Obituary Notice Pioneer of Geochemistry: Harmon Craig

Professor Harmon Craig, a leader in global investigations of the earth's chemical properties and a world explorer at Scripps Institution of Oceanography, University of California, San Diego, died Friday, March 14, at Thornton Hospital in La Jolla, Calif., from a heart attack. He was one day shy of his 77th birthday.

During his 47-year career with Scripps Institution of Oceanography, Craig led scientific expeditions to such remote spots on Earth as Tibet, Polynesia, and the Great Rift Valley in East Africa. He searched for elusive gases and rocks in some of Earth's most inaccessible places, such as 12,000 feet deep in the Pacific Ocean's Mariana Trough, where he discovered hydrothermal vents; and in the crater of an active underwater volcano off Hawaii.

"Harmon's curiosity and sense of adventure knew no bounds," said Dr. Charles Kennel, director of Scripps Institution of Oceanography. "His drive for scientific achievement was unparalleled in my experience. The ocean and earth science world has lost a truly spirited adventurer and one of the greatest geochemists of the 20th century."

In 1998, Craig was the first geochemist to receive the Balzan Prize, the international honor considered to be the equivalent of the Nobel Prize in the fields of natural sciences, humanities, and social sciences that are not Nobel award categories. Craig was recognized by the Balzan Foundation for his work as "a pioneer in earth sciences who uses the varied tools of isotope geochemistry to solve problems of fundamental scientific importance and immediate relevance in the atmosphere, hydrosphere and solid earth."

Craig was listed among the top Earth scientists in the world in the recently published "A to Z of Earth Scientists," part of a notable scientists series published by Facts On File, Inc. His entry begins, "If there were an Indiana Jones of the Earth sciences, it would be Harmon Craig. Not only does he work on some of the most important problems in Earth science, he does it while having the most daring of adventures."

Harmon Craig was born March 15, 1926, in New York City. He entered the University of Chicago in 1943 and served in the U.S. Navy as an ensign during 1944-46. In 1951, he received his Ph.D. from the University of Chicago in geology/geochemistry and stayed on as a research associate at the University's Enrico Fermi Institute for Nuclear Studies until 1955. At the University of Chicago, Craig studied the isotopes of carbon in the earth and the element iron in various classes of meteorites under Nobel Laureate Harold C. Urey, who joined the fledgling UC San Diego faculty in 1958.

Craig had joined Scripps Institution of Oceanography in 1955 and, in 1957, he published a paper on the distribution of radioactive carbon-14 in the earth's atmosphere and oceans and concluded that atmospheric carbon dioxide is replaced once every seven years by exchange with the oceans and that the global oceans circulate vertically at a rate of once every 700 years.

Craig was awarded a Guggenheim Fellowship in 1963. He spent a year in Pisa, Italy, at the Istituto de Geologia Nucleare.

In 1970, Craig joined forces with W.S. Broecker of Lamont-Doherty Geological Observatory, Arnold E. Bainbridge of Scripps Institution, and Derek W. Spencer of Woods Hole Oceanographic Institution to initiate and direct a multi-institutional and international oceanographic project called Geochemical Ocean Sections Study (GEOSECS) for a global investigation of chemical and isotopic properties of the world oceans. The results obtained by the GEOSECS program represent the most complete set of ocean chemistry data ever collected and contributed significantly to the advancement of chemical oceanography. Based upon the data obtained during this program, Craig estimated the rate of oxidation of organic carbon in the deep ocean. Another result was the discovery of the scavenging of lead and other trace elements from the deep sea by sinking particulate matter.

Craig also has investigated geothermal and hot springs processes, which are a manifestation of the upward transportation of heat and materials from the earth's interior. A series of papers published in the mid-1960s by Craig and his associates demonstrated how the isotopes of hydrogen and oxygen can be used to understand the origin of the volcanic gases. In 1969, Craig in collaboration with W.B. Clarke and M.A. Beg of McMaster University, Canada, demonstrated for the first time that the isotope helium-3, which was trapped in the earth's interior at the time of its formation some 4.5 billion years ago, is being released from mid-ocean volcanoes and sea-floor spreading centers. Release of primordial hydrogen and neon gases has subsequently been added to his list of discoveries.

A major finding by Craig's group during the GEOSECS Pacific Expedition was the existence of two major primordial helium-3 plumes that mark the cores of westward flowing water at mid-depths (~2,500m) from the East Pacific Rise. The discovery of these two jets revealed for the first time the direction of horizontal flow and the nature of the deep circulation pattern in this major region of the Pacific.

Other recent work by Craig and his colleagues include the discovery of submarine hydrothermal vents found on the Galapagos spreading center, as well as discoveries of similar vents on the East Pacific Rise, on Loihi submarine volcano in the Hawaiian chain, and in the Mariana Back-arc Basin, using the Alvin submersible, and the emission of abiogenic methane from the earth's interior in submarine volcanic regions. In other work on methane, he analyzed the gases trapped in Greenland ice cores and showed that the methane content of the atmosphere has doubled over the past three hundred years, a finding which is important for studies of the atmospheric greenhouse effect.

Craig and his wife and frequent collaborator, Valerie, had a long-term project that identified the various sources of marble in ancient Greek sculptures and temples using carbon and oxygen isotopes.

On recent expeditions, Craig had sampled volcanic rocks and gases in Yunnan, China, in the East African Rift Valley, in oceanic expeditions to six Pacific marginal basins, and in the north Pacific to the southernmost island of the Austral Chain. This work is concerned with delineating mantle hotspots and other regions where volatiles from the earth's interior are emerging at the surface and are a part of continuing studies of deep circulation in the Pacific Ocean.

In recognition of his scientific achievements, Craig has received a number of honors. In addition to the 1998 Balzan Prize, he was elected to membership in the American Academy of Arts and Sciences in 1976 and the National Academy of Sciences in 1979. He received the V.M. Goldschmidt Medal of the Geochemical Society in 1979, the National Science Foundation "Special Creativity" Award in Oceanography in 1982, the Arthur L. Day Medal of the Geological Society of America in 1983, and the honorary degree of Docteur of the University de Paris (Pierre et Marie Curie) in 1983. In 1987 he was awarded the Arthur L. Day Prize and Lectureship of the National Academy of Sciences and was co-recipient of the Vetlesen Prize from Columbia University. In 1991 he was awarded an honorary doctorate degree from the University of Chicago, and in 1993 he was named an honorary fellow of the European Union of Geosciences.

Craig is survived by his wife of 55 years, Valerie, of La Jolla, daughters Claudia Craig Marek of Los Angeles, Calif., Cynthia Craig of East Lansing, Mich., and Karen Craig of Auckland, New Zealand, a brother John R. Craig III of Wittman, Maryland, and four grandchildren.

A memorial service will be held on Friday, April 4, at 3:30 p.m. in the Martin Johnson House on the campus of Scripps Institution of Oceanography in La Jolla.