Such events can be dated by luminescence methods and the age employed to determine the age of an archaeological site through its related sediments.
Luminescence dating is an absolute radiometric method of determining the age of a material since a key event in its history - typically burial (in the case of sediments) or firing (in the case of ceramics or burnt stone).
The energy released by stimulating the crystals is expressed in light (luminescence).
The intensity of blue, green or infrared light that is created when an object is stimulated is proportional to the number of electrons stored in the mineral's structure and, in turn, those light units are converted to dose units.
TL dating is a matter of comparing the energy stored in a crystal to what "ought" to be there, thereby coming up with a date-of-last-heated.
In the same way, more or less, OSL (optically stimulated luminescence) dating measures the last time an object was exposed to sunlight.
the emission of a characteristic colour of light) when stimulated.
Stimulation can be achieved by heating (thermoluminescence or TL) or exposure to light (optically-stimulated luminescence or OSL).
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.
Minerals—and, in fact, everything on our planet—are exposed to cosmic radiation: luminescence dating takes advantage of the fact that certain minerals both collect and release energy from that radiation under specific conditions.
Crystalline rock types and soils collect energy from the radioactive decay of cosmic uranium, thorium, and potassium-40.
It is this signal that is the key to luminescence dating techniques.