Disentangling polygenetic relief of low mountains at the margin of inland glaciation – Upper Nysa Szalona drainage basin, Sudetes, Central Europe

Abstract

The drainage basin of the upper Nysa Szalona river in the West and Middle Sudetes shows polygenetic topography considered representative for the low- to medium-altitude mountain belt of Central Europe. It consists of mountain ridges and massifs, uplands and intramontane basins, with total relief energy up to 400 m. Geology is diverse and includes pre-Variscan basement rocks, here represented mainly by greenschists and slates, and post-Variscan sedimentary cover of Permian age. Volcanic rocks of various ages occur subordinately. In the Middle Pleistocene the area was invaded by the Scandinavian ice sheet and only the highest elevations remained as nunataks. Mountain and upland morphology in detail is controlled by lithology and structure, manifested in distinctive structural grain and association of higher ground with more resistant greenschists. Relief on Permian rocks is more subdued, except for the volcanic ones, and two shallow basins are excavated in Permian sedimentary rocks, with their margins coinciding with the lithological boundaries. Rock strength variability accounts for up to ~200 m of relative relief, whereas higher elevation differences are due to non-uniform uplift in the late Cenozoic. However, the area lacks typical mountain fronts, which are replaced by broader belts of surface deformation. The impact of inland ice was modest and only a few short epigenetic gorges were eroded. The contemporary topography of the area integrates landforms resulting from rock-controlled denudation, non-uniform uplift and glacial imprint, which evolved over the protracted timescale of the late Cenozoic.