]Charles Langmuir has been instrumental in shaping our understanding of the origin of oceanic crust at spreading axes and its fate during subduction. These are fundamental processes that govern the geochemical evolution of the silicate Earth and are key drivers of plate tectonics. Charlie’s transformational work on the genesis of mid-ocean ridge basalts (MORB) began as a graduate student at Stony Brook and serves as the paradigm for explaining the melting process that creates the dominant igneous rock on Earth. He followed his ocean ridge work by quantifying how partial melting of subducting MORB and overlying sediments contribute to arc and back-arc basin magmas and how the residues of this process mix with the mantle and influence global mantle chemistry. His more recent work has revealed key relationships between global volcanism and glacial cycles. Charlie has achieved this with students, postdocs and colleagues through regional studies and global syntheses. Few geoscientists have covered so much ground in such a significant and comprehensive manner. His contributions over more than four decades underlie a unified theory that embraces central aspects of the igneous geochemistry of ocean ridge, island arc and back-arc basin magmas, producing a remarkably coherent, quantitative understanding of magma genesis at both divergent and convergent plate margins.

Charlie’s significant contributions to the marine sciences extend beyond scientific results to include analytical and field sampling innovations, with major impacts on ocean exploration. He built one of the first portable instruments to measure major and trace elements while on research cruises, which he used to inform real-time decisions on where to sample next. His “wax coring” approach made sampling essential volcanic glasses fast and efficient and is widely used to complement dredging, drilling and submersible sampling. With Bill Ryan, Charlie originated the National Science Foundation-funded PetDB (the Petrological Database of ocean floor basalts), which has fundamentally changed the way we do science by making all the ocean floor basalt geochemical data easily available to all users at their desks. PetDB is also used extensively as an educational as well as a research tool. A summary of Charlie’s achievements would be incomplete without mentioning Langmuir and Broecker’s magisterial revision of How to Build a Habitable Planet, which received Honorable Mention for Best Professional-Scholarly Book in Earth Sciences by the Association of American Publishers in 2012. In the spirit of Maurice Ewing, Charlie exemplifies the life and accomplishments of a deep-sea explorer.

— Steven L. Goldstein
Lamont-Doherty Earth Observatory, Columbia University
Palisades, New York

— Peter B. Kelemen
Lamont-Doherty Earth Observatory, Columbia University
Palisades, New York

Thank you, Steve and Peter, for your nomination and kind words and to AGU and the U.S. Navy. My initial reactions to this honor were surprise and gratitude, for I am keenly aware of the many other scientists who would be worthy recipients. I feel fortunate and honored to be associated with Maurice Ewing, who firmly believed in discovery through observation.I began work in solid Earth geochemistry when there were few data and even less understanding. In the 1970s, in our first graduate seminar on ocean ridges, we could write down on one page all the relevant papers. None of us had the imagination to know the wonderful discoveries that were in store. As a Lamont postdoc I managed to bootleg a trip to the Aleutians, which got me started on convergent margins. And one day Henry Dick suggested, “You should become a seagoing petrologist, because Lamont needs that.” I followed his advice, and gradually, many of us sampled the zero-age ridge system, using it as a window into Earth’s interior. The insights from ocean ridges then led to new understanding of convergent margins and a general model for geochemical variations in response to mantle melting. All this work, however, only revealed variations at “zero age.” An off-axis core on a recent cruise unexpectedly revealed 100,000-year time series of perfectly fresh glass on 600,000-year-old ocean crust, opening the time dimension, with the potential through coring of ultimately producing the best continuous volcanic time series anywhere on Earth. Discovery through new observations — it is the revelation of the unknown, and it is ongoing. What a gift to be able to participate in that.Seagoing science would not be possible without the funding agencies and the ship operators who make everything work. Virtually everything I have accomplished has come from teamwork. I am also increasingly aware that understanding often pops up as a collective emergent property, rather than being attributed to a particular person. I have been lucky to have great students such as Emily Klein, Terry Plank, Allie Gale, and Steve Turner, among many others; gifted postdocs; and wonderful colleagues such as John Bender, Steve Goldstein, Kerstin Lehnert (with whom we started the PetDB database), Jackie Dixon, Peter Michael, Peter Huybers, Liz Cottrell, Sung-Hyun Park, Alexandra Yang, and Zhongxing Chen. All the best science has come from us working together, and this award should be shared with you all.— Charles H. Langmuir, Harvard University, Cambridge, Massachusetts

The 1996 N. L. Bowen Award was presented to Charles Langmuir at the AGU Fall Meeting on December 16, 1996. The award is given by the Volcanology, Geochemistry, and Petrology section for a single outstanding contribution to volcanology, geochemistry, or petrology made during the preceding 5 years.  

"It gives me great pleasure to have the honor of introducing Charles Langmuir as the 1996 recipient of AGU's Norman L. Bowen Award. Charlie is a fitting recipient of this award. Like Norman Bowen, he is a great scientist whose origins go back to Canada and one who has keen insights into both broad- and fine-scale processes of igneous petrogenesis. As a leading petrologist-geochemist of our time, Charlie distinguishes himself by his quantitative approach to major and trace element studies of basalts.

"Charlie graduated from Harvard in 1973 with an honors degree in the history of science and geology. Following this, he went on to receive his Ph.D. from the State University of New York, Stony Brook, in 1980, under the guidance of Gil Hanson. After a year as a postdoctoral fellow at Lamont-Doherty Geological Observatory, he joined the faculty of Columbia University and is now their Arthur Storke Professor.

"A hallmark of Charlie's approach is that he begins by making a simple geochemical observation and proceeds through quantitative modeling to reach startling results with far-reaching implications. Amazingly, it was Charlie's first published paper where he immediately had an impact on his field. In this paper, on basalts from the French-American Mid-Ocean Undersea Study (FAMOUS) area of the mid-Atlantic Ridge, he helped us all to begin to understand the realistic complexities of melting processes with the concepts of incremental melting and residual porosity. Charlie reasoned that these basalts, which possessed crossing rare earth element patterns and constant ratios of isotope and highly incompatible trace elements, were produced by dynamic melting,' where melting and melt segregation, with partial melt retention, occur continuously during adiabatic ascent.

"Charlie is an innovator who thinks deeply and unconventionally about the way nature works. While many others were projecting into Ca-Mg-Al-Si phase space, Langmuir demonstrated that major element compositions could be treated in other ways with new ideas to be gained. Together with Gil Hanson, he used a novel premise that major element variations in multicomponent magmatic systems could be modeled using the same quantitative methods involving distribution coefficients that are successfully applied to trace elements, with the added constraint of stoichiometry. Charlie later presented a more generalized approach with his widely used liquid line of descent modeling program (1990), originally written for one atmosphere crystallization and more recently adapted for modeling crystallization at higher pressures (1992).

"Charlie has clearly been a great inspiration to our next generation of petrologists and geochemists; I will give but three of many examples. First, working jointly with students Emily Klein and Terry Plank, he led a major revolution in thinking about the petrogenesis of mid-ocean-ridge basalts. Starting with the now classic 1987 paper by Klein and Langmuir, they showed that regional averages of basalt chemistry correlate with both the depth and crustal thickness of the ridge axis from which the basalts are recovered. Global correlations in key chemical parameters (e.g., Na8.0 and Fe 8.0) were shown to reflect a fundamental association between the extent of melting and the pressure of melting, which in turn appears to result from regional variations in subsolidus mantle temperature. In 1989, Charlie revealed for us the important consequences of in situ crystallization in a boundary layer using simple and elegant quantitative modeling. Later, with Terry Plank, he evaluated the effects of melting regime and mantle flow paths beneath ridges and predicted that continuous mixing of melts occurs beneath ridges with high degree melts dominating. All this culminated with their tour de force published in AGU monograph 71 in 1992.

"Second, Charlie and his graduate students have also made important contributions in the field of arc magma petrogenesis. In 1988 Terry Plank and Charlie showed that chemical parameters indicative of the extent of melting correlate with the thickness of the arc crust. This surprising find was explained in terms of variations in the height of the melting column above the downgoing lithosphere imposed by variations in the thickness of the overriding crust, a model that has excited a good deal of interest and controversy.

"Third, Charlie and his students have developed a high-quality geochemical laboratory. Initially established with a direct current plasma emission spectrometer, this lab maintained the Langmuir tradition in that it was dedicated to major and trace element measurements on the same samples. Going beyond the traditional fare, Charlie, in collaboration with Jeff Ryan, published a series of studies in 1987, 1988, and 1993, reporting on the abundances of lithium, beryllium, and boron in a wide variety of lavas and ultramafic rocks. These innovative studies on light elements have had a significant impact on the community, including providing constraints on magmatism at ridges, arcs, and intraplate settings, and adding to our understanding of the evolution of ocean island basalts and their abundances in the bulk silicate earth.

"Professor Langmuir's contribution to basalt geochemistry on a global scale, his quantitative approach to combined major and trace element studies, and his application of these chemical observations to developing physical models of melting and melt extraction place him among the leading international workers in this field. A number of his graduate students have gone on to establish themselves as distinguished scientists in various universities. There are very few scientists working in these fields accorded the universal respect that Charlie has gained. In the words of Claude Allegre, and I am sure they are shared by those of us here, Charlie is an imaginative and extremely bright scientist, and also a perfect gentleman.' It gives me great pleasure to present to you the Bowen medalist for 1996, Charlie Langmuir."

—William McDonough, Harvard University, Cambridge, Mass.

"Thanks very much, Bill, for those generous comments. I am very grateful to receive the Bowen award from the Volcanology, Geochemistry, and Petrology section, particularly so since I have such high regard for the past recipients, many of whom are my scientific heros. I feel fortunate to be one of their number. "One of the advantages of receiving an award like this is that it leads to reflection on how it happened, and an appreciation for all the people who helped: a mentor like Gil Hanson, gifted students, generous and patient colleagues, stimulating and contentious postdocs, and those who were willing to take the time from their busy lives to write supporting letters. Of course, I owe an enormous amount to my wife, Diane, who was able to hold our home together, and give me the flexibility and time that creative science requires. Adequate thanks to all these people would take up all of the time available, because the thanks are long and each one is a special case. "There is one specific debt that I would like to acknowledge at more length, however, and that is my debt to my parents, who are present here tonight. When I was a boy, my father played at science with me: working with Cartesian divers, dry ice, and liquid nitrogen; seeing how the tone of a flute would change if you blew CO2through it; growing crystals; and making simple instruments. The combination of fun, amazement, and analysis that my father conveyed was a source of frustration to my grade school science teachers, because I knew that science was a lot more fun and interesting than the boring books we were reading. To this day, I feel that I learned more from those very early experiences concerning what science was and how to go about it than from all my schooling until graduate school. The debt to my mother is more subtle, but somehow she conveyed that exploration was infinite, that a sense of humor was essential, and that there was no sense in feeling limited, even if you were. I feel very much that many of the good things that have happened to me come directly from their influence. "In general, I feel somewhat uncomfortable with awards of this kind, because of the way that I find science happens. For me, ideas sometimes miraculously come together in discussion in front of a whiteboard, and without the questions from and interaction with the other person, nothing would happen. On a very broad scale, ideas often appear to different people at the same time, because that is the natural evolution of the field. That is why, I think, some of the most important developments have us reacting with Of course! I knew that!' because the idea was there in the scientific atmosphere, just waiting to crystallize. Moreover, in each specific instance, ideas often appear because of the subtle chemical interaction between two people confronting a problem together, or going over a paper in a seminar, or even listening to a talk on an apparently unrelated subject. I view this award as being the result of those interactions, and hence it is shared in a real sense with the large number of people I have worked or interacted with over the years. "The work for which this award is given came about from a series of bizarre accidents. I took only a few geology courses as an undergraduate at Harvard and spent most of my time doing theater. The most daunting and boring course I took was petrology/mineralogy, from Thompson and Burnham. I went sporadically, and there was always this one student sitting in the middle of the second row, with 10 or 20 kilograms of notes and notebooks piled around him. The lectures were an arcane dialogue between the professors and this dedicated individual, some guy named Stolper. I knew from this experience that although I liked geology, petrology was no field for me. It was only much later, actually, when reading Bowen, that I came to appreciate the beauty of the field. "After a year pursuing a career in theater, I went to graduate school in the one place that had been willing to accept me and defer admission: The State University of New York at Stony Brook. I wanted to study either geomorphology, because you could see what was happening, or economic geology, because the minerals were pretty, but to my surprise found no one in these fields in this small department. I liked Gil Hanson's geochemistry course, but Ted Bence was the one with some funding, so we compromised and I worked in Gil's lab on Ted's rocks: ocean ridge basalts. No subject could have had less promise—fine-grained black rocks that were all the same, with no pretty minerals at all, and they had been characterized already—our seminar at the time had a complete list of mid-ocean ridge basalt petrology papers, and it filled a whole page. However, Gil assured me that there are no bad problems, only bad scientists, and that with good data and thinking,' things would turn out all right. I think one might add that it helps if the bad problem' is a virtually unexplored frontier that has produced two thirds of the Earth's surface. "Later, landing at Lamont-Doherty Geological Observatory as a postdoc, I was somewhat at loose ends, since there was no postdoctoral adviser and poor equipment. Henry Dick came through Lamont one day and said You know, what Lamont needs, and what the field needs from Lamont, is a sea-going petrologist.' I was a lab scientist, and with no experience there was no chance of getting a sea-going proposal funded. Then a short time later, a Sloan Fellowship gave me the funds to go to sea and learn the ropes from a generous geophysicist, Brian Taylor, which made it possible to embark on a series of investigations of that wonderful frontier of the sea floor. "I had no idea of the excitement of sea-going science. At ocean ridges, you can see structures that are the direct result of related magmatic and tectonic processes and pose clear hypotheses that can be tested by a combination of geochemical and geophysical methods. This leads to a problem-oriented approach and inevitable cross-fertilization among fields, rather than a specialty-oriented approach. Petrology as a field became a tool for study of the Earth. We're after a solution to the problem, of how the Earth works, and that requires combining the physical and chemical aspects into a unified model. So instead of plotting major elements on a triangular diagram or one trace element versus another, we started plotting geochemical parameters versus geological and geophysical parameters: distance to a transform fault, axial depth, crustal thickness, and mantle Bouguer anomaly. These relationships of geochemistry to real physical observables of the Earth inevitably lead to models that tie together the geophysics and geochemistry and make geochemistry real.' A unifying goal that now spans many fields is to find the important relationships among geochemical and geophysical data and how both relate to quantitative models of the Earth system. "The ocean ridges are best suited to this approach—they demand it—because sampling and geophysics inevitably follow on together from a new map. The problems leap out at you from the map on the page. The combined understanding of the processes of melting, melt migration, and differentiation in magma chambers that have come about through the study of ocean ridges now are seen to cast new light on petrogenesis in many other igneous environments. So starting from boring black rocks that are all the same,' I now view ocean ridges as the Rosetta stone' of igneous petrology. They reveal how igneous systems work and that understanding can then be applied to other settings. For example, the work that we have done on convergent margins builds upon the paradigms from the ridge developed with Emily Klein. The work with Terry Plank showing how sediment inputs correlate to volcanic outputs could only come about because of the understanding of how the mantle melts and the global systematics of both ocean ridges and convergent margins that relate geochemical data to geophysical data and real tectonic variables. In fact, it is often only with the understanding of ridges that many other igneous terrains can be interpreted and understood. "I consider now that petrology' is no longer the appropriate title for much of what many of us do. We are working on problems that relate to the circulation of the solid Earth, to linkages between different parts of the Earth system, to understanding how the whole Earth functions, and to learning more about this marvelous machine by whatever means are necessary. What is most exciting are the unforeseen linkages between the different parts of the system, as we discover that all parts of the system are far more connected than we have been able to imagine. What could be more lucky than continuing to be able to participate in this accidental adventure?" —Charles H. Langmuir, Lamont-Doherty Earth Observatory, Palisades, N.Y.