For example, in 1991, two hikers discovered a mummified man, preserved for centuries in the ice on an alpine mountain.
Later called Ötzi the Iceman, small samples from his body were carbon dated by scientists.
Relative dating uses observation of location within rock layers, while radiometric dating uses data from the decay of radioactive substances within an object.
They estimated the age of the Earth by substituting the lead isotope ratios of certain meteorites in the Holmes-Houtermans equation.
In this equation the primordial lead ratios are required.
Despite this, the momentum gained in the two decades prior to 1972 has made 4.5 b.y.
a popularly accepted “universal constant” even though the foundations on which it was based have been virtually removed.
The results showed that Ötzi died over 5000 years ago, sometime between 33 BC. Uranium has a very long half-life and so by measuring how much uranium is left in a rock its approximate age can be worked out.