Ideally, a series of dates should be obtained for any deposit as a series may cluster around a central point.New refinements continue to improve the technique's accuracy as well as extend the range of dates which can be achieved.Variation in the rate of sedimentation sometimes makes the number of years represented uncertain; absolute counts for different samples may therefore not be compatible.
It can be used for the dating organic material up to 75,000 years old. Libby (1947); his radioactive-carbon dating provided an extremely valuable tool for archaeologists, anthropologists, and earth scientists.
When organic matter dies it ceases to exchange its carbon, as carbon dioxide, with the atmosphere, so its C14 dwindles by decay and is not replenished.
Determination of the radioactivity of carbon from a sample will reveal the proportion of C14 to C12, and this will in turn, through the known rate of decay of C14, give the age of, or more accurately the time elapsed since the death of, the sample.
Secondly, the rate of decay of C14 is based in all published examples on a of 5730 /- 40 years (after 5730 years, one half of the C14 will have disintegrated, after another 5730 years one half of the remainder, and so on).
Correction tables are used to correct 'raw' radiocarbon dates (quoted as years ad or ).