ReviewUranium series dating reveals a long sequence of rock art at Altamira Cave (Santillana del Mar, Cantabria)
Introduction
Rock art was originally dated by making stylistic comparisons with the depictions on portable objects recovered from datable archaeological levels and by studying the order of superimposed figures (Lorblanchet, 1995: 241–280). The first method provided evidence of the synchronicity of the figures, whereas the second revealed diachronic differences. Later, accelerator mass spectrometry radiocarbon dating (Valladas et al., 2005) opened new perspectives as a way to obtain radiometric dates and determine the diachronic development and synchronic and spatial variability of Palaeolithic art. This method has specific limitations in procedure (size of the samples, problems of contamination) and interpretation of the results (e.g. the possible use of charcoal some time after the fuel – either wood or bone – was burnt) (Clottes and Valladas, 2003; Pettit and Bahn, 2003; Valladas, 2003). Additionally, as this method could only be applied to black paintings made with organic matter (charcoal), it meant that few depictions painted in the first half of the Upper Palaeolithic could be dated, as most black figures were produced in the middle and late phases of the Magdalenian period (Valladas et al., 2005; Alcolea and Balbín, 2007; Pettitt and Pike, 2007; Ochoa, 2011). Due to these problems, Uranium series dating of carbonates directly associated with the parietal art is an indispensable procedure to obtain high-quality chronological information for engravings and paintings made with inorganic colouring matter (Aubert et al., 2007; Taçon et al., 2012).
Precise chronological determinations of cave art are essential to be able to understand and study the social and symbolic structure of human groups, and advance beyond the inferences made from generic considerations. For instance, it is necessary to determine which figures are synchronic or diachronic, the relationship between the human occupations in the caves and the production of parietal art, and the number of times the same places were used for symbolic acts. It is therefore necessary to apply high-resolution chronological procedures to obtain precise information about the dates of Palaeolithic rock art ensembles and approach the symbolic structure of Palaeolithic human groups with greater precision.
In an attempt to provide greater chronological constraints on cave art in northern Iberia, Pike et al. (2012) reported 50 U-series determinations on calcite deposits overlying, and occasionally underlying cave paintings and engravings from 11 caves in Spain. Here we report in greater detail on the dates Pike et al. (2012) obtained from Altamira Cave and integrate them with site's broader archeological context.
Section snippets
Altamira Cave: archaeological context and palaeolithic cave art
Altamira Cave, listed as World Heritage by UNESCO in 1985, is located in the north of the Iberian Peninsula, in Santillana del Mar (Cantabria, Spain) (Fig. 1). It was the first cave where Palaeolithic cave art was identified, as the discoverer, Marcelino Sanz de Sautuola, affirmed in 1880 that the engravings and paintings were Palaeolithic in age (Sautuola, 1880). This claim, which implied that “Prehistoric Men” were capable of producing Art, was widely dismissed, and the controversy about the
Method
The decay of radioactive 238U to radiogenic and radioactive 234U and 230Th can be used to date the formation of calcite precipitates such as stalactites and stalagmites (e.g. Ivanovich and Harmon, 1992; Richards and Dorale, 2003). Where these precipitates have formed directly on cave paintings or engravings, the date of precipitation can provide a minimum age for the underlying art, or where previously precipitated calcite has been painted a maximum age can be provided. The sample removal,
Sampling and results
A total of eight calcite samples associated with the rock art were taken and analysed by the Uranium series method. Four samples were either taken for a minimum age determination but not dated because of detrital contamination detected at an early stage of the analysis, or taken for a maximum age determination and their age turned out to be too old for them to be of any significance. The representations associated with the relevant samples are (Table 1):
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BIG-UTh-O-71 (a and b; Table 1 and Fig. 4
Discussion
Detrital contamination was a problem for many of the samples taken at Altamira Cave. However, three (BIG-UTh-O-46, 50 and 53) of the samples contained acceptable levels of contamination and yielded meaningful dates. This proportion justifies the application of the method as a way to obtain valuable chronological information for Palaeolithic parietal art. In addition, Uranium series dating is a vital tool in discussions about the authenticity of figures, as the dates of even Holocene carbonates
Conclusion
Uranium-series dating is a geo-chronological procedure enabling the determination of a minimum age for Palaeolithic parietal art. The results obtained by sampling calcite deposits at Altamira Cave show that part of the non-figurative graphic ensemble belongs at least to the Aurignacian period, during the first expansion of Homo sapiens in the Iberian Peninsula. The thematic and stylistic similarities between the motifs associated with the dated samples and other representations on the
Acknowledgements
This research was funded by a grant to AWGP from the Natural Environmental Research Council (NE/F000510/1) and a grant (Climatic Background and Chronology of Iberian Upper Paleolithic Cave Art -CGL2011-27187-) to DLH from the Ministerio de Ciencia e Innovación (Spanish Government). The research of MGD was supported by the High Yield Research Group of Prehistory (IT622-13). We are grateful to Carolyn C. Taylor who performed the sample preparation, and assisted in collecting samples in the field
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