Deposits of the Mazovian Interglacial (MIS 11c) beneath sinuous ridge-forms as a record of palaeogeographical transformations in Western Polesie (eastern Poland)

Abstract

Two sites (Rozkopaczew and Garbatówka) include biogenic deposits that provide a record of the Mazovian Interglacial in the Łęczna–Włodawa Lakeland (eastern Poland). The profiles comprise peat, gyttja, and organic silts occurring several metres below the present ground surface and overlain by Vistulian clastic deposits. Palynological analyses revealed a typical interglacial vegetation succession (mesocratic and telocratic phases). The sites are distinguished by their unusual location within elevated sinuous ridges. In contrast to previously known sites, interpreted as infilling depressions formerly occupied by small lakes, the examples described here indicate a change in depositional regime. Following a phase of lake development under interglacial conditions, the original depressions were filled with younger sediments, probably as a result of fluvial accumulation, and subsequently aggraded and transformed into positive landforms. The results highlight the significant role of later sedimentary and morphogenetic processes in reshaping the original relief.