The paper deals with the geology of the Geneseo uplift, Rice, Ellsworth, and McPherson counties, Kansas, and of the associated oil and gas fields. The subject area includes Ts. 17-21 S., W. 1/2 of R. 5 and all of Rs. 6, 7, 8 W., inclusive.

Geologically, this feature is the easternmost, semi-detached lobe of the Central Kansas uplift. The structure, as mapped on pre-Permian horizons, is that of an ovoid uplift complicated by superimposed anticlinal folding. The principal period of folding was late Mississippian or early Pennsylvanian in age as evidenced by the major non-conformity between the Mississippian and Pennsylvanian sediments. The structure was further complicated by regional tilting and recurrent uplift during post-Mississippian time.

Surface and subsurface rocks include beds of Quaternary, Cretaceous, Permian, Pennsylvanian, Mississippian, Ordovician, and Cambrian age, the latter resting unconformably on the pre-Cambrian complex. The major gaps in this stratigraphic column represent, for the most part, periods of non-deposition.

Six oil fields and one gas field are associated with the Geneseo uplift. As at September 30, 1946, these fields include 768 wells yielding 14,471 barrels per day. The fields have produced 51,771,212 barrels of oil and approximately 13 1/2 billion feet of gas and are estimated to represent a reserve of 32,228,788 barrels of oil and 405 million feet of gas.

The Geneseo and Edwards oil fields and the Lyons gas field are anticlinal accumulations located on a sharp structural ridge which extends along the west edge of the Geneseo uplift. The principal producing formation is the Arbuckle limestone, although in the Lyons field minor quantities of oil and gas are produced from the Simpson sand. The Wherry field, which produces from the basal Pennsylvanian (Sooy) conglomerate, and the Welch, Bornholdt, and Smyres fields, which produce from the Mississippian chert, are primarily stratigraphic accumulations and are located on the south and east flanks of the uplift.