Radioactive Dating of Fossils Scientists find the ratio of parent isotope to daughter isotope. By comparing this ratio to the half-life logarithmic scale of the parent isotope, they are able to find the age of the rock or fossil in question.

## How does radioactive dating determine the age of fossils?

Geologists use radiometric dating to estimate how long ago rocks formed, and to infer the ages of fossils contained within those rocks. The universe is full of naturally occurring radioactive elements. Radioactive atoms are inherently unstable; over time, radioactive parent atoms decay into stable daughter atoms.

## How is radioactive decay used to date rocks?

Radioactive decay can be used to date igneous rocks by assuming making some assumptions, finding the percentages of parent to daughter products and using experimentally determined half-lives.