Holocene land- and sea-level changes in Great Britain

Abstract

Analysis of more than 1200 radiocarbon dated samples that constrain relative sea-levels in Great Britain over the past 16 000 yr provides estimates of current land-level changes (negative of relative sea-level change). Maximum relative land uplift occurs in central and western Scotland, ca. 1.6 mm yr-1, and maximum subsidence is in southwest England, ca. 1.2 mm yr-1. Sediment consolidation, arising from autocompaction as the sediment accumulates and from land drainage, increases the subsidence in areas with thick sequences of Holocene sediments, with an average effect equivalent to at least an extra ca. 0.2 mm yr-1 land subsidence, but more in parts of southeast England, 0.5-1.1 mm yr-1. Modelled changes in tidal range during the mid- to late Holocene in eastern England suggest that the calculated rate of land subsidence is overestimated unless such changes are quantified. The effect is most significant for large coastal lowlands, the Fenland and Humber (ca. 0.5 and 0.6 mm yr-1), that were tidal embayments during the mid- to late Holocene.