By analogy, a stop watch will not keep accurate time if it is not wound, if it is not in good repair, or if the operator forgets to press the button.Methods are precise insofar as they are properly used.The first is the use of wood from long-lived species, such as teak, in archaeological contexts.The archaeologist dating such material must be aware of the significance of a date range that relates to the period when a tree was alive rather than to when the wood was actually used in the construction or reconstruction.
Thus the physical principle of the method is well established. The dates obtained by radiometric dating are verified by independent methods, including dendrochronology (tree rings), varve chronology (sediment layers), ice cores, coral banding, speleotherms (cave formations), fission track dating, and electron spin resonance dating.
The strengths and limitations of radiocarbon dating as applied to samples taken in and around the walled city center of Pagan, in Burma, are addressed.
The last thousand years in mainland Southeast Asia remains a difficult period to date absolutely because of two critical issues.
When the carbon dioxide, containing C14 as well as stable C12 and C13, is taken in by plants it is no longer exposed to the intense cosmic ray bombardment in the upper atmosphere, so the carbon 14 isotope decays without being replenished.
Measuring the ratio of C14 to C12 and C13 therefore dates the organic matter for periods back to about eight half-lives of the isotope, 45,000 years.
Coral growth patterns are also seasonal and provide a long independent date history. The dates obtained by different radiometric isotope pairs cross-check each other.