What is uranium 238 used for dating rocks
The reason for stopping at lead is because lead is not radioactive and will not change into a different element.
It may sound straight-forward, but there are many variables that have to be considered.
All of the radioisotopes in this series decay by alpha or beta emission. is the first-order rate constant, called the decay constant, and N is the number of atoms of the particular radioisotope present in the sample being studied.Uranium, thorium, radon, potassium-40, carbon-12, and tritium (H-3) are naturally occurring radioisotopes.Uranium, which is fairly abundant in Earth's crust, is the start of a radioactive decay series.By comparison with the tree rings in the extremely old bristle-cone pines, however, a corrected carbon date can be found for objects over about 1500 years old.
The trees are themselves dated by the carbon-14 method using dead parts in the bark.The three main parameters that have to be set are the original amount of uranium and lead in the sample, the rate at which uranium and lead enter and leave the sample, and how much the rate of decay changes.