The Remarkable Geologic Mapping Career of Thomas Wilson Dibblee, Jr.

H. E. Ehrenspeck
Dibblee Geological Foundation, Goleta, CA

This abstract barely scratches the surface of Tom Dibblee’s prodigious career, spanning seventy years so far. He not only mapped the geology of about one-fourth of California, but made major contributions to field geology, stratigraphy, structural geology and tectonics. Born in 1911 in Santa Barbara, he grew up there and on nearby Rancho San Julian, a historic Spanish land grant. As teenager, without formal training in geology, Tom mapped this entire 110-square mile ranch! After his degree in geology (Stanford, 1936) he joined Richfield Oil Company to map geology of all potential petroleum basins on the West Coast. For 15 years, Dibblee mapped vast areas of California’s Transverse and Coast Ranges, as well as in coastal Oregon and Washington. On his own time, he fill-in mapped the areas between potential oil basins. When Richfield in 1948 made a major oil discovery in the Cuyama basin based on Tom’s mapping, they named the oil-producing horizon the “Dibblee Sand”. In 1952, he joined the USGS western Mojave Desert mapping project, later extended to include the central and southern Mojave. In 1967, with over 40 15-minute quadrangles completed there, Tom worked the entire 600-mile long San Andreas fault zone from the Mexican border to northern California. He produced over 100 open-file 15- minute quadrangles over the next decade; these maps are still being incorporated into a USGS database! Retiring in 1978 to Santa Barbara, Tom soon became research associate at UC Santa Barbara, and geologic consultant for various agencies. Entirely as volunteer, he produced over 100 7.5-minute quadrangles for the Los Padres National Forest, Ventura County to Monterey. In addition to over 500 7.5-minute geologic quadrangles mapped, Dibblee established the definitive geologic framework for many areas of California. His prolific bibliography, including over 70 major reports, is listed on the Dibblee Geological Foundation website: www.dibblee.geol .ucsb.edu.

AAPG Search and Discovery Article #90904©2001 AAPG Pacific Section Meeting, Universal City, California