Dunes of the Toruń Basin against palaeogeographical conditions of the Late Glacial and Holocene

Abstract

Dunes are generally found in Poland either along the seacoast or inland, mainly in river valleys and on glaciofluvial outwash fans. The position of the dune fields of the Toruń Basin is unique also due to the fact that it is dominated by large dune forms, while the western part of the European sand belt is dominated by aeolian coversands. Dunes in the Toruń Basin are found on all terraces and make up vast clusters (complexes). W. Mrózek (1958) delimited there six dune fields. The dunes located in the Toruń Basin take the shape of crescent (parabolic) forms, simple ramparts (longitudinal and transversal) and irregular hilly forms. Additionally, there are numerous vast and plain areas covered with aeolian sand up to 4-5 m deep, which contain scattered irregular low dunes. The dunes of the Toruń Basin are mainly built of fine-grained and medium-grained sands which come from the local substratum of fluvioglacial and river deposits. The results of the studies on aeolian deposits carried out in the in Europe indicate that the earliest aeolian series (Older Coversand I, van der Hammen 1971) were deposited as early as Late Pleniglacial. In Poland this series has not been recognized, although the river deposits of that age have a larger content of quartz grain abraded in aeolian environment (Kozarski 1990; Manikowska 1991; Goździk 1991). New research claims in the Toruń Basin that the dunes formed chifly in the Younger Dryas, but probably also in the Older Dryas and even in the Preboreal.