List of absolute dating methods - Absolute dating Science Learning Hub


One of the most widely used and well-known absolute dating techniques is carbon-14 (or radiocarbon ) dating, which is used to date organic remains. This is a radiometric technique since it is based on radioactive decay. Carbon-14 is an unstable isotope of normal carbon, carbon-12. Cosmic radiation entering the earth’s atmosphere produces carbon-14, and plants take in carbon-14 as they fix carbon dioxide. Carbon-14 moves up the food chain as animals eat plants and as predators eat other animals. With death, the uptake of carbon-14 stops. Then this unstable isotope starts to decay into nitrogen-14. It takes 5,730 years for half the carbon-14 to change to nitrogen; this is the half-life of carbon-14. After another 5,730 years only one-quarter of the original carbon-14 will remain. After yet another 5,730 years only one-eighth will be left. By measuring the proportion of carbon-14 in organic material , scientists can determine the date of death of the organic matter in an artifact or ecofact .

In an undisturbed sequence of rocks, such as in a cliff face, it is easy to get a rough idea of the ages of the individual strata – the oldest lies at the bottom and the youngest lies at the top. This is because new sediments are always laid down on top of sediments that have already been deposited. So, when looking at the history of a cliff face, it is important to read the story it tells from the bottom layer up.


List of absolute dating methods

List of absolute dating methods