Luminescence dating and sedimentological observations at the Thalgut site, Aare Valley. Switzerland, imply deposition of glaciofluvial sediments and consequently a glacier advance during the earliest Late Pleistocene, just after the Last Interglacial. This glaciation possibly reached the margin of the Alpine foreland. but was probably of much smaller extent than the Wurm glaciation sensu stricto. A significant glacier expansion during the initial Wurmian has already been deduced from pollen analyses, indicating cool but moist climatic conditions. The age of fluvial sediments front the Mattstetten site supports this interpretation of prevailing climatic conditions. The dated sediment apparently represents reworked weathered molasse in a periglacial, but presumably moist. environment during the earliest Late Pleistocene.