C13 carbon dating
Therefore, the percentages of the three isotopes will be the same in a living organism as it is in the organism’s environment.Carbon-14 is not stable against beta-minus decay with a half-life of 5,730±40 years, but is constantly replenished in the atmosphere by cosmic ray interaction with nitrogen-14.
Through this method we can produce a curve or table that shows exactly what the C-14/C-12 ratio was for thousands of years into the past.
There are three naturally occurring isotopes of carbon in the environment: carbon-12, carbon-13, and carbon-14.
They all have six protons since they are carbon, and therefore they are identical chemically.
After about ten half-lives there is so little C-14 left that dating is impossible.
Therefore carbon dating can only be used on organisms that were alive less than ≈57,000 year ago.