Archaeometry

When certain materials such as quartz, feldspar, and flint are buried, they store trapped electrons that are deposited by background sources of nuclear and cosmic radiation. As long as the material is buried, the population of trapped electrons accumulates at a constant rate. Once the material is exposed to daylight or heat, however, the trapped electrons are released from their traps. By monitoring the luminescence produced by the released electrons, it is possible to determine the length of time that an object has been underground.