Geologists often need to know the age of material that they find. They use absolute dating methods, sometimes called numerical dating, to give rocks an actual date, or date range, in numbers of years. This is different to relative dating, which only puts geological events in time order.

How do scientist do relative dating?

Scientists also use direct evidence from observations of the rock layers themselves to help determine the relative age of rock layers. By correlating fossils from various parts of the world, scientists are able to give relative ages to particular strata. This is called relative dating.