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      Denudation of the continental shelf between Britain and France at the glacial–interglacial timescale

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          Abstract

          The erosional morphology preserved at the sea bed in the eastern English Channel dominantly records denudation of the continental shelf by fluvial processes over multiple glacial–interglacial sea-level cycles rather than by catastrophic flooding through the Straits of Dover during the mid-Quaternary. Here, through the integration of multibeam bathymetry and shallow sub-bottom 2D seismic reflection profiles calibrated with vibrocore records, the first stratigraphic model of erosion and deposition on the eastern English Channel continental shelf is presented. Published Optical Stimulated Luminescence (OSL) and 14C ages were used to chronometrically constrain the stratigraphy and allow correlation of the continental shelf record with major climatic/sea-level periods. Five major erosion surfaces overlain by discrete sediment packages have been identified. The continental shelf in the eastern English Channel preserves a record of processes operating from Marine Isotope Stage (MIS) 6 to MIS 1. Planar and channelised erosion surfaces were formed by fluvial incision during lowstands or relative sea-level fall. The depth and lateral extent of incision was partly conditioned by underlying geology (rock type and tectonic structure), climatic conditions and changes in water and sediment discharge coupled to ice sheet dynamics and the drainage configuration of major rivers in Northwest Europe. Evidence for major erosion during or prior to MIS 6 is preserved. Fluvial sediments of MIS 2 age were identified within the Northern Palaeovalley, providing insights into the scale of erosion by normal fluvial regimes. Seismic and sedimentary facies indicate that deposition predominantly occurred during transgression when accommodation was created in palaeovalleys to allow discrete sediment bodies to form. Sediment reworking over multiple sea-level cycles (Saalian–Eemian–early Weichselian) by fluvial, coastal and marine processes created a multi-lateral, multi-storey succession of palaeovalley-fills that are preserved as a strath terrace. The data presented here reveal a composite erosional and depositional record that has undergone a high degree of reworking over multiple sea-level cycles leading to the preferential preservation of sediments associated with the most recent glacial–interglacial period.

          Highlights

          • We resolve continental shelf stratigraphy by integrating geophysics with core data.

          • Chronometric data links shelf processes to major climate/sea-level periods.

          • Palaeogeography of the eastern English Channel from MIS 6 to MIS 1 is reconstructed

          • The timing and mechanism of erosion and deposition on the shelf is examined.

          • We present evidence of noncatastrophic erosion in the English Channel.

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          Most cited references88

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          The Geographical Cycle

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            The northern sector of the last British Ice Sheet: Maximum extent and demise

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              The Lake Missoula Floods and the Channeled Scabland

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                Author and article information

                Contributors
                Journal
                Geomorphology (Amst)
                Geomorphology (Amst)
                Geomorphology (Amsterdam, Netherlands)
                Elsevier
                0169-555X
                1872-695X
                01 December 2013
                01 December 2013
                : 203
                : 100
                : 79-96
                Affiliations
                [a ]School of Environmental Sciences, University of Liverpool, Liverpool, L69 7ZT, UK
                [b ]The Crown Estate, 16 Burlington Place, London, W1S 2XH, UK
                [c ]School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK
                Author notes
                [* ]Corresponding author. Tel.: + 44 151 795 0126. mellettc@ 123456liverpool.ac.uk
                [1]

                Present address: School of Environmental Sciences, University of Liverpool, Liverpool, L69 7ZT, UK.

                Article
                S0169-555X(13)00189-X
                10.1016/j.geomorph.2013.03.030
                3990419
                24748702
                ebebcecf-dc05-44fa-a725-694b49973e45
                © 2013 Elsevier B.V.

                This document may be redistributed and reused, subject to certain conditions.

                History
                : 12 March 2012
                : 28 February 2013
                : 29 March 2013
                Categories
                Article

                Geophysics
                drowned landscapes,english channel,sea level,straits of dover,continental shelf stratigraphy,quaternary

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