Reconstruction of the Vistula ice stream during the Last Glacial Maximum in Poland

Abstract

The variability of ice movement directions within the Vistula lobe of the Main Stadial ice sheet of the last glaciation is analysed. Reconstruction of the ice movement directions is made based on analysis of the orientation of glacial morpholineaments. Linear glacial landforms are analysed on the basis of data from 26 map sheets of the Detailed Geological Map of Poland (DGMP), scale 1:50 000, compiled earlier by various authors. The morpholineaments were investigated in a belt of morainic plateau that adjoins the Vistula valley on both sides. The analysis revealed that the last glaciation ice sheet advanced directly from the north within the broadly understood Vistula ice lobe zone, and that the ice flow direction was constant. However, within a narrow belt of the pre-Vistula River valley that was formed in the Eemian Interglacial, the 30-50 km wide ice stream was characterized by locally variable ice flow directions consistent with the pre-existing valley trend. Changes in ice flow direction are recorded in the locally variable orientation of linear glacial landforms, indicating that the ice stream was active until the deglaciation period when the present-day shapes of the glacial landforms developed.