Radiometric dating Radioisotopes can be used to date rocks. Rocks often contain traces of uranium which is a radioisotope. It is unstable and eventually decays to form lead, which is stable. Isotopes have a property know as their half-life.

Why is it important to date rocks?

Dynamic Earth - Dating rocks. Gaining estimates of ages of rocks is crucial for establishing not only the history of geological events but also for determining the rates of geological processes. It is possible to establish the relative order of events in some rocks.