On-site spectroradiometric analysis of Palaeolithic cave art: Investigating colour variability in the red rock art of Points cave (France)

Abstract

The colour of Palaeolithic cave art is an important parameter to consider when examining possible links between different pieces of rock art. Recent developments in portable, non-invasive spectroradiometry have given researchers the ability to carry out in-situ colorimetric analyses of rock art, even in deep-cave environments. Although these methods provide quantitative data that can be used to compare the colours of different paintings, differences in chromaticity values can be difficult to interpret from an archaeological point of view.We investigated factors that may contribute to this colour variability by combining a series of visible spectroradiometric analyses of the Palaeolithic red rock art in Points Cave (Aiguèze, France) with macrophotography of the surfaces analysed. This fieldwork was supplemented by laboratory experiments to produce reference data we could use to assess the impact of environmental factors on the results of the in-situ spectroradiometric analyses.The variability in the chromaticity values we obtained can be explained almost entirely by colour differences in the underlying cave wall and by the extent to which the pigment layer masks the substrate. These results suggest that the rock art in Points Cave is homogenous in colour and support the hypothesis suggested by archaeological analyses that the rock art belongs to a single prehistoric iconographic project.