Obituary Professor Allan Cox (1926-1987) Nearly one and a half years have passed since Allan Cox , Professor of Geophysics at Stanford University, was killed in an accident . I still find it difficult to realize that Allan is no longer with us. As is well recognized, Allan's greatest contribution to the last revolution in the solid earth sciences was the confirmation of reversals in the geomagnetic field by establishing the world synchroneity of each polarity epoch and event for the last four and half million years. To accomplish this, he had to collect a great number of rocks from all over the globe and make paleomagnetic measurements and radio- metric absolute age determinations on them with great care and accuracy . This painstaking job was carried out during the 1960's at the United States Geological Survey in Menlo Park, California in close cooperation with Drs . Richard R. Doell 1043 1044 Obituary and G. Brent Dalrymple. During the years preceding their project, I was totally absorbed in the investigation of the physical mechanism of self-reversal of thermo- remanent magnetization of Haruna dacite, which we discovered in the early 1950's in Japan. The reverse thermoremanent magnetization has been, and still is, a fascinating phenomenon, at least to me. However, it soon became clear to all of us that the phenomenon was much too rare to be useful for explaining the many world-wide occurrences of reversed remanent magnetization. The way to go, as far as geophysics was concerned, was to establish a reliable geomagnetic reversal time- scale. Allan with his two colleagues at Menlo Park, was committed to this task. Dr. Ian McDougall's group at the Australian National University, Canberra, Australia, also joined the race a few years later. It was always an enjoyable experience to visit Allan and his colleagues at their laboratory, filled with rocks and measuring apparata, to find out how much progress they had made since the last visit and to hear their adventures in such places as the Pribilof and Galapagos Islands. If I remember correctly their laboratory at the Survey was labeled "Theoretical Geophysics". The work was laborious, but it was more than apparent that they were immensely enjoying themselves and that they knew they were establishing a milestone. However, no one yet knew the full significance of their work and the key role their results would soon play, through the Vine-Matthews-Morley hypothesis, in establishing the sea-floor spreading theory and hence leading to the plate tectonic revolution. In 1967, Allan moved to Stanford University as a professor of geophysics. At Stanford the scope of his research was considerably broadened to include such aspects as the statistical and theoretical nature of the geomagnetic field and the applications of paleomagnetism to plate tectonics. His research at Stanford naturally involved young students and Allan proved to be a superb educator. He had a special talent for stimulating scientific curiosity in his students. The eager, proud and happy face he showed everytime he would tell me about some interesting results of his students is still vivid in my memory. Allan published two very important books. One is "Plate Tectonics and Geomagnetic Reversals" (Freeman, 1976) and the other is "Plate Tectonics: How It Works" (Blackwell, 1986). The former is essentially a collection of papers carefully selected by Allan, to which he added an interesting and enlightening historical and explanatory commentary. The latter book, written jointly with Robert Brian Hart, is a workbook of plate tectonics. It is written in such a lucid and simple language that the students who read it gain understanding in a way that only the best of books provide. Both books are unique and will remain highly useful in the years to come. Allan was a good friend of Japan and many Japanese scientists. I met him for the first time in the fall of 1959 on my way back from England where I had my first overseas post-doctoral study. It was also my first visit to the United States. Allan took me around the Bay Area, including the University of California at Berkeley where I met Professor J. Verhoogen and Dick Doell. Both of them became my life-long friends. Allan insisted that I stay at his little log cabin in the redwood forest, Woodside. As I was so deeply impressed that when leaving the cabin after a Obituary 1045 week-long stay I could not help but keep waving to it and mumble to myself "Now I bid farewell to the typical American house". Allan was somehow greatly amused by this and kept telling this story to later visitors to his home. In 1961 Allan visited Japan for the first time to participate in the International Conference on Magnetism held in Kyoto. The conference was mainly on the solid state physics of ferromagnetism and ferrimagnetism, but there were some sessions for rock magnetism and paleomagnetism, and a number of great scholars in geomagnetism, such as Professors E. Thellier, P. M. S. Blackett, and S. K. Runcorn attended from overseas. Both Allan and me were among the youngsters. Allan stayed on in Japan for several months after the conference, at the Geophysical Institute of the University of Tokyo as a guest to Professor T. Nagata. During this stay and two later visits to Japan, he made many friends here. He served as a member of the editorial board of this journal. In 1964-65, I was at the Department of Geophysics of Stanford University as a visiting professor. Although this was a couple of years before Allan moved to that Department, he was with the US Geological Survey and Stanford being almost next door, my whole family became friends of Allan. The highlight of our stay was the horse-back trip into the Sierra Nevadas. Together with Clyde Wahrhaftig and Rob Coe, Allan made such expert arrangements that all my family, including our two kindergarten age children, none with any horse riding experience, had a wonderful week. I shall never forget this experience. Not surprisingly, Allan received many distinctions for his feat. The John Adam Fleming Medal of the American Geophysical Union (1969), the Vetlesen Prize (1971) and the Arthur L. Day prize of the United States National Academy of Sciences, of which he was elected a member, are examples. He was also a member of the American Academy of Arts and Sciences, and the American Society of Philosophy, and was President of the American Geophysical Union for 1978-1980. Moreover, Allan became Dean of the School of Earth Sciences at Stanford in 1979 and proved to be an excellent dean. Despite all these honors and high positions, Allan remained a shy, warm and sincere person, absolutely without a speck of arrogance. I join all his friends in deeply mourning his passing. Seiya Uyeda.