The Cowms Rocks Landslide

Abstract

AbstractThe Cowms Rocks landslide was the result of a translational movement which occurred downslope of a stream junction but involved part of the tributary valley side. Its morphology is described and a Gradient Index has been used to identify the component slide units. Slippage occurred on a 7° planar surface at about 40 m below the original ground surface, and consequent upon slope failure the main slump moved en masse. The tensional stresses controlling the slide were not uniform and a series of upslope‐facing escarpments developed within the main slump with some toppling and flexuring taking place at the slump's inner edge. At its margins, the slump broke into several blocks, some of which were tilted or deformed during the slip movement. The dominant factor leading to slope failure was rock (mass) creep which developed when periglacial climates prevailed in Pleistocene times. This led to differential weakening of the rocks within the slope but the exact timing for this deterioration is not known. The ultimate failure was delayed until some time in the Flandrian when stream undercutting was the ‘trigger’ mechanism.