A comparative analysis of the palaeoecological and palaeohydrological records of two neighbouring Eemian lakes: Implications for palaeolake evolution in Central Poland

Abstract

The paper presents high-resolution palaeoecological studies of two neighbouring palaeolakes, Struga and Parysów, in Central Poland based on the presence of inter alia pollen, Cladocera, diatoms, and sediment analyses (loss-on-ignition). The investigated sites belong to the Eemian Lake District in the Polish Lowlands. The analysis of the two lakes revealed considerable differences in terms of the duration of their Eemian phases (Regional Pollen Assemblage Zones E1–E7) and their evolution. The Struga palaeolake began functioning in the Late Saalian (MIS 6) and survived as a lake into the terminocratic interglacial phase. In contrast, the Parysów palaeolake was a rapidly overgrowing water body that ceased functioning during the hornbeam phase (E5 RPAZ) and was reactivated by increased climate humidity at the end of the Eemian. It hence seems that different types of lakes functioned in a small region of the Garwolin Plain during the Last Interglacial period (MIS 5e) but experienced different shallowing processes under the same climate conditions; this finding emphasises the important role played by the local context in palaeoenvironmental interpretations. The differences observed in the present study may be attributed to the geomorphological situations of the lakes and the possibility of groundwater recharge. Indeed, groundwater levels fell during the earlier part of the climatic optimum of the Eemian interglacial due to drier climate conditions; this may have been responsible for the shallowing observed in lakes at the high-altitude tops of kettle holes, such as Parysów, but not those in low-lying subglacial troughs, such as Struga.