Presentation by Kaleb Wagner.
Extensive Eurasian Ice Sheets from ~2.4 million years ago
Reconstructing Northern Hemisphere ice sheets is fundamental to resolving the coupled evolution of Quaternary sea level and climate. Yet, terrestrial records of Europe’s earliest glaciations are fragmentary and difficult to align with more continuous marine archives. Here we present new cosmogenic 26Al–10Be burial chronologies and detrital zircon U–Pb provenance constraints for key glacigenic successions across northwest and central Europe that challenge prevailing models for the timing and extent of the first Eurasian Ice Sheets (EIS).
Our results show that expansive EIS configurations were established from ~2.41 Ma and recurred throughout the Early and Middle Pleistocene, substantially predating the conventional onset of widespread lowland glaciation during Marine Isotope Stages (MIS) 12–16 (~425–675 ka). Ice flow through the Baltic corridor was active by ~1.72 Ma, sustaining extensive ice sheets that inundated the North European Plain and eroded the headwaters of the Baltic (Eridanos) River system; leading to its collapse by at least ~1.6 Ma. Pulsed freshwater flux to the North Atlantic during these intervals may have influenced overturning circulation and contributed to cyclical climate variability on orbital- and millennial-scales.
These revised chronologies place the EIS maximum before the Middle Pleistocene Transition (MPT), within the apparent low-amplitude glacial cycles of the ‘41-kyr world’. Integrated with new and existing North American constraints, our findings support a broadly synchronous picture of Early–Middle Pleistocene continental-scale ice-sheet growth across the Northern Hemisphere. Early attainment of such sizable ice volumes provides a terrestrial framework for new and emerging reconstructions that depict pronounced glacial sea-level lowstands throughout the entirety of the Pleistocene.
