Radio isotope dating methods
Rutherford was the first scientist to apply it for determination of age of geological samples.
Systemic errors were serious and the science of radioactivity was not understood well at that time. This certainly gave the established geologists a big excuse to criticize the new science and it was really the solo fight by Arthur Holmes that eventually brought radio-isotope dating technique to universal acceptance by about 1950.
They were formed early on in the process for the nebula contracting and the chondrules in the meteorites have preserved their purity and initial composition at the time of their formation.
In the 1920s and 30s, radio-isotope dating was getting established and was measuring ages of some rocks as 2 or more billion years.
By the way, Patterson was responsible for banning of leaded petrol - this he achieved through a thirty year struggle with the government bodies and the petrochemical industry!
by Tas Walker A geologist works out the relative age of a rock by carefully studying where the rock is found in the field.
Half life is the time that an isotope will require for half of the original amount to decay to another isotope (called the daughter).
The daughter isotope may or may not be stable and can decay in turn but eventually produces a stable isotope that maintains its quantity over time.
In fact, we can plot the abundance of elements found in the Sun and compare this to elemental abundance of early formed meteorites and find an exact correlation in these abundances.