Joshua Irving Tracey Jr., 89, a geologist with the U.S. Geological Survey who helped support Charles Darwin's theory on the development of atolls, died Oct. 18 at Virginia Hospital Center. He had heart disease.
In the 19th century, Darwin noted the resemblance of atolls to fringing reefs surrounding volcanic islands and surmised that atolls represent a later stage of volcanic islands' development in which islands sink into the ocean over time. As an island sinks, coral continues to grow around the fringe of the island until the island disappears, leaving only the coral or atolls.
That scientific observation was only a hypothesis until drills were available to retrieve core samples. The results that were analyzed by Dr. Tracey, who spent his career investigating geology in ocean environments.
"Dr. Tracey's pioneering studies of reef limestone from drill core, coupled with related investigations, provided the first conclusive evidence supporting Darwin's classic coral-reef hypothesis," said then-Secretary of the Interior Rogers C.B. Morton, in a citation for meritorious service. Morton also called Dr. Tracey a recognized authority on island and seafloor movements, geologic history and mineral resources.
Dr. Tracey, a native of New Haven, Conn., received all his degrees from Yale University: a bachelor's in physics and mathematics in 1937, a master's in geology in 1943 and a doctorate in geology in 1950.
His work began at the outbreak of World War II, when he joined the Geological Survey and was sent to Alabama, Georgia and Arkansas to explore for bauxite, the ore used to make aluminum, which was critically needed for the war effort.
For two years after the war, Dr. Tracey worked under Harry Ladd doing core drilling on Bikini Atoll before and after atomic bomb tests. From 1951 to 1954, Dr. Tracey served the Geological Survey as field party chief in mapping the geology of Guam, the largest of the Mariana Islands. While on Guam, Dr. Tracey made surveying trips to Pagan, Fais and Ifaluk atolls.
During the 1960s, Dr. Tracey drilled on Midway Island in conjunction with the Department of Defense, the Atomic Energy Commission, the National Science Foundation and Scripps Institution of Oceanography. For several summers, he surveyed the Green River formation in southwestern Wyoming.
During the 1970s, Dr. Tracey was co-chief of deep-sea drilling in the Pacific on the Glomar Challenger. The project consisted of seismic and magnetic surveys, in-hole measurements and laboratory analysis of the recovered cores. It verified that the ocean basins are relatively young and confirmed aspects of seafloor spreading and plate tectonics.
His other research involved expeditions to Enderbury and Enowetok islands. He served as scientific adviser with the U.S. delegation to the U.N. Seabeds Committee, which met in Geneva in 1971. He also served for several years as chairman for the Geologic Names Committee.
Dr. Tracey retired from the Geological Survey in 1985 and was given office space in the Smithsonian Institution's National Museum of Natural History, where he continued to write for several years and where his papers were deeded to the archives in 2002.
He lived in Arlington and was a member of Sigma Xi, the Geological Society of America, the American Association of Petroleum Geologists, the Explorers Club and the Cosmos Club. He also was a fellow of the American Association for the Advancement of Science. He held an honorary membership in the International Society for Reef Studies, among other affiliations.
Dr. Tracey was a member of Mount Vernon Place Methodist Church in Washington, singing bass in the choir for more than 50 years. He also was a member of the Rustin Couples class in the church. He was known for being self-effacing and unpretentious.
Survivors include his wife of 58 years, Frances Louise Tracey of Arlington; two sons, Dan Britton Jones of Lancaster, Pa., and Douglas Irving Tracey of Flemington, N.J.; a sister; eight grandchildren; and six great-grandchildren.