Rock Glaciers in Svalbard

ABSTRACT

A long-term approach based on detailed mapping and lichenometry provides additional information concerning talus-foot rock glaciers overstepping raised beaches in Svalbard. Their regional distribution is primarily controlled by the tectonic pattern and especially by the network of major thrusting faults. Tentative dating suggests that the rock glacier formation started ca. 3500 B.P., i.e. during the initial phase of a Neoglacial cooling period following the Atlantic optimum. Average rates of movement of rock glacier fronts inferred for the whole period of activity have been tentatively estimated at 1–7 cm/yr. Such values are consistent with those obtained from monitoring of similar forms performed in the eighties by Sollid and Sørbel (1992). Nevertheless, the gradual decrease of the debris size from the rock glacier fronts to the adjoining rock walls is still unexplained. On the NW coast, the possible role of stress relaxation during the initial phase of rock glacier development comes up against the early age of the deglaciation.