2 examples of relative dating
Relative dating methods are used to determine only if one sample is older or younger than another.
Absolute dating methods are used to determine an actual date in years for the age of an object.
Dendrochronology: Also known as tree-ring dating, the science concerned with determining the age of trees by examining their growth rings.
Half-life: Measurement of the time it takes for one-half of a radioactive substance to decay.
Since certain species of animals existed on Earth at specific times in history, the fossils or remains of such animals embedded within those successive layers of rock also help scientists determine the age of the layers.