Holocene sediment storage in the Humber Estuary

Abstract In order to determine the processes that have governed the accumulation and erosion of sediments in the Humber Estuary (English North Sea coast) through the Holocene, the character, volume and source of sediments were studied. Eight sediment suites were identified on the basis of chemostratigraphy, lithostratigraphy and mineralogy. The locally sourced, freshwater, Basal Suite is overlain by the Newland and Butterwick Suites, deposited between c. 8 and 7.4 cal. ka bp in brackish environments behind a morainic barrier at St Andrew’s Dock, Hull. These are overlain by the largely marine, saltmarsh sediments of the Garthorpe Suite, which in turn are overlain, with erosional contact, by the channel sandflat and mudflat deposits of the Saltend, Sunk Island and Skeffling Suites. Most of the Saltend Suite is likely to have been deposited since c. 4 ka ago, whilst the Sunk Island and Skeffling Suites are likely to have been deposited since Medieval times and from the late eighteenth century onwards, respectively, as indicated by their concentrations of anthropogenic metals. On the coast, the Spurn Suite consists of sediments, associated with a spit system, which are almost entirely marine in origin. The suites show a progressive increase in marine influence; sediments of the oldest suite being entirely from the terrestrial catchment, those of the younger suites from erosion of the North Sea floor and coast. The relationships between suites show that during the last 4 ka the geomorphological evolution of the estuary has been marked by widespread erosion episodes that have led to the partial removal or redistribution of earlier deposits. By modelling the volumes of the suites it can be shown that, of the total volume of the estuarine fill (9.6 km 3 ), over half is likely to have been deposited during this period.