Harmon Craig: The Gumshoe of Geochemistry
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In his search for clues to the composition of the Earth’s interior, Harmon Craig, the venerable professor of oceanography and geochemistry at the Scripps Institution of Oceanography, has led 28 deep-sea oceanographic expeditions, made 17 dives to the bottom of the ocean in the ALVIN submersible vehicle, including the first descents into the Mariana Trough, and the first investigation from inside the crater of an active underwater volcano. He surfaced last year in Rome to claim the Balzan Prize.

by Douglas Page,   1999

A lot can be learned about someone by what they carry in their pants pocket.

Harmon Craig, for instance, professor of oceanography and geochemistry at the Scripps Institution of Oceanography, University of California, San Diego, is never without his indispensable Hastings Triplet hand lens, in case he happens on an interesting rock.

He also carries a vial of polished green olivine crystals, to remind him of fascinating rocks he has already found. Craig, a Scripps faculty member since 1955, is good at finding interesting rocks.

"Most geologists take what they call a hand-specimen," Craig says. "But for our work with noble gases you need to take 10 to 20 kg of lavas because you need several grams of olivine crystals. We have a rule in my lab that we generally don’t analyze samples that other people collect. You have to get your own samples."

Never satisfied with classroom or laboratory science, Craig has taken the scenic route in the collection of his own samples, venturing to some of the most remote spots on Earth in pursuit of the elusive gases and rocks that provide clues to the composition of the Earth's interior.

His wall-to-wall chase has produced so many fundamental findings about how the deep Earth, oceans and atmosphere work that last year [Ed. note: Nov 1998] he was awarded the Balzan Prize, the first time the Balzan, considered the equivalent of the Nobel Prize in the fields of natural sciences, was awarded in geochemistry.

He received it with suffusion. "The Prize’s most significant effect was to establish that Geochemistry, especially Isotope Geochemistry, which began in 1947, had come of age and is a mature science," Craig says. "This was much more important than the specific person chosen for the award. Besides, prizes and awards are not worth much when they come after one's mother has died."

It is, of course, the weight of his own work that anchors geochemistry in scientific bedrock. According to John Edmond, professor of earth, atmosphere and planetary sciences at the Massachusetts Institute of Technology, "Harmon Craig is really one of a handful of people who invented the field of modern geochemistry. If it weren’t for Harmon, there would be a lot of floundering going on."

His work has been honored many times before the Balzan, including election to the National Academy of Sciences and V.M. Goldschmidt Medal of the Geochemical Society in 1979, the National Science Foundation’s Special Creativity Award in Oceanography in 1982 and the Arthur L. Day Prize of the National Academy of Sciences in 1987, among others.

Craig’s University of Chicago thesis on carbon isotope geochemistry under Nobel Laureate Harold Urey earned a geology-geochemistry Ph.D. in 1951, after which he remained as a research associate at the Enrico Fermi Institute. His contributions began immediately.

During this time he and Urey discovered that meteorites fall into discrete groups based on their oxidation states and iron content. Next, he studied the distribution of heavy hydrogen (deuterium) and oxygen isotopes in natural waters, establishing the Global Meteoric Water relationship of these isotopes, work which has become fundamental for studies in hydrology and climatology.

MAKING WAVES

In 1969, Craig and colleagues from McMaster University in Canada demonstrated for the first time that helium 3, a rare isotope of helium that was trapped in Earth's interior at the time of its formation 4.5 billion years ago, is being released from mid-ocean volcanoes by a process called "degassing" that played a key role in the evolution of the atmosphere. Using helium 3 as a tracer in ocean currents, Craig discovered the Pacific Ocean deep water circulates in the opposite direction to what scientists had previously theorized.

In 1970, Craig, once described by the Los Angeles Times as a "gumshoe of geochemistry", teamed up with colleagues at Scripps, Columbia University's Lamont-Doherty Earth Observatory, and the Woods Hole Oceanographic Institution to direct an international project called the Geochemical Ocean Sections Study (GEOSECS) for a global investigation of chemical and isotopic properties of the world's oceans. Results from GEOSECS represent the most complete set of ocean chemistry data ever collected and contributed significantly to the advancement of chemical oceanography. One of Craig's discoveries during this program was that lead is rapidly scavenged from the deep sea by particulate material, which turned out to be the major route by which many trace metals are removed from the ocean.

Later, Craig led two expeditions on Lake Tanganyika, using the GEOSECS methodology to study the geochemistry and limnology of this 1,400 m-deep lake.

Using the Scripps "Deep-Tow" vehicle to measure helium 3 and radon along the axis where the tectonic plates in the Galapagos sea floor spreading center are rifting apart, Craig and colleagues also discovered the existence of submarine hydrothermal vents. Then, driving the submersible ALVIN, he discovered similar vents in the caldera of an active volcano called Loihi, located over 900 m below the sea surface, that is erupting to form the next Hawaiian island. On another voyage aboard ALVIN, into the Mariana Trough, he discovered hydrothermal vents nearly 3,700 m deep.

Craig has also cored and analyzed gases trapped in Greenland ice, showing that the methane content of the atmosphere has doubled over the past three hundred years, a finding important for studies of the atmospheric greenhouse effect. He is currently measuring temperatures of past glaciations, using his discovery of gravitational enrichment of heavy noble gases in the air trapped in polar ice cores.

Other projects have taken Craig to sample volcanic rocks and gases throughout the East African Rift Valley from Northern Ethiopia to Lake Nyasa, and to the Dead Sea, Tibet, and Yunnan, China. He has made field expeditions to all the major volcanic island chains of the Pacific and Indian Oceans collecting lava samples. Craig's aim was to delineate mantle hotspots where volcanic "plumes" are rising from the earth's core through the deep mantle and can be identified by their primordial helium 3 content. He has identified 16 such hotspots where the helium 3 to helium 4 ratio is much higher than in the upper mantle and crust of the earth, fourteen in oceanic islands, and two on the continents, in Ethiopia and Yellowstone Park.

In 1972, Craig and his wife, Valerie, showed that carbon and oxygen isotopes can be used to determine the origin of marbles used in ancient Greek sculptures and temples, a study that continues.

Now, regrettably, after more than 40 years of resolute research in Earth’s margins, Harmon Craig reluctantly admits his expedition days may be over, that time may have "beached" him.

The research may be dry-docked, but there are plenty of cores to read, rocks to analyze and papers to write. Once in a while there is even a moment to reflect.

"I guess I’m proudest of the expeditions and field work I’ve carried out in pursuit of the elusive and primordial isotope helium 3," he says, "especially the work along the entire length of the East African Rift and on most of the Pacific volcanic island chains. These were the most complicated and difficult things I have done, so they were sources of great satisfaction."

While the Balzan Prize will be retired to the Balzan Room at the UCSD Faculty Club (to share the wall with three already there, won by the late oceanographer Roger Revelle, geophysicist Freeman Gilbert and oceanographer Wolfgang Berger), Craig is not about to retire. He may not launch any more ocean-going expeditions, but his research continues to sail.

At the moment he is working on two fronts. First, in terms of the gases brought up from the deep mantle of the earth and emitted in volcanic eruptions, he is trying to determine isotope ratios and their concentrations in magmas and lava minerals. "These gases are a probe to try and understand the structure of the Earth's mantle and where the volcanic eruptions that make hotspots come from," he says.

"Second is a recent discovery I made that helium from the earth is injected into the deep regions of the Greenland Ice Sheet, in the lowermost 250 m, not as a simple upward exponential curve, as one would expect from diffusion, but as large cusps which must be due to injection of ice layers from places where they accumulate helium." This is the first look anyone has had at actual transient major ice flow at the bottom of thick (3050 m) ice caps, and may help tell us if the West Antarctic sheet is going to slip off into the ocean, with possible dire consequences.

AN UNDERSTANDING WIFE

As has been his practice for years, he sleeps until noon, reads the International Herald Tribune with breakfast, does some writing, then heads to the lab in the middle of the afternoon, where he works and writes until going home for dinner at 9 p.m. At home, he writes more and reads until 4 or 5 a.m.

"I have a very understanding wife," he says. Valerie, his wife of 51 years, is also his Administrative Assistant at the lab, as well as his companion and colleague on all expeditions.

Much of Craig’s recreational reading reflects his interest in science and the sea. Currently, he is reading "The Story of Spin" by Sin-itiro Tomonaga (University of Chicago Press, 1998), the history of quantum mechanics by the 1965 Nobel Prize winner whose work was unknown in the U.S. here until after World War II; and "Cochrane: Britannia's Last Sea King" by Donald Thomas (Viking, NY, 1978), a biography of Thomas, Lord Cochrane, one of the greatest of the British Admirals during the Napoleonic wars.

Craig’s passion for adventure and discovery is equaled only his love of the written word. The grandson of famous stage actors, Craig was raised in a Thespian family and displayed a "bookish" aptitude for both literature and science, as symbolized by the vial of olivine crystals in his pocket. "The gem form of olivine was invoked by Othello, who said: ‘Make me such another world/ Of one entire and perfect chrysolite’", he recites.

"I can’t imagine living without poetry," he says. "Many scientists don’t care much for it, but poetry is one of my greatest loves."

Poetry’s saraband swirl of syllables and ideas intrigue him. Among his favorite books, he lists T.S. Eliot’s "Complete Poems and Plays: 1909-1950" (Harcourt Brace, NY, 1952), and, even though he professes atheism, the King James Bible. "I love it for the language, the entrancing story of how people developed a concept of a god and his interactions with humans, and the threads of the different writers that run through the Old Testament."

Another book he treasures is Edgar Rice Burroughs’ "Tarzan of the Apes" (Ballantine Books, NY, 1993). "It first incited my lifelong interest in Africa."

Science, of course, continues to intrigue him. "What I enjoy most about science is the incredible rush when something snaps into place and one suddenly finds or understands something

that has not been previously known," says Craig. "I think of science as very similar to a chess game. There is an opening game (discovery), middle game (enlarging a subject), and end game (tidying up). My style and preference are the opening game. Of course, one has to play the middle game to get funding for research, because it is difficult to get funded for exploring new ideas, generally because proposal reviewers and program managers are playing the middle game. So, I generally write middle-game proposals to keep working on a subject I have started. This keeps the lab running and one can use part of the funding for exploring new ideas."

Specifically, what interests Craig about geology and oceanography is that "there are so many unexpected and wonderful things to discover that have been lying around unsuspected in the rocks and oceans and if one is lucky or serendipitous one can sometimes find these things."

THE UNANSWERABLE QUESTION

One question fascinates Craig above all others, the only one he says that’s probably unanswerable: What is the origin of the universe, if it had an origin, and what was there before the Big Bang, if there was a Big Bang?

"I think the greatest frustration, not only in science but in all human thinking, is that this most important question of all will never be answered."

Craig sees it really as two questions. "If there is a god that started things going, what was that god doing before the origin of the universe, and what, if anything has that god been doing since," he wonders. "Remember that the Hebrew God stopped all conversation with humans. After his encounter with Job he never speaks again. More probably in my estimation there are no gods, and then the question is: how did things get started without them. Or has the universe always existed, and then why? These are the ultimate questions, which render all others insignificant by comparison.

Craig’s catalog of credits is certainly not insignificant, even for someone who claims he doesn’t believe in goals or adhere to the ‘scientific method’.

"I’ve never had any goals," says Craig, who grew up in New York and Boston. "I’ve just wandered through science working on what interests me at the moment. I have some long term studies, but no real goals. I feel if you can define goals, you know what you’re going to find already."

To illustrate this paradox, Craig says he’s been rejected twice recently by Marine Geology in NSF Ocean Sciences for a proposal to dredge some newly-discovered seamounts in a high-helium 3 gap in the Austral islands at the point where the Austral fracture zone intersects the chain.

"The tenor of the review is ‘Craig doesn’t follow the scientific method. He doesn’t lay out exactly what he expects to find and what it will mean,’" Craig says. "I wrote the Program Director and said, ‘I’ve never used the scientific method in my life’. I don’t know any good scientist who ever worked with the scientific method."

As Harmon Craig explains it, a lot of times you work on something for completely the wrong reasons. "As the Dark Lady of the Sonnets said, ‘After all, the road always leads somewhere.’"

-end-

Comments? Questions? Corrections? Assignments? douglaspage@earthlink.net
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