Pre-Anglian gravel deposits of the River Thames and its tributaries between Goring and Cromer

Abstract

On the basis of gravel composition, the earliest evidence of a Thames drainage system that extended into East Anglia is in the Norwich Crag. An influx of quartz into the high level pebble gravels of the middle Thames is traced across Essex into the Creeting Sands in the Norwich Crag near Ipswich. Another influx of far-travelled material entered the Thames system in Westland Green times, and Thames gravels, incorporating quartz-rich far-travelled material, form the Kesgrave Sands and Gravels in Essex and Suffolk. Gravels of Kesgrave type are traced northward in East Anglia to the north Norfolk coast, but their presence in Norfolk is often masked by mixing with quartzite-rich gravels of the Bytham River, which was confluent with the Thames near Bury St Edmunds, or by incorporation in the Weybourne Crag, which is largely of northern derivation. Distinctive Kesgrave components, in particular cherts from the Lower Greensand of the Weald, are, however, widely present in Norfolk and confirm the passage of the Thames into this area. The onset of Kesgrave sedimentation, post-dating the Westleton Beds and predating the Weybourne Crag, provides an important stratigraphic datum in the Plio-Pleistocene sequence in East Anglia.