|
|
|
|
 |
|
||
 |
|
||
|
|||
Authentication via Thermoluminescence Testing
The technique of dating by TL measures the emission of light by crystals when submitted to an external source of energy. The process involves taking a small sample for testing. Each sample is ground, washed by chemicals and placed on discs on which the luminescence is counted. In the case of TL, heating provides the source of energy. The heating process provokes the emission of all light stored during geological time in the crystalline structure of a clay piece. By heating the same clay piece a second time, at a much later date, a certain amount of light is emitted. The amount of light emitted is directly proportional to the amount of time between each heating process.
 |
Calibration via Carbon Dating
Found inside some Nok sculpture was some carbonized material, evidently produced during the burn-off of a supporting armature. By measuring the Carbon-14 content, another measure of the age of the terracotta can be deduced. Significantly, the two approaches correlate, narrowing our estimates of the chronological epoch of the Nok culture.
The attached graph shows how the time estimates from the two methods overlap, effectively closing in on the actual archeological era.