The stratigraphy, structure, and historical geology of the West Edmond oil field, are presented in detail made possible by electric logs and drill cuttings which have been available for study on approximately 750 wells drilled in the field to June 1, 1947.

Following a brief discussion of the stratigraphy of the Permian and Pennsylvanian rocks, a detailed description of the Hunton group is given. One new member of the Hunton is described and named (the lower Bois d'Arc) and this is subdivided into three zones. An unconformity is recognized between the Bois d'Arc and the underlying Haragan limestone. Several lithologic criteria for the separation of the Haragan and Henryhouse limestones are suggested. A normal section of Chimneyhill limestone, not exceeding 50 or 60 feet, constitutes the lowest formation of the Hunton group in the West Edmond field.

The structural geology is presented by a cross section and a series of maps contoured on the more important horizons in association with paleotopographic maps of three unconformable surfaces.

The historical geology of the West Edmond oil field is considered in relationship to the entire Oklahoma City uplift. The sequence of deposition and structural movements is covered. Integrated into this pattern are the time of accumulation and the source of the oil of the West Edmond field. Formation of the porosity of the Bois d'Arc was largely post-Hunton pre-Woodford and enhanced in post-Mississippian pre-Cherokee. There is evidence that it was formed by subaerial erosion. An old buried stream channel, the West Edmond valley, is of two consecutive ages, post-Hunton pre-Woodford and post-Mississippian pre-Cherokee, and this latter gradient is computed at 8 feet per mile. This valley, in furnishing a run-off that seeped through the Frisco and the Bois d'Arc enabled these waters great y to improve the permeability derived from primary porosity and later fracturing, so that they became a potential reservoir for oil. The post-Mississippian pre-Cherokee surface was uplifted for a short period following the peneplanation which exposed Cambro-Ordovician rocks in the core of the Oklahoma City uplift.