E. Bruce Watson

2006 Walter H. Bucher Medal Winner

Rensselaer Polytechnic Institute, Troy, N.Y.

E. Bruce Watson was awarded the Walter H. Bucher Medal at the AGU Fall Meeting honors ceremony, which was held on 13 December 2006 in San Francisco, Calif. The medal recognizes original contributions to the basic knowledge of crust and lithosphere.


It is with great pleasure that I introduce Bruce Watson as this year’s recipient of the Walter H. Bucher Medal. This honor comes at an opportune moment, as 2006 represents the thirtieth anniversary of Bruce’s first publications on the role of silicate melt structure in trace element partitioning. As always, Bruce’s approach to the problem was original, in this case investigating mineral-melt partitioning by simply eliminating the mineral, and instead focusing the distribution of trace elements between immiscible melts. In 2006, a conceptually identical paper appeared in the pages of Science. This affords a quantification not often observed at awards ceremonies: Exactly how far ahead of his time was Bruce Watson? The answer is, 30±1 years.

Bruce has been honored many times, and I have been fortunate to have either coauthored or edited a number of previous citations. The most economical approach to the task is to simply take previous citations and change the adjectives. One citationist referred to Bruce as a ‘taciturn Yankee.’ I much prefer ‘reserved son of the Granite State.’ Another, at least in draft, discussed the fastidious manner in which Bruce runs his lab. A number of Freudian terms were used. Instead, I like the sound of ‘Bruce is meticulous and well-organized, and capable of instilling those qualities in others.’

Experimental geochemists have necessarily focused much effort on phase equilibria and partitioning, and Bruce continues to make important contributions in this area. However, Bruce has also gained distinction as one of the leaders in bringing dynamics to experimental geochemistry in the form of kinetics and mass transfer. With apologies to Bowen and a handful of others, we knew virtually nothing about diffusion in magmas and minerals 30 years ago. Bruce was the first to characterize the effects of pressure and volatile content on diffusion in melts, and his elegant experiments inspired a generation of geochemists. Similarly, although we blamed aqueous fluids for a lot, we knew little about their microstructural distribution in crustal and upper mantle rocks, a parameter that is essential to understanding fluid transport and the effects of fluids on physical properties. As in his studies of diffusion, Bruce’s efforts isolated the important parameters and developed the interpretational framework for those that followed.

Another of Bruce’s signature contributions concerns the role of accessory minerals in crust and mantle petrogenesis. Unlike fluids, which were blamed for a lot, accessory minerals were largely ignored. With Mark Harrison, Bruce developed a set of ‘accessory phase parameters’ describing accessory phase solubility, trace element partitioning, and controls on the approach to equilibrium. These parameters defined that utility of accessory minerals in petrogenetic investigations. Most recently they have transformed zircon, our premiere geochronometer, into a new geothermometer based on titanium solubility and used the temporal and thermal information contained in the Earth’s oldest minerals to redefine our view of the Hadean Earth.

The one constant in Bruce’s work is that his experiments always look so simple—at least after the fact. His work is characterized by its elegance and economy and is performed in a style totally his own. His contributions span the boundaries between petrology, geochemistry, and mineral physics, but more often than not, he succeeds in making those boundaries transparent. It is a great pleasure to honor Bruce’s continuing contributions to our knowledge of the Earth’s crust and lithosphere and to present him for AGU’s Walter H. Bucher Medal.

—F. J. RYERSON, Lawrence Livermore National Laboratory, Livermore, Calif.


I am deeply honored to be the recipient of this year’s Walter H. Bucher Medal, and I am humbled by the company I am joining.

In his generous comments, Rick Ryerson noted that 2006 marks the thirtieth anniversary of my first publications. This is amazing, perhaps to me more than anyone. I have to accept the written record, but I also see more things I have to do in the next 5 years than I did back in 1976. Whether or not you accept Rick’s characterization of me as ‘taciturn’ or just ‘reserved,’ those of you with whom I have worked closely know that when it comes to science (and a few other things) I am still quite energized.

Both geochemistry and my perspective on it have evolved a great deal in the past 30 years, and I am increasingly inclined to inflict advice on young scientists and students. I think it is vital that scientists of all ages be able to anticipate, detect, and respond to change; somehow the education and attitude we impart to our students should build in these abilities.

Perhaps the greatest change in my 30-year career has been in the funding climate. I see a striking incongruity in the geosciences today: On the one hand, there has not been a more exciting time for our science, but on the other hand there have never been fewer funds to support that science. This dichotomy filters down to young scientists in ways that are both obvious and subtle. Consider, for example, a dean or department head who advises a new assistant professor that ‘scientific collaboration is essential, but be sure to make your own mark.’ The same hard-to-decipher signals are apparent in the organization of federal funding programs, where ‘multidisciplinary’ is advertised as the way to do science, but most practitioners understand that individual knowledge, insights, and creativity are still crucial. It is essential that young scientists understand the complexity of the terrain they will have to navigate, mainly so they will not be daunted by it.

The most effective beacon for younger and older Earth scientists alike is the realization that those of us who have knowledge about the Earth have an obligation to maintain the passion and vigor of our fields. Two of the most challenging issues the world now faces—environment and energy—are inseparably interwoven with the Earth sciences, and expanding the knowledge of our discipline will be essential for decades to come.

There are a great many people to thank for the roles they played in my being here today, including family, friends, mentors, colleagues, and students. Because I can not thank all of them individually, I will just say that I feel very fortunate to have all of you in my life. You know who you are.

—E. BRUCE WATSON, Rensselaer Polytechnic Institute, Troy, N.Y.