One method or relative dating
Cross-dating is a technique used to take advantage of consistencies in stratigraphy between parts of a site or different sites, and objects or strata with a known relative chronology.A specialized form of cross-dating, using animal and plant fossils, is known as biostratigraphy.Hutton, a Scottish geologist, first proposed formally the fundamental principle used to classify rocks according to their relative ages.
These tests have been performed on what are thought to be the earth's oldest surviving rocks, meteorites, and moon rocks.
Trees from the same species, growing in the same area or environment will be exposed to the same conditions, and hence their growth rings will match at the point where their lifecycles overlap.
Earth's oldest living inhabitant "Methuselah" at 4,767 years, has lived more than a millennium longer than any other tree.
The Carbon14 technique has been and continues to be applied and used in many, many different fields including hydrology, atmospheric science, oceanography, geology, palaeoclimatology, archaeology and biomedicine. Isochron methods avoid the problems which can potentially result during radiometric testing.
Be sure to see An Animated Isochron Diagram, or, Watching a Rock Age on an Isochron Diagram. Radiometric Dating from The Evolution Evidence Page.
Keyed to the relative time scale are examples of index fossils, the forms of life which existed during limited periods of geologic time and thus are used as guides to the age of the rocks in which they are preserved.