2006
Arthur L. Day Medal

Frank M. Richter
University of Chicago

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Presented to Frank M. Richter

 Citation by E. Bruce Watson

The basis for this important medal is “outstanding distinction in contributing to geologic knowledge through the application of physics and chemistry to the solution of geologic problems.” Given the emphasis upon both physics and chemistry, it is difficult to imagine a more appropriate recipient than Frank Richter. Prof. Day may not have intended that each year’s medalist be skilled in both physics and chemistry, but Frank most certainly is. Indeed, his work is so diversified across geophysics, geochemistry, and cosmochemistry that the full breadth and depth of his contributions are appreciated by few individuals. I will briefly summarize what I feel are his major contributions, while at the same time try to paint a picture of this distinguished scientist and gentleman.

I have known Frank Richter for 20 years, and we began a formal (though intermittent) collaboration about 13 years ago when Frank and his gifted student Yan Liang came to me for help with experiments on diffusion in silicate melts. It is an unnerving experience to have Frank take an interest in your past work. It is flattering to realize that he might value your contributions, but he is so perceptive and insightful that you also know he will find all the weaknesses and probably do things better.

Frank’s diverse contributions have involved two essential aspects that define his talent: he has an uncanny sense of key problems, and he has the ability to distill these problems down to a simple physical or mathematical essence or a strategic experiment. This has been true from the very beginning of his career when he tackled mantle convection and plate tectonics as a graduate student at the University of Chicago. Much has been written on these topics since Frank published his influential series of (mostly sole-author) papers in the mid-1970s, but I think it is accurate to say that his deductions about mantle convection have never been truly superseded or made irrelevant. Considering the advancements in computational power that have occurred over the past three decades — and ignoring Frank’s own recent statement that today he could “write his entire thesis in a single page” — this is a remarkable thing.

After addressing layered convection and the thermal state of the Earth, Frank began to drift away from his early work in geodynamics, initiating a slow migration toward more strictly geochemical topics. As a collaborator and sometime competitor of Dan McKenzie, he explored the geochemical implications of melt segregation and migration, and their work formed the underpinnings of a whole new school of quantitative thinking about the chemical dynamics of basalt production. Frank then migrated closer to the surface of the Earth to develop, with Don DePaolo, quantitative relationships for fluid flow and fluid-solid interactions during carbonate diagenesis.

Frank’s next path of scientific inquiry led into the realm of diffusion kinetics and the application of diffusion models to tectonics, geochemistry, and cosmochemistry. This began as a collaboration with Oscar Lovera and Mark Harrison on ⁴⁰Ar/³⁹Ar thermochronology, producing the multi-diffusion domain model that has been so fruitfully applied to problems in tectonics. Frank’s more recent diffusion efforts have focused on multi-component diffusion in silicate melts and the mass (isotopic) effect on diffusion in fluids — both silicate melts and aqueous fluids at near-ambient conditions. I consider his efforts on the mass effect to be some of his best work to date, which is saying quite a lot. Frank defined the conceptual framework for this phenomenon and designed the experiments to measure its magnitude, as described in a seminal 1999 paper by Richter, Yan Liang, and Andy Davis. For the benefit of readers not familiar with the work, the bottom line is that, under some circumstances, isotopes of a given element having mass differences as small as ~2% can be fractionated during diffusive transport to an extent that is easily measurable and possibly significant in data interpretation (that is, at the several parts per thousand level). Given the proliferating technology for measuring isotope ratios, the need for understanding the factors that affect these ratios in nature becomes paramount. Frank Richter has put in place the foundation for a great deal of future work in this area.

While still pondering diffusion on Earth, Frank has also given considerable attention to outer space — specifically, to the processes affecting element and isotope ratios in condensates in the solar nebula. Through a combination of strategic experiments and rigorous theory, he demonstrated the effects of diffusion and selective evaporation on the major components of Ca-, Al-rich inclusions, and used these to place constraints on thermal histories of these materials. This work is remarkable in its power and rigor, and — like many of Frank’s papers — will serve as a foundation for future experimental and theoretical work, as well as an interpretational framework for analytical studies of extraterrestrial materials.

In summary, for three decades Frank Richter has defined the state of the art in several fields, spanning geophysical fluid dynamics, chemical geodynamics and diffusion theory. He has not only laid the theoretical foundation for future work in all these areas, but also shown how his results can be used to address first-order geologic and cosmochemical problems. Please join me in congratulating Prof. Frank M. Richter of the University of Chicago as we honor him with this year’s Arthur L. Day Medal.

  2006 Day Medal - Response by Frank M. Richter

Few things are as sweet as the public praise of one’s peers — and especially so when the peers represent the Geological Society of America. This occasion makes me remember Julian Goldsmith, a past president of this Society, a long-time dear friend and mentor, and now sorely missed. He would often refer to the embarrassment of honors, something I didn’t appreciate at the time given that I was long on sources embarrassment but short on honors. Perhaps he was referring to that nagging voice that keeps asking — do I really deserve this? You tell yourself, of course I do — but it’s hard to keep a trickle of self-conscious doubt from creeping in. Arthur L. Day’s intent was that the medal that bears his name should not only recognize achievement but also inspire further effort — and so perhaps he had the embarrassment of honors in mind and how this could be used to stimulate the critical introspection so necessary for creative work.

I would like to share a bit of the sweetness and the embarrassment of this moment using the story of how the hawk and the cowbird approach geology. Earth Science is a natural science, and pure geology, as recognized by the Penrose Medal, is the very soul of our science. The pure geologists, like the hawk, live by their good eyes. They have to do a lot of looking and a lot of seeing (which is not the same thing) and then, in ways often not easy to explain, they have to sort through all that they have seen to come up with a compelling story about the Earth. Evidence of the subtlety of this style of geology can be seen in how long it sometimes take for what one person may have seen very clearly to become widely accepted. I’m at the University of Chicago where we love the story of J Harlen Bretz (no period after the J) who was the first to “see” that the extraordinary landscape of the channeled scablands of Northern Idaho, Washington and Oregon was the result of an otherwise unimaginable flood that devastated the area when the glacial lake Missoula burst its confining ice dam. After almost fifty years of ridicule and at an age of 96 years, Harlen’s good eyes were finally recognized with a Penrose Medal in 1979. After receiving the award he remarked to his son that “All my enemies are dead, so I have no one to gloat over."

What success I’ve had in geology owes more to my imitating the cowbird than to the good eyes of the hawk. The cowbird, you may recall, places its eggs in the nests of other bird species and leaves the nurturing of its offspring to them. I’ve made good use of this practice by placing many of my students in foreign nest. For example, Neil Ribe (professor at Yale, now at Paris) did a large part of his thesis work at Columbia with Tony Watts using gravity and bathymetry data to investigate the origin of the extraordinary bathymetric roughness of the Western Pacific. Oscar Lovera, now at UCLA, made very important and elegant contributions to argon thermochronometry thanks to help from Mark Harrison (we’re not quite sure where he is these days — somewhere between ANU and UCLA, or vice cersa). Another good example is Yan Liang, now a professor of petrology at Brown, who became a leading authority on chemical diffusion in silicate melts with lots of mentoring by my very close friend and citationinst Bruce Watson (RPI). And then there’s Dan Shrag, who can’t seem to decide what nest he came from, but who always speaks with great affection of his time at Chicago. There is, however, one important difference between me and the cowbird — I actually join my “offspring” in their foreign nest and we end up learning a new topic together. It’s been said, with more than a bit of truth, that my students get their degree only after they have mentored me enough for me to pretend to some mastery of their thesis topic. Well, this is my chance to thank them and those that nurtured us in their nests.

In closing, I want to again thank the Geological Society of America for the Arthur L. Day medal, which has been made especially honorific by those that have been awarded it before me. And by way of highlighting the pleasure this award gives me and my family — my wife Theresa who is here tonight — my children Fritz and Emy, and Emy’s husband Dan — I want to show you — actually I’ll have to describe it for those too far to see it — a bumper sticker. Emy’s children are too young for her to have a bumper sicker proclaiming her to be the proud parent of an honor student at such and such a school. Instead she has a bumper sticker that reads “Proud Daughter of a Geological Society of America Medalist”. Thank you for the honor, and I’ll be the better for the embarrassment.