Stanford University
Stanford, California
Allan Cox, the son of a house painter, was born in Santa Ana, California, in 1926. Chemistry was his major when he entered the University of California at Berkeley, but summer jobs in Alaska with Clyde Wahrhaftig convinced him that geology was a better choice. When he started graduate work in 1954, his adviser, John Verhoogen, was much interested in rock magnetism, and this became the focus of Cox's doctoral research. Cox was influenced also by the fact that Verhoogen was one of the very few on the Berkeley faculty at that time who was sympathetic to the then radical notion of continental drift.
After receiving his Ph.D. degree (1959), Cox joined the U.S. Geological Survey at its western headquarters in Menlo Park. There he worked with another survey geophysicist, Richard Doell, and in the early 1960s these two geophysicists wrote many important papers on rock magnetism. A major question concerned the timing of reversals in the polarity of the Earth's field as shown by measurements of the magnetism of rocks of different ages. This required accurate dating of rock specimens, and for this purpose they were joined by another former Berkeley student, Brent Dalrymple. In a protracted effort, the Cox-Doell-Dalrymple trio determined ages of suitable rocks collected from all over the world, and eventually, they established a timescale or calendar showing the complicated and irregular schedule of polarity changes in the Earth's past.
This was important because others had noted a similar pattern of polarity changes in rocks of the ocean crust on either side of mid-ocean ridges. It seemed clear that crustal rocks were moving away from the ridge crests or that the seafloor was spreading apart. This was the first convincing evidence for movement of large areas of the Earth's solid crust, and it led quickly to the postulates of plate tectonics. Thus early in his professional career, Allan Cox played a major role at the beginning of the scientific revolution that within the next few years would profoundly transform the Earth sciences. The magnetic field preserved in rocks provides much information about Earth history besides the simple reversal of field direction at various times in the past, and in the 1960s, Cox turned his attention to some of these other aspects. In 1967 he moved from the U.S. Geological Survey to the geophysics department at Stanford University, where he continued work on paleomagnetism and attracted the interest of many students to this field. He became widely known for his teaching and especially for his talent in designing research projects for undergraduate students. In 1979 he became part of the university administration, as Dean of the School of Earth Sciences.
Cox died in 1987 as a result of a bicycle accident in the hills behind Stanford. By this sad mishap, geophysics lost a major contributor to the theory of plate tectonics, Stanford University lost an able and innovative dean, and the community lost a stimulating and compassionate teacher and counselor.
Cox's scientific work brought him honors in abundance, including election to the National Academy of Sciences (1974), the American Philosophical Society, and the American Academy of Arts and Sciences. He served as President of the American Geophysical Union (1978-1980) and was awarded AGU's Fleming Medal (1969); the Day Medal of the Geological Society of America (1975); and the Vetlesen Medal of Columbia University (1971). He was the author of more than 100 scientific papers and of two well-known books on plate tectonics. He had an extraordinary combination of scientific acumen, humility, concern for his fellows, and love of the natural world that makes his death at an early age seem especially tragic.
Konrad B. Krauskopf
Stanford University
Stanford, California