Zarys budowy geologicznej i ewolucji północno-zachodniej części sandru kurpiowskiego

Abstract

W północno-zachodniej części sandru kurpiowskiego stwierdzono kilkakrotny rozwój sandrów (podczas zlodowaceń) oraz dolin rzecznych (w interglacjałach). Strefy wododziałowe zachowały w plejstocenie położenie stabilne. Obecna powierzchnia sandru powstała w kilku etapach zmiany kierunku odpływu wód roztopowych u schyłku zlodowacenia Wisły. OUTLINE OF GEOLOGY AND EVOLUTION OF THE NORTHWESTERN KURPIE OUTWASH, NORTHERN POLANDResults of geologic and geomorphologic studies of the northwestern Kurpie Outwash are presented. This outwash is to be subdivided (Fig. 1) from a geomorphologic point of view into the Mazury Plain (developed entirely within the extent of the Wisła Glaciation) and the Kurpie Plain ( in forefield of the maximum extent of the ice sheet of this glaciation). In spite of incomplete knowledge of geologic structure of the Kurpie Outwash (Figs 2 and 3), this area is found to have been the scene of repeated glaciofluvial (during glaciations) and fluvial outflows (during interglacials), however with a varied intensity. Present elevations and relics of morainic plateau constituted also many a time the watersheds, either during interglacials or/and glaciations. The present surface of the Kurpie Outwash has been mostly developed at the end of the Wisła Glaciation (minute fragments of older glaciofluvial levels are almost exclusively preserved in margins of relics of older morainic plateau). In that time a gradual change in direction of outflow took place. The initial, generally southward outflow (mainly in the Nidzica area), has changed step by step into a southeastward one i.e. towards the Lower Narew valley.