Radiocarbon dating samples Cam2cam no inscription
It is calculated on the assumption that the atmospheric radiocarbon concentration has always been the same as it was in 1950 and that the half-life of radiocarbon is 5568 years.
For this purpose `present' refers to 1950 so you do not have to know the year in which the measurement was made.
If you have a radiocarbon measurement on a sample, you can try to find a tree ring with the same proportion of radiocarbon.Once calibrated a radiocarbon date should be expressed in terms of cal BC, cal AD or cal BP.The cal prefix indicates that the dates are the result of radiocarbon calibration using tree ring data.To extend this method further we must use the fact that tree ring widths vary from year to year with changing weather patterns.
By using these widths, it is possible to compare the tree rings in a dead tree to those in a tree that is still growing in the same region.The pair of blue curves show the radiocarbon measurements on the tree rings (plus and minus one standard deviation) and the red curve on the left indicates the radiocarbon concentration in the sample.