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.

Why is it important for biologists to understand how rocks are dated?

Geologists use radiometric dating to estimate how long ago rocks formed, and to infer the ages of fossils contained within those rocks. So in order to date most older fossils, scientists look for layers of igneous rock or volcanic ash above and below the fossil.