Steven M. Pawley

Revised Pre-Devensian glacial stratigraphy in Norfolk, England, based on mapping and till provenance

Mapping combined with till provenance studies have resulted in a re-appraisal of the pre-Devensian glacial stratigraphy of Norfolk, England. The traditional model invoked two formations, a North Sea Drift Formation (NSDF) overlain by a Lowestoft Formation, formed by co-existing icesheets originating in Scandinavia and Northern Britain respectively. The NSDF included three diamictons, the First, Second and Third Cromer tills. The Briton’s Lane Sands and Gravels were considered to overlie the Lowestoft Formation. However, our work has shown this stratigraphy to be untenable, and we propose a model of several glaciations instead of co-existing ice-sheets. In our revised stratigraphy, the oldest formation, the Happisburgh Formation (including the Happisburgh or First Cromer Till) includes massive, sandy tills derived from northern Britain. The overlying Lowestoft Formation, including the Second Cromer (Walcott) Till is confirmed as derived from the west, introducing much Jurassic material as well as Chalk. The Sheringham Cliffs Formation includes both brown sandy tills (the Third Cromer Till) and ‘marly drift’, in a variety of tectonic relationships, and derived from the north and NNW. Finally the Briton’s Lane Formation is the only formation to include Scandinavian erratics. Dating of the four formations is at varying levels of confidence, with the Lowestoft Formation most confidently confirmed as MIS 12. The Happisburgh Formation is believed to represent an earlier glaciation, and MIS 16 is proposed. The Sheringham Cliffs Formation is tentatively believed to date from MIS 10, and the Briton’s Lane Formation is assigned to MIS 6.

Middle Pleistocene sedimentology and lithostratigraphy of Weybourne northeast Norfolk, England

This paper investigates pre-glacial and glacial deposits exposed in coastal cliff sections of the Weybourne area, northeast Norfolk. At this site, shallow-marine sediments of the early Middle Pleistocene Wroxham Crag Formation are overlain by two glaciotectonized and interbedded tills and glaciofluvial sands and gravels of Middle Pleistocene age. The lower sandy Runton Till (Third Cromer Till) is tectonized and incorporated into the overlying chalk-rich till forming the banded Weybourne Town Till (Marly Drift). Structures within these tills indicate that they were deposited subglacially and the two till lithologies were intermixed as the water-saturated Runton Till was remoulded and assimilated within the banded and chalk-rich Weybourne Town Till. Although the Runton Till has been traditionally attributed to deposition by a Scandinavian-based ice sheet, clast lithologies indicate that both the Runton and Weybourne Town tills were deposited by a Scottish-based ice-advance that moved down the coast of eastern England. The overlying sand and gravel succession, preserved only in large synform ‘sag-basins’ is interpreted as glacial outwash on the basis of its sedimentology and clast lithology, and is correlated with the Britons Lane Sand and Gravel by the presence of a Scandinavian clast component.