Radiocarbon dating measures radioactive isotopes in once-living organic material instead of rock, using the decay of carbon to nitrogen In only a couple of special cases have any decay rates been observed to vary, and none of these special cases apply to the dating of rocks as discussed here. They use absolute dating methods, sometimes called numerical dating, to give rocks an actual date, or date range, in number of years. For example, most people don't realize that carbon dating is only rarely used on rocks. Notice the large range in the half-lives. Telescopes allow us to see supernovae exploding stars at distances so vast that the pictures take hundreds of thousands to millions of years to arrive at the Earth.
The idea of a false appearance of great age is a philosophical and theological matter that we won't go into here.
Examples of Dating Methods for Igneous Rocks. Work to date shows that dating of tooth enamel can be quite reliable. Figure 9. This will be discussed further in a later section. Over a thousand research papers are published a year on radiometric dating, essentially all in agreement. The precision of a dating method depends in part on the half-life of the radioactive isotope involved.