A
crevasse is a
fracture in a
glacier caused by a large
tensile stress at or near the glacier's surface. Accelerations in glacier speed cause extension and can initiate a crevasse. Crevasses often have vertical or near-vertical walls, which can then melt and create
seracs, arches, etc.; these walls sometimes expose layers that represent the glacier's
stratigraphy.
A crevasse may be covered, but not necessarily filled, by a snow bridge made of the previous year's snow. Falling into a hidden crevasse that is covered by a weak snow bridge is thus a danger for mountaineers. Anyone planning to travel on a glacier should be trained in crevasse rescue.
"Crevasse" is also a traditional term for a levee failure, such as those along the Mississippi River.
Crevasse on the Gorner Glacier, Zermatt, Switzerland
