TIMING, VERTICAL EXTENT AND THE FOLLOWING DEGLACIATION OF THE LATE WEICHSELIAN SCANDINAVIAN ICE-SHEET MAXIMUM IN THE “RONDANE DRY VALLEYS” OF EAST-CENTRAL SOUTHERN NORWAY

The “Rondane dry valleys” in east-central southern Norway are located between the former ice divide and the present main watershed to the north within the suggested cold-based ice sheet region of central Scandinavia. Within the “Rondane dry valleys” there exist extensive lateral meltwater channels after downwasting ice sheets and remnants after large ice-dammed lakes from the final stages of deglaciation. Except for cirque glaciation at altitudes well below the present glaciation limit, there are no indications of active glaciers since the vertical downwasting of the Late Weichselian Scandinavian ice-sheet maximum (20-18 ka) started, and the final deglaciation.

The general deglaciation pattern of the downwasting Scandinavian ice sheet within the “Rondane dry valleys” has been reconstructed by mapping of lateral meltwater channels and related overflow gaps, ice-dammed lakes, the occurrence of low-altitude cirque glaciation and stratigraphical investigations. The timing of events has been dated by using three independent methods; optically stimulated luminescence (OSL), terrestrial cosmogenic nuclides (TCN) and AMS radiocarbon dating on terrestrial plant macrofossils. Suggested to be the result of precipitation starvation, the vertical extent of the late Weichselian glacial maximum of the Scandinavian ice sheet in east-central southern Norway is much less than previously suggested, and except for cirque glaciation, no or limited glacier activity took place during the Younger Dryas. Deglaciation events in the “Rondane dry valleys” may be linked to contemporaneous events along the coastal ice margins of southern Norway during the Allerød, Younger Dryas and Preboreal chronozones.