LITOSTRATYGRAFIA GLIN LODOWCOWYCH I OSADÓW PROGLACJALNYCH OKOLIC SZCZECINA, POLSKA PÓŁNOCNO-ZACHODNIA

Abstract

LlTHOSTRATIGRAPHY OF TILLS AND PROGLAClAL DEPOSITS IN THE SZCZECIN VICINITY, NORTHWESTERN POLANDAbstract. In the vicinity of Szczecin, NW Poland, 9 till horizons occur which have been defined by their petrographic composition and position in lithostratigraphic succession. The tills include to the "oldest glaciation", two tills to Elsterian, three tills to Saalian and three tills to Weichselian (two of them with regional extent, and one local, connected with the marginał zone of the Pomerania Phase). This stratigraphic subdivision was formalized. Same tills of the Szczecin region indicate features which are correlative with till horizons in western and central Poland. The age of older tills has been established in relation to these index horizons. Glaciał palaeotransport was usually from NW lo SE during the first stadials af each glaciation, then changed from NE to SW in the middle, and finally to ENE-WSW in the final stadials. There are no interglacial ar interstadiał deposits near Szczecin, but proglacial sediments have a widespread accurrence, particularly głaciolacustrine series. The latter are quite thick and occur in almost all glacial horizons. Glaciolacustrine deposits were formed mainly during the ice sheet advances. Twa regional, buried palaeosurfaces have been documented in the studied area. They were formed during the Mazovian (Holstein) Interglacial (Elsterian/Saalian ice free period) and during the Eemian and early Visrulian. Each of them was formed by different processes, the first one by regional denudation and slow lowering of the surface, and the second one probably also by more intensive and deep fluvial erosion. The sediments from the oldest glaciations (San 1 and San 2) and Vistulian contain admixtures of early Cenozoic materiał, whereas Middle Polish (Saalian) deposits do not. From this it follows that during the first there were many outcrops of older sediments, exposed due to intensive erosion, whereas the Middle Polish (Saalian) ice sheets advanced to the area covered by continuous cover of older glacial deposits.