Age is also a problem: Samples that are older than about 40,000 years are extremely difficult to date due to tiny levels of carbon-14. Over 60,000 years old, and they cant be dated at all. But its the most accurate dating tool at archaeologists disposal, thanks to carbon-14s predictable disappearing act.
Why cant carbon-14 be used to date items older than 60000 years?
Carbon-14 has a half life of 5730 years, meaning that 5730 years after an organism dies, half of its carbon-14 atoms have decayed to nitrogen atoms. Because of the short length of the carbon-14 half-life, carbon dating is only accurate for items that are thousands to tens of thousands of years old.
Why does carbon dating only go about 60000 years?
By the time you reach 60K years the amount of Carbon-14 in it would have decayed to the point where it would be gone or at the very least unable to be detected. This is why its useless for more than 60K years and you need to use other dating methods like Potassium-Argon or Uranium-Lead for older substances.