calculating the age of rocks requires investigating the original amount of the elemental isotopes of the parent isotopes
radiometric_dating is not estimating_age. need_to has not oxygen_in_mines_and_excavations need_to has oxygen_in_mines_and_excavations geological_age is geological_time_period. radioactive_isotope is not isotope. dating is chemical_analysis. radiometric_dating is estimating_age. radioactive_dating is measurement. radioactive_isotope is isotope. estimating_age is calculating.