Weichselian glaciations in the middle Notec River region, northwest Poland

Abstract: This thesis presents results of studies on the ice flow pattern and ice movement mechanism during the Weichselian glaciations in the middle Notec River area, NW Poland. A new lithostratigraphy of the study area has been established, based on correlation of stratigraphical position, clast lithology, fabrics and grain size composition of till units. The lithostratigraphy covers two glacial advances of presumed Weichselian (Vistulian) age. The ice flow pattern during these glacial events was reconstructed using directional elements such as clast fabrics, striations and deformations. The first ice (Dziembowo ice advance), tentatively assigned to the Middle or Late Weichselian, initially moved towards the SE while creating large thrust ridges. The ice movement direction shifted towards the SW at the time of till deposition. The last glacial advance (Ujscie ice advance), assumed to be Late Weichselian, has a twofold history with an initial advance towards the WSW and a final radial ice flow pattern towards the W. The occurrence of an ice readvance during the Chodziez subphase of the last deglaciation is rejected. The present results and information on the last ice flow direction in adjacent areas suggest that the western flank of a lobate ice front, centred in the Wisla Valley, covered the study area during the last deglaciation. The lobate ice front seems to have existed during the deglaciation from the Late Weichselian maximum ice marginal position in the Wisla Valley and probably back to the present Baltic Sea coastline. It is suggested that the lobate ice front represents the terrestrial termination of an ice stream following the Wisla Valley.