A method to date rock engravings using luminescence – tested at Murujuga, Western Australia

Abstract

Rock engravings are globally ubiquitous, provide evidence for symbolic behaviours, and demonstrate connections to country and the desire to communicate with other humans. However, rock engravings have proven difficult to date. The development of luminescence rock surface dating approaches has the potential to address this deficiency in applicable dating techniques. Specifically, luminescence rock surface exposure dating methods can be used to tell how long a rock surface has been exposed to sunlight, thus providing a potential avenue to date rock engravings. Here, we present results from laboratory and field bleaching experiments from the Murujuga rock art complex in Western Australia. Four major art-bearing lithologies are petrographically characterised and tested for useable luminescence signals. Three bleaching experiments are conducted: two in the laboratory and one at the study area. The gabbro and microgranite lithologies are shown to be bleachable and show potential for rock surface burial dating. The microgranite can be used to accurately estimate exposure duration over the timescales tested in all experiments, demonstrating promising potential to date rock engravings.