Add to this number the age measurements made by from 50 to 100 other laboratories worldwide, and it is easy to see that the number of radiometric ages produced over the past two to three decades and published in the scientific literature must easily exceed 100,000.Taken as a whole, these data clearly prove that the Earth’s history extends backward from the present to at least 3.8 billion years into the past.
” The answer to this question was provided by radiometric dating and is now known to within a few percent.
Before reviewing briefly the evidence for the age of the Earth, I emphasize that the formation of the Solar System and the Earth was not an instantaneous event but occurred over a finite period as a result of processes set in motion when the universe formed.
It is, therefore, more correct to talk about formational intervals rather than discrete ages for the Solar System and the Earth.
The last modification to the geologic time scale of Figure 1 was in the 1930s, before radiometric dating was fully developed, when the Oligocene Epoch was inserted between the Eocene and the Miocene.
Although early stratigraphers could determine the relative order of rock units and fossils, they could only estimate the lengths of time involved by observing the rates of present geologic processes and comparing the rocks produced by those processes with those preserved in the stratigraphic record.
Present evidence indicates, however, that these intervals were rather short (100-200 million years) in comparison with the length of time that has elapsed since the Solar System formed some 4 to 5 billion years ago.