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George Wetherill was the Director Emeritus, Department of Terrestrial Magnetism, Carnegie Institution of Washington, DC, USA.
George Wetherill benefited from the G.I. Bill to receive four degrees, the Ph. B., S.B., S.M., and Ph. D., in physics, all from the University of Chicago. He did his thesis research, on the spontaneous fission of uranium, as well as nuclear processes in nature, as an U.S. Atomic Energy Commission Predoctoral Fellow. Upon receiving his Ph. D., Wetherill became a staff member at Carnegie's Department of Terrestrial Magnetism in Washington, D.C. There, he joined an interdepartmental group of Carnegie scientists who were working to date the Earth's rocks by geochemical methods involving natural radioactive decay. This involved determining the concentration and isotopic composition of inert gases such as argon, as well as the isotopes of strontium and lead. He originated the concept of the Concordia Diagram for the uranium-lead isotopic system; this diagram became the standard means for determining precise ages of rocks, and of detecting the possibility of metamorphism, and it forms the basis for all high-precision geochronology in rocks dating back to the early history of the Earth. He was also a member of the Carnegie group that accurately determined the decay constants of potassium and rubidium, an effort that has also become fundamental to the measurement of geological time.
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