It cannot be used to accurately date a site on its own.
Fossil dating methods relative
Heating an item to 500 degrees Celsius or higher releases the trapped electrons, producing light.
This light can be measured to determine the last time the item was heated. Fluctuating levels can skew results – for example, if an item went through several high radiation eras, thermoluminescence will return an older date for the item.
Carbon-14 moves up the food chain as animals eat plants and as predators eat other animals. It takes 5,730 years for half the carbon-14 to change to nitrogen; this is the half-life of carbon-14.
After another 5,730 years only one-quarter of the original carbon-14 will remain.
The development of accelerator mass spectrometry (AMS) dating, which allows a date to be obtained from a very small sample, has been very useful in this regard.
Other radiometric dating techniques are available for earlier periods.
Absolute dating provides a numerical age or range in contrast with relative dating which places events in order without any measure of the age between events.
In archaeology, absolute dating is usually based on the physical, chemical, and life properties of the materials of artifacts, buildings, or other items that have been modified by humans and by historical associations with materials with known dates (coins and written history).
K-Ar dating was used to calibrate the geomagnetic polarity time scale.
Thermoluminescence testing also dates items to the last time they were heated.
Many factors can spoil the sample before testing as well, exposing the sample to heat or direct light may cause some of the electrons to dissipate, causing the item to date younger.