Periglacial talus slopes. Geomorphological studies on spitsbergen and in Northern Scandinavia

Abstract

The article focuses on the differences in evolution and behavior between talus‐mantled rectilinear slopes and talus cones, on the basis of field observations on Spitsbergen and in Northern Scandinavia. Whereas in the case of talus cones the talus derives from free faces above, in the case of rectilinear slopes the talus is autochthonous, the product of the weathering of the local bedrock or of resorting of till. The talus on rectilinear slopes commonly displays striking sorting and segregation: a surface layer of large slab‐shaped rocks, arranged in an imbricated fashion, rests on a layer of finer material which acts like ball‐bearings, provoking downslope movement of the larger rocks. Below this layer again lies a layer consisting of boulders embedded in a fine sandy matrix. Formation of rectilinear slopes with the arrangement just described is dependent on both lithology and climate. They are best developed and most dynamic on sedimentary rocks and in areas with continuous permafrost.