Radiocarbon dating is a technique used by scientists to learn the ages of biological specimens – for example, wooden archaeological artifacts or ancient human remains – from the distant past. It can be used on objects as old as about 62,000 years. Here’s how it works.
Radiocarbon dating relies on the carbon isotopes carbon-14 and carbon-12. Scientists are looking for the ratio of those two isotopes in a sample. there’s a near-constant level of carbon-14 to carbon-12 ratio in Earth’s atmosphere.
The same saturated amount remains with the living organism but once the animal dies , it starts to decay. The rate of decay is known to us. Hence, by calculating the C-14/C-12 ratio one can ascertain the age of the rock.