EARLY WEICHSELIAN DUST STORM LAYER AT ACHENHEIM IN ALSACE, FRANCE

The cause of the rapid transition from lush grasslands and woodlands o f the Early Glacial interstadial to Pleniglacial barrens in Europe is still a mystery. In the loess sections of Bohemia and Austria this tra nsition is associated with thin layers of fine-grained airborne dust k nown as 'markers', believed to be deposited by major continental-scale dust storms. Here we present evidence that a similar, sharply delimit ed layer with a minimum TL age of 64.9 +/- 6.9 ka separates the autoch thonous humus steppe soils from abiogenic sediments of the Achenheim 1 pedocomplex in France. The soil complex has been previously correlate d on pedostratigraphic grounds with marine oxygen isotope stage (MIS) 5. Given its age and stratigraphic position, the dust layer correlates with the PKII marker in Bohemia. The recognition of a marker in Achen heim suggests that the development of the Early Glacial steppe soils e nded abruptly not only in central Europe, but also in Alsace. France, prior to 65 ka, possibly as a result of a single continental-scale dus t storm.