What is Radiometric Dating?

Radiometric dating is a technique used to determine the age of rocks, fossils, and other geological materials by measuring the decay of radioactive isotopes. This method relies on the principle that certain isotopes decay at a predictable rate, known as their half-life. By measuring the ratio of parent isotopes to daughter isotopes in a sample, scientists can calculate how long it has been since the material was formed or last heated. Radiometric dating is an important tool for understanding the history of Earth and the evolution of life on our planet.

What Is Radiometric Dating

Forms of Radiometric Dating

Carbon Dating

Animals take in carbon across their lifetimes as they eat. A certain proportion of this carbon will be the unstable C14. After the animal dies, it will no longer take in more C14. As we know the half life of C14, we can determine when the animal died by measuring the amount of C14 still present in its body.

Potassium - argon dating

When volcanic rocks form, any argon inside it is released into the atmosphere and none can re-enter the rock after it cools and solidifies. This means that any argon present in the rock must have been caused by the decay of radioactive potassium. Measuring the ratio of potassium to argon allows us to date the sample.

Uranium - Lead Dating

This method uses a cross-checking system measuring the ratio of various uranium and lead isotopes in very old rocks.

Fission-track dating

This measures the density of marks left in a polished surface by the spontaneous fission of impurities in uranium. It can date naturally occurring minerals and man-made glass.

Chlorine-36 dating

This measures the prevelance of a rare isotope produced in the atmosphere by the action of cosmic rays on argon. It can be used to date groundwater.

Luminescence Dating

Not technically a form of radiometric dating because it does not measure radioactive isotopes - though it does still use radioactive material.