What is absolute and relative age dating
With the development of miniaturized analytical equipment, evaluation of rock properties down a small drill hole has become possible.
The technique, called well logging, involves lowering a small instrument down a drill hole on the end of a wire and making measurements continuously as the wire is played out in measured lengths.
Following Smith’s pioneering work, generations of geologists have confirmed that similar and even more extensive fossil sequences exist elsewhere.
Smith’s geologic map was extremely crude, but in its effect on Earth study it was a milestone.Correlating two separated outcrops means establishing that they share certain characteristics indicative of contemporary formation.The most useful indication of time equivalence is similar fossil content, provided of course that such remains are present.The basis for assuming that like fossils indicate contemporary formation is faunal succession.However, as previously noted, times of volcanism and metamorphism, which are both critical parts of global processes, cannot be correlated by fossil content.