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*.By definition, D* = N-1) (2) Now we can calculate the age if we know the number of daughter atoms produced by decay, D* and the number of parent atoms now present, N.
Radiometric dating is also used to date archaeological materials, including ancient artifacts.
Different methods of radiometric dating vary in the timescale over which they are accurate and the materials to which they can be applied.
Uranium-thorium dating has an upper age limit of somewhat over 500,000 years, defined by the half-life of thorium-230, the precision with which we can measure the thorium-230/uranium-234 ratio in a sample, and the accuracy to which we know the half-lives of thorium-230 and uranium-234.
Note that to calculate an age using this technique the ratio of uranium-234 to its parent isotope uranium-238 must also be measured.
Therefore, one can assume that the entire lead content of the zircon is radiogenic, i.e.
it is produced solely by a process of radioactive decay after the formation of the mineral.
Among the best-known techniques are radiocarbon dating, potassium-argon dating and uranium-lead dating.
By allowing the establishment of geological timescales, it provides a significant source of information about the ages of fossils and the deduced rates of evolutionary change.
Thus the current ratio of lead to uranium in the mineral can be used to determine its age.