Fossil and recent debris flows in medium–high mountains (Moravskoslezské Beskydy Mts, Czech Republic)

The significance of debris flows for the morphogenesis of the medium–high mountains of Central Europe has long been neglected. Herein we provide evidence from the Moravskoslezské Beskydy Mountains (flysch Western Carpathians, Czech Republic) where fossil (Pleistocene) debris-flow events (in spite of their low recent activity) were important erosion and accumulation agents in shaping the mountainous terrain. Geomorphological and sedimentological analyses helped to differentiate between two classes of debris-flow deposits. Deposits of the 1st class are relatively voluminous contemporary terraced landforms which originated in the Pleistocene transport-limited conditions. Recent activity of debris flows, presented by the 2nd-class accumulations, is characterized by the presence of low-magnitude events, mostly originated during the reworking of older diamictons. The inheritance of large volumes of old debris flow diamictons in steep mountainous terrain is the evidence of slow erosional transformation of the Last Glacial landforms pointing to the fact that recent topography of the mountains is not in full equilibrium with contemporary climatic and environmental conditions.