A central problem in archaeological research has been the Chronometrie dating of petroglyphs (rock engravings). Recent improvements in the understanding of the chemistry of rock varnish (or patina) that develops on rock surfaces in arid regions has resulted in the development of a calibrated dating technique, cation-ratio (CR) dating. This is based on calibrating chemical changes in minor and major trace elements in the varnish over time. PIXE is used to determine the bulk chemical constituents of small samples of varnish mechanically removed from within petroglyphs. Recent applications in western North America have yielded petroglyph dates of great importance in understanding the origins of art and the antiquity of human settlement in the western hemisphere. In particular the CR dates on petroglyphs suggest that humans moved into the New World about 10 K yrs earlier than previously believed, and that the making of petroglyphs was one of the most ancient and long-lived cultural traditions in aboriginal North America.
ASJC Scopus subject areas
- Nuclear and High Energy Physics