EVOLUTION OF SCANDINAVIAN PLATEAU LANDSCAPES DURING THE LATE QUATERNARY

Abstract

The widespread occurrence of high plateau landscapes along passive continental margins of the North Atlantic remains debated. A key question in this debate concerns whether glacial and periglacial surface processes have substantially eroded plateau areas during late Cenozoic climatic cooling. Plateau morphologies range from gently undulating, regolith-mantled slopes often displaying periglacial sorting features, to lake-dotted bedrock landscapes with abundant signs of glacial scouring and plucking. The relatively low relief of the plateau landscapes provide a distinct geomorphic contrast to the steep glacial troughs and fjords that dissect them. Estimates of Quaternary plateau erosion span from several hundred meters based on balancing offshore sediment budgets with onshore eroded areas, to less than a few meters based on suggested pre-Quaternary weathering characteristics of surficial materials. Here we review a number of recent studies that derive late Quaternary erosion rates via inverse modelling of cosmogenic 10Be and 26Al measurements of bedrock and regolith within plateau landscapes in Scandinavia. Modelled late Quaternary erosion rates range from a few to > 20 m/Myr, demonstrating that periglacial and glacial erosion within plateau landscapes is substantial and yield important contributions to offshore Quaternary sediment volumes.