The Riss Valley - not to be confused with the Riss, a small tributary of the Danube in Baden-Württemberg and type locality of the Riss Glaciation - is one of the major valleys in the Karwendel Mountains. We have started to map this 23 km-long valley between Vorderriss and the Great Ahornboden a few years ago in great detail in order to unravel its fascinating Quaternary history. In contrast to other valleys in this mountain range the Riss Valley contains frequent sediment outcrops starting with the deltaic complex opposite of Oswald Hütte just north of the German-Austrian border. Most of these sediments are over-compacted and record episodes of rapid aggradation and drowning immediately predating the ice advance during the Last Glacial Maximum.
The Late Glacial and Holocene evolution of this valley is equally fascinating and currently focus of our research at the northern tip of Großer Ahornboden. Declared a natural monument in 1927 the conspicuously wide and flat Großer Ahornboden is home of some 2200 sycamore maple trees. These trees root in fine-grained sediments and are buried by debris-flow gravel. Our studies of the clayey silts beneath the gravel layer revealed the existence of a lake in the central and northern part of the Great Ahornboden, which existed at least during the 4th millennium BC.
Mair, D., Chwatal, W., Reimer, P.J., Spötl, C.: Quaternary evolution of the inner Riss Valley, Tyrol (Austria) - an integrated sedimentological and geophysical case study. – Austrian Journal of Earth Sciences, 109/2, 277-288.