A sealed flint knapping site from the Younger Dryas in the Scheldt valley (Belgium): Bridging the gap in human occupation at the PleistoceneeHolocene transition in W Europe Philippe Cromb  e a, * , Joris Sergant a , Arne Verbrugge b , Arne De Graeve b , Bart Cherrett  e b , Jari Mikkelsen b , Veerle Cnudde c , Tim De Kock c , Hans D.J. Huisman d , Bertil J.H. van Os d , Mark Van Strydonck e , Mathieu Boudin e a Department of Archaeology, Ghent University, Sint-Pietersnieuwstraat 35, B-9000 Ghent, Belgium b SOLVA, Joseph Cardijnstraat 60, B-9420 Erpe-Mere, Belgium c Department of Geology and Soil Science, Ghent University, Krijgslaan 281/S8, B-9000 Ghent, Belgium d Cultural Heritage Agency, Smallepad 5, 3811 MG, Amersfoort, The Netherlands e Royal Institute for Cultural Heritage, Jubelpark 1, B-1000 Brussels, Belgium article info Article history: Received 13 May 2014 Received in revised form 9 July 2014 Accepted 20 July 2014 Available online 7 August 2014 Keywords: Late Glacial Younger Dryas Lithic technology Climate change Raw material procurement abstract Based on the evidence of a recently excavated, sealed site, situated at Ruien “Rosalinde” in the Belgian Scheldt valley, the response of hunter-gatherers to changing climate at the transition from the temperate Allerød to the cold Younger Dryas is discussed. Radiocarbon dated to the end of the Allerød or the very beginning of the Younger Dryas, the site of Ruien provides the earliest evidence of a refined lithic technology characterized by the use of a soft stone hammer and the production of straight and regular blade(let)s from intensively prepared cores with two opposite platforms and sharp striking angles. In the course of the Younger Dryas and Early Pre-boreal this knapping method will become standard all over Europe, from the Tanged Point Technocomplex in the North to the (Epi)Laborian in the South. It contrasts sharply with the knapping style of previous lithic traditions, such as the late Federmesser/Azilian and Bromme Technocomplexes, which was much less elaborated and mainly oriented towards the knapping of short irregular blades with a hard stone hammer. This apparently abrupt technological change was also accompanied by increased raw material procurement networks, extending over up to 250 km, and a marked microlithisation of the hunting equipment. Finally, the site of Ruien is also important as it demonstrates the limited archaeological visibility of Younger Dryas sites, explaining the scarcity of such sites within western Europe. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Despite long-term and extensive interdisciplinary research into the Late Glacial (Final Palaeolithic) and Early Holocene (Mesolithic), the Scheldt basin in western Belgium still completely lacks evi- dence of human occupation dating to the Younger Dryas (YD) and Pre-boreal (PB) (Cromb e and Verbruggen, 2002; Cromb e et al., 2014). This contrasts sharply with the very high site density dur- ing the preceding Allerød and posterior Boreal, when the Scheldt basin was occupied by hunter-gatherers belonging respectively to the Federmesser Culture (or Curve-Backed Point Groups, CBP) and the Early Mesolithic (Cromb e et al., 2011, 2013b). Except for some stray-finds of lithic armatures (Cromb e et al., 2013b; Devriendt et al., 2010), no clear occupation sites belonging to either the (Epi)Ahrensburgian or (Epi)Laborian are currently known, resulting in an apparent occupation hiatus of ca. 2 millennia. A similar occupational gap has been attested in other research areas within western Europe (Fig. 1), e.g. in northern and western France (Fagnart and Coudret, 2000; Naudinot, 2013; Valentin, 2008), western Netherlands (Arts and Deeben, 1981) and Britain (Barton and Dumont, 2000). Except for a series of special purpose sites belonging to the Bruised/Long Blade or Belloisian Technocomplex (Barton, 1998; Barton and Dumont, 2000; Fagnart, 2009; Valentin, 2009) and dated to the transition from the YD to the PB, less than ten sites (Ercheu, Vieux-Moulin, Reuil-Malmaison, La Fosse, etc.) * Corresponding author. Tel.: þ32 9 331 01 53. E-mail address: philippe.crombe@ugent.be (P. Cromb e). Contents lists available at ScienceDirect Journal of Archaeological Science journal homepage: http://www.elsevier.com/locate/jas http://dx.doi.org/10.1016/j.jas.2014.07.021 0305-4403/© 2014 Elsevier Ltd. All rights reserved. Journal of Archaeological Science 50 (2014) 420e439