Relative dating geology examples
Techniques include tree rings in timbers, radiocarbon dating of wood or bones, and trapped-charge dating methods such as thermoluminescence dating of glazed ceramics.
Coins found in excavations may have their production date written on them, or there may be written records describing the coin and when it was used, allowing the site to be associated with a particular calendar year.
Thus dating that particular tree does not necessarily indicate when the fire burned or the structure was built.
For this reason, many archaeologists prefer to use samples from short-lived plants for radiocarbon dating.
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.
Because of these and other factors, Thermoluminescence is at the most about 15% accurate.
This is a radiometric technique since it is based on radioactive decay.
Cosmic radiation entering the earth’s atmosphere produces carbon-14, and plants take in carbon-14 as they fix carbon dioxide.
This process frees electrons within minerals that remain caught within the item.
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.