Guide to Geologic Hazards in Alaska

Rockfall
The relatively free falling or precipitous movement of a newly detached segment of bedrock (usually massive, homogeneous, or jointed) of any size from a cliff or other very steep slope; it is the fastest form of mass movement and is most frequent in mountains during spring when there is repeated freezing and thawing of water in cracks in the rock. Syn: sturzstrom (Neuendorf, K.K.E. and others, 2005)