3D seismic evidence for a single Early Pleistocene glaciation of the central North Sea.

Efforts to understand how Pleistocene climate changes were translated into fluctuations in ice sheet extent and volume are limited by a lack of consensus about the glacial history of the North Sea. Here, we use high-resolution 3D seismic data to interpret the landforms and sediments of the central North Sea in unprecedented detail. In contrast to previous interpretations of multiple extensive early glaciations, our data suggest that grounded ice extended across the central North Sea only once, from western Norway, during the Early Pleistocene. This ice sheet advance, which probably occurred ~1.1 million years ago, deposited an up to 120-meter-thick layer of till across >10,000 square kilometers of the central basin. During the rest of the Early Pleistocene, elliptical pockmarks and elongate contour-current furrows show that the central basin was instead scoured by along-slope currents. These findings constrain the extent of ice sheets before and during the Mid-Pleistocene Transition and reconcile marine and terrestrial evidence for glaciation in northwest Europe.