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1 School of Geography, Queens University, Belfast BT7 1NN, UK j.orford{at}qub.ac.uk
2 School of Environmental Studies, University of Ulster, Coleraine BT52 1SA, UK
3 Institute of Geography and Earth Sciences, University of Wales in Aberystwyth, Aberystwyth SY23 3DB, UK
Relative sea-level (RSL) control on dune initiation during the Holocene is examined in the context of chronostratigraphies established from 43 vibracores through dunes and into sub-dune sediments taken from the Northumberland and Norfolk (UK) coasts. The chronology is based on 23 accelerated mass spectroscopy and conventional 14C dates, and 37 infra-red-stimulated luminescence dates. The oldest dunes in Northumberland are c. 4 cal. ka BP with phases of dune development at 2.8 and 1.51 ka BP. Most dune deposition is of last millennium age, with a concentration, especially in Norfolk, around 500200 a BP. The initiation and survival of coastal dune sequences relate to macroscale RSL changes over the last 4 ka. Northumberland dunes reflect a gradient of RSL change from a northern RSL fall (forced regression) through to a southern RSL rise (normal regression through sediment supply). The north Norfolk coast has been dominated by a rising RSL through the Holocene, though associated with a sediment supply sufficient to offset the transgressive tendency and allow normal regressive deposition at numerous positions along the coast over the last 1 ka. It is suggested that the development of Little Ice Age (LIA) dunes in both Norfolk and Northumberland identifies the onset of specific conditions in which intertidal sediment sources were exposed (falling sea-level) to onshore winds (LIA circulation changes), which reflect a brief west North Sea period in dune initiation and deposition rates. A comparison of this consolidated dune chronology with statements of RSL elevation and climate conditions in the last 2.5 ka leads to some recognition of RSL fall preceding major dune building in two phases post 1.5 ka BP and post 0.6 ka BP.
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