Reconstruction of Quaternary landscape formation as a tool to understand present geomorphological processes in the eastern Prealps (Austria)

Abstract

The Rhenodanubian Flysch of the N Vienna Forest is composed of various layers of sandstones, marly shales, calcareous marls and clay schists, covered by Quaternary periglacial cover beds and loess deposits. There is a characteristic sequence of slope evolution during the Quaternary. Seven main phases are related to Pleistocene processes and two stages reflect the most recent geomorphodynamic processes. Phases of erosion, redeposition, sedimentation, and soil formation demonstrate stages of activity and stability under varying climatic conditions. On the basis of pedological and geomorphological investigations, it is possible to differentiate Pleistocene and Holocene sediments and processes. In particular, the distribution of periglacial cover beds, loess and modern soils allows the reconstruction of the undisturbed Pleistocene slope and sediments. The sequence of slope formation causes a distinct spatial distribution of Quaternary sediments and solid rock at the present land surface. In consequence, the influence of Quaternary landscape formation significantly influences slope stability conditions in the study area. This applies to the specific composition of the basal periglacial cover bed in the study area. It often consists of densely bedded marls and sandstone and is therefore impermeable, which can induce mass movements in the study area. Loess deposits frequently slide on top of the basal periglacial cover bed and form a susceptible pre-requisite for the occurrence of landslides in the study area.