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
![](http://photos1.blogger.com/img/225/3516/200/cpatterson.jpg)
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.