Rock Art Research

A review of the history of uranium-series dating of fossil bone and calcite skins related to rock paintings reveals significant limitations to the credibility of many such results. The ‘closed system’ conditions required do not seem to apply to many ancient faunal remains and may be lacking in many cases also in the types of speleothems frequently used to secure minimum or maximum ages for cave paintings or petroglyphs. The studies comparing 14C dates with U–Th results from such reprecipitated carbonates, particularly of the Pleistocene, suggest that the latter tend to be much higher. Recent testing of the method implies that the taphonomy of most such deposits is far too complex to allow the determination of age-governed 230Th/234U ratios. The U concentrations in coeval calcite skins vary significantly on a millimetre scale, and in some cases, apparent ages can be hundreds of times greater than actual ages. Tests also reveal that results obtained by different laboratories from the same samples differ greatly. The lack of reproducibility and testability of such results, combined with the interventional method of obtaining samples, excludes it from sustainable approaches to rock art dating.