This model, which describes the accumulation of lead isotopes in meteorites, the Earth, and the Solar System, was proposed independently by E. The amount of 204Pb will remain constant throughout the history of a rock because it is a stable isotope that is not the product of any decay series, thus allowing for the normalization (Dalrymple 201-163).Two requirements of the Gerling-Holmes-Houtermans model make it difficult to use.
He used young terrestrial ores to obtain data for young ores and assumed the lead composition of the meteorite Canyon Diablo was representative of primordial lead.
Lead isotopes are commonly used in dating rocks and provide some of the best evidence for the Earth's age.
In order to be used as a natural clock to calculate the age of the earth, the processes generating lead isotopes must meet the four conditions of a natural clock: an irreversible process, a uniform rate, an initial condition, and a final condition.
The use of lead isotope ratios makes this isochron self-checking.
A large scattering of measurements would indicate the sample is multi-stage rather than single-stage, making the isochron unreliable.