Dating method in geology
Many geologists claim that radiometric “clocks” show rocks to be millions of years old.
They said the sample was contaminated with excess argon.In practice, the isochron approach has many inherent advantages.When a single body of liquid rock crystallizes, parent and daughter elements may separate so that, once solid, the isotopic data would define a series of points, such as those shown as open circles designated R.The end result is stable atoms of the ‘daughter’ elements lead, argon, and strontium respectively.Thus the first step in the radioactive dating technique is to measure the amounts of the parent and daughter elements (isotopes) in a rock sample via chemical analyses.Using new samples of feldspar and pumice they ‘reliably dated’ the tuff at 2.61 million years, which agreed nicely.
Later, this date was confirmed by two other dating methods (paleomagnetism and fission tracks), and was widely accepted.
It is not about the theory behind radiometric dating methods, it is about their , and it therefore assumes the reader has some familiarity with the technique already (refer to "Other Sources" for more information).
As an example of how they are used, radiometric dates from geologically simple, fossiliferous Cretaceous rocks in western North America are compared to the geological time scale.
So by 1980 there was a new, remarkably concordant date for the KBS tuff, and this became the one that was widely accepted.
his document discusses the way radiometric dating and stratigraphic principles are used to establish the conventional geological time scale.
Some types (technically known as ‘isotopes’) of ‘parent’ elements such as uranium, thorium, potassium and rubidium are said to be radioactive because the nuclei of the atoms are unstable, resulting in readjustments between the ‘particles’ (primarily neutrons and protons) in the nuclei with time.