to glacier flow, making an angle less than 45° with the margin. At the centre line of the glacier, there is zero pure shear from the margins, so this area is typically crevasse-free.[citation needed]
  • Transverse crevasses are the most common crevasse type. They form in a zone of longitudinal extension where the principal stresses are parallel to the direction of glacier flow, creating extensional tensile stress. These crevasses stretch across the glacier transverse to the flow direction, or cross-glacier. They generally form where a valley becomes steeper.[2]

Gallery[edit]

Crevasses around the world
Crevasse on the Gorner Glacier, Zermatt, Switzerland 
Measuring snowpack in a crevasse on the Easton Glacier, Mount Baker, North Cascades, United States 
Exploring the bottom of a crevasse in Antarctica 
Crevasse on the Ross Ice Shelf, January 2001 
Crevasses on the Upper Price Glacier of Mt. Shuksan, North Cascades, WA. Photo taken August 2011 
Split-boarder skiing up past open crevasses on the Coleman Glacier of Mt. Baker. Photo taken October 2009 
Looking down into a crevasse on Mt. Rainier, Cascade range, WA. Photo taken Mid August 2009 
Crevasses on Mt. Rainier. Photo taken from the Disappointment Cleaver Route on Mt. Rainier. Photo taken August 2009 
Mountaineers crossing a crevasse on Mt. Rainier. Photo taken August 2009 
Ladder bridging a crevasse on Mt. Rainier. Photo taken Aug. 2009 

See also[edit]

References[edit]

  1. ^ van der Veen, C (1990). "Crevasses on Glaciers". Polar Geography 23 (3): 213–245. doi:10.1080/10889379909377677. 
  2. ^ a b Holdsworth, G (October 1956). "Primary Transverse Crevasses". Journal of Glaciology 8 (52): 107–129. 

Bibliography[edit]

  • Paterson, W.S.B., 1994, The Physics of Glaciers, 3rd edition, ISBN 0-7506-4742-6.
  • Boon, S., M.J. Sharp, 2003, The role of hydrologically-driven ice fracture in drainage system evolution on an Arctic glacier, Geophysical Research Letters, 30, pp. 1916.
  • van der Veen, C.J., 1998, Fracture mechanics approach to penetration of surface crevasses on glaciers, Cold Regions Science and Technology, 27, pp. 31–47.
  • Zwally, H.J., W. Abdalati, T. Herring, K. Larson, J. Saba, K. Steffen, 2002, Surface melt-induced acceleration of Greenland ice-sheet flow, Science, 297, pp. 218–222.
  • Mountaineering: The Freedom of the Hills, 5th edition. ISBN 0-89886-309-0.
  • "Crevasse." Encyclopædia Britannica. 2010. Encyclopædia Britannica Online. 17 Oct. 2010.
  • Das, S. B., I. Joughin, M.D. Behn, I.M. Howat, M.A. King, D. Lizarralde, M.P. Bhatia, 2008, Fracture propagation to the base of the Greenland Ice Sheet during supraglacial lake drainage, Science, 320, pp. 778.
  • Colgan, W., H. Rajaram, W. Abdalati, C. McCutchan, R. Mottram, M. S. Moussavi, and S. Grigsby (2016), Glacier crevasses: Observations, models, and mass balance implications, Rev. Geophys., 54, doi: 10.1002/2015RG000504

External links[edit]

  • Media related to Crevasses at Wikimedia Commons

Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Crevasse — Please support Wikipedia.
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19675 news items

Evening Standard

Evening Standard
Wed, 20 Apr 2016 00:07:30 -0700

The body of a British backpacker missing for two weeks has been found at the bottom of a crevasse in the Peruvian Andes. The family of Harry Greaves, 28, launched an appeal to find him after he went missing while hiking in the mountains. The furniture ...

Chamonet.com

Chamonet.com
Tue, 05 Apr 2016 01:48:29 -0700

Two Italian skiers were descending from the Grands Mulets above the Glacier des Bossons yesterday morning at around 9am, when one of them fell into a crevasse. Thankfully the two men were roped together, the second man managed to stop his friend ...

Ouest-France

Ouest-France
Wed, 27 Apr 2016 06:41:15 -0700

Deux Européens meurent en tombant dans une crevasse. Népal - Publié le 27/04/2016 à 15:50. écouter. Deux alpinistes, un Suisse et un Autrichien, sont morts après avoir chuté dans une crevasse lors de l'ascension du Shisha Pangma, un sommet de ...

Villages-News

Villages-News
Mon, 02 May 2016 12:41:15 -0700

A third party, PSI Orlando, is preparing the analysis of the soil borings. The study was called for after a significant “event” occurred more than two years ago at the northeast corner of the island, said District officials. In that event, trees fell ...

Le Matin Online

Le Matin Online
Sun, 17 Apr 2016 14:47:58 -0700

Vers 12h30, deux randonneurs à ski d'un groupe de six personnes ont fait une chute dans une crevasse au glacier du Théodule. L'une d'elles a été blessée. Elle a été héliportée par Air-Zermatt au CHUV à Lausanne où elle est décédée. Cette intervention ...

Seeker (registration) (blog)

Seeker (registration) (blog)
Sun, 01 May 2016 18:30:00 -0700

... Statistics highlighted on Arnette's site shows that 36 people died climbing the North Ridge route over one decade, while 15 died attempting the South Col route. Altitude is the No. 1 cause of death on the north side, whereas falling into a crevasse ...

NDTV

NDTV
Tue, 01 Mar 2016 23:35:16 -0800

“After locating the body, rescue teams moved inside the crevasse and anchored it to the ice wall to prevent it from further slipping down. The opening and gap of the narrow crevasse was also widened to retrieve the body intact,” said a statement by the ...

Le Nouvelliste

Le Nouvelliste
Sun, 10 Apr 2016 13:26:15 -0700

Vers 12h15, l'un des snowbordeurs a quitté la piste sécurisée. Il a fait une chute d'environ 25 mètres dans une crevasse, en dehors du domaine skiable. Acheminés sur place par un hélicoptère d'Air Zermatt, les secouristes n'ont pu que constater son décès.
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