Palaeolake sediment records reveal a mid‐ to late Younger Dryas ice‐sheet maximum in Mid‐Norway

Abstract

We present a revised chronology of the Scandinavian Ice Sheet’s glacial maximum during the Younger Dryas (Tautra event) in Mid‐Norway. Sediment records from palaeolakes near Leksvik show the occurrence of thick, laminated silt units with numerous dropstones between organic‐rich units and indicate that a proglacial lake was dammed between the Tautra ice margin and a local spillway. Ash beds and several radiocarbon‐dated plant macrofossil samples from corresponding stratigraphical sequences in different basins provide robust chronological constraints for the timing and duration of the proglacial lake and, consequently, the Tautra event. The existing chronological constraints on the Tautra event suggest that the glacial episode occurred at 12.9–12.6 ka. Our new chronology indicates that the Younger Dryas ice‐sheet re‐advance culminated close to 12.1 cal. ka BP, maintained this position for a maximum of 700 years and started retreating inland at c. 11.4 cal. ka BP. Our revised age for retreat from the Younger Dryas glacial maximum thus differs from the existing deglaciation chronology by approximately a thousand years, and hints at a similar late Younger Dryas glacial maximum throughout most of southern Norway.