Archaic biological features and organisms are succeeded in the fossil record by more modern versions.
The wavy rock is a old metamorphic gneiss, A and F are faults, B is an igneous granite, D is a basaltic dike, and C and E are sedimentary strata. Now, the underlying mechanism of the principle does allow for the principle to be violated in particular instances.
Stratigraphic succession is the order in which units of rock were deposited over time. The sequence begins with the folded metamorphic gneiss on the bottom. But, since the rhyolite dike does not cut across the shale, we know the shale is younger than the rhyolite dike.
Evolution explains the observed faunal and floral succession preserved in rocks. This section discusses principles of relative time used in all of geology, but are especially useful in stratigraphy.
The final events affecting this area are current erosion processes working on the land surface, rounding off the edge of the fault scarp, and producing the modern landscape at the top of the diagram.