Early stage Quaternary overdeepening in Upper Swabia - Germany

Overdeepenings are glacially shaped basins, incised into the bedrock deeper than the fluvial base level by subglacial erosion. Their sedimentary fillings are important archives for understanding glacial and postglacial history and the glacial impact on environmental transformation. Investigation of overdeepened features and their sedimentary contents is essential for understanding the processes and drivers of subglacial erosion, the timing and sequence of past glaciations, and accordingly their cumulated impact on landscape and topography.

This study is centred around an already acquired high quality drill core plus a correlating outcrop on the highest summit of Upper Swabia (The Hoechsten) in the North of the Lake Constance area (southwestern Germany). We investigate an overdeepening in an exceptional stratigraphic position: The sediment succession at Hoechsten is one of only a few examples of glacial basin fills that are correlated with the Early Pleistocene, and a key profile for this otherwise merely poorly constrained period. Situated in an elevated position, it is considered a component of an old highland-ramp topography that has since been largely reshaped over the course of repeated glaciations (Ellwanger et al. 2011).

Besides sedimentological analysis we apply standard geotechnical methods to reconstruct the deglaciation and potential phases of readvancement. Geotechnical data has proven valuable for the identification of a glacial sediment component, of previous mechanical loading by ice, or of the modification of a deposit by non-glacial processes. Furthermore, we compare micromorphological structures on the basis of microscale computed tomography analysis with results of a previously conducted thin-section study (Menzies & Ellwanger 2011). In the future, these analyses will be complemented by a multi-method dating approach (integrating e.g. luminescence and paleomagnetic properties and cosmogenic nuclides).

References:
Ellwanger, D., Wielandt-Schuster, U., Franz, M., & Simon, T. (2011). The Quaternary of the southwest German Alpine Foreland (Bodensee-Oberschwaben, Baden-Wuerttemberg, southwest Germany). E&G Quaternary Science Journal, 60(2/3), 306-328, DOI 10.3285/eg.60.2-3.07
Menzies, J. & Ellwanger, D. (2011). Insights into subglacial processes inferred from the micromorphological analyses of complex diamicton stratigraphy near Illmensee-Lichtenegg, Hoechsten, Germany. Boreas, 40(2), 271-288, DOI 10.1111/j.1502-3885.2010.00194.x