What is uranium-dating?

Answer 1

What you are referring to is actually called Uranium-Lead dating, a form of radioactive decay dating based on how long it takes various Uranium isotopes to decay to their ultimate stable daughter Lead isotopes. By measuring the relative ratios it is possible to calculate the original quantity of Uranium in the sample, then knowing the amount currently present the period of time for the missing amount to decay gives the age of the sample.

When gasoline used tetraethyl lead to boost octane ratings, lead contamination was often high enough that this method was very hard to get accurate results from (usually due to contamination of the lab facilities accidentally transferring to the sample).