Try it risk-free Discover how geologists study the layers in sedimentary rock to establish relative age.Learn how inclusions and unconformities can tell us stories about the geologic past.Some fossils, called index fossils, are particularly useful in correlating rocks.

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Relative dating cannot establish absolute age, but it can establish whether one rock is older or younger than another.

Relative dating requires an extensive knowledge of stratigraphic succession, a fancy term for the way rock strata are built up and changed by geologic processes.

Different species of ammonites lived at different times within the Mesozoic, so identifying a fossil species can help narrow down when a rock was formed.

Correlation can involve matching an undated rock with a dated one at another location.

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Plus, get practice tests, quizzes, and personalized coaching to help you succeed.Suppose you find a fossil at one place that cannot be dated using absolute methods.That fossil species may have been dated somewhere else, so you can match them and say that your fossil has a similar age.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.Throughout the history of life, different organisms have appeared, flourished and become extinct.