Sinuous ridges in the Polesie region (SE Poland) as inverted fluvial channels: morphology, structure, and genesis

Abstract

We describe unique forms of sinuous ridges found only in Polesie, Poland, described from elesewhere in the world as palaeochannels and inverted fluvial channels. Sinuous ridges documented in Polesia represent two genetic types: glacial forms and inverted fluvial channels. The examples described of inverted fluvial channels are the only ones of this type documented in Poland. They formed at the transition between the Vistulian and Holocene, as a result of deposition of fine-grained sediments in fossil subglacial troughs. As a result of climatic changes and warming as the Vistulian gave way to the Holocene, the ice sheet covering the floodplains in the area thawed, and positive forms were formed from the deposits that had accumulated in channels in the ice. An important factor intensifying the process of inverted fluvial channel formation in Polesie was the mechanical properties of the rocks. Under specific climatic and geological conditions, with a high water content, the carbonate rocks building the sub-Quaternary substrate were subject to swelling. This resulted in the upward pushing of deposits accumulated in the troughs and the eventual formation of sinuous ridges. Our results reveal new mechanisms and considers new factors in the formation of sinuous ridges of inverted fluvial channel type, which can be applied at a planetary scale