Late Middle Pleistocene glaciation in East Anglia, England

Investigation of a group of landforms and their underlying deposits on the eastern margin of the Fenland in East Anglia has demonstrated that they represent a series of glaciofluvial delta-fan and related sediments. Section logging, borehole records and previous descriptions combine to indicate that the sediments were deposited in ice-marginal deltaic settings in an ice-marginal lake. The internal structure and form of the fan-like deltas has been demonstrated using extensive ground-penetrating radar investigation. The lake formed by the ice damming westward-aligned river valleys. Together, this evidence confirms historical descriptions of a glaciation of the Fenland, and clarifies the interpretation of gravels of the eastern Fenland margin. Recent reinterpretations of the latter as of fluvial rather than glacial meltwater origin are shown to be incorrect. It is concluded, on the basis of regional correlation, supported by optically stimulated luminescence dating, that the glaciation occurred at c. 160 kyr, i.e. in the Wolstonian (=Saalian) Stage (broadly equivalent to MIS ?11b-6). Comparison with The Netherlands' sequence shows a similarity of glacial marginal morphology, and the dates confirm the time equivalence with that during the late Saalian Drenthe Substage, Amersfoort ice-pushed ridge complex. The implications include that the c. 200 kyr interval, between the Hoxnian (Holsteinian) temperate Stage and the Wolstonian glaciation, was a period during which fluvial and periglacial activity modified the landscape under cold climates, with organic sediments laid down during warmer events. Palaeolithic humans were periodically present during this interval, their artefacts having been reworked by the subsequent glaciation.