Z zagadnień geologii czwartorzędu dorzecza górnej Narwi

Abstract

ON QUATERNARY GEOLOGY OF THE UPPER NAREW RIVER BASIN Summary The area here considered embraces the south-eastern part of the Białystok-Zabłudów upland and the Biała plain with the area of the Białowieża primeval forest. These two regions are separated by the Upper Narew River valley. Thickness of the Quaternary deposits occurring in the area discussed ranges from 80 up to 107 m. The substratum is built up of Miocene, Oligocene and Upper Cretaceous deposits. In the Quaternary formations, three complexes of deposits have been distinguished, as follows: I complex - comprising one or two horizons of boulder clays interlayered by the arenaceous-gravelly sediments corresponding to the South-Polish glaciation, II camplex - represented by the fine- and middle-grained sands passing to the top into silts and marginal lake clays - referred to the decline of the Great Interglacial and to the beginning of the Middle-Polish glaciation, III complex - built up to two horizons of boulder clays divided by clays and silts, rarely by sands with gravel - belong to the Middle-Polish glaciation. On the surface of the area mapped there occur either upper boulder clay, silts and clays, or sands and gravels of morainic aprons, referred to the inland ice of the North-Masovian stage, as well as sands and gravels building the recession moraines of the Masovia-Podlasie stage. The Narew river bed, beds of its tributaries and undrained basins are filled up with sands, muds, and peats, at places.