Early and early Middle Pleistocene river, coastal and neotectonic processes, southeast Norfolk, England

This paper investigates the interaction between coastal and river processes and neotectonics, prior to glaciation of northern East Anglia, eastern England. The study is based on results obtained from two boreholes drilled into the plateau of southeast Norfolk, between the Yare and Waveney valleys. Diagnostic sedimentary and lithological indicators from core samples are used to describe the main lithological units, and to compare them with the type sites of the Norwich Crag, and members of the Bytham Sands and Gravels, and Corton Formation. The results provide evidence for coastal sedimentation in the Early Pleistocene, when the Norwich and Wroxham Crags were deposited, and evidence to establish links between the coastal deposits and the contemporary river systems. The Norwich Crag received only suspended sediment from low energy rivers, whereas the Wroxham Crag received bedload transported from the whole catchment. Neotectonic subsidence within the region is proposed to explain the transgression of the Wroxham Crag across the Norwich Crag. The succeeding stratigraphical units are fluvial sediments of the Bytham river, which was the major river draining Midland England during the Middle Pleistocene. These sediments are located in a valley cut into the Crag, indicating uplift between the deposition of the coastal and river deposits. After their deposition, the whole region was overridden by glaciers that deposited the sediments of the Corton and Lowestoft formations, and shifted the Bytham river to a more southerly route.