John Laurence Kulp (February 11, 1921 – September 25, 2006) was a 20th-century geochemist. He led major studies on the effects of nuclear fallout and acid rain. He was a prominent advocate in American Scientific Affiliation circles in favor of an Old Earth and against the pseudoscience of flood geology. Kulp died on September 25, 2006, at the age of 85. Early life and education Kulp was raised in Trenton, New Jersey and was brought up as a practically atheistic Episcopalian. As a young man he left the Episcopal Church and entered into fellowship with the Plymouth Brethren. He attended Drew University, then entered Wheaton College as a junior transfer student. He spent a year in graduate school at Ohio State University before moving to Princeton University, where he obtained a Ph.D. in physical chemistry in 1945. Scientific career Kulp was professor of geochemistry at Columbia University between 1947 and 1965. He was also at various times vice president for research and development at Weyerhaeuser Company, director of research of the National Acid Precipitation Assessment Program, affiliate professor at the University of Washington, a consultant in environmental and energy affairs, and owner of Teledyne Isotopes. His primary field was radiometric dating, which was transforming the field of geology in the 1950s. He was a pioneer in the field of Carbon 14 dating and in 1950, established the Carbon 14 research centre at Columbia University, the second in the United States. During the 1950s he helped convince politicians that atomic bomb testing was a danger to health in regard to strontium-90 finding its way into the human food chain. Kulp's research in radiometric dating included: Potassium-argon dating Rubidium-strontium dating Uranium-lead dating Carbon-14 In 1960, using the findings of radiometric dating, he published a geological time scale estimating the age of each geological era. Strontium-90 nuclear fallout research Kulp led a team, financed by the United States Atomic Energy Commission, that investigated the levels of strontium-90 finding itself into the human food chain because of nuclear weapons testing. Strontium-90 was chosen as it can easily find its way into the human body, through the food chain, by being first absorbed by vegetation and then directly or perhaps indirectly via, for example, cattle, into the human body. In February 1957, Kulp and his team reported that a human has typically about "0.12 micromicrocuries of strontium-90 for each gram of body calcium". (A micromicrocurie