1 Developing a framework of Quaternary dune accumulation in the northern Rub’ al-Khali, Arabia. Andrew R Farrant a , Geoff A T Duller b , Adrian G Parker c , Helen M Roberts b , Ash Parton d , Robert W O Knox a# , and Thomas Bide a . a British Geological Survey, Keyworth, Nottingham, NG12 5GG, UK. arf@bgs.ac.uk [corresponding author 0115 9363184]. b Aberystwyth Luminescence Research Laboratory, Department of Geography & Earth Sciences, Aberystwyth University, Aberystwyth, SY23 3DB, Wales, UK c Department of Social Sciences, Faculty of Humanities and Social Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK d Research Laboratory for Archaeology and the History of Art, School of Archaeology, University of Oxford, Oxford, OX1 2HU, UK #Deceased Abstract Located at the crossroads between Africa and Eurasia, Arabia occupies a pivotal position for human migration and dispersal during the Late Pleistocene. Deducing the timing of humid and arid phases is critical to understanding when the Rub’ al-Khali desert acted as a barrier to human movement and settlement. Recent geological mapping in the northern part of the Rub’ al-Khali has enabled the Quaternary history of the region to be put into a regional stratigraphical framework. In addition to the active dunes, two significant palaeodune sequences have been identified. Dating of key sections has enabled a chronology of dune accretion and stabilisation to be determined. In addition, previously published optically stimulated luminescence (OSL) dates have been put in their proper stratigraphical context, from which a record of Late Pleistocene dune activity can be constructed. The results indicate the record of dune activity in the northern Rub’ al -Khali is preservation limited and is synchronous with humid events driven by the incursion of the Indian Ocean monsoon. Keywords: Arabia, dunes, palaeoclimate, OSL dating, United Arab Emirates, Monsoon. 1. Introduction Reconstructing environmental change in Arabia is vital for improving our understanding of the context for demographic variability during the Mid-Late Pleistocene (Groucutt and Petraglia, 2012). During much of this time, the presence of the hyper arid Rub’ al-Khali desert presented a major environmental barrier for human dispersal. However, fluctuations in the regional climate, driven by the varying latitudinal interface between the south-westerly Indian Ocean Summer Monsoon (IOSM) and the Westerly driven Shamal winds, created occasional humid interludes generating the potential for human migration across this region. Although IOSM rainfall is currently restricted to southern coastal regions of Yemen and Oman, at times it increased in strength and penetrated much further north across Arabia, bringing moist conditions across the now hyper-arid Rub’ al-Khali (Fleitmann et al., 2007; Rosenberg et al., 2011; Atkinson et al., 2013). Constraining the timing of these moist incursions is essential for determining when human migration may have occurred (Armitage et al., 2011; Parton et al., this issue). However, this necessitates having high-quality palaeoclimatic records from the region, combined with good chronological control. One such source of palaeoclimatic information are the Quaternary sediments that occupy the Rub’ al-Khali basin. This region (Figure 1), which extends over 600,000 km 2 and covers one-third of the Arabian subcontinent (Edgell, 2006; White et al., 2001), has an extensive cover of Quaternary deposits. These mostly comprise aeolian dune systems with a suite of alluvial fans along the margins of the Hajar Mountains, and localised palaeolakes and inland sabkhas (Farrant et al., 2012a). The importance of these Quaternary sediments