Continue Reading During the formation of the Earth, radioactive elements became embedded in the minerals that make up the Earth's crust.
In our atmosphere there are particles of carbon, when rays from the sun hit them it turns a few of them into carbon 14 (a radioactive carbon).
The other two isotopes in comparison are more common than carbon-14 in the atmosphere but increase with the burning of fossil fuels making them less reliable for study (2); carbon-14 also increases, but its relative rarity means its increase is negligible. After this point, other Absolute Dating methods may be used.
Today, the radiocarbon-14 dating method is used extensively in environmental sciences and in human sciences such as archaeology and anthropology.
Living things contain carbon-14 and carbon-12 in a ratio that is the same as in the atmosphere at the time.
When the organism dies, the ratio of carbon-14 to carbon-12 decreases, as carbon-14 decays and is no longer incorporated into the organism.
Radiometric dating works by determining the ratio of the number of isotopes of an element and the number of isotopes the element it turns into over time.