Modelling the Development of Rocky Shoreline Profiles along the Northern Coast of IrelandEmail: robin.edwards@tcd.ie AbstractA mathema�cal wave-erosion model is used to simulate postglacial shoreline profiles along the rocky, high energy coast of the north of Ireland. The wave erosion model is driven by a suite of rela�ve sea-level (RSL) curves for the last 16,000 years produced from four glacial rebound models. Mul�ple runs are performed with different ini�al shore profiles and rock resistances to inves�gate shoreline evolu�on and the significance of inherited morphology on the resultant profile shape. The simulated profiles are then compared with mapped profiles from three areas of the north of Ireland with different lithological and hydrographic proper�es.Modelled profiles generally replicate the overall mean shoreline gradients observed across the region when rock resistance is rela�vely high and erosion rates correspondingly low. In these profiles, breaks in mean slope are observed at depths comparable to the RSL minima in several of the RSL scenarios (at c. -10m, -15m and -20m for North Antrim, Derry and Donegal respec�vely). At Portrush and Portballintrae (Derry), profiles may be influenced by structural controls rela�ng to the underlying basalt surface and the removal of overlying glaciogenic sediments.All RSL scenarios replicate the observed eastward increase in cliff-pla�orm junc�on height, reflec�ng the differen�al glacioisosta�c rebound experienced along the coast. However, the precise eleva�on at which the simulated cliff base occurs is sensi�ve to the choice of RSL scenario, sugges�ng that this parameter may prove useful in evalua�ng glacial rebound model performance. Several of the RSL scenarios generate raised shore pla�orms or terraces in North Antrim and Derry at heights comparable to raised shoreline features reported in the literature. However, no single curve or combina�on of parameters is capable of genera�ng the range of pla�orm and terrace features observed in the bathymetric and topographic data. These misfits are consistent with the idea that many rock pla�orm or terrace features are inherited from an earlier phase or phases of RSL.Keywords: wave erosion, model, rela�ve sea level, rock coast, shore pla�orms, marine terraces, IrelandAbbrevia�ons: Rela�ve Sea Level (RSL); Joint Irish Bathymetric Survey (JIBS); Digital Eleva�on Model (DEM); mean high water spring �de (MHWS), mean high water neap �de (MHWN), mid-�de (MT), mean low water neap �de (MLWN), and mean low water spring �de (MLWS); Ordnance Datum Malin Head (OD) This is the author's final copy of a published manuscript made available via Trinity's Access to Research Archive (TARA). This item is protected by original copyright. For full details visit the TARA website at www.tara.tcd.ie Author's Final Copy Available via Trinity College Dublin's Open Access Repository (www.tara.tcd.ie) 2 Introduc�onThe high energy, wave dominated coastline of the north of Ireland comprises rocky cliffs and shore pla�orms, commonly associated with g...
A new map of the seabed geomorphology on the Porcupine Bank, located at the western edge of the north-eastern Atlantic shelf west of Ireland, uses high-resolution multibeam bathymetric and backscatter data as well as numerous shallow seismic profiles to identify individual landforms. They are described based on their acoustic signature on the various datasets. The landforms comprise sharp-crested ridges, mounds and outcrops often associated with and expressing underlying bedrock topography; sand waves highlighting modern currents directions; and iceberg scours with strongly preferred orientations. The map is intended as baseline evidence to test models of the palaeoceanographic and palaeoglaciological history of the Porcupine Bank.ARTICLE HISTORY
Citation for published item:wgrronD tephen nd regD hniel nd gofighD golm ¡ yF nd wonteysD vier nd h¡ eudeuD fenjmin nd grvenD uiern nd qD wuhmmd wudsr nd govD endre @PHIVA 9e lioEleistoene sediment wedge on the ontinentl shelf west of entrl srelnd X the gonnemr pnF9D wrine geologyFD QWW F ppF WUEIIRF Further information on publisher's website: httpsXGGdoiForgGIHFIHITGjFmrgeoFPHIVFHPFHHW Publisher's copyright statement: c 2018 This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Abstract Glacigenic sediment fans recording shelf edge deposition from marineterminating ice sheets have previously been recognised along the NW European continental margin from Svalbard to as far south as Donegal, off north-west Ireland. Here we present evidence of a previously unrecognised partially glacially-fed Plio-Pleistocene sediment wedge on the continental shelf west of central Ireland using 2D and 3D seismic reflection data correlated to a commercial borehole. The 'Connemara Fan' covers a shelf area of approximately 9000 km 2 in water depths of 125 -310 m, extending westwards into the Porcupine Seabight from the Irish Mainland Shelf. The wedge comprises up to 160 m of sediment that culminates in a prominent moraininc ridge at seabed and contains two discordant reflection surfaces (R1 and 2) that subdivde it into three seismic units (SU1-3). Stratigraphic boreholes 27/24-2 and 2A located on the inner shelf show that the lower unit (SU1) is composed of Pliocene marine sediments, while SU2 and 3 comprise glacially influenced facies of Quaternary age. Extracts from a 3D seismic data volume within the central part of the fan show channels within the Pliocene succession, while iceberg scours are observed on the R1 and R2 reflectors. The Connemara Fan is inferred to record sediment supply from central western Ireland, with Quaternary units probably recording at least two glacial advance-retreat cycles with ice sheets repeatedly grounding across the inner (Irish Mainland) shelf. Our findings extend the range of glacially-influenced grounding line depocentres southwards along the NW European continental margin.
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