Uwarunkowania rozwoju pogrązów w aluwiach doliny Wisłoka w okolicach Rzeszowa (południowo-wschodnia Polska)

The article presents the results of geological and geomorphological research concerning load-cast structures outcropping in the alluvial terrace sediments of theWisłok River in the Fore-Carpathian Erosional Valley. Given the large dimensions of these structures, reaching 1.5 m in some places, as well as their strong accumulation and diversity (i.e. drop-like and pocket-like structures), the authors attempted to establish the environmental factors that had determined the development of the structures in periglacial deposits of the Weichselian Glaciation. The structures were analysed in two accessible outcrops where sediments are represented by flood rhythmite and organic deposits, overlain by channel sands. Sandy load-cast structures occur in flood rhythmite and loamy deposits. The formation of load-cast structures probably started due to earthquakes in the Upper Pleniglacial period. The various shapes of load-cast structures were constrained by the various physical properties of the sediments and the escape of water during the deformation process.