Comparing relative dating to absolute dating
The amount of carbon 14 remaining in the material to date is compared to a reference standard (ratio 14C/total carbon, 12C and 13C) to calculate the time elapsed since its occurrence.
A sample requires 10 to 20 grams of matter and usually consists of charred organic material, mainly charcoal, but bones (zooarchaeology) and shells can also be dated using this technique.
Dendrochronology mainly uses softwood species that are sensitive to changes in growth conditions, while hardwoods show rather little variation in ring width.
Subsequently, the calibration of that date provides a time interval where the event or object being dated can be situated (eg, 1275-1425 AD).
Radiocarbon dating, however, can only be used for dating objects that are less than 50 000 years.
There are two main categories of dating methods in archaeology: indirect or relative dating and absolute dating.
Relative dating includes methods that rely on the analysis of comparative data or the context (eg, geological, regional, cultural) in which the object one wishes to date is found.