The essential points in the stratigraphy of the Mid-Continent region with maps of outcrops, correlation of formations and a review of previous work are presented in introduction. Paleogeographic maps based on detailed stratigraphic studies are presented and their significance in relation to the occurrence of oil at various horizons considered. The probable orgin of the oil in shale, the most favorable basins from a paleogeographic standpoint, problems of accumulation of oil, production zones in relation to historical geology and the relation of production to structure are considered. The reasons for basin movement, the mechanics of mountain

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making and of minor structures are treated with reference to their importance in the production of oil.

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