Mass-wasting in the Tasersiaq area, West Greenland

Abstract

The ice-free lake Tasersiaq area, marginal to the Sukkertoppen Iskappe is underlain by jointed granite and gneiss which have only a thin covering of ground moraine.

With local exceptions, patterned ground is not well developed. Solifluction lobes occur on both valley slopes, but solifluction sheets are restricted to the gentler northeast-facing slope. Many sheets and lobes show an imbricate arrangement of boulders at their frontal margins. These features appear to be of rather recent age.

Slump features which show imbrication of boulders on their frontal margins are common, both as recent and " fossil" forms.

Micro-mudflows and debris slides are the most active features of the area in terms of volume of material moved. The amount of soil displaced at any one time by a single flow ranges between a few hundred cubic centimeters and several cubic meters. There is evidence of large mudflow activity in the past, but no recent activity was observed.

Water, both under pressure and on the surface, and wind are important contributors to mass-was ting in the Tasersiaq area.

Qualitative and quantitative observations of mass-wasting in the valley suggest that the processes are operating at a rate two to three times faster on the northeast-facing slope than on the opposing valley slope.