(As published in 1992)

Tom DibbleeIn over 60 years of active mapping, Thomas Wilson Dibblee has created a true California legacy for his geologic maps and reports. They provide an unsurpassed regional perspective that contribute a wealth of locally important information. His knowledge of regional stratigraphy, structure, and paleontology has been basic to understanding much of California's geology. The magnitude, integrity, and permanence of Dibblee's geologic mapping of one fourth of the state of California is unprecedented and legendary.

Thomas Wilson Dibblee, Jr. and his Spanish and English ancestry embodies the rich history of California. Captain Jose Antonio De la Guerra y Noriega, in 1800 became Commandante of the Presidio at Santa Barbara and Resident General of Upper and Lower California. An English ancestor, Ebonezer Dibblee, immigrated to Massachussetts in 1635, and his descendants came to California in 1859. Tom's father, Thomas Wilson Dibblee, and his mother, Anita Oreña, were both descendants of Captain De la Guerra. Thomas Dibblee, Jr., born in 1911, the first of four children, was raised on 20,000 acre Rancho San Julian, west of Santa Barbara which was part of the original 1837 Mexican land grant to Captain De la Guerra.

Tom's father, having taken a class in geology from Joseph LeConte at the University of California, Berkeley, recognized anticlinal structures on Rancho San Julian area so he hired consulting geologist Harry R. Johnson to map the ranch for its oil potential. Tom's experience as a high school student accompanying Johnson in mapping the ranch initiated his life's career in geology. Training at Stanford honed his skills under the tutelage of Siemond W. Muller, Austin Flint Rogers, C.F. Tolman, Hubert G. Schenck, and Aaron Waters. As one of his fellow students, Ben Page wrote "...(Tom) reveled in the geology and established his legendary reputation for roaming harsh country with the greatest of ease on his own two feet. Moreover, he understood most of what he saw...

Upon graduation in 1936, Tom briefly worked briefly under Olaf Jenkins for the California Division of Mines inventorying mercury deposits. Later on his own time he authored several California Division of Mines bulletins, including southwestern Santa Barbara County, Saltdale quadrangle, Breckenridge Mountain quadrangle, central Santa Ynez Mountains of Santa Barbara County, and Fremont Peak and Opal Mountain quadrangles; all as labors of love.

In 1937. after working for a year for Union Oil Company, Tom was hired by Richfield Oil Company through Harold Hoots. Major oil finds for Richfield resulted from Tom's geologic mapping from 1937 to 1952. His mapping included the Temblor, Caliente, San Emigdio and Southern Diablo Ranges, Carrizo Plain, Cuyama, Salinas, and Imperial Valleys, Santa Cruz Mountains, Eel River area, and areas in western Oregon and Washington. Tom often mapped in remote areas, camping out with enough food and water for a week, sleeping each night sheltered from the wind on the car seat with one door open and a board extending outward on which to rest his legs. This enabled him to cover a lot of ground at little expense.

By 1952 Tom had mapped all the oil-potential sedimentary basins in California. He was hired by the United States Geological Survey for the Mojave Project. This project, centered at Claremont, headed by D. Foster Hewett, was evaluating known and potential borate deposits for boron in making rocket fuel. He worked on this project until its completion in 1967, culminating in numerous geologic quadrangles maps and USGS Professional Paper 522, 'Geology of the Western Mojave Desert'.

In 1953, after many years of geological collaboration while working for Richfield, Mason L. Hill and Tom wrote a paper entitled "San Andreas, Garlock and Big Pine faults, California: A Study of the Character, History and Tectonic Significance of Their Displacement." This paper, proposing a lateral displacement along the San Andreas fault of more than 350 miles, is considered fundamental to the plate tectonics theory.

In 1967 Tom was reassigned to Menlo Park's National Earthquake Research Branch to map the geology of the Transverse and Coast ranges for 25 miles on each side of the San Andreas fault from the Coachella Valley to San Francisco Bay. This was part of the San Andreas fault project organized by Park D. Snavely, then chief of Western Regional Branch of the USGS. The results included many published geologic maps and reports, two professional papers, and nearly 100 open-file geologic quadrangles.

Tom DibbleeIn 1977 Tom retired from the USGS and returned to Santa Barbara. At the request of the U.S. Forest Service in 1978 he began mapping the geology of the 1.2 million acre Los Padres National Forest of central coastal California on a voluntary basis. His efforts resulted in more than 100 geologic quadrangles. In the 1980s he also mapped the geology of the entire Santa Monica Mountains on a volunteer basis resulting in 14 new geologic maps.

In recognition of Tom's numerous contributions to the advancement of geological understanding in California, he has been given many prestigious awards which include the United States Geological Survey's Distinguished Service Award (1967), the American Association of Petroleum Geologists' Human Needs Award (1981), and the Presidential Volunteer Action Award from President Reagan in 1983.

While working at Richfield's Bakersfield office Tom met Loretta Escabosa, who was secretary of the exploration department. They were married in 1949 and she has been his devoted wife ever since.

Tom has remained continuously active in field work, is a research associate in geology with the University California, Santa Barbara and a consultant and volunteer for various government and civic agencies. He still goes out to map new areas one day each week in the cooler months!

A testimonial to the high regard in which he is held by his colleagues was the formaton of the Thomas Wilson Dibblee Jr. Geological Foundation, a nonprofit corporation. This group realized that his many unpublished geologic maps should be preserved for their scientific and educational value and that as many as possible should be made published. So far the Foundation has published a mosaic of 60 full color maps encompassing 78 1:24:000-scale quadrangles. With Tom's philosophy of creating maps that provide basic field data to the geologic community, these maps, produced through a unique technique devised by Helmut Ehrenspeck of the Foundation, are used by engineering geologists, oil companies, planning agencies, US Forest Service, researchers, educators and students, environmental consultants, archaeologists, and realtors and developers.

Dorothy L. Stout

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