Lucyna Wachecka-Kotkowska

Petrography of Glacial Tills in the Szczerców Outcrop, Central Poland – Problems of Stratigraphic Interpretation

Abstract The paper presents results of petrographic analyses of glacial tills in the western part of the Kleszczów Graben and the attempt of their stratigraphic interpretation. Petrographic coefficients have allowed the identification of five till lithotypes: T1, T2A, T2 and T2B – assigned to the South Polish Complex (Elsterian) and T4 correlated with the Middle Polish Complex (Saalian). The well-expressed tills that represent the South Polish Complex, occur at the bottom of the section. A new till lithotype, T2B, has been distinguished, corresponding to the Kuców Formation. It supplements the Pleistocene lithostratigraphic section of central Poland and corresponds to the Sanian 2 Glaciation. Among the younger tills, the T4 one (Odranian Glaciation) is well developed. The uppermost tills of the Wartanian cold stage have been reduced by glaciofluvial and fluvial erosion. It is, to some extent a consequence of the existence of a depression in this area, called the Szczerców Basin. The paper highlights the interpretational difficulties concerning the rank and the number of ice sheet advances during the Polish and Middle Polish Complexes in central Poland.