The atoms of some chemical elements have different forms, called isotopes.These break down over time in a process scientists call radioactive decay.
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.
As one answer to his critics, Kelvin produced a completely independent estimate -- this time for the age of the Sun.
The table below shows characteristics of some common radiometric dating methods.
Geologists choose a dating method that suits the materials available in their rocks. Measuring isotopes is particularly useful for dating igneous and some metamorphic rock, but not sedimentary rock.
was published, the earth was "scientifically" determined to be 100 million years old. In 1947, science firmly established that the earth was 3.4 billion years old.