Age estimates for the rock art at the Rocky Ridge site (Utah) based on archaeological and archaeometric evidence

Abstract

Rock art provides unique information on human prehistory, but the difficulty of dating these images limits our ability to place them into a larger archaeological context. In this study, we apply a combination of archaeological information and archaeometric measurements to address this challenge in a field study at the rock art site at Rocky Ridge, Utah. We developed a preliminary classification scheme of descriptive figure types and performed measurements of Mn and Fe areal densities by portable X-ray fluorescence (pXRF) to examine the suitability of the rock varnish for deriving age estimates based on the degree of varnish re-accumulation on the petroglyphs. The pXRF-based age estimates indicate rock art creation from the Early Archaic through the Late Prehistoric periods and are generally consistent with independent archaeological information, but also highlight some of the limitations of the technique.