Development of Pleistocene glaciomarginal lake in the foreland of the Sudetes (SW Poland)

Numerous glaciomarginal lakes existed during the Pleistocene in the Sudetes and their foreland (SW Poland) because of damming off by an ice sheet. In the mountain area they were formed in the valleys or intermountain basins during the phase of maximum ice extent. In the mountain foreland they were developed at the front of the more active ice margin in the period preceding the maximum ice sheet advance. The latter lakes were less confined by the topography and their contact with the ice sheet was often considerably larger. This caused their different development.The sedimentological development of a small lake of this type, located near Mokrzeszów, was studied. The lake was characterized by high variability in water level and high energy depositional processes. Because of its small size, the lake responded very quickly to all changes in external factors. The lake became filled mainly by a coarse-grained delta. This happened in several phases because the water level fluctuated considerably owing to oscillations in the ice sheet extent. During lowstands, the delta became incised. Locally, subaqueous fans were formed. The lake basin eventually became overridden by the ice sheet.