Patterson (June 2, 1922 - December 5, 1995) was a U.S. geochemist who in 1953 made the first precise measurement of the Earth's age, 4.55 billion years. He is

He also established the patterns of isotopic evolution of lead on earth, by analysis of critical rocks, sediments and waters of the planet. Thus he created a powerful tool for identifying, tracing and evaluating the nature of the major geochemical reservoirs in the crust, mantle, and oceans.
Photo from HERE.