"That’s why I became aware of the contamination problem, because I kept getting the wrong answer for lead in these zircons. We could calculate how much lead there should be and what its isotopic composition should be, and it kept coming [out] the wrong number."
-Clair Patterson, talking about uranium-lead dating
Patterson in his laboratory
Clair Patterson did not begin as an environmentalist, but as a scientist. He and a colleague, George Tilton, were attempting to accurately date the age of the earth. This was a complicated process involving a mass spectrometer and uranium-lead dating techniques. It was during this process that Patterson discovered that the ratio of uranium to lead was extremely skewed, with lead levels about two hundred times higher than their naturally occurring levels. This was, of course, very befuddling, but it would be a number of years before he discovered the cause of this contamination and the person responsible, a hapless inventor named Thomas Midgley Jr.