Big Four Ice Caves - Photo by Karsten Winegeart

Big Four Mountain is a mountain in the Cascade Range at the bottom of its steep north face, debris piles form from avalanches and are able to remain there year round because of the continuous shade provided by the mountain. This ice forms the lowest-elevation glacier in the lower 49 states. During the summer, snow-melt streams flow beneath the debris piles and cause caves to be formed in the ice. The Big Four Mountain and the ice caves are part of an ever changing environment, with winter and spring avalanches, rock and ice falls a potential hazard year round. It is never safe to leave the designated trail and the ice caves should only be viewed from the designated trail - it can be quite dangerous to views the caves from the inside. (Silverton, Washington, USA)