University of Cambridge
Dan McKenzie was awarded the William Bowie Medal at the AGU Fall Meeting Honors Ceremony, which was held on 12 December 2001, in San Francisco, California. The medal recognizes outstanding contributions to fundamental geophysics and for unselfish cooperation in research.
“Dan McKenzie has made outstanding contributions in almost all major branches of Earth sciences. He wrote the first paper defining the principles of plate tectonics. His early work on mantle convection created the modern discussion of planetary interiors. Using earthquake source mechanisms as a guide, he initiated first principle modeling of continental deformation. By bringing dynamical considerations to bear, he revolutionized the field of magma genesis and galvanized an important branch of Earth sciences. Above all, he has demonstrated, to an entire field, that simple models based on sound physical reasoning can provide quantitative explanations for most geological and geophysical observations.
“The Bowie medal, AGU’s leading honor, recognizes an individual for his or her outstanding scientific contributions and for unselfish cooperation in research. Dan’s scientific contributions are well known. What is not so well known is the extent of his collaboration with his colleagues and students.
“Dan, together with Bob Parker, published the first paper defining the quantitative principles of plate tectonics. His collaboration with Jason Morgan, who independently had presented the same principles earlier at an AGU meeting, determined the stability of triple junctions, the point where three plate boundaries meet. In addition to working on these topics, he persuaded me to tackle the problem of the heat flow and subsidence across a mid-ocean ridge. Though our initial attempts were unsuccessful, our effort jump-started my career by demonstrating the power of using simple one-parameter physical models to explain a number of related geophysical observations. In 1968, he joined me in Colombo, Sri Lanka, to spend a month at sea on Scripps Institution of Oceanography’s (SIO) R/V Argo. I had been told to study the chemical composition of the Ninety East Ridge. To the consternation of the expedition coordinator, he persuaded me to change the entire ship track once we were at sea. At the time we were in our mid-twenties and both still post-docs! Only the spectacular nature of our magnetic profiles which resolved the post-Cretaceous tectonic history of the entire Indian Ocean stayed a reprimand when I returned to SIO.
“Many others have benefitted from collaboration with Dan. In the early 1970s, his papers with Nigel Weiss, Greg Houseman, Dave White, Gary Jarvis, and Barry Parsons explored a series of issues in mantle convection. They form a coherent whole which these authors and Dan have used to lay down the basic principles of convection in silicate planets. During the same time span, he devoted a significant effort to studying continental deformation using earthquake focal mechanism solutions. His early tectonic model of the continental Anatolian plate has stood the test of time. His approach spurred much additional investigation. James Jackson and he demonstrated the importance of block rotation for understanding the deformation of continents. Phil England studied continental evolution by modeling the lithosphere as a thin viscous sheet with a time-dependent rheology. Countless others, myself included, have investigated the subsidence of continental basins and continental margins using a simple one-parameter approach first presented by Dan.
“In the early 1980s, Dan realized that surface magmas provided much information regarding convection within the mantle. He studied melt migration and the chemical composition of these magmas to solve for their temperature evolution. Not only did this work rescue a moribund field from the doldrums, but also it spurred Mark Spiegleman, Mike Bickle, and Bob White into remarkably profitable areas of research.
“Dan has great passion for the Earth sciences, keen physical insight, a lively imagination, and profound respect for the value of good observations. Those of us who have had the opportunity to work with him over the years and the many others who have benefitted from his insights feel much gratitude for both his encouragement and his support.
“As a group, we believe that Dan’s approach can best be understood by appealing to a horticultural analogy. He deals with us all more from the attitude of the hardy vintner who believes that stressed vines yield the best fruit than from the standpoint of the oversolicitous gardener who pampers his roses with fertilizer.
“His outstanding scientific contributions and his remarkably effective collaboration with so many colleagues make Dan McKenzie an ideal recipient of the Bowie Medal.”
—JOHN G. SCLATER, University of California, San Diego, USA
“I am delighted and profoundly honored to have been chosen to receive this year’s Bowie award. It is wonderful to be acknowledged in this way, and especially by the AGU, which is the foremost society of Earth scientists in the world.
“My scientific career started when I became Teddy Bullard’s graduate student in 1963, and I will always be very grateful to him for starting me off in the right direction. In 1963, most of the major figures in geophysics knew each other well, and I also came to know most of them in my first 2 years as a graduate student, either because they were visiting Teddy or because they were at Cambridge on sabbatical. Most were American, and I quickly took a profound liking to the American way of doing science, feelings which have never changed. What impressed me was the total lack of interest in the incidentals: what nationality you were or whether you were old or young. They were interested in ideas and in understanding how the Earth worked and were wonderfully supportive of a young Englishman at the start of his career. Three people in particular profoundly influenced me-Freeman Gilbert and Walter Munk at Scripps, and Don Anderson at Caltech. I was deeply impressed by their generosity and support, and it is a real pleasure to me that all three are here this evening.
“I was extremely lucky to be a young postdoc when the plate tectonics revolution really got under way, though at the time I had little idea of how anomalous this period was. Bowie would have approved of my first paper on the subject, which showed that ridges are compensated by Pratt, not Airy, isostasy. I recently wrote an article about this time period for a book that Naomi Oreskes has edited, which was released here on Monday. I had forgotten how easy it had then been to solve major problems that had worried generations of Earth scientists. I don’t think any of those involved have experienced anything like it before or since.
“Good times don’t last forever, though, and for me at least they were clearly coming to an end in the 1970s. I cannot decide whether this was true in an absolute sense, or whether I had by then been working in the subject for a long time and had simply run out of new ideas. Whatever the cause, it was time to change direction, and so I thought I would apply some simple physical ideas that had worked so well in plate tectonics to try to understand the relationship between mantle convection, melt generation, and the isotopic anomalies in ocean island basalts. This change took me into one of the most active areas of Earth science. I found the petrological and geochemical community to be very different from the geophysical one I was leaving. I was, and still am, very surprised by the way they behave to each other, and found the isotope geochemists especially to be quite brutal. At the beginning they were very nice and welcoming to me, but I knew they had accepted me when they started to behave to me like they did to each other! Of the various groups of Earth scientists I have worked with, I have found them to be the most scientifically sophisticated. They need to be, because trying to understand physical processes by studying their chemical effects is much more difficult than understanding plate motions.
“I have been a member of the audience at a number of such presentations in the past and am always brought up by the phrase in the citation for this medal that talks about unselfish cooperation in research. Out of curiosity, I counted the number of people, 119, with whom I have published papers, but I cannot claim that this cooperation was for unselfish reasons. I work with people because they know things I don’t, or have data or programs or equipment I want to use. So I cannot claim to live up to the words of the citation, although I don’t intend to refuse the award!”
—DAN MACKENZIE, Bullard Laboratory, University of Cambridge, U.K.