Advance mechanisms of rock glaciers

Rock glacier advance is believed to be the result of the advection of frozen debris to and over the front, (partial) melt-out of ice, and incorporation and subsequent overriding of the mass at the base of the rock glacier. In this contribution, an approach to measure mass balance and transport within rock glacier fronts is presented. The technique is applied to Gruben and Suvretta rock glaciers, Swiss Alps. The results confirm a ‘conveyor belt’-like advance mechanism for both features. At the Gruben rock glacier front, an average excess ice content of approximately 65% was detected, 15% more than at Suvretta rock glacier. The frontal part of Suvretta rock glacier turned out to have a linear velocity profile over the entire thickness. At Gruben rock glacier, the horizontal mass transport is, for the most part, concentrated in a 5–10 m thick surface layer. Copyright © 2005 John Wiley & Sons, Ltd.