Jürgen M. Reitner

Deformation of high slopes in different rocks after würmian deglaciation in the Gailtal (Austria)

Abstract In the southern part of the Eastern Alps extended mass movements in different rocks are described. In a sequence of crystalline rocks (mainly mica schists and phyllonite) and sediments (sandstone, siltstone and limestones) various types of mass movements due to mechanical properties of the rocks occurred. Therefore a great-scale bending along with rotational gliding and toppling of the bigger blocks can be recognized in the mica schists in the major parts of the slopes. This slope failure leads to a complete disintegration of structures in the phyllonites. In the sedimentary part of the sequence the brittle limestone as the competent part failed above the soft incompetent base. The main reason for this mostly active deformation of the slopes is glacial erosion causing overdeepened valleys and steep slopes. Especially active parts are caused by strong river erosion. All these phenomena are temporarily closely related to the development of the glaciers.