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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. They are widely distributed across Antarctica and are more narrow at depth as it is here that pieces of the glacier may rub and break against each other. 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 can be up to several hundred metres long.

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.

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 lubricate the bed and accelerate ice flow.

Types of crevasses[edit]

  • Transverse crevasses are the most common crevasse type and 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]
  • Splashing crevasses form as a result of shear stress from the margin of the glacier, and longitudinal compressing stress from lateral extension. They extend from the margin of the glacier 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.
  • 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-glacier, and form an angle greater than 45° with the margin.[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.

External links[edit]

  • Media related to Crevasse at Wikimedia Commons

Templates[edit]


Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Crevasse — Please support Wikipedia.
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7379 news items

Tignesnet.com

Tignesnet.com
Fri, 14 Aug 2015 02:56:15 -0700

Alarm calls went out yesterday afternoon as a number of people spotted a rope leading into a crevasse where a man had fallen, near the top of the Grande Motte glacier in Tignes. Thankfully the two men were roped together, as a snow bridge collapsed ...

Discovery News

Discovery News
Fri, 04 Sep 2015 06:52:30 -0700

“When that snow is frozen, you walk right across [the crevasse], but once it gets really hot, that snow bridge may not support you anymore,” Horner told Live Science. To beat the heat when beginning their ascent of Kahiltna Glacier, the researchers ...

ABC News

ABC News
Tue, 02 Jun 2015 13:37:30 -0700

A French man skiing in the Swiss Alps plummeted into a deep, snowy crevasse recently -- and his scary fall was captured on his helmet camera. "I thought I was going to die," Benjamin Spilthooren said in a translated interview, according to France 2 ...

Telegraph.co.uk

Telegraph.co.uk
Thu, 04 Jun 2015 04:37:30 -0700

French skier survives dramatic plunge into crevasse. Dramatic headcam footage shows skier trapped alone in crevasse for up to 20 minutes before being lifted to safety by strangers. By Charlotte Krol, video source Storyful / YouTube / Roland Spilthooren.

National Post

National Post
Fri, 04 Sep 2015 05:00:00 -0700

In a brief backstory we learn something of his relationship with his mentor, Terrance “Mugs” Stump (died from falling into a crevasse, 1992), and of his friendship with Alex Lowe (died in an avalanche, 1999), whose widow he later married. The mountain ...

Daily Mail

Daily Mail
Thu, 03 Sep 2015 04:25:25 -0700

Little puts off daring Sebastien Montaz-Rosset, who not only scales the narrowest peaks in the French Alps, but tackles them at a run. He has released terrifying GoPro footage of his runs over the Lac Blanc trail, which shows him scampering along it, ...

Telegraph.co.uk

Telegraph.co.uk
Mon, 08 Jun 2015 04:34:51 -0700

Last week, a video of Frenchman Benjamin Spilthooren skiing into a crevasse in the Swiss Alps before being rescued made headlines. He was luckily unharmed, but sounds fairly shaken up in the footage as he calls up for help – as is only to be expected.

WWL

WWL
Tue, 01 Sep 2015 20:33:45 -0700

CPRA Executive Director Kyle Graham says the state is still moving forward with its plans to build a diversion from scratch in that area, rather than doing anything to manage the existing crevasse. But he said that if the location near Mardi Gras Pass ...
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