Memorial to Thomas Prence Thayer (1907–2004) C. ERVIN BROWN 10608 Good Spring Avenue, Great Falls, Virginia 22066, USA

Thomas P. Thayer died of a stroke in St. Petersburg, Florida, on 14 May 2004, eight days before his 97th birthday. His wife, Arnetta, died seven days later of a heart attack. Tom was one of the rapidly declining number of geologists who gained much mineral resource experience when the United States was scrambling for minable deposits of critical minerals before and during World War II. An assignment to study chromite deposits in eastern Oregon was the seed for his becoming recognized worldwide as the prime expert on chromite and other resources in ultramafi c rocks. With enthusiasm, Tom disseminated his geologic fi ndings through informal discussions with colleagues and formal publications here and abroad. His continuing interest in mapping the regional geological setting of the John Day area in Oregon was equally important to him and also resulted from the wartime assignment to study chromite deposits there. Tom was born in Scarsdale, New York, on 22 May 1907, and grew up in Eugene, Oregon, where the family moved sometime before 1920. In 1929, he received a B.A. degree in geology from the University of Oregon; in 1931, an M.A degree from Northwestern University; and in 1934, a Ph.D. from the California Institute of Technology. His major was physical geology and his minor, invertebrate paleontology. In 1931, he married Harriet Marjorie “Marj” Clark, who was a classmate in geology at the University of Oregon. They had two children, Thomas and Carolyn. The family mainly lived close to Washington, D.C. Shortly after Tom’s retirement in 1977, he and Marj moved to Florida. Marj died in 1985, and their son, Thomas, died in 1996. In 1986, Tom married Arnetta Brown, a close family friend. He is survived by his daughter, Carolyn Thayer, three grandchildren, James Glenwood Thayer, John Edward Thayer, and Tina Maria Thayer Johnson, and seven great- grandchildren. Tom’s doctoral study was on the geology and petrology of the volcanic rocks of the Willamette Valley and along the North Santiam River leading up into the high Cascades. Additional research there in the mid-1930s led to publications that stand today as authoritative work on those rocks. Following his research in the Oregon Cascades, Tom held several short-term jobs. He mapped with Eugene Callaghan of the U.S. Geological Survey (USGS) in Nevada, was an instructor at the MacKay School of Mines, and mapped in the vicinity of the Comstock Lode in Nevada with W.D. Johnston Jr. of the USGS. He also did geologic studies for the Bonneville Power Authority. In 1937, Tom began full-time employment with the USGS and mapped with Levi F. Noble in the vicinity of Furnace Creek Wash in Death Valley. Disagreements with Levi on geologic interpretations, brought on by youthful enthusiasm for geology, resulted in the nadir of this young geologist’s career. Tom said that he was essentially “on probation” and was reassigned early in

Geological Society of America Memorials, v. 34, June 2005 17 18 THE GEOLOGICAL SOCIETY OF AMERICA 1939 to work with S.G. Lasky on manganese deposits in New Mexico. Later that year, because of pre-WWII demand for sources of critical strategic commodities, his supervisor, W.D. Johnston Jr., who had faith in him, assigned him to a project to map chromite deposits. Tom, totally unfamiliar with the geology of chromite, began mapping the rocks around deposits being drilled by the U.S. Bureau of Mines in Grant County, Oregon. This assignment became the cornerstone on which his expertise on chromite was built. The assignment also was the beginning of a long- term project to map the geology of John Day Valley and its regional surroundings. In 1940, Tom was assigned to study the Twin Sisters chromite deposits in Washington, followed by a one-and- a-half-year project mapping chromite deposits in Cuba with P.W. Guild and W.D. Johnston Jr. During WWII, Tom also searched for sources of quartz crystals in the southwestern United States. In 1943 and 1944, he took part in a detailed study of the Bomi Hill iron deposit in Liberia. In 1949 and 1950, he went on leave without pay from the USGS and was employed for six months in Liberia by the Liberia Mining Co. For his work there, the government of Liberia presented him with the Commander, Star of Africa Award. The search for strategic minerals during WWII produced a group of geologists in the Mineral Deposits Branch of the USGS each knowledgeable about a commodity. Tom was actively involved in administration of the Metals Section of that group from 1946 to 1949, and of the Mineral Resource Section from 1952 to 1960. The demand for commodity information continued after WWII and through the decades of the cold war, when the United States was stockpiling strategic minerals such as chromite. Tom pursued knowledge about his commodity, chromite, aggressively and energetically and visited and studied deposits in many places around the world. He was invited as a participant in international symposia and fi eld conferences by treaty organizations such as the Central Treaty Organization (CENTO), and as a speaker by several national geological surveys and societies, by the Academy of Sciences of the USSR, and as a co-convener of a Penrose Conference on ophiolites. These trips gave him opportunities to study chromite and related rocks in the Philippines, New Caledonia, New Zealand, South Africa, Rhodesia, Finland, Turkey, Pakistan, Iran, Yugoslavia, Cyprus, Greece, Greenland, and Brazil, and occurrences of ultramafi c rocks elsewhere in the world. Ebrahim Shekarchi of the U.S. Bureau of Mines attended CENTO fi eld conferences with him and said that in the Middle East, Tom was known as “Mr. Chrome.” Two important results of his worldwide study of chromite deposits were a correlation between chromite deposits and wall-rock types that is used as a guide to ore, and a determination of criteria for distinguishing stratiform from podiform deposits. Tom published extensively, and his conclusions were much respected, but they were not immune from controversy. He defended them readily, capably, and sometimes with humor. Harvey Belkin recalls that in 1972, a paper was presented at the Geological Society of Washington titled “The Blind Men and the Ophiolite” with Tom being an oblique target. When it came time for discussion, Tom rose from the audience wearing dark glasses and carrying a white cane. He tapped out onto the aisle, took off his glasses, and lectured for ten minutes on how the speaker’s conclusions had serious problems. This was a classic Tom Thayer act. Although Tom’s education about chromite and related rocks was from deposits and rocks seen around the world, his classroom on the subject was a bedrock ridge in his beloved Canyon Mountain Range in Grant County, Oregon. Many USGS and university colleagues and foreign geologists have been baptized in the lore of ophiolites by Tom on fi eld trips along that ridge from peridotite on Baldy Mountain to gabbro that forms the crest of Canyon Mountain. Here are exposed a great array of magmatic and tectonic relations in ophiolitic rocks. Many features defi ed known explanations and evoked an oft-used phrase from Tom, “things that are and cannot be.” Tom was not above having fun, and these trips usually involved purposely dislodged boulders that crashed and bounded down the steep slopes to the delight of all. If there ever is a monument MEMORIAL TO THOMAS PRENCE THAYER 19 to honor Tom Thayer, it should be on Baldy Mountain at the head of this well-worn Baldy Ridge trail. Tom Thayer had a deep and abiding affection for the John Day area of Oregon. Despite his world-renowned expertise on chromite, he considered himself fi rst a fi eld geologist whose great passion was to unravel the geology of this part of eastern Oregon. Persistent demand for his expertise on chromite repeatedly delayed his progress on geologic mapping. In 1957, I was assigned to work with him, and together over the next several years we advanced the mapping and published the geology of more than six 15 quadrangles. Regional reconnaissance and photogeologic mapping that followed resulted in the publication of the 7000-square-mile area of the 2° Canyon Mountain Quadrangle. Tom’s last fi eldwork in the John Day area was in 1975 when he supervised a team doing a mineral resource appraisal of the Strawberry Mountain Wilderness area. He is recognized as the authority on the geology of the region. While there in 1975 Tom led a group of 75 people from the Forest Service, Park Service, and local offi cials on an extensive popularized geologic fi eld excursion. A booklet on the geologic setting of the John Day country was published by the U.S. Department of Interior in cooperation with Grant County and Oregon state agencies using information supplied by him. Tom mapped on air photos and used photogeology supported by fi eld mapping. In 1960, he designed a convenient folding magnifying stereoscope for ease of plotting directly on a stereoscopic model in the fi eld. It was produced commercially and used widely in the profession. Those of us who did fi eldwork with Tom were much infl uenced by his fi eld mapping techniques and adopted his systematic and effi cient method of recording notes, samples, and geologic data. In 1975, he began working with Bruce Lipin of the USGS in order to study the petrology of chromite and its host rocks in ophiolitic and stratiform intrusions. Political turmoil at that time in South Africa, however, threatened a major world resource of chromite there, and caused them to shift their attention to an assessment of the critical future supply of chromium for the United States. Thus his career of studying chromite resources ended as it began in a search for sources of chrome for the nation. Involvement in this work for Tom diminished after his retirement in 1977. Tom published more than 100 reports and maps here and abroad. In addition to the Commander, Star of Africa Award by Liberia, he received the Distinguished Service Award of the U.S. Department of the Interior. He was a member of the Society of Economic Geology, the Geological Society of America, the American Geophysical Union, and the Mineralogical Society of America. In 1962, he served as president of the Geological Society of Washington. Tom’s life was deeply immersed in geology. Bruce Lipin heard Marj say at his retirement luncheon in 1977, “I never suspected another woman, but oh, those damned rocks!” At the same event, the then- director of the USGS, Vince McKelvey, said, “Hang onto your hats folks, because the USGS has just lost one of its pillars.” Now with his passing, a giant of the geologic community has joined the ranks of history.

ACKNOWLEDGMENTS

This memorial was prepared from information in a Professional Technical Record prepared by T.P. Thayer in 1977, from my personal recollections of a long association with him, from family information supplied by Carolyn Thayer, and from information and personal recollections of Bruce Lipin, Norman J. Page, Eric Force, Ebrahim Shekarchi, W.R. Dickinson, and Harvey Belkin. The author is grateful for an editorial review by Nancy Lesure. 20 THE GEOLOGICAL SOCIETY OF AMERICA SELECTED BIBLIOGRAPHY OF T.P. THAYER

1937 Petrology of later Tertiary and Quaternary rocks of the north-central Cascade Mountains in Oregon, with notes on similar rocks in western Nevada: Bulletin of the Geological Society of America, v. 48, p. 1611–1652. 1939 Geology of the Salem Hills and the North Santiam River basin, Oregon: Oregon Department of Geology and Mineral Industries Bulletin 15, 40 p. 1940 Chromite deposits of Grant County, Oregon—a preliminary report: U.S. Geological Survey Bulletin 922-D, p. 75–113. 1942 Chrome resources of Cuba: U.S. Geological Survey Bulletin 935-A, p. 1–74. 1944 (and Newhouse, W.H., and Butler, A.P., Jr.) Report of the Geological Mission to Liberia: U.S. Geological Survey, 110 p. 1949 (with Johnston, W.D., Jr.) Chromite, in AIME, Industrial Minerals and Rocks, p. 194–206. 1956 Mineralogy and geology of chromium, in Udy, M.J., ed., Chromium: American Chemical Society Monograph 132, v. 1, p. 14–52. 1957 Some relations of later Tertiary volcanology and structure in eastern Oregon: 20th International Geological Congress, sec. 1, v. 1, p. 231–245. 1960 Some critical differences between Alpine-type and Stratiform peridotite-gabbro complexes: 21st International Geological Congress Report, pt. 13, p. 247–259. 1961 Application of geology in chromite exploration and mining, in Symposium on Chrome Ore, Ankara, Turkey, September 1960: Central Treaty Organization (Ankara), p. 197–223. ____ The magnifying single-prism stereoscope, virtually a new fi eld instrument, in Short Papers in the geologic and hydrologic sciences: U.S. Geological Survey Professional Paper 424-D, p. 386–387. 1963 (with Brown, C.E.) Low-grade mineral facies in Upper Triassic and Lower Jurassic rocks of the Aldrich Mountains, Oregon: Journal of Sedimentary Petrology, v. 33, p. 411–425. 1964 Principal features and origin of podiform chromite deposits, and some observations on the Guleman-Soridag district, Turkey: Economic Geology, v.59, p. 1497–1524. ____ Geologic features of podiform chromite deposits, in Woodtli, R., ed., Methods of Prospecting for Chromite: Organization of Economic Cooperative Development, Paris, p. 135–148. 1966 (with Brown, C.E.) Geologic map of the Canyon City quadrangle northeastern Oregon: U.S. Geological Survey Miscellaneous Investigations Map I-447. ____ (and Brown, C.E.) Geologic map of the Aldrich Mountain quadrangle, Grant County, Oregon: U.S. Geological Survey Geological Quadrangle Map GQ-438. ____ (with Brown, C.E.) Geologic map of the Mount Vernon quadrangle, Grant County, Oregon: U.S. Geological Survey Quadrangle Map GQ-548. 1967 Chemical and structural relations of ultramafi c and feldspathic rocks in alpine intrusive complexes, in Wylie, P.J., ed., Ultramafi c and related rocks: New York, John Wiley & Sons, chap. 7-IV, p. 222–239. 1968 (and Himmelberg, G.R.) Rock succession in the alpine-type mafi c complex of Canyon Mountain, Oregon: 23rd International Geological Congress, Prague, v. 1, p. 175–186. 1969 Gravity differentiation and magmatic re-emplacement of podiform chromite deposits: Economic Geology Monograph 4, p. 132–146. ____ The geologic setting of the John Day Country, Grant County, Oregon: U.S. Geological Survey pamphlet, 23 p. MEMORIAL TO THOMAS PRENCE THAYER 21 ____ Peridotite-gabbro complexes as keys to petrology of mid-oceanic ridges: Geological Society of America Bulletin, v. 80, p. 1515–1522. 1970 Chromite segregations as petrogenetic indicators, in Visser, D.J.L., and Von Gruenewald, G., eds., Symposium on the Bushveld Igneous Complex and other layered intrusions: Geological Society of South Africa Special Publication No. 1, p. 380–390. 1971 Authigenic, polygenic, and allogenic ultramafi c and gabbroic rocks as hosts for magmatic ore deposits: Geological Society of Australia Special Publication No. 3, p. 239–251. 1973 Chromium, in Brobst, D.A., and Pratt, W.P., eds., U.S. Geological Survey Professional Paper 820, p. 111–121. 1977 The Canyon Mountain Complex, Oregon, and some problems of ophiolites, in Coleman, R.G., and Irwin, W.P., eds., North American Ophiolites: Oregon Department of Geology and Mineral Industries, Bulletin 95, p. 93–105. 1977 (with Brown, C.E.) Geologic map of pre-Tertiary rocks in the eastern Aldrich Mountains and adjacent areas to the south: U.S. Geological Survey Miscellaneous Investigations Series Map I-1021. 1978 (with Dickinson, W.R.) Paleogeographic and paleotectonic implications of Mesozoic stratigraphy and structure in the John Day inlier of central Oregon, in Howell, D.A., and McDougall, K.A., eds., Mesozoic paleogeography of the western United States: Pacifi c Section, Society of Economic Paleontologists and Mineralogists, Pacifi c Coast Paleogeography Symposium 2, p. 147–161. 1978 (with Lipin, B.R.) A geological analysis of chromite production to the year 2000 A.D., in Proceedings Council of Economics, AIME 1978 Annual Meeting, Denver, Colorado, p. 143–152. 1981 (and Case, J.E., and Stotelmeyer, R.B.) Mineral Resources of the Strawberry Mountains Wilderness and adjacent areas, Grant County, Oregon: U.S. Geological Survey Bulletin 1498, 67 p.

Note: A complete bibliography is available from the author.

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