Large-scale slope remodelling by landslides - Geomorphic diversity and geological controls, Kamienne Mts., Central Europe

The Kamienne Mts. in the Sudetes, Central Europe, bear widespread evidence of landsliding which mainly occurred at the boundary between Carboniferous and Permian clastic sedimentary rocks and overlying Permian volcanic and sub-volcanic rocks. 47 individual landslides have been delimited using a combination of LiDAR-derived DEM analysis and field mapping. They have been characterized through a range of geomorphometric parameters and cluster analysis reveals four major groups in terms of surface expression and consequently, likely origin and history. Spatial analysis confirms distinct association of landslides with the steepest terrain and north to east aspect of slopes, but distance from lithological contact emerges as the critical parameter. > 80% of the total landslide area is located within 200 m of a contact, on either side of it. Joint measurements within head scarps at selected landslides indicate that displacements took place along steeply dipping joints in the volcanic cap, but the existence of low angle detachment surfaces in the underlying sedimentary formations is inferred. The spatial distribution of slope deformations coupled with apparently different (although yet unspecified) ages of individual landslides suggests that remodelling of the mountain range by landslides is an ongoing process. Geomorphic history of the area excludes glacial or fluvial erosion and resultant slope de-buttressing as the cause of instability. Rather, landslides are considered as mechanisms by which slopes which have become too high and steep due to long-term differential erosion restore their strength equilibrium.