In these studies the isotopic ratios of all the noble gases (He, Ne, Ar, Kr, and Xe) of neutron-irradiated meteorites were measured.
This led to the discovery of There is, of course, one radiometric dating method that appears to overcome the vital “zero date problem”.
Of course, this was a close as Kelvin ever came to publicly recanting his position.
Later, after radioactivity had been proven to be a significant source of the Earth’s internal heat, he did privately admit that he might have been in error.
The answer of 25 million years deduced by Kelvin was not received favorably by geologists.
Both the physical geologists and paleontologists could point to evidence that much more time was needed to produce what they saw in the stratigraphic and fossil records.
The first isotopes of potassium (Ar in older K-bearing rocks.
In his study Rutherford measured the U and He (He is an intermediate decay product of U) contents of uranium-bearing minerals to calculate an age.
One year later Boltwood (1907) developed the chemical U-Pb method.
At first, the use of “key” diagnostic fossils was used to compare different areas of the geologic column.
Although there were attempts to make relative age estimates, no direct dating method was available until the twentieth century.
“The fascinating impressiveness of rigorous mathematical analyses, with its atmosphere of precision and elegance, should not blind us to the defects of the premises that condition the whole process.