Radioactive dating methods beyond 60000 years tanja dating ukraine
However, although 5730 years is the correct half-life, it is not the one used for most C-14 dating, simply because the original half-life used to determine dates back in the 1950s was wrong, and to be consistent we still tend to use the wrong value (a bit like the direction of current flow in electronics, which is the opposite of that which the electrons take, but was the original and incorrect assumption).
The practical range for dating is in the order of a few hundred to about 40,000 years BP.
Tree ring data (dendrochronology) can be used to even out this inconsistency, however the oldest trees used for calibration are in the order to about 6,000 years old, so any further back than that and you can't correct your dates (although there are reportedly some preserved huon pines in Tasmania that could take this right back to 30,000 years or so, if anyone wants to spend half their life time counting tree rings).
Even if dates are corrected with tree ring data they are still not considered calendar years, but rather radiocarbon years.
Radiometric dating works on the principle that certain atoms and isotopes are unstable.Fortunately, we are able to date older fossils using the radiometric breakdown of other elements (Potassium-Argon dating, Argon-Argon dating, and Rubidium dating [I'm writing this without any refs - so this last one might be wrong]).