Direct dating archeology
This energy is lodged in the imperfect lattices of the mineral's crystals.
Heating these crystals (such as when a pottery vessel is fired or when rocks are heated) empties the stored energy, after which time the mineral begins absorbing energy again.
Thermoluminescence was first clearly described in a paper presented to the Royal Society (of Britain) in 1663, by Robert Boyle, who described the effect in a diamond which had been warmed to body temperature.
The possibility of making use of TL stored in a mineral or pottery sample was first proposed by chemist Farrington Daniels in the 1950s. The potential of using thermoluminescence to date buried soils developed on colluvial and fluvial sediments from Utah and Colorado, U.
This finding has profound implications for our understanding of hunter-gatherer religion in southern Africa.”Research was conducted in the Thune Dam in Botswana, the Metolong Dam area in the Phuthiatsana Valley of Lesotho, and the Drakensberg Escarpment of the Eastern Cape in the ‘Nomansland’ region of South Africa.
A total of 43 new dates were produced from these three areas, including the first direct dates on rock paintings ever in Botswana and Lesotho.
Over the decades rock art has proved extremely difficult to directly date.Better still, unlike radiocarbon dating, the effect luminescence dating measures increases with time.As a result, there is no upper date limit set by the sensitivity of the method itself, although other factors may limit the method's feasibility.Electrons from these substances get trapped in the mineral's crystalline structure, and continuing exposure of the rocks to these elements over time leads to predictable increases in the number of electrons caught in the matrices.But when the rock is exposed to high enough levels of heat or light, that exposure causes vibrations in the mineral lattices and the trapped electrons are freed.