As a rule, carbon dates are younger than calendar dates: a bone carbon-dated to 10,000 years is around 11,000 years old, and 20,000 carbon years roughly equates to 24,000 calendar years. The problem, says Bronk Ramsey, is that tree rings provide a direct record that only goes as far back as about 14,000 years.

Why wouldnt you use carbon-14 dating on a piece of shell that was estimated to be 1 million years old?

Why wouldnt you use carbon-14 dating on a piece of sea shell that was estimated to be 1 million years old? The correct answer is: The amount of radioactive carbon in the sample would be too small to measure accurately. .