A snow bridge is an arc formed by snow across a
crevasse
A crevasse is a deep crack that forms in a glacier or ice sheet. 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 rate ...
, a crack in rock, a
creek, or some other opening in terrain. It is typically formed by
snow drift
A snowdrift is a deposit of snow sculpted by wind into a mound during a snowstorm. Snowdrifts resemble sand dunes and are formed in a similar manner, namely, by wind moving light snow and depositing it when the wind has virtually stopped, usu ...
, which first creates a
cornice
In architecture, a cornice (from the Italian ''cornice'' meaning "ledge") is generally any horizontal decorative Moulding (decorative), moulding that crowns a building or furniture element—for example, the cornice over a door or window, ar ...
, which may then grow to reach the other side of the opening.
Dangers
A snow bridge may completely cover the opening and thus present a danger by creating an illusion of unbroken surface under which the opening is concealed by an unknown thickness of snow, possibly only a few centimetres.
Snow bridges may also form inside a crevasse, making it appear shallow.
A snow bridge is thicker and stronger at the edge of a crevasse; therefore, a fall through a bridge usually happens at some distance from the edge.
[''Mountain Operations'' (September 1947) United States War Department Field Manual FM-10,]
p. 204
/ref>
See also
*Ice bridge
An ice bridge is a frozen natural structure formed over seas, bays, rivers or lake surfaces. They facilitate migration of animals or people over a water body that was previously uncrossable by terrestrial animals, including humans. The most signi ...
References
Glaciology
Snow
Bridges
Ice bridges
{{glaciology-stub