Optical dating of rock art
This article describes the principles of optical dating-an umbrella term for a family of related techniques based on the storage of radiation energy in light-sensitive traps in natural minerals-and its application to rock art. Optical dating has been applied predominantly to sand- and silt-sized grains of quartz (optically stimulated luminescence, OSL) and feldspar (infrared stimulated luminescence, IRSL) that were exposed to sunlight prior to deposition, where the age represents the time elapsed since the grains were last bleached by the sun's rays. Only a few studies have used OSL or IRSL dating to constrain the age of rock paintings and engravings, and these applications can be grouped under two broad headings: dating of associated sediments and dating of rock surfaces. These studies are briefly reviewed in this chapter, together with some comments on future directions and challenges for OSL and IRSL dating of rock art.