Hoxnian interglacial freshwater and marine deposits in northwest Norfolk, England and their implications for sea-level reconstruction

Abstract

An interglacial site is described from Tottenhill, in the Nar Valley in northwest Norfolk. A transgressive surface is recorded at this site with marine Nar Valley Clay overlying lacustrine Nar Valley Freshwater Beds. Biostratigraphical analyses indicate that these units span the latest part of the Anglian (Elsterian) glacial Stage and the first half of the Hoxnian (Holsteinian) Stage. Several other sites in the valley contain evidence for sea-level changes during the Hoxnian and the relevant information from these sites is briefly discussed. This gives an estimate of the timing of the Hoxnian maximum flooding surface, the maximum extent of the marine incursion and possible water depths attained. Evidence for Hoxnian sea-level changes at other sites in eastern England are briefly discussed. Although a regional sea-level highstand during the Hoxnian seems very likely, the details of the extent and timing of salt-water penetration are conflicting. It is suggested that post-depositional effects, particularly isostatic re-adjustment, may account for some of these differences and that the modern height of interglacial sediments can be misleading when depositional sea-levels are reconstructed.