Memorial to William F. Jenks

1909–1999

LEONARD H. LARSEN

Department of Geology, University of Cincinnati, Cincinnati, Ohio 45221

Bill Jenks was a reserved man who rarely articulated his feelings to his fellow professionals, but it quickly became apparent when working with him, within the halls of academe or in the field, that he was a kind and caring man and a man of great principle.

Bill Jenks was born on June 28, 1909, in Philadelphia, the son of Horace Jenks and Eloise North. After attending the Hill Friends School in Haverford, Pennsylvania, he received an A.B. degree at Harvard University (1932) an M.A. degree at the University of Wisconsin (1933), and a Ph.D. degree (geology) at Harvard University (1936). His dissertation concerned the structure and stratigraphy of the Belt Series rocks of Montana and Idaho. During his doctoral studies he married the woman who became his lifelong partner, Elizabeth. She became the mother of their three daughters and an accomplished artist as well. Best remembered by his colleagues were the many welcoming evenings she provided in their gracious home.

Employment for Bill followed as junior geologist for the Texas Company in the Rocky Mountain states (1936–1938) and by the Cerro de Pasco Corporation in Peru (1938–1945). In Peru, Bill made extensive regional studies of stratigraphy and volcanology. For a short period he served as lecturer at the University of Arequipa. For the academic year 1945–1946, he was the U.S. State Department visiting professor of geology at the University of Arequipa. While Bill and Elizabeth were in Peru, one of the their three daughters, Helen, was born.

At the Cerro de Pasco Corporation, Bill was put in charge of studying the mineral deposits of southern Peru. He began to dedicate his free time and even his vacations to the study of the geology in Cerro de Pasco and its surroundings, convinced it was necessary to understand the regional geology in order to interpret mineralization. During these studies he decided to dedicate himself to teaching and research as visiting professor at the University of Arequipa training Peruvian geologists.

Bill taught, above all, by example, touring the area surrounding Arequipa with his students, initiating them into the art and joys of geological field work while continuing his research and completing the Arequipa geological survey map (scale 1:200,000). This laid the basis for understanding the stratigraphy in southern Peru, and he began mapping the intrusive phases of the coastal batholith and the volcanic series.

Bill founded the first field school in Peru and, together with his students, completed the survey of the geology of the Yura region. Equal in importance with his instruction in the techniques of geological fieldwork were his care and precision in observation and exact sampling of rocks. Rarely have the actions and good will of one person, one teacher, in only one year had such a repercussion and lasting importance.

Bill’s academic bent later took him to the University of Rochester, New York (1946–1955), as assistant and then associate professor. Research interests during the Rochester years concerned various aspects of structural, stratigraphic, and volcanologic geology, especially with relation to the western coast of South America.

At the University of Cincinnati, Bill was professor of geology from 1955 to 1979 and served as department head from 1955 to 1968. Primarily a field geologist with great experience in North and South America, he was a wonderful teacher in the field and led many field trips. He taught a full range of courses in structural geology and ore deposits. A dedicated mentor to younger faculty and graduate students, he supervised the work for nine theses and five dissertations.

Bill was an active member of many scientific professional societies, among which were the American Association for the Advancement of Science, American Association of Petroleum Geologists, American Geophysical Union, Geological Society of America (Fellow), American Institute of Mining Engineering, Sociedad Geológica del Peru, and Società Geologica Italiana. He was active in politics in the community and served as president of the local chapter of the American Civil Liberties Union.

Summers from 1956 to 1964 were spent as a consultant in Mexico, Yukon Territory, British Columbia, and the western United States, but it was never possible for Bill to make complete studies for scientific, rather than economic reasons. Still, he published several important papers on ore deposits. A major work, published in 1956 as GSA Memoir 65, was Handbook of South American Geology. He was both editor of the memoir and author of the section on Peru.

Bill Jenks was a generous and happy man whose uncompromising honesty made him somewhat Lincolnesque. He retired to Newburyport, Massachusetts, where he and his wife were ardent in their work and support of civil rights and environmental issues. In later years, he devoted his energies to the peace movement and became an active member who took on leadership roles in Beyond War and Merrimack Valley People for Peace.

At the IX National Geology Congress in Peru in 1997, William F. Jenks and his daughters were present when he received the doctorate honoris causa from the University of Arequipa. The new building that houses the geology department now bears his name in his honor as “Father of Peruvian Geology,” as he is known to his former students.

SELECTED BIBLIOGRAPHY OF W.F. JENKS

1934 Petrology of the alkaline stock at Pleasant Mountain, Maine: American Journal of Science, v. 28, p. 321–340.

—— Heavy minerals in the syenites of Pleasant Mountain, Maine: American Mineralogist, v. 19, p. 476–479.

1935 Pegmatites at Collins Hill, Portland, Connecticut: American Journal of Science, v. 30, p. 177–197.

1938 (with Gibson, R., and Campbell, I.) Quartz monzonite and related rocks in the Libby Quadrangle, Montana, and the effects on them of deuteric processes: American Journal of Science, v. 35, p. 345–369.

—— (with Gibson, R.) Amphibolization of sills and dikes in the Libby Quadrangle, Montana: American Mineralogist, v. 23, p. 203–213.

1941 (with Gibson, R.) Stratigraphy of the Belt Series in the Libby and Trout Creek quadrangles, northwestern Montana and northern Idaho: Geological Society of America Bulletin, v. 52, p. 363–380.

—— Mesozoic stratigraphy of the central Peruvian uplands: American Philosophical Society Yearbook for 1940, p. 115. 1947 Geología y aguas subterraneas del Valle de las Termas de Yura: Revista de la Universidad de Arequipa, v. 19, p. 133–171.

1948 Geology of the Arequipa Quadrangle of the Carta Nacional del Peru: Instituto Geológico del Peru Boletin 8, p. 1–104 (in Spanish).

1951 Triassic to Tertiary stratigraphy near Cerro de Pasco, Peru: Geological Society of America Bulletin, v. 62, p. 203–220.

1953 (with Harris, E.G.) Plutonics near Arequipa as a petrologic sample of the coastal batholith of Peru: Sociedad Geológica del Peru, Boletin, v. 26, p. 79–94.

1956 Peru, in Handbook of South American geology: Geological Society of America Memoir 65, p. 215–245.

—— (with Goldich, S.S.) Rhyolitic tuff flows in southern Peru: Journal of Geology, v. 64, p. 156–172.

1966 Some relations between Cenozoic volcanism and ore deposits in northern Japan: New York Academy of Sciences Transactions, v. 28, p. 463–474.

Geological Society of America Memorials, v. 31, December 2000, p. 47-49