Twenty topples are described from Rock Glacier Site, 2 km north of the summit of the Highwood Pass in the Front Ranges of the Rocky Mountains in Alberta. In situ field testing and laboratory tests indicated that the external force driving the toppling process is frost action within a weathered shale zone. A stability analysis of the slope included examining rock falls, rupture surface formation, and slides. Rock falls were the dominant mode of landsliding. Surfaces of rupture develop when the amount of angular rotation of the toppling rock mass is over 16°. Slides along continuous surfaces of rupture are possible in rock masses with no cohesion and reduced friction angles. Topples cause rock falls, which lead to shallow slides in the rock-fall colluvium.
No takes yet. Share an insight, caveat, or question.
McAffee et al. (1996) studied this question.