On September 14, US marine geologist, geophysicist and oceanographer Robert Sinclair Dietz was born. He is best known for his pioneering research along with Harry Hammond Hess concerning seafloor spreading (a term he coined), in which new crustal material continually upwells from the Earth’s depths along the mid-ocean ridges and spreads outward at a rate of several inches per year.
Robert Dietz was educated at the University of Illinois starting from 1933 and received his Ph.D. in geology and minor in chemistry. During his studies, Dietz worked together with the Scripps Institution of Oceanography (SIO) under the direction of his mentor, Francis P. Shepard. As part of their research, Dietz and his professor Shepard first described the submarine phosphorites off California. Unfortunately, Robert Dietz was not able to get a position as a marine geologist after receiving his doctorate and was called to active duty as a ground officer in the U.S. Army Air Corps. After his service, Dietz was asked by Dr. Eugene LaFond to organize a sea-floor studies group at the Naval Electronics Laboratory (NEL) in San Diego, which he accepted. Robert Dietz became the director and founder of the Sea Floor Studies Section of NEL and now had the opportunity to be a geological oceanographer on Admiral Richard E. Byrd’s last expedition to Antarctica. Dietz devoted much of his time to oceanographic cruises to explore the Pacific basin. In 1950, Robert Dietz and H. William Menard described the Cape Mendocino submarine scarp on MidPac. Along with Robert Dill, Dietz also made the first map of the deep sea fan at the mouth of Monterey Submarine Canyon that showed large amounts of sediments channeled into the deep sea from the continent.
However, Robert Dietz was not only a scientist, he was also a founding member of a private consulting firm called Geological Diving Consultants. The company was hired by major oil companies interested in initiating oil exploration off the central California coast. For instance, GDC’s maps were used in the discovery of two major oil fields off Santa Barbara and Point Conception.
Robert Dietz and his colleagues accomplished numerous cruises to the Gulf of California and mapped the submarine canyons while diving. The team also filmed underwater footage and took pictures of the geological processes. Their work contributed to many scientific publications. Dietz himself served as a scholar at the University of Tokyo where he studied the trans-Pacific transmission of underwater sound and also became interested in the Emperor chain of seamounts. The scientist came to believe that some force must be carrying these old volcanic mountains northward like a conveyer belt and his papers on the topic posed some significant questions in connection with plate tectonic theory. His papers highly contributed to the concept he called sea-floor spreading.
During his later career, Robert Dietz turned his interest towards meteorite impacts and was possbily the first to recognize the Sudbury Basin as an ancient impact event. From the American Geophysical Union, Dietz received the Walter H. Bucher Medal and the Barringer Medal from the Meteoritical Society.
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