Radiometric dating determines the age of rocks and minerals by measuring the amount of radioactive isotopes and their daughter products. Radioactive isotopes decay at a constant rate, with each isotope having a known half-life, or the time it takes for half of the parent atoms to decay into daughter atoms. By measuring the ratio of parent to daughter isotopes in a sample, scientists can calculate the time elapsed since the material formed.
Different isotopes are used for dating different materials and time ranges. For example, carbon-14 dating is used for organic materials up to around 50,000 years old, while uranium-lead dating is used for much older rocks. This method has been essential in establishing the geologic time scale and understanding Earth’s history.