Mollusc faunas of lake deposits in Gorzów Wielkopolski (NW Poland) as an indicator of environmental changes during Eemian and Early Weichselian

During the construction of the S-3 road near Gorzów Wielkopolski, a sedimentary succession of the Eemian Interglacial and the older part of the Weichselian Glaciation were exposed. The succession, ~22 m thick, consists of lacustrine and fluvioglacial deposits. Lake sediments, mainly calcareous gyttja with peat intercalations, represent the infills of two palaeolakes. The almost complete skeleton of a forest rhinoceros, Stephanorhinus kirchbergensis, and a bone of the fallow deer Dama dama were found in the older lake deposits. Mollusc shells were numerous in both lake sequences, analysis of which revealed two types of assemblage, representing the coastal, littoral zone of a shallow lake with a muddy bottom. The sequence of mollusc communities observed in vertical succession allowed reconstruction of environmental changes during deposition. Several hydrological changes have been recognized within the palaeolake, especially water level fluctuations probably due to climate change.