Scientists measure the proportion of carbon-14 left in the organism to determine its age.
Continue Reading Relative dating observes the placement of fossils and rock in layers known as strata.
Basically, fossils and rock found in lower strata are older than those found in higher strata because lower objects must have been deposited first, while higher objects were deposited last.
For example, carbon dating is used to determine the age of organic materials.
Once something dies, it ceases taking in new carbon-14, and the existing carbon-14 within the organism decays into nitrogen at a fixed rate.
He is presently employed in the Space & Atmospheric Sciences Group at the Los Alamos National Laboratory.Radiometric dating--the process of determining the age of rocks from the decay of their radioactive elements--has been in widespread use for over half a century.