As stated previously, carbon dating cannot be used on artifacts over about 50,000 years old.
These artifacts have gone through many carbon-14 half-lives, and the amount of carbon-14 remaining in them is miniscule and very difficult to detect.
These isotopes have longer half-lives and so are found in greater abundance in older fossils.
Some of these other isotopes include: back to the last global catastrophe (i.e.
If it sounds like circular reasoning, it is because this process in reality is based upon circular reasoning.