In 1938, the Mississippi Geological Survey, cooperating with the W.P.A., undertook a geological survey in ten counties, and assistant state geologist Fredric F. Mellen supervised several county surveys while searching for good ceramic clays. He observed indications of geologic structure, and in February 1939 near Tinsley in Yazoo County he noted an outcrop of Moodys Branch Marl at an elevation 250 feet above its normal position. Drawing on his training in physical, historical, and paleontological geology, he concluded that a structure favorable to the accumulation of gas and oil was present. A press release on April 12, 1939, announced the discovery and suggested further geologic study and seismographic exploration. After the release, Union Producing Company, already active in western Mississippi, assembled a lease block near Tinsley and began drilling on July 8. On August 29, 1939, the well struck oil. Union Producing Company's G.C. Woodruff No. 1 was officially completed on September 5, 1939, becoming the first commercial oil well in Mississippi and the discovery well of the Tinsley oil field, the largest oil field in the Southeast. All major oil companies moved support personnel into the state, and geologists, landperson, geophysicists, engineers, seismic crews, production personnel, and drilling crews converged on Mississippi from every section of the country. Since its discovery, 452 producing wells and 42 dry holes have been drilled at Tinsley. New fields were discovered as a result of Tinsley, and oil or gas has been found in 42 of the 82 counties. The economic impact of the oil industry on the state has been paramount. Producing oil and gas fields included Cranfield, Carthage Point, Bruinsberg, Langsdale, Quitman, Jackson, Heidelberg, Soso, Fayette, Gwinville, Baxterville, Brookhaven, Mallalieu, Pickens, Flora, Hub, Cary, Eucutta, Tinsley, and Amory, which was later abandoned.
