Quaternary International 223-224 (2010) 293–298 Contents lists available at ScienceDirect Quaternary International journal homepage: www.elsevier.com/locate/quaint A 300–600 ka ESR/U-series chronology of Acheulian sites in Western Europe Christophe Falgue`res a,*, Jean-Jacques Bahain a, Mathieu Duval a,c, Qingfeng Shao a, Fei Han a, Matthieu Lebon a, Norbert Mercier b, Alfredo Perez-Gonzalez c, Jean-Michel Dolo d, Tristan Garcia d a De´partement de Pre´histoire du Muse´um national d’Histoire naturelle, UMR 7194 CNRS, 1 rue Rene´ Panhard, 75013 Paris, France b Institut de Recherche sur les Arche´omate´riaux, UMR 5060 CNRS, Universite´ de Bordeaux, Centre de Recherche en Physique Applique´ea` l’Arche´ologie (CRP2A), Maison de l’Arche´ologie, 33607 Pessac Cedex, France c National Research Center on Human Evolution (CENIEH), Avenida de la Paz 28, 09004 Burgos, Spain d CEA, LIST, Laboratoire National Henri Becquerel, 91191 Gif-sur-Yvette, France article info abstract Article history: For a long time, the establishment of the chronology of Acheulian settlements in Western Europe was Available online 30 October 2009 restrained by the lack of reliable dating methods. During the Middle Pleistocene, the archaeological sites in this area are generally associated with fluvio-lacustrine and karstic contexts. The main geochrono- logical methods (e.g. K/Ar, Ar/Ar, U-series, OSL and TL) could not be applied because of a lack of suitable material for dating, or the expected ages were beyond the upper limit of the dating technique. For several years, the combination of ESR and U-series data has allowed the direct dating of palaeontological remains from the entire Middle Pleistocene period. Combined ESR/U-series dating was applied to several major Acheulian sites in Spain, Italy and France. This paper presents the dating results, their implications for the chronology of the Acheulian in Western Europe as well as the methodological limits of the ESR/U- series dating method caused by the effect of weathering on the uranium uptake into the teeth. Ó 2009 Elsevier Ltd and INQUA. All rights reserved. 1. Introduction archaeological strata that contain evidence of human occupation. The method is particularly well suited for sites between 300 and at For a long time, it has been difficult to establish the chronology least 800 ka. In many cases, it is the only method which can be of the early Acheulian settlements in Western Europe because of applied beyond 500 ka in carbonate and karst environments the lack of suitable dating methods. Most Acheulian archaeological (Fig. 1). Subsequent applications have resulted in a number of sites are associated with fluvial or lacustrine environments or karst publications reporting the dates of many Pleistocene archaeological infillings. The most commonly used geochronological methods, sites (Schwarcz et al., 1989; Gru¨ n et al., 1996; Falgue`res et al., 1999). such as 40K–40Ar, 39Ar–40Ar, thermoluminescence (TL) or U-series, This paper focuses on the period between 300 and 600 ka in usually cannot be applied, because the age of the sites is beyond the Western Europe, and particularly in northern Spain, in Italy, and in range of these methods or did not contain materials suitable for France, which is particularly interesting for the arrival of the dating. Acheulian culture, probably in association with a settlement phase Electron Spin Resonance (ESR) dating was first applied to fossil from Africa or the Middle East (Goren-Inbar et al., 2000). During the teeth in the 1970s (Ikeya, 1978) and appeared to have great Lower Pleistocene, the oldest European archaeological evidences potential to address this problem. However, ESR dating was greatly are restricted to the southern part of Europe (Guadix-Baza Basin, hampered by the problem of the unknown U-uptake, which may Sierra de Atapuerca, Spain; Ceprano, Italy) and their lithic assem- cause very large errors. Ten years later, a model combining ESR and blages do not contain bifaces. On the other hand, the oldest U-series data was proposed which made it possible to calculate Acheulian sites, dated around 600–700 ka, have been found at a specific uranium uptake parameter p for each dental tissue and a latitude north of 45 in Europe, like Pakefield in Great Britain a single age for each tooth (Gru¨ n et al., 1988). The development of (Parfitt et al., 2005; Roebroeks, 2005) and La Noira in Central France this combined ESR/U-series (ESR–US) model applied on fossil (Desprie´e et al., 2009, 2010). During the same period, the Acheulian dental enamel allows the calculation of direct ages for culture seems to have been absent or just emerging in the southern part of the continent. Hence, at Isernia la Pineta, a locality in southern Italy dated to 600 ka by 39Ar/40Ar method (Coltorti et al., * Corresponding author. 2005), no bifaces were found among the very abundant lithic E-mail address: [email protected] (C. Falgue`res). assemblage (Peretto, 2006) while in the same region, at Venosa, 1040-6182/$ – see front matter Ó 2009 Elsevier Ltd and INQUA. All rights reserved. doi:10.1016/j.quaint.2009.10.008 294 C. Falgue`res et al. / Quaternary International 223-224 (2010) 293–298 Fig. 1. Applicability range for the main numerical dating methods available for the last two million years. The blue space corresponds to the period covered by radiocarbon dating. The yellow to red space is the domain of TL dating on burnt flints and of U-series dating. The three columns correspond to the main different environments in which archaeological sites are found in Western Europe. In comparison with other methods, the ESR/U-series method applied on teeth has the advantage to be potentially applied on the three domains. For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article. several localities dated to between 500 and 600 ka display Hence, a major potential of the combined ESR–US method is to Acheulian assemblages (Piperno et al., 1998). In northern France, provide an alternative way to establish a reliable chronological the probable migration route between the European continent framework of the human settlement in non-volcanic contexts. and the British Isles, the oldest Acheulian localities, such as Moreover, as shown by the samples presented in this paper, this Cagny-la-Garenne in the Somme Valley or La-Celle-sur-Seine, in method also yields chronological information for the uranium the Seine Valley, were dated to around 450 ka and earlier, uptake in teeth and geochemical behaviour of uranium in dental Acheulian evidence is scarce and poor (see Antoine et al., 2010). tissues, and thus on the taphonomy of the localities. Thus, the establishment of a reliable chronology is crucial to understand the timing and dynamics of the Acheulian settle- 2. Methods ments of Europe. For the period between 300 and 600 ka, it is possible to obtain One of the major difficulties in dating large herbivorous teeth is U-series dates on speleothems which are in stratigraphical relation linked to the complexity of the system which has to be considered. with the human remains and Acheulian levels. At Arago Cave, A mammal tooth consists of several tissues (enamel, dentine and France, a set of more than 50 U-series dates on a stalagmitic cement), which have different chemical compositions (see Hillson, floor located stratigraphically above the Acheulian palae- 2005) and sensitivities to diagenetic processes (Piepenbrink, 1989; oanthropological layers suggests that the human remains Kohn et al., 1999; Dauphin and Williams, 2004), inducing unearthed from these levels and associated lithic industry are older differential U-incorporations. Fossil bones and teeth usually behave than 350 ka (Falgue`res et al., 2004). Mass spectrometric U-series as open systems, increasing the difficulty to get reliable ages. But dating can provide age results with much higher precision. because of fossilization and taphonomic conditions according to For example, at the Acheulian site of Orgnac 3, France, a stalagmitic the nature of the site, cave or open-air locality, the degree of formation was dated by Thermal Ionization Mass Spectrometry ‘‘opening’’, in terms of uranium uptake, can be very different from (TIMS) to a maximum age of 318 Æ 9 ka for the upper human levels one tissue to another from the same tooth, or from one site to (Ayliffe, personal communication). This result confirms those another (Gru¨ n, 2009). previously obtained by ESR and U-series on the same calcitic level The combined ESR–US model allows an estimation of the history (Falgue`res et al., 1988). However, the use of these methods is of uranium uptake in each dental tissue using a one parameter restricted to karst sites and to travertine localities such as La-Celle- (p-value) diffusion equation. This approach is different to the sur-Seine, where the Acheulian layer is overlain by a thick conventional methods where the mode of uranium uptake is carbonate tufa dated by TIMS to around 390 ka (Limondin-Lozouet assumed, such as the early uptake (EU) model which postulates et al., 2006, 2010). that uranium was incorporated shortly after the sample was buried C. Falgue`res et al. / Quaternary International 223-224 (2010) 293–298 295 In Gru¨ n et al. (1988), the uranium content of each dental tissue is then given by the following general equation: UðtÞ¼Umðt=TÞp þ 1 (1) where U(t) ¼ U concentration at time t, Um ¼ measured U concen- tration, and T ¼ age. Using the isotopic ratios of U-series and the DE values, one can calculate the evolution of the internal dose rate. The definition range is limited to p-values greater than or equal to À1, i.e.