STRATIGTRAPHY OF THE PLEISTOCENE DEPOSITS AT PACEW ON THE PILICA RIVER

Abstract

In the zone of the Pilica valley escarpment at Pacew (swveral tens km. south from Warsaw) three horizons of glacial accumulation have been found above the "Pre-glacial" deposits. They are separated by erosive surfaces and by fluvial deposits (fig. 3). The oldest horizon is represented mainly by boulder clay, showing in some places gravel or varved clay intercalations (fig. 1). It corresponds to the Cracovian (Mindel) Glaciation. The Cracovian boulder clay is cut by comparalively large valleys, filled with fluvial sands (fig. 2, layer 1). The erosion of these valleys as well as the accumulation of the sands were connected with the Great Interglacial period. Two younger horizons of glacial origin correspond respectively to the maximal and the Warta substages of the Middle Polish (Riss) Glaciation. The lower one is represented by bouIder clay and by coarse glacial gravels, while the upper horizon - mainly by boulder clay. They are separated by an erosive surface (small valleys), which cut down the lower Middle Polish horizon, and by bedded loess silts, filling these valleys and spreading in some places over the surface of the above mentioned glacial horizon. The loess material has been brought here by wind and accumulated in water environment. The erosion of the small valleys and then the accumulation of the loess silt materiaI was connected with a cool and comparatively short space of time, corresponding to the Pilica Interstadial (the interstadial following immediately the maximal reach of the Middle Polish Glaciation). The Warta boulder clay, covering the interstadial deposits, represents at Pacew the youngest Pleoistocene link of glacial origin.