ABSTRACTThe paper describes a catastrophic landslide (rock avalanche or sturzstrom) of Holocene age in Verkilsdalen, Rondane, southern Norway. The feature with a rock debris volume of about 20×106m3, represents one of the largest landslides in northern Europe. The process of debris movement appears to have been related to an initial phase of sliding followed by a phase of rapid flowage. Flowage seems to have been induced by the impact of the rapidly sliding mass against the lower valley-side slopes. This also resulted in the production of a complex network of bedrock fissures and in the displacement of several sections of hillside. During flow, the fastest moving material was propelled in front of the leading edge of the moving mass and was deposited as a relatively fine-grained debris apron. It is proposed that the Verkilsdalen sturzstrom took place principally by momentum transfer through block collision (cohensionless grain flow). This process of formation contrasts with those suggested for many other catastrophic landslides where air layer lubrication and fluidisation due to air entrapment have often been invoked as agencies of rapid debris movement.