Relative dating methods allow one to determine if an object is earlier than, later than, or contemporary with some other object.It does not, however, allow one to independently assign an accurate estimation of the age of an object as expressed in years.ugs / online publications / survey notes / glad you asked / rock ages How Do Geologists Know How Old a Rock Is?by Mark Milligan Geologists generally know the age of a rock by determining the age of the group of rocks, or formation, that it is found in.Furthermore, useful fossils are either rare or totally absent in rocks from Precambrian time, which constitutes more than 87 percent of Earth history.Precambrian rocks must therefore be correlated by means of precise isotopic dating.

To tell it simply, fossils and archaeological objects are supposed to have the same age as the sediment in which they are embedded.The most common relative dating method is stratigraphy.Other methods include fluorine dating, nitrogen dating, association with bones of extinct fauna, association with certain pollen profiles, association with geological features such as beaches, terraces and river meanders, and the establishment of cultural seriations.is, as mentioned earlier, the technique of piecing together the informational content of separated outcrops.When information derived from two outcrops is integrated, the time interval they represent is probably greater than that of each alone.