Thompson, James B., Jr. (earth scientist)

 
(1921- ) American Metamorphic Petrologist, Field Geologist

Soon after World War II, there was a revolution in petrology and geochemistry to better formulate geologic problems by classical thermodynamic methods. This heralded a major change in meta-morphic petrology from classic mostly descriptive efforts to a modern geochemical approach. James B. Thompson can be considered the “father of modern metamorphic petrology” because he emerged as the leader in this revolution. It was his work in developing a physical framework that guided experimental petrologists to choose critical petrologic systems in which to conduct their experiments. This physical framework was based on observations of rocks in the field or through a microscope. Throughout his theoretical research, he was always sure to return to the real rock systems to make sure that he remained solidly based. His famous statement exemplifies this attitude: “It would be embarrassing indeed if we were to construct an internally consistent geology, chemically and physically sound, perfect in fact but for one flaw—the lack of a planet to fit it.”

Thompson’s research dealt with the thermodynamics of individual minerals as part of larger chemical (metamorphic) systems. He employed the Gibbs method in new ways to explain meta-morphic facies (conditions). Standard triangular diagrams used in plotting the minerals found in aluminous metamorphic rocks (schist to gneiss) are referred to as “Thompson Diagrams.” Famous papers on this work are “The Graphical Analysis of Mineral Assemblages in Pelitic Schists” and “A Model System for Mineral Facies in Pelitic Rocks.” He later wrote a treatise on a new idea of “reaction space,” a kind of thermodynamic virtual space in which metamorphic reactions could be displayed. The major publication on this work is entitled Reaction Space: An Algebraic and Geometric Approach. Finally, he also worked on the properties of certain mineral systems including amphiboles, white mica, and feldspars. He even has minerals named after him, jimthompsonite and clinojimthompsonite.

Jim Thompson was able to base his thermo-dynamic work on real rocks so well because he was also a talented field geologist. Much of the stratigraphy and structural geology of New England, and especially that of Vermont, is understood as the result of his work. He mapped from low-grade to high-grade metamorphic rocks and looked at the characteristic structures of New England like domes and large flat folds called nappes. The astounding discovery of fossils in high grade metamorphic rocks, where they should have been destroyed, allowed Thompson to connect the stratigraphy of the crystalline part of New England to the sedimentary part. This alone is a major contribution to the understanding of the geology of New England.

James B. Thompson Jr. was born on November 20, 1921, in Calais, Maine. He attended Dartmouth College, New Hampshire, and earned a bachelor of arts degree in geology in 1942 and served as an instructor that same year. He entered the U.S. Army Air Force in 1942 and served as a first lieutenant for the duration of World War II. After his discharge, he entered Massachusetts Institute of Technology and earned a doctorate in geology in 1950. He joined the faculty at Harvard University, Massachusetts, in 1950 and remained there for the rest of his career. He was named the Sturgis Hooper Professor of Geology in 1977 and retired as an emeritus professor in 1992. During his tenure at Harvard he was a visiting professor at University of Bern, Switzerland (1963), Dartmouth College (1988-1992, part-time) and Arizona State University (1991), a distinguished visitor at University of Cincinnati, Ohio (1974), a guest professor at Swiss Federal Institute of Technology (1977-1978) and a visiting research geologist for the U.S. Geological Survey (1985-1986), among several others. James Thompson married Eleonora Mairs in 1957; they have one child.

James Thompson has had a very productive career. He was an author of some 41 articles in international journals and professional volumes as well as 12 field guides and four geologic maps. He was coeditor of one professional volume. The absolute numbers may not be as impressive as others in this topic but publishing was much less convenient and emphasized in the 1950s and 1960s than it is today. In addition, many of his papers set new benchmarks in petrology and geochemistry. Thompson has been well recognized by the geologic profession for his contributions in terms of honors and awards. He is a member of the National Academy of Sciences, and the American Academy of Arts and Sciences. He received the Arthur L. Day Medal from the Geological Society of America (1964), the Roebling Medal from the Mineralogical Society of America (1977), and the Victor M. Goldschmidt Medal from the Geo-chemical Society (1985). He received a Ford Faculty Fellowship (1952-1953), a Guggenheim Fellowship (1963), and he was an Ernst Cloos

Memorial Scholar at the Johns Hopkins University (1983) and a Fairchild Distinguished Scholar at California Institute of Technology (1976), among numerous distinguished lectureships.

Thompson has also performed significant service to the profession serving on numerous committees and panels for the National Science Foundation, National Research Council, the Geo-chemical Society, Geological Society of America, and the Mineralogical Society of America. He was president of the Mineralogical Society of America in 1967 and 1968, as well as the Geochemical Society in 1968 and 1969.

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