Major rock slides in the Rockies

Abstract

The Frank Slide is the best known of a number of major rock slides in the Canadian Rockies. Seven other slides of the same order of magnitude are described from the Front and Main Ranges between Jasper and the United States border.The geometry and kinematics of the slides are controlled by discontinuities in the rock slide mass. Typically, the major part of the rupture surface is parallel to bedding; the orientation of the lateral margins and the scarp of the slide may be controlled by joint sets.Sliding tends to occur on slopes where bedding dips towards valleys at angles between 30 and 40° and in thickly-bedded, massive weathering rocks such as quartzites, dolomites, and limestones. Major causes of sliding appear to be erosion at the foot and lateral margins of the slide mass.The slides may be easily identified on aerial photographs by their effect on the local vegetation and by the characteristic appearance of their debris. All the slides observed are post-glacial, their frequency seems to have been underestimated and, in places, they may impose major constraints on further development.