Using relative dating the fossil is compared to something for which an age is already known.For example if you have a fossil trilobite and it was found in the Wheeler Formation.
The atoms of each element may vary slightly in the numbers of neutrons within their nuclei.
Each atom is thought to be made up of three basic parts.
The nucleus contains protons (tiny particles each with a single positive electric charge) and neutrons (particles without any electric charge).
Scientists can use certain types of fossils referred to as index fossils to assist in relative dating via correlation.
Index fossils are fossils that are known to only occur within a very specific age range.
There are two main methods determining a fossils age, relative dating and absolute dating.