The evolution of coastal barrier systems: a case study of the Middle-Late Pleistocene Wilderness barriers, South Africa Mark D. Bateman a, * , Andrew S. Carr b , Adam C. Dunajko a , Peter J. Holmes c , David L. Roberts d , Sue J. McLaren b , Robert G. Bryant a , Margaret E. Marker e , Colin V. Murray-Wallace f a Sheffield Centre for International Drylands Research, Department of Geography, University of Sheffield, Winter Street, Sheffield S10 2TN, UK b Department of Geography, University of Leicester, University Road, Leicester LE1 7RH, UK c Department of Geography, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa d Council for Geoscience, PO Box 572, Bellville 7535, South Africa e 5 Wytham Close, Eynsham, Oxfordshire Ox29 4 NS, UK f School of Earth & Environmental Sciences, University of Wollongong, NSW 2522, Australia article info Article history: Received 16 July 2010 Received in revised form 4 October 2010 Accepted 4 October 2010 Available online xxx abstract Barrier systems contain lengthy, but complex, records of long-term environmental fluctuations. The Wilderness embayment, South Africa, contains a system of shore-parallel barriers reaching up to 200 m above modern sea level. This study reports the results of chronological, topographical (both on- and off- shore), sedimentological and micromorphological analyses within the Wilderness embayment. Sixty-one new luminescence ages from sixteen sites in unconsolidated dunes and three separate barriers are presented which, when combined with previously published luminescence ages from the area, provide a high-resolution chronological framework for the emplacement and evolution of the barrier system. The preserved barriers have been constructed within at least the last two glacialeinterglacial cycles with notable phases between 241e221 ka, 159e143 ka, 130e120 ka, 92e87 ka and post 6 ka. Multiple phases of barrier construction occurred during sea-level highstands, with sediment deposition on each indi- vidual barrier occurring over at least two interglacials. Holocene evolution of the system sheds light on earlier events, with dune preservation occurring only during early regression from the Mid-Holocene highstand. Tectonic stability at Wilderness allowed glacio-eustatically formed shorelines to occupy similar positions on multiple occasions. This, in conjunction with a relatively humid climate and a well- vegetated landscape, enabled deflated sediment from beaches to form dunes which stacked upon each other to form an extensive and complex vertical accretionary sequence. Repeated erosion and recycling of pre-existing barriers as well as barrier construction on what is currently the off-shore platform during still-stands in sea-level regressional cycles, when sea levels dropped below ca 50 m from the present day, has added to the complexity of the preserved terrestrial barrier record. The Wilderness barrier system contrasts with barriers developed elsewhere in the world where higher rates of crustal uplift have allowed preservation of a more complete and more widely spaced palaeorecord. This research also shows the utility of integrating off-shore topography as revealed by bathymetry, with terrestrial topo- graphic data for the better understanding of the evolution of palaeo-coastlines and the preserved dune record found on present-day coastal plains. Local variation in the topography of the continental shelf at Wilderness has generated spatial and temporal complexity within the sedimentary records of individual barriers as well as having a significant influence on preservation. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction The geomorphological evolution of barrier-estuarine systems on wave-dominated coastlines has been considered in the literature for some time (e.g. Roy et al., 1980, 1994; Cowell et al., 1995; Murray- Wallace et al., 1998, 1999; Sloss et al., 2005, 2006). Such systems commonly reveal a complex history of estuarine and barrier sedi- mentation in response to long-term fluctuations in eustatic sea level, as well as sediment supply from the marine environment and the terrestrial hinterland (e.g. Antony et al., 2002). Aeolian and marginal marine sediments represent major facies within barrier systems (e.g. Brooke et al., 2003), which through time may be cemented or lithified to form aeolianite and beachrock respectively. This enhances their * Corresponding author. Tel.: þ44 114 222 7929; fax: þ44 114 222 7907. E-mail address: m.d.bateman@sheffield.ac.uk (M.D. Bateman). Contents lists available at ScienceDirect Quaternary Science Reviews journal homepage: www.elsevier.com/locate/quascirev 0277-3791/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.quascirev.2010.10.003 Quaternary Science Reviews xxx (2010) 1e19 Please cite this article in press as: Bateman, M.D., et al., The evolution of coastal barrier systems: a case study of the Middle-Late Pleistocene Wilderness barriers, South Africa, Quaternary Science Reviews (2010), doi:10.1016/j.quascirev.2010.10.003