The composition of rock glaciers is tipped more toward rock than snow and ice. Rock glaciers sometimes form when slow-moving glacial ice is covered by debris. They are often found in steep-sided valleys, where rocks and soil fall from the valley walls onto the ice. Rock glaciers may also form when frozen soil creeps downslope.

This rock glacier in the Chugach Mountains of Alaska shows the overlapping lobes characteristic of glacial ice motion. —Credit: Photographer and date unknown. Courtesy United States Government.

This rock glacier slumps down off of the northeast face of Gilpin Peak in Colorado. —Credit: Bob Webster