Although petroleum has been known since a very early date, its geological occurrence became of interest only after discovery of its economic value, and active exploitation began. First mention of the occurrence of oil on anticlines was by William Logan, in 1844, and within a few months after completion of the Drake well both T. Sterry Hunt and H. D. Rogers recalled Logan’s earlier observation and noted also that the Drake well was located on an anticline. Numerous other workers confirmed these observations, but it appears that little practical use was made of the theory until I. C. White, in 1885, began to apply it in search for natural gas in Pennsylvania and surrounding states. Coincidently Edward Orton, in Ohio, brought out the importance of geologic structure and by every possible means endeavored to impress on the public the value of geology in prospecting.
During the years following 1900 the United States Geological Survey published a series of studies of oil fields in the eastern states which further supported the theory and served also to give it wider publicity and greater prestige, until finally little or no criticism was heard. When the huge expansion in use of petroleum began, about 1910, the geologist became, for the first time, an important factor in the search for new fields.