This is a way to estimate the order of geologic events by using rock layers, index fossils, or other methods.

RELATIVE DATING is a way to estimate the order of geologic events by using rock layers, index fossils or other methods. 
Relative dating is used by geologists to arrange geological events in sequential order. Relative dating usually use six principles to determine the relative age of any rock or fossil. The principles are: principle of superposition, principle of original horizontality, principle of lateral continuity, principle of cross cutting, principle of inclusions and principle of fossils succession.

The way of estimating of geologic events by using rock layers, index fossils, or other methods is called Relative Dating