Age range of radiocarbon dating
To extend this method further we must use the fact that tree ring widths vary from year to year with changing weather patterns.
This is very useful as a record of the radiocarbon concentration in the past.If archaeologists find a site they believe to be older than 40,000 years, they must compare radiocarbon dates with different dating methods to ensure an accurate result (see luminescence dating Since the first radiocarbon dates were announced in the mid-20th Century, our understanding of Australia’s antiquity has altered dramatically.As each year passes, earlier dates are being published, extending Australia’s occupation further into the past.Radiocarbon measurements are always reported in terms of years `before present' (BP).This figure is directly based on the proportion of radiocarbon found in the sample.By using dead trees of different but overlapping ages, you can build up a library of tree rings of different calendar ages.
This has now been done for Bristlecone Pines in the U. A and waterlogged Oaks in Ireland and Germany, and Kauri in New Zealand to provide records extending back over the last 14,000 years.
Basically, it is correct to suggest 50,000–95,000 years.
The former is the practical limit (based on the calibration materials presently used in radiocarbon labs), while the latter is the theoretical limit of the AMS instrument.
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.
Sites older than 26,000 years present greater issues for radiocarbon dating.