Take the example, Figure
Dating Rocks and Fossils Using Geologic Methods
If both the blue and orange ammonites are found together, the rock must have been deposited during the time interval indicated by the red box, which represents the time during which both fossil species co-existed. Every reversal looks the same in the rock record, so other lines of evidence are needed to correlate the site to the GPTS. The strata A to E was deposited first, tilted, subjected to erosion peneplained and submerged. The atomic nucleus in C 14 is unstable making the isotope radioactive. The isotope that forms as a result of radioactive decay electrons: Hutton also was the first to realize the vast amounts of time that would be needed to create an unconformity, a place where sedimentary rocks lie above an eroded surface. Determination of the absolute age of rocks and minerals using certain radioactive isotopes.