'Pre-glacial' Quaternary sediments from Trimingham, North Norfolk, England

Abstract

Pre-glacial sands and gravels are described from coastal exposures at Trimingham, near Cromer, north Norfolk and divided on the basis of sedimentary structures, particle size distribution, clast lithological content, pollen analysis and palaeocurrent directions into six sedimentary facies. The deposits are interpreted as having formed in a shallow marine environment by tidal current flow, with significant fluctuations in water depth and changes of
\ncurrent direction. Indicator lithologies show sediment sources to the coastal system both from the ancestral river Thames and from an as yet uncharted 'Northern' river. Pollen preserved in fine grained organic sediments in the lower part of the section, and ice-wedge casts from the
\nupper part of the section suggest that the environment changed from a temperate-climate coastal zone fringed with alder-carr backswamp, to a permafrost environment with thermal contraction patterned-ground. The temperate deposits formed during the Cromerian Stage and the permafrost structures as part of the early Anglian Barham Soil.