Petroglyphs and Pictographs

A major limitation in rock art studies is that rock art can be difficult to date. The dating techniques currently in use fall into two broad categories: relative dating and absolute dating.

Relative dating techniques include observations of patterns of chemical and physical weathering, evidence that art has been painted over, stylistic patterns, and variations in the spatial patterns of rock art indicating chronological sequences of site occupation.

Absolute dating methods include analyses based on subjects depicted (e.g., representations of extinct animals), one-to-one mappings with datable deposits, dating of stratified deposits associated with the rock art, and the actual dating of the art itself.

Occasionally, it has been possible to date rock art directly by chemically analyzing the organic materials that were used to draw it, for example, charcoal, plant fibers, and protein binders. A major problem with this approach, however, is that the sampling procedure damages the rock art to a certain extent.

Dating technologies include standard radiocarbon dating, cation ratio analysis (based on separate rates of leaching for the chemical constituents of desert varnishes), amino acid racemisation (based on the decomposition rates of amino acids), optically stimulated luminescence (based on the length of time that quartz grains have been removed from sunlight), lichenometry (based on lichen growth rates), and micro-erosion analyses (based on weathering patterns).