Dating it complicated issue 69
Plants transpire to take in atmospheric carbon, which is the beginning of absorption of carbon into the food chain.Animals eat the plants and this action introduces carbon into their bodies.
The method was developed immediately following World War II by Willard F.Libby and coworkers and has provided age determinations in archeology, geology, geophysics, and other branches of science.Radiocarbon dating estimates can be obtained on wood, charcoal, marine and freshwater shells, bone and antler, and peat and organic-bearing sediments.They can also be obtained from carbonate deposits such as tufa, calcite, marl, dissolved carbon dioxide, and carbonates in ocean, lake and groundwater sources.Carbon dioxide is distributed on a worldwide basis into various atmospheric, biospheric, and hydrospheric reservoirs on a time scale much shorter than its half-life.Measurements have shown that in recent history, radiocarbon levels have remained relatively constant in most of the biosphere due to the metabolic processes in living organisms and the relatively rapid turnover of carbonates in surface ocean waters.
However, changes in the atmosphere over the ages are a source of uncertainty in the measurements. Both C-12 and C-13 are stable, but C-14 decays by very weak beta decay to nitrogen-14 with a half-life of approximately 5,730 years.
Naturally occurring radiocarbon is produced as a secondary effect of cosmic-ray bombardment of the upper atmosphere.
"Radio-carbon dating is a method of obtaining age estimates on organic materials.
The word "estimates" is used because there is a significant amount of uncertainty in these measurements.
Each sample type has specific problems associated with its use for dating purposes, including contamination and special environmental effects.
More information on the sources of error in carbon dating are presented at the bottom of this page.