Evidence for a Middle Pleistocene glaciation of MIS 8 age in the southern North Sea

In the coresof borehole 89/2, situated at 541 00 010N and 51 00 040E about 70 km north of the Frisian Islands in the southern North
Sea, two diamictonsle vels are found at 770 and 100m below sea floor (i.e. 7110 and 140 below present sea level), respectively. Both
diamictonsap pear to be older than Saalian (=MIS 6), in contrast to earlier interpretations. The upper diamicton is overlain by about
20m of shallow marine sands followed by a chaotic alternation of fine-grained clay-rich Eemian (MIS 5e) sediments and sands
deposited in a glacially excavated basin. It was originally assumed that this diamicton was Saalian (MIS 6) in age and lined the base of
the basin. Seismic lines crossing the borehole location, however, show that the upper diamicton is truncated by the basin, and,
consequently must be older than Saalian. This is corroborated by new investigations on the Saalian–Eemian transition in the
Netherlands and new data on the age of the molluscs and foraminifera in the sands directly overlying the upper diamicton. The age
data, based on measurements of the isoleucine epimerisation of mollusc shells and foraminiferal tests favour an MIS 8 age.