Oldest rocks on earth radiometric dating
He concluded that Earth was born 20 to 400 million years ago.
Today’s scientists believe that answer is incorrect, but Kelvin’s calculations were in being based on logical thinking and mathematical calculation.
Scientists tried to determine Earth’s age via our planet’s layers of rock, which must have been built over time.
Using this technique, scientists could, for example, analyze a sample from Earth’s crust, figure out the quantities of uranium and lead, plug those values along with the half-life into a logarithmic equation, in order to compute the age of the rock.
Over the decades of the 20th century, scientists documented tens of thousands of radiometric age measurements.