Preliminary U-series and Thermoluminescence dating of excavated deposits in Liang Bua sub-chamber, Flores, Indonesia Emma J. St Pierre a, * , Kira E. Westaway b , Jian-xin Zhao a, c , Michael K. Gagan d , Carol Lentfer e , Rokus Awe Due f , Michael J. Morwood g , Wahyoe S. Hantoro h , Tony Djubiantono f , Bambang W. Suwargadi h a School of Earth Sciences, University of Queensland, St. Lucia, Brisbane, QLD 4072, Australia b Department of Environment and Geography, Macquarie University, Sydney, NSW 2109, Australia c Radiogenic Isotope Laboratory, Centre for Microscopy and Microanalysis, University of Queensland, Brisbane, QLD 4072, Australia d Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200, Australia e School of Social Science, University of Queensland, Brisbane, QLD 4072, Australia f Indonesian Centre for Archaeology, Jl. Raya Condet Pejaten No. 4, Jakarta 12001, Indonesia g School of Human and Environmental Studies, University of New England, Armidale, NSW 2351, Australia h Research and Development Center for Geotechnology, Indonesian Institute of Sciences, Bandung 40135, Indonesia article info Article history: Received 21 October 2011 Received in revised form 13 July 2012 Accepted 15 July 2012 Keywords: Cave geomorphology Flores, Indonesia Liang Bua Red Thermoluminescence dating Soda straw stalactites Uranium-series dating abstract We report the results of a test excavation of deposits in a limestone cave sub-chamber located beneath the main chamber of Liang Bua, Flores, Indonesia; the discovery site of the small hominin species, Homo floresiensis. Well-preserved remains of extinct Pleistocene fauna and stone artefacts have previously been identified on the surface of a sediment cone within the sub-chamber. Our excavation of the deposits, at the base of the sediment cone in the sub-chamber (to 130 cm depth) yielded only a few fragmentary bones of extant fauna. Uranium/Thorium (U-series or U/Th) dating of soda straw stalactites excavated from 20 to 130 cm in depth demonstrates that the excavated sediments were deposited during the Holocene. Red Thermoluminescence (TL) dating of the sediments at the base of the excavation (130 cm depth) indicates these sediments were last exposed to sunlight at 84  15 ka (thousand years), similar to red TL ages of cave sediments from the main chamber. Together, these results indicate that the surface faunal remains, which are morphologically analogous to Pleistocene finds from the main chamber excavations, were transported to the sub-chamber relatively recently from the main chamber of Liang Bua and probably originated from conglomerate deposits at the rear of the cave and from deposits around the front entrance. There is no evidence for hominin occupation of the sub-chamber, instead it seems to have acted as a sink for cultural materials and fossil remains transported from the surface via sinkholes. Despite the small number of finds from the test excavation, it is possible that more extensive excavations may yield additional transported cultural and faunal evidence at greater depths. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction The site of Liang Bua, western Flores, is important as the only currently known fossil site of the hominin species, Homo floresiensis (Brown et al., 2004; Morwood et al., 2004)(Fig. 1). These fossil remains have significant implications for our understanding of hominin evolution, migration and cultural development. Liang Bua formed in limestone of Miocene age through karst dissolution that began at least 600 ka and was exposed approximately 190 ka ago by the incision of the Wae Racang River (Westaway et al., 2007, 2009a). Tectonic uplift in the region caused the lowering of the palaeo- water table and the formation and abandonment of dissolution chambers in the limestone which created a stacked system of caves connected by sinkholes known as The Liang Bua cave system (Westaway et al., 2009a). Unlike the main chamber of Liang Bua, a sub-chamber located beneath (23 m  24 m  5.4 m and surface area of w430 m 2 e Gagan et al., 2007) is not exposed and, based on tectonic uplift rates, development is estimated to have begun around 200 ka (Westaway et al., 2009a). Presently, the only means of accessing the sub-chamber is via a 23 m sinkhole (with a slope of 60  ) located in the rear chamber of Liang Bua (Gagan et al., 2007)(Figs. 1 and 2). * Corresponding author. Tel.: þ61 400838640. E-mail address: e.stpierre@uq.edu.au (E.J. St Pierre). Contents lists available at SciVerse ScienceDirect Journal of Archaeological Science journal homepage: http://www.elsevier.com/locate/jas 0305-4403/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jas.2012.07.007 Journal of Archaeological Science 40 (2013) 148e155