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Crevasse is also a traditional term for a levee breach.

A crevasse is a deep crack in an ice sheet or glacier, as opposed to a crevice, which 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 normal 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 compressing 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.
This page uses Creative Commons Licensed content from Wikipedia. A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia.
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Inside a crevasse on Mt. Rainier's Nisqually Glacier

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mike falls in crevasse

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Climber films 20m crevasse fall in Himalayas - BBC News

Watch this dramatic video as seriously injured US climber John All struggles to survive after falling 70 feet (20m) into a crevasse in the Himalayas. He brok...

Skier Falls into Crevasse - Hangs by one toepiece

Ben Ditto falls into a crevasse in Alaska and is saved by his Dynafit toepiece!

Extreme Snowboarder falls into Crevasse

After a morning of powder Brad managed to find a small Crevasse in the mountains of Japan.

Crevasse Rescue

A practical demonstration of crevasse rescue using an unassisted hoist. Taken from the Mountaineering Council of Scotland's Alpine Essentials DVD. Full DVD a...

Programa "I Shouldn't Be Alive" (Sobreviví), Episodio "Killer Crevasse" (Discovery Channel)

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2 Person Rope Team Crevasse Rescue

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Himlung Crevasse Fall 01

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The Crevasse - Making of 3D Street Art

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74261 videos foundNext > 

16663 news items

NOLA.com

NOLA.com
Wed, 17 Dec 2014 07:33:45 -0800

"Crevasse 22," is a picturesque exhibit of outdoor sculpture by 10 New Orleans artists arranged beside a placid lake that marks the site of a 1922 flood caused by levee break in Poydras, La., just a few miles downriver. The theme of the art stroll is ...

NolaVie

NolaVie
Fri, 05 Dec 2014 00:15:52 -0800

Curated by Jeanne Nathan of The Creative Alliance of New Orleans, the installation consists of an outdoor sculpture exhibition staged at the sight of a devastating crevasse, or massive breach, in the Mississippi River levee that flooded much of St ...
 
WGNO
Tue, 02 Dec 2014 14:34:44 -0800

Among the oaks and moss is a thriving habitat, a site called Crevasse 22. “There was a natural crevasse in the levee here in 1922, flooded St. Bernard Parish,” says Nathan. Hurricanes have threatened the crevasse time and time again, which sits on ...
 
NOLA Defender
Thu, 18 Dec 2014 08:30:00 -0800

New Orleans is known for its art, and now Poydras is too. Poydras, Louisiana that is, not Poydras Street. Nestled next to the Mississippi River levee and the lake created by the Crevasse of 1922, a new art space, The River House, is taking center stage ...

Press & Sun-Bulletin

Press & Sun-Bulletin
Fri, 19 Dec 2014 10:33:45 -0800

No one goes in alone — there's an experienced guide to help you crawl around every rock formation and through each crevasse. Be prepared to crouch, duck and sink your boots into the mud. After navigating back to the starting point, the filthy ...

Fox News

People Magazine
Fri, 23 May 2014 08:58:44 -0700

A Western Kentucky University professor is recovering from serious injuries after hiking on a research trip and surviving a harrowing, 70-foot fall into an ice crevasse in Nepal. John All, 44, used an ice axe and one arm to fight his way back to the ...

International Business Times

TIME
Sat, 24 May 2014 10:07:17 -0700

Professor John All fell 70 feet into an icy crevasse as he was hiking a Himalayan mountain. He had a broken arm, broken ribs, and was all by himself. It's a story that feels like the premise to the survival drama 127 Hours – and indeed, All recorded ...
 
Outside Magazine
Tue, 16 Dec 2014 16:35:03 -0800

Osservoort, leading a team of five, endured 23-hour driving stints, battling crevasse fields, steep climbs, deep snow, meter-high sastrugi (solid ice waves), and temperatures as low as minus-69 degrees Fahrenheit with wind chill. The group missed its ...
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