21. Giant “Bergsturz” Landscapes in the Tyrol

The line connecting the Zugspitze and the central Ötz Valley is characterized by a remarkably high density of large prehistoric landslides, with distinctive “Bergsturz” landscapes in their deposition areas. Those events north of the Inn Valley (e.g., Fernpass, Tschirgant) originated in carbonate rock units and those south of the Inn Valley in metamorphic rocks (e.g., Köfels). All events were geologically predisposed by complex fold-, fault- and fracture systems. The failed slopes mobilized substantial rock mass volumes and led to the accumulation of fluvio-lacustrine backwater sediments. Temporally, these early and middle Holocene landslides cluster with other events in the surrounding regions in the Alps. The landslide accumulation areas are characterized by rough debris and rather permeable terrain, and are therefore unfavourable for agricultural use. Distinctive forest ecosystems often dominated by Scots pine (Pinus sylvestris) are best adapted to these conditions. Whilst the deposition areas of large landslides were—and are still—obstacles for traffic and unfavourable for many types of land use, they are often perceived as appealing and scenic, and are therefore popular for recreational activities.