Crevasse

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Crossing a crevasse on the Easton Glacier, Mount Baker, in the North Cascades, Washington

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]

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 skinning 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. 
  2. ^ a b Holdsworth, G (October 1956). "Primary Transverse Crevasses". Journal of Glaciology 8 (52): 107–129. 

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