To establish the age of a rock or a fossil, researchers use some type of clock to determine the date it was formed. Geologists commonly use radiometric dating methods, based on the natural radioactive decay of certain elements such as potassium and carbon, as reliable clocks to date ancient events.

How are fossils dated kids?

Fossils may be dated by taking samples of rocks from above and below the fossils original position. Radiometric dating is also used to date archaeological materials, including ancient artifacts. Radiometric dating methods are used to establish the geological time scale.