Bob Coleman hailed 2016 graduates with a single imperative: “Keep the Earth green and prosperous!" Credit: Stacy Geiken
Bob Coleman wins 2016 Distinguished Alumni Award
Robert G. Coleman, PhD ’57, has a knack for being in the right place at the right time. Driven by a keen mind and an adventurous spirit, he has more than once pursued a rather obscure geological phenomenon and found himself the leading expert when it turned out to be of significance.
Raised in Oregon, and built like the logger that he was, Coleman had planned to study forestry when he entered Oregon State University (OSU) on a football scholarship in the early 1940s. War soon led him to Cherry Point, North Carolina, however, where he served as a radar technician in the U.S. Marine Corps. Combining knowledge gained from a correspondence course in geophysics with his radar expertise, he mapped groundwater levels under the Cherry Point airport. This feat, which had so far eluded local officials, put him on the threshold of a new career.
Returning to OSU after the war, Coleman gave up both football and forestry to study for his bachelor’s and master’s degrees in geology. He later spent three decades with the U.S. Geological Survey (USGS) and served on the Stanford Earth faculty for 11 years. Aided by his proclivity for fieldwork and an exquisite sense of timing, he produced pioneering field studies throughout the American West, as well as in New Zealand, Japan, China, Inner Mongolia, Kazakhstan, Oman, Saudi Arabia, Cuba, Guatemala, and the Western Alps.
In recognition of his scientific achievements, Coleman was presented with the School of Earth, Energy & Environmental Sciences Distinguished Alumni Award on June 12 during the school’s diploma ceremony following Stanford University commencement exercises. The award recognizes highly significant, long-lasting contributions to the civil, government, business, or academic communities by members of the school’s alumni body.
“Long before plate tectonics had been proposed as a unifying theory to explain Earth processes, Bob Coleman identified some of the geochemical fingerprints of it in the ocean crust,” said Pamela Matson, the Chester Naramore Dean of the school and the Richard and Rhoda Goldman Professor in Environmental Studies, during the award presentation.
“Over the course of his nearly 70-year career, Bob has made important scientific contributions in the areas of mineralogy, petrology, geochemistry, geophysics, structural geology, plate tectonics, and even environmental geobotany,” she said. “Among his special achievements is developing our current understanding of the formation conditions and tectonic setting of ophiolites, a type of rock that forms where oceanic crust is subducted beneath continental crust. This award recognizes this seminal work as well as Bob’s other major contributions to the geological sciences over a long and distinguished career.”
From timber harvester to tectonic sleuth
Admitted to both Caltech and Stanford in 1950 for his PhD, Coleman chose Stanford—in part because the university had offered him a mineralogy fellowship of approximately $300 per year. After completing his required coursework, Coleman accepted an assignment from his advisor, Professor Colin Hutton, to analyze the mineralogy of the New Idria serpentinite mass within the Franciscan Complex of the California Coast Ranges. He soon found, however, that he could not understand how the minerals had developed without first understanding the geology and origin of the entire formation.
Overturning conventional wisdom, he demonstrated in his thesis that state maps characterizing the serpentine rock as igneous intrusion were wrong. Contacts with the enclosing host rocks showed fault activity, he pointed out. Of course, these were signs of tectonic processes at work, but few knew that at the time. And without the theoretical underpinning that came many years later, Coleman was not sure how this conclusion would go over in his dissertation defense.
Now 93 years old and still active professionally, he remembers the moment of truth. “I held my breath and they passed me,” he says. His thesis is now considered a classic study that helped define the nature and formation conditions of serpentinite.
To supplement his GI Bill and fellowship income while completing his PhD, Coleman spent two years working as a New York-based mineralogist for the U.S. Atomic Energy Agency, and several more years with the USGS in Washington, D.C. Doctorate officially in hand, he eagerly moved his family back to California when the USGS opened its Menlo Park field office in 1958.
Now close enough to return often to the Franciscan Complex, Coleman continued to uncover new clues to the area’s geologic mysteries. For example, he documented recrystallized minerals that could only have been formed at very high pressures.
“Bob was one of the leaders in documenting why the rocks recrystallized at high pressures,” explains Gary Ernst, the school’s former dean and Benjamin M. Page Professor, Emeritus. “This was interesting in itself, but at the time we all wondered, ‘what did it mean?’ We geologists felt like detectives looking at a crime scene that was largely obscured.
“Of course, we found out later that the rocks had spent time sequestered deep within the Earth and subsequently risen toward the surface. Bob was a leader in this area, identifying signatures associated with plate tectonics before the theory came along to explain it.”
The opportunity to apply the illuminating lens of plate tectonics to previously observed geologic relationships may be the most dramatic change Coleman has experienced during his long career, but it’s certainly not the only change.
Technological advances have had a profound impact on the field, says Coleman, who as a graduate student was all too familiar with the wet chemical analysis traditionally involved in analyzing rock samples. “I used to separate out each mineral very carefully by hand. It took me about a week to analyze each sample,” he remembers. “Now we can do this with an electron probe and a graduate student can do 20 to 30 analyses in an afternoon.”
Coleman considers one of the biggest technological game changers of his time to be the mass spectrometer. Its introduction allowed geologists to identify different isotopes of the same element present in a mineral or rock sample, providing important information about the conditions and/or time at which the Earth material formed. When he was a graduate student, says Coleman, “I couldn’t separate atoms of different weights that had the same chemistry. Now you can get a much better story from just a single mineral.”
The story of oceanic crust, read on land
Coleman’s seminal work on serpentinites launched his lifelong interest in high-pressure, low-temperature metamorphism and led to his particular interest in ophiolites, remnants of oceanic crust that are often transformed in fascinating ways when they meet the edge of a continental plate. He has traveled all over the world in pursuit of readily accessible ophiolite specimens—that is, those that are no longer underwater.
Those of the Persian Gulf are best preserved, says Coleman, who led a large National Science Foundation (NSF) project in the southern Oman Mountains. He is well known for being able to adapt to nearly any environment or circumstance.
“In Oman, I was the cook for our field camp because our NSF grant didn’t provide for one,” he remembers. “Fortunately, at that time a French company was working nearby on a highway building project and they let us go into their commissary. So we had rich French food on that trip.”
Geologists without borders
The rare scientist elected to both the American and the Russian Academies of Sciences, Coleman has nurtured his international relationships and leveraged them in collaborations that few others would have been able to manage. These included a research trip aboard the Russian oceanographic vessel Dmitri Mendeleev to study ophiolites on the floor of the Pacific and Indian oceans.
Coleman was also one of the first to connect with his Chinese counterparts soon after changes in relations between the two countries made collaboration possible. He played an important role in documenting the history of the Paleoasian Ocean, working with other scientists from Japan, China, Russia, the U.S., and a host of European countries. Sponsored by what is now called the United Nations International Geoscience Programme, the team worked together to map the tectonic features that lay across the geopolitical boundaries of the Asian continent—from Lake Baikal to the edge of the Tibetan Plateau.
Managing the international relations was the easy part of that endeavor, he recalls. “In my experience you can go to any country and talk geology without a political agenda,” he says. But sleuthing out the ancient geology? That was difficult. “Mapping California is simple compared to rebuilding Asia,” he says.
Coleman has published more than 500 papers over 66 years and received innumerable honors. In addition to being elected a member of the National Academy of Sciences in 1980 and a foreign associate of the Russian Academy of Sciences in 1994, Coleman is a fellow of the Geological Society of America, an honorary fellow of the American Geophysical Union, and a fellow of the American Association for the Advancement of Science.
At the USGS, Coleman held a variety of administrative appointments, including serving as chief of the Isotope Geology Branch and later of the Field Geochemistry and Petrology Branch. In 1982, he joined the Stanford geology faculty, where he famously held Introduction to Rocks and Minerals classes outdoors.
“We went outside on the lawn, where we could look at rocks with magnifying glasses in bright sunlight,” he says, explaining that he sought to empower his students with the knowledge that, armed with these two important tools, “a geologist can go anywhere in the world, look at a rock, and figure out how that rock formed.”
Interdisciplinary before it was cool
Not one for an idle retirement, Coleman has continued to work, including publishing a paper on ophiolites in the journal Elements in 2014. But retirement has given him more time to explore one of his other professional interests: geobotany. The former forestry major had long ago found an outlet for this interest through his work with serpentinite terrains.
Especially low in two of the most important minerals for plant growth, phosphorous and nitrogen, serpentinite makes inhospitable soil. Of course, this creates an opening for the unusual plants that can adapt to it.
“Serpentinite plants are all weird,” says Coleman, who keeps regular company with the environmental geobotanists who have made careers out of studying this relationship. He has attended their conferences all over the world. “Usually I am the only geologist there,” he says. “But I enjoy that, because I think getting two sciences together is useful. That’s where our problems lie now, and people with different abilities and different instruments can approach them in new ways.
“That is the thing that fascinates me about Earth science. We’ve just started finishing the first chapter.”