Uranium-Lead dating is a radiometric dating method that uses the decay chain of uranium and lead to find the age of a rock.As uranium decays radioactively, it becomes different chemical elements until it stops at lead.The radiometric dater then uses the half-life of all four isotopes to find an age range the rock should be in.
of sediments from either a marine or a playa lake environment.
The half-life is the amount of time it takes for one half of the initial amount of the parent, radioactive isotope, to decay to the daughter isotope.
Thus, if we start out with 1 gram of the parent isotope, after the passage of 1 half-life there will be 0.5 gram of the parent isotope left.
After the passage of two half-lives only 0.25 gram will remain, and after 3 half lives only 0.125 will remain etc.
To see how we actually use this information to date rocks, consider the following: Usually, we know the amount, N, of an isotope present today, and the amount of a daughter element produced by decay, D*.