Early Pleistocene onset of glacial incision in the Baltic Basin revealed by 10Be-26Al burial dating of the Hattem Beds

In Northwest Europe, the earliest presence of the Fennoscandian Ice Sheet (FIS) is registered in the Dutch-German border region, where fluvio-deltaic sediments of the ancient Eridanos river system contain weathered Nordic erratics within the so-called “Hattem Beds” (Upper Pieze Fm. [f.k.a. Lower member of the Enschede Fm.]). The Eridanos operated from the Early Miocene, integrating drainage across the east Fennoscandian Shield and Baltic Platform, until its headwaters were overridden by the FIS for the first time. The Hattem Beds, conventionally attributed to the Dutch Menapian Stage (~MIS 34; 1.1 Ma), mark the onset of glacial erosion within the Baltic Basin and termination of the Eridanos system. Here we provide new sediment burial ages for this key stratum by exploiting the cosmogenic 10Be-26Al pair in quartz. We measure nuclide concentrations in archived drill-core samples obtained from the type locality at the Wapenveld quarry near Molenweg (NL), including those of the overlying Urk and underlying Lower Pieze Fms. (f.k.a. Harderwijk Fm). Results with our Particle Pathway Inversion of Nuclide Inventories (P-PINI) burial dating model suggest a significantly older age for the Upper Pieze Fm. than has been previously inferred, underscoring glacial incision of the Baltic Basin and collapse of the Eridanos river system beginning in the Early Pleistocene (~2 Ma). This initial advance of the FIS into the Baltic Basin tracks the overall intensification of Northern Hemisphere glaciation indicated by marine records and alludes to the expansion of European ice masses prior to the Middle Pleistocene Transition (MPT; ~1.2–0.8 Ma). These findings add to a growing sense of mismatch between large empirically-derived pre-MPT ice sheet extents and low coeval glacial-interglacial ice volumes implicit in the global δ18O record.