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What is a cornice?

A cornice is formed when wind blows snow over sharp terrain breaks, such as on the top of a mountain, ridge or along the side of gullies, creating an overhanging shelf of snow.

Although these overhangs look solid enough to stand on, they can be fragile. There are many potential dangers related to cornices:

  • Due to the structure of a cornice, it is very difficult to see its edge from the ridge, making it challenging to know where to stop when travelling on a cornice.
  • Cornices often break off further back from the edge than expected, making it risky to venture further towards its apparent edge.
  • They can collapse suddenly, putting people travelling above and below at risk of serious injury.
  • Cornice collapses can cause avalanches.

How can I protect myself from cornice collapses?

  • Leave a generous distance between you and the edge of the cornice when walking along ridges.
  • Look up to make sure that you are not about to walk under a cornice that might collapse.
  • Avoid travelling on or near overhanging cornices.
  • Limit the amount of time you spend travelling under a cornice, especially during periods of warming temperatures, low visibility and active weather.
  • Know your route and ensure that you are avoiding hazards like cornices and are taking extra caution when travelling on ridges.
  • Look into weather conditions before leaving, as heavy snowpacks, previous or occurring storms, gusting wind, limited visibility and warming temperatures can all increase the risk of a cornice collapse.