From Today In Science History:
Patterson was a U.S. geochemist who in 1953 made the first precise measurement of the Earth's age, 4.55 billion years. He is
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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.