Igneous and metamorphic rocks were treated as chemical systems early in the history of geology because there are diverse minerals involved and they are large enough to analyze. On the other hand, sedimentary rocks hold most of the economic reserves whether petroleum related or ore related. Robert Garrels did for the chemistry of sedimentary rocks what the likes of NORMAN L. BOWEN did for igneous rocks; he established the chemical systems. His 1952 paper, “Origin and classification of precipitants in terms of pH and oxidation-reduction,” sums up much of his early research, which was specifically on rocks which formed as precipitants from water. One of his main areas of study at this time was the origin of iron deposits, which he would return to several times. However, he also worked on uranium and vanadium geochemistry. His later work looked at the rock-water interface geochemistry. This work involved both experimental research and advanced thermodynamics. The latter of these set him apart from many of the other researchers of the time and several of his students still maintain that position.
Garrels investigated the interaction of oceans and the sediments produced in them in chemical terms. He studied chemical mass balances between rivers, which carry on the chemical species, and oceans, which receive them. He set the standard for research on geochemical cycles with research on carbon, sulfur, and phosphorus. He modeled the interaction between oceans and the atmosphere with ROBERT BERNER to explain carbon dioxide abundances in the atmosphere in his famous “BLAG” model.
Much of this work was translated into books that became the handbooks for all geologists who ventured into this field. His book, Mineral Equilibria at Low Temperatures and Pressures, in 1960 showed how minerals form at surface and near surface conditions. His famous textbook, Evolution of the Sedimentary Rocks, published in 1971, set the standard for understanding the sedimentary cycle. It uniquely emphasized his research on the ocean-sediment interactions and clearly advanced the level at which students were introduced to the chemistry of sedimentary rocks.
Robert Garrels was born in Detroit, Michigan, on August 24, 1916, the second of three children. He spent some of his early years in Saltville, Virginia, before moving to Grosse Ile, Michigan, in 1928, where he attended high school. Garrels was a true athlete as well as a scholar, specializing in track and field. In fact, later in life he would hold the world high jump record for men over 57 years of age. Garrels entered the University of Michigan, Ann Arbor, at 17 years of age, vacillating between chemistry and literature. Instead, he turned to geology and graduated with a bachelor of science degree with honors in 1937. He entered graduate school at Northwestern University in Illinois the same year. He earned a master of science degree in 1939 and a Ph.D. in 1941. He then joined the faculty at Northwestern University, but quickly joined the Military Geology Unit of the U.S. Geological Survey for the duration of World War II. He returned to Northwestern University in 1945, but then returned to the U.S. Geological Survey in 1952. In 1955, he accepted a position at Harvard University, Massachusetts, where he remained for 10 years, including serving as chair. He moved back to Northwestern University in 1965, but only remained until 1969, when he accepted a position at Scripps Institution of Oceanography at the University of California at San Diego. There he was married to Cynthia Hunt in 1970. However, Garrels moved to the University of Hawaii in 1971, where he was named the James Cook Professor of oceanography. In 1974, he returned to Northwestern University, only to leave once again in 1980. He accepted the St. Petersburg Progress Chair in marine science at the University of South Florida, where he remained until his death. He contracted cancer of the spine in 1987 and succumbed to it on March 8, 1988. His wife, Cynthia, two daughters and a son by a previous marriage, and 13 grandchildren survived him.
In his very productive career, Robert Garrels produced numerous articles in international journals and volumes as well as several books. Many of these books and papers are the classical defining works for the field of sedimentary geochemistry. His work was well recognized and rewarded with honors and awards. He was a member of the National Academy of Sciences. He received honorary doctorates from the Free University of Brussels, Belgium, in 1969; the Louis Pasteur University of Strasbourg, Austria, in 1976; and the University of Michigan, Ann Arbor, in 1980.
He received both the Arthur Day Medal (1966) and the Penrose Medal (1978) from the Geological Society of America. He received the Gold-schmidt Medal from the Geochemical Society (1973), the Roebling Medal from the Mineralogical Society of America (1981), and Wollaston Medal from the Geological Society of London, England. He served as the president of the Geo-chemical Society in 1962.
