DISTRIBUTION OF GLACIAL LANDFORMS IN SOUTHERN NORWAY IN RELATION TO THE THERMAL REGIME OF THE LAST CONTINENTAL ICE-SHEET

The zonation of moraines and meltwater landforms in southern Norway indicates that the ice sheer was cold-based during the deglaciation of the central areas. Flutes, drumlins, Rogen moraines and end moraines in these central areas most probably predate the late Weichselian. There is also a vertical zonation of landforms which indicate that the highest areas became cold-based at an early stage during the last glaciation. These higher areas are characterized by blockfields and other weathering phenomena, and no traces of glaciation except meltwater channels and erratic boulders. Later the cold-based zone of the glacier expanded both downwards to lower parts of the terrain and outwards to areas further away from the culmination zone. In these areas the glacier stayed cold-based throughout the deglaciation period. Flutes, drumlins and end moraines were fossilized beneath cold-based ice, while Rogen moraines were formed by ice movement in warm-based patches with trapped water beneath a glacier that was otherwise frozen to the ground. In more distal areas of southern Norway the ice sheet was warm-based, and glacial landforms therefore directly reflect the course of deglaciation.