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Clair Patterson
Clair Cameron Patterson (June 2, 1922 – December 5, 1995) was an American geochemist. Born in Mitchellville, Iowa, Patterson 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 from the 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 total (US and worldwide) re-evaluation of the unregulated growth of concentrations of industrial lead in the atmosphere and in the human body. His activism about this problem proved seminal in the banning of "leaded gasoline", as well as "leaded solder" in food cans.
Patterson was born in Mitchellville, Iowa. His father was a mail carrier, his mother was a member of the local school board. He had two siblings, a brother and a sister. From a young age he developed an intellectual curiosity and in 1939 he graduated high school at age 16. He then attended nearby Grinnell College, meeting his future wife, Lorna (Laurie) McCleary, there and graduating with a degree in chemistry in 1943. Both students attended graduate school at the University of Iowa, where he completed an M.A. in molecular spectroscopy and they married in 1944. Both were then employed on the Manhattan Project as civilians, first at the University of Chicago and then at Oak Ridge, Tennessee, where he specialized in mass spectrometry.
After World War II, the Pattersons returned to Chicago, where Laurie worked as an infrared spectroscopist and supported Patterson while he studied for his Ph.D. at the University of Chicago under Harrison Brown. While conducting experiments in an old laboratory, Patterson uncovered "the widespread presence of lead as a contaminant throughout the laboratory, including in his own hair." (This subject—the occurrence of lead broadly in the atmosphere and the environment—came to be a focus of study later in his career. His later work produced shocking results showing the ubiquitous presence of toxic lead in the broad environment.) After a postdoctoral year at Chicago, in 1952 Patterson moved with Brown to the California Institute of Technology (Caltech) in Pasadena, California, specifically to the (now) Division of Geological and Planetary Sciences, where they served as founding members of Caltech's new geochemistry program. He remained at Caltech for the rest of his life. He and Laurie had four children.
Patterson's postdoc work at the University of Chicago was under Harrison Brown, who teamed him with George Tilton to study geological aging of zircon crystals. Zircon is extremely useful for geological dating: when forming, it collects tiny imperfections of uranium, but never lead. It follows that if lead is present in zircon, it must have come from decay of the uranium present. (The process is known as U-Pb dating.) The team measured the concentrations and isotopic compositions of foreign elements inside the zircon. Tilton measured the uranium and Patterson the types and amounts of lead. Patterson's goal was to calculate the composition of primordial lead in the Earth. Then it would be possible to calculate the age of the Earth—and, in turn, of the Solar System by using the same techniques on meteorites.[citation needed]
After beginning their work in 1948, Patterson soon noted that his lead samples were being contaminated. The age of the igneous rock from which the zircon came was known, and Tilton's uranium measurements aligned with what was expected in the zircon at that particular age; but Patterson's data typically was skewed with "too much" lead. After six years, the team published a paper on methods of determining the ages of zircon crystals and Patterson earned his Ph.D., but they were no closer in determining the age of the Earth.[citation needed]
Brown received a grant from the United States Atomic Energy Commission to continue work on dating the Earth, but more importantly, he was selected to commission a new mass spectrometer in Pasadena, California at Caltech. In 1953, Brown and Patterson arrived at Caltech, where Patterson was authorized to build his own lab from scratch. He proceeded to secure all points of entry from air and other contaminants. He acid-cleaned all apparatuses and even distilled all chemicals shipped to him. In essence, Patterson created one of the first laboratory clean rooms, here to prevent lead contamination of his work and his data. He finished his analysis of the Canyon Diablo meteorite in 1953, and used the mass spectrometer at the Argonne National Laboratory on isolated iron-meteorite lead to collect data on the abundance of lead isotopes. With the new data, he published "Age of Meteorites and the Earth" in 1956, the first paper explaining the "true" age of the solar system's accretion as 4.550Gy ± 70My; a figure that has remained largely unchallenged since.
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Clair Patterson
Clair Cameron Patterson (June 2, 1922 – December 5, 1995) was an American geochemist. Born in Mitchellville, Iowa, Patterson 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 from the 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 total (US and worldwide) re-evaluation of the unregulated growth of concentrations of industrial lead in the atmosphere and in the human body. His activism about this problem proved seminal in the banning of "leaded gasoline", as well as "leaded solder" in food cans.
Patterson was born in Mitchellville, Iowa. His father was a mail carrier, his mother was a member of the local school board. He had two siblings, a brother and a sister. From a young age he developed an intellectual curiosity and in 1939 he graduated high school at age 16. He then attended nearby Grinnell College, meeting his future wife, Lorna (Laurie) McCleary, there and graduating with a degree in chemistry in 1943. Both students attended graduate school at the University of Iowa, where he completed an M.A. in molecular spectroscopy and they married in 1944. Both were then employed on the Manhattan Project as civilians, first at the University of Chicago and then at Oak Ridge, Tennessee, where he specialized in mass spectrometry.
After World War II, the Pattersons returned to Chicago, where Laurie worked as an infrared spectroscopist and supported Patterson while he studied for his Ph.D. at the University of Chicago under Harrison Brown. While conducting experiments in an old laboratory, Patterson uncovered "the widespread presence of lead as a contaminant throughout the laboratory, including in his own hair." (This subject—the occurrence of lead broadly in the atmosphere and the environment—came to be a focus of study later in his career. His later work produced shocking results showing the ubiquitous presence of toxic lead in the broad environment.) After a postdoctoral year at Chicago, in 1952 Patterson moved with Brown to the California Institute of Technology (Caltech) in Pasadena, California, specifically to the (now) Division of Geological and Planetary Sciences, where they served as founding members of Caltech's new geochemistry program. He remained at Caltech for the rest of his life. He and Laurie had four children.
Patterson's postdoc work at the University of Chicago was under Harrison Brown, who teamed him with George Tilton to study geological aging of zircon crystals. Zircon is extremely useful for geological dating: when forming, it collects tiny imperfections of uranium, but never lead. It follows that if lead is present in zircon, it must have come from decay of the uranium present. (The process is known as U-Pb dating.) The team measured the concentrations and isotopic compositions of foreign elements inside the zircon. Tilton measured the uranium and Patterson the types and amounts of lead. Patterson's goal was to calculate the composition of primordial lead in the Earth. Then it would be possible to calculate the age of the Earth—and, in turn, of the Solar System by using the same techniques on meteorites.[citation needed]
After beginning their work in 1948, Patterson soon noted that his lead samples were being contaminated. The age of the igneous rock from which the zircon came was known, and Tilton's uranium measurements aligned with what was expected in the zircon at that particular age; but Patterson's data typically was skewed with "too much" lead. After six years, the team published a paper on methods of determining the ages of zircon crystals and Patterson earned his Ph.D., but they were no closer in determining the age of the Earth.[citation needed]
Brown received a grant from the United States Atomic Energy Commission to continue work on dating the Earth, but more importantly, he was selected to commission a new mass spectrometer in Pasadena, California at Caltech. In 1953, Brown and Patterson arrived at Caltech, where Patterson was authorized to build his own lab from scratch. He proceeded to secure all points of entry from air and other contaminants. He acid-cleaned all apparatuses and even distilled all chemicals shipped to him. In essence, Patterson created one of the first laboratory clean rooms, here to prevent lead contamination of his work and his data. He finished his analysis of the Canyon Diablo meteorite in 1953, and used the mass spectrometer at the Argonne National Laboratory on isolated iron-meteorite lead to collect data on the abundance of lead isotopes. With the new data, he published "Age of Meteorites and the Earth" in 1956, the first paper explaining the "true" age of the solar system's accretion as 4.550Gy ± 70My; a figure that has remained largely unchallenged since.