The determination of age of minerals and rocks is an important part of ancient geological studies. The age of rock can be estimated by uranium-lead dating. Suppose xg of ‌82206‌Pb is found with yg of ‌92238U. λ→ decay constant of uranium (known) ‌92238U⟶‌82206‌Pb Amount of ‌92238U disintegrated =‌
x
206
×238 in time t Hence initial amount of ‌92238U =y+‌
x
206
×238 λt=2.303‌log(‌
N0
N
) where, N0=y+‌
x
206
×238 and ‌‌N=y ∴‌‌t=‌
2.303
λ
‌log[‌
y+
x
206
×238
y
] where, ‌‌t= age of rock On the other hand, the age of minerals is determined by helium dating and the age of animals and plants died, i.e., fossils is determined by radiocarbon dating.