Clair Patterson

Clair Cameron Patterson (born Claire Cameron Patterson Jr.; June 2, 1922 – December 5, 1995) was an American geochemist. Born in Des Moines and raised in nearby Mitchellville, Iowa, he graduated from Grinnell College. He later received his Ph.D. from the University of Chicago and spent his entire professional career at the California Institute of Technology (Caltech). In collaboration with George Tilton, Patterson developed the lead–lead dating method, adapting established procedures for uranium–lead dating. By using lead isotopic data from the Canyon Diablo meteorite, he calculated an age for the Earth of 4.55 billion years, a figure far more accurate than estimates existing at the time and one that has remained largely unchallenged since 1956. Patterson first encountered ubiquitous lead contamination in the late 1940s as a graduate student at the University of Chicago. Later, his work on this subject led to a major reevaluation in the United States and worldwide of the unregulated growth of industrial lead concentrations in the atmosphere and human body. His activism on this issue proved seminal in the banning of leaded gasoline and leaded solder in food cans.