Radiometric dating age of earth
Radiometric dating verified that the relative time scale determined by stratigraphers and paleontologists (Figure 1) is absolutely correct, a result that could only have been obtained if both the relative time scale and radiometric dating methods were correct.
The abundance and variety of fossils in Phanerozoic rocks have allowed geologists to decipher in considerable detail the past 600 million years or so of the Earth’s history.
Thus, the ages of the Earth, the Moon, and meteorites as measured by different methods represent slightly different events, although the differences in these ages are generally slight, and so, for the purposes of this chapter they are here treated as a single event.
All the major continents contain a core of very old rocks fringed by younger rocks.
The last modification to the geologic time scale of Figure 1 was in the 1930s, before radiometric dating was fully developed, when the Oligocene Epoch was inserted between the Eocene and the Miocene.
There can be no doubt about the Earth’s antiquity; the evidence is abundant, conclusive, and readily available to all who care to examine it.
The best evidence is contained in the Earth’s incomplete and complex but accurate stratigraphic record — a record that has been the subject of nearly two centuries of study.
A metamorphic event may change the apparent radiometric age of a rock.
Most commonly, the event causes partial or total loss of the radiogenic daughter isotope, resulting in a reduced age.