Knowing when a dinosaur or other animal lived is important because it helps us place them on the evolutionary family tree.Accurate dates also allow us to create sequences of evolutionary change and work out when species appeared or became extinct. These are: Where possible, several different methods are used and each method is repeated to confirm the results obtained and improve accuracy.Geologists establish the age of rocks in two ways: numerical dating and relative dating.Numerical dating determines the actual ages of rocks through the study of radioactive decay.Relative dating is a dating method that used to determine determine the relative ages of geologic strata, artifacts, historical events, etc.This technique does not give specific ages to items.
Uranium is present in many different rocks and minerals, usually in the form of uranium-238.
Different methods have their own limitations, especially with regard to the age range they can measure and the substances they can date.
A common problem with any dating method is that a sample may be contaminated with older or younger material and give a false age.
Between the years of 17, James Hutton and William Smith advanced the concept of relative dating.
Hutton, a Scottish geologist, first proposed formally the fundamental principle used to classify rocks according to their relative ages.