The other method is “Relative Dating” which gives an order of events without giving an exact age (1): typically artefact typology or the study of the sequence of the evolution of fossils.There are three carbon isotopes that occur as part of the Earth's natural processes; these are carbon-12, carbon-13 and carbon-14.

Isotopes participate in the same chemical reactions but often at differing rates.

When isotopes are to be designated specifically, the chemical symbol is expanded to identify the mass (for example, C is not stable.

The amount of carbon-14 in the air has stayed the same for thousands of years.

There is a small amount of radioactive carbon-14 in all living organisms because it enters the food chain.

Common materials for radiocarbon dating are: The radiocarbon formed in the upper atmosphere is mostly in the form of carbon dioxide. Because the carbon present in a plant comes from the atmosphere in this way, the radio of radiocarbon to stable carbon in the plant is virtually the same as that in the atmosphere.