Holocene relative sea-level movements along the North Norfolk Coast, UK

Abstract

Relative changes in Holocene sea level are reconstructed from foraminiferal assemblages in seven cores recovered from the intertidal zone of North Norfolk (Eastern England). A total of 33 radiocarbon and infra-red stimulated luminescence dates provide a detailed chronological framework for these changes. A transfer function approach, developed from modern UK foraminiferal datasets, establishes a series of 21 new sea-level index points for this coastline which are combined with 18 existing index points and a further number of limiting values. Errors associated with changing tidal ranges through the Holocene are reduced by adopting recently developed tidal models for this period. This new approach allows the use of foraminiferal assemblages to be extended from the upper saltmarsh environment (traditionally used for sea-level studies) to lower elevations in the tidal frame and include clastic detrital sediments. The results confirm the previously observed trend of continuously rising sea-levels in this area during the last 10 000 years which is consistent with a Glacial Isostatic Adjustment model. Relative sea-level (RSL) rises from an observed minimum of approximately − 13.50 m OD at about 7500 cal. BP to approximately − 4.0 m at about 5300 cal. BP, which equates to a mean rise of c. 4.3 mm yr − 1 . Subsequently, RSL rose gradually to present levels, although there is evidence that a minor reverse in this trend occurred between 4000 and 2000 cal. BP when sea-level fell by about 1 m to c. − 3.5 m. The rate of land subsidence for North Norfolk is 0.54 ± 0.03 mm yr − 1 (inverse of Late-Holocene sea-level rise).