How reliable is Carbon dating?

Question

well...I guess I should have asked...how far back? 5,000 years,50,000 yrs or 50 million years.

Could being in submerged in water or ice do that?

Answer 1

It is quite reliable when properly applied. It can't be trusted when:

(1) it is applied so far in the past that it is extreme extrapolation of limited data.

(2) the sample and its food source were radiation-protected.

(3) the sample came from a situation or time where the C14/C12 ratio was different from what it is today, or is unknown.

For all these reasons, the farther back in time you try to read, the less reliable the dating.