Glacial advance and stagnation caused by rock avalanches

New model results show that a glacier advance caused by deposition of a rock avalanche on the ice will be followed by stagnation of the advanced ice lobe, producing distributed, hummocky deposits quite different from the single moraine ridges typically dated in paleoclimatic reconstructions. We obtain these results using a numerical flow-line glacier model with superimposed rock debris. In particular, our results imply that the single moraine ridge known as the Waiho Loop of the Franz Josef Glacier, New Zealand, is not the result of an advance triggered by a rock avalanche, else there would be a widespread, hummocky, glacial stagnation deposit associated with it.