In order to answer this question, fossils are of crucial importance.
The paleontological method is based on the study and interpretation of animal and vegetal organisms’ evolution during geological history, and in order to determine the relative age of a rock, the principle of superposition is used as a starting point, as well as fossil deposits preserved within a rock.
It dates durations of events in terms of seconds, years, millions of years, etc.
Although the Geologic Column was developed as a relative time scale, geologists wanted to figure out the numerical age dates for Era-Era boundaries and other events.
In defining the order of deposits by relative dating, only the order of deposits has been determined, i.e.Index fossils are often used to determine a specific era.Sedimentary rocks naturally form horizontal layers (strata, singular stratum).Only certain types of fossils are useful for correlation.
To be a good index fossil, the species should: Using index fossils, geologists were able to correlate across Europe, and then to other continents. Reference Websites For more information about relative geological time check out the USGS website: