Harmon Craig, a professor of oceanography and geochemistry at the Scripps Institution of Oceanography, University of California, San Diego, has been awarded the Balzan Prize for his fundamental contributions to the field of geochemistry. The Balzan Prize of the International Balzan Foundation of Milan, Italy, has several times been given in astrophysics and geophysics, but this is the first award in geochemistry.

Craig was presented with the award by the President of Italy at a ceremony held in the Palazzo del Quirinale in Rome on Nov. 23, 1998.

The Balzan Prize is considered the equivalent of the Nobel Prize in the fields of natural sciences, humanities, social sciences and international affairs that are not in Nobel awards categories. The Balzan Prize was established in 1961 by the late Italian heiress Lina Balzan in memory of her father, publisher Eugenio Balzan. Three awards were made this year. Andrzej Walicki of Poland and the United States was awarded the prize for history and Sir Robert May of Australia and the United Kingdom received the award for his work in biodiversity.

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."

A faculty member at Scripps since 1955, Craig has ventured to some of the remotest spots on Earth in search of elusive gases, rocks and other materials that provide clues to the composition of the Earth’s interior. In his quest, he has descended into the crater of an active underwater volcano, led the first dives into the 2-mile-deep Mariana Trough, and sailed atop an erupting undersea volcano to collect rock and gas samples. He has led 28 deep-sea oceanographic expeditions and has made 17 dives to the bottom of the ocean in the ALVIN submersible.

His daresome adventures have yielded a host of significant scientific findings that have greatly enriched our understanding of the workings of the oceans, atmosphere and deep Earth. In 1969, he 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. Craig went on to use the helium 3 injected into the deep sea to track ocean currents, leading him to discover that the Pacific ocean deep water circulates in the opposite direction to what scientists had theorized.

In 1970, Craig joined forces with colleagues at Scripps, Columbia University’s Lamont-Doherty Geological 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 this program 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 4600-foot-deep lake.

Craig and colleagues went on to discover the existence of submarine hydrothermal vents in the Galapagos seafloor spreading center, using the Scripps "Deep-Tow" vehicle to measure helium 3 and radon along the axis where the tectonic plates are rifting apart. Using the submersible ALVIN, he discovered similar vents in the caldera of an active volcano called Loihi, located 3,000 feet below the sea surface, that is erupting to form the next Hawaiian island. Another journey aboard ALVIN, into the Mariana Trough, discovered hydrothermal vents nearly 12,000 feet deep.

Craig also analyzed 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. 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 goal 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 sixteen 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 provenance of marbles used in ancient Greek sculptures and temples, a study that is still continuing.

Born in New York City on March 15, 1926, Craig did his thesis on carbon isotope geochemistry under Nobel Laureate Harold Urey. After receiving a Ph.D. in geology-geochemistry from the University of Chicago in 1951, Craig stayed on as a research associate at the Enrico Fermi Institute for Nuclear Studies at the University of Chicago. During this time he and Urey discovered that meteorites fall into discrete groups based on their oxidation states and content of iron. He went on to study the distribution of heavy hydrogen (deuterium) and oxygen isotopes in natural waters, establishing the "Global Meteoric Water" relationship of these isotopes which has become fundamental for studies in hydrology and climatology.

In recognition of his scientific achievements, Craig has received many honors. He was elected to membership in 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 (Honoris Causa) of the University de Paris (Pierre et Marie Curie) in 1983. In 1987, he was awarded the Arthur L. Day Prize 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.