Utwory czwartorzędowe w dolinie Skawy między Wadowicami a Zatorem

Abstract

Quaternary deposits in the skawa river valley between Zator and Wadowice (Carpathians) The pre-Quaternary basement is composed of Flysch rocks belonging to the sub-Silesian unit, as well as of Miocene deposits (Moravian-Badenian). Four separate socles, overlaid by alluvial deposits from different Pleistocene periods, are cut in pre-Quaternary sediments. The authors attribute the uppermost terrace, with a socle 22 m above river level, to the Preglacial period. In the interglacial preceding the Cracovian Glaciation there is a cutting down to 12.5—14 m above river level. Gravels and sands related to the Cracovian Glaciation, overlaid by glacial sediments, are deposited on this socle. In the Great Interglacial (Mazovian) there is a cutting down to 2.5—5 m above river level. Gravels, as well as sands, loams and clays are accumulated on the latter socle; they form an 11—12 m terrace whose age is attributed by the authors to the Middle-Poland Glaciation. In the Eemian Interglacial the river split up its own deposits and cut down into the pre-Quaternary basement at a depth of 0—4 m above the contemporary river level. At the same time peat was deposited in the previously cut-down dead channels. The period of the last glaciation was characterized by an intensified accumulation. The formerly deepened valley was filled up with gravels and sands 9.5—12.0 m thick. The latter sediments constitute an 8.5—11 m terrace; a t the same time, both the thickness of the deposits and the height of the socle increase downstream, this phenomenon being connected with diversified neotectonic movements. The floor of the valley is occupied by a 4—5 m accumulation terrace whose bottom consists of sediments from the Baltic Glaciation, overlaid by Holocene deposits. Younger infilling terraces of the Holocene age are put into the former terrace. The occurrence of alluvial deposits on rock socles connected with consecutive glaciations provides evidence fox a cyclic deepening of the valley in later Pleistocene periods. The above assumption is not consistent with the hitherto accepted opinion that sediments from the Cracovian Glaciation might be deposited on or below the level of the contemporary Skawa river bed. Within the investigated part of the Skawa valley there were found silty-loamy and sandy deposits whose thickness amounted to 22 m. In the upper part they are mainly yellow loesses and loess-like deposits, overlying grey loess sediments. They are divided by a distinct horizon of loams coloured with iron compounds or a horizon of loams containing organic remains, which are connected with the Brerup Interstadial. This horizon can be correlated with stratigraphic organic deposits which overlie gravels from the last glaciation, found both in the investigated area and north of it, in Zator (Koperowa, Środoń, 1965). It is also noteworthy that alluvial deposits of the last glaciation are overlaid by yellow loesses and loess-like sediments only. On the other hand, however, earlier Pleistocene sediments are found to be overlaid by loamy-silty deposits, divided by two loam horizons containing organic remains. They may correspond to soil horizons of an Interglacial age (Mazovian-Emian), attributed to them by the authors.