The Pottsville Gas Area, as it is defined in this paper, is geographically located 90 miles southwest of Fort Worth in Hamilton County and southern Comanche County, Texas. Geologically, it is in the west part of the Fort Worth basin approximately 20 miles east of the Bend flexure. The Marble Falls limestone in the Atoka series of the Middle Pennsylvanian is the gas-producing formation of the area. This limestone occurs in an area 25-35 miles wide trending northeast from its outcrop on the Llano uplift in San Saba County. Under the Pottsville gas area the Marble Falls limestone is deposited on top of the Comyn limestone and is encountered at depths ranging from 2,369 feet to 3,850 feet.

The Energy field of Comanche County and the Pottsville and South Pottsville fields of Hamilton County are Marble Falls gas fields located in the west part of the Pottsville gas area. These fields overlie adjacent anticlinal structures developed on a horst which was formed by post-Marble Falls forces associated with the Llano uplift. Structural relief on the Marble Falls in these fields ranges from 300 feet in the Energy and South Pottsville fields to 500 feet in the Pottsville field with synclinal troughs separating the individual features.

Exploration in the Pottsville gas area for undiscovered fields of the Energy, Pottsville, and South Pottsville type should be confined to the depositional limits of the Marble Falls limestone. Seismograph work guided by subsurface control appears to be the most efficient method to explore for these traps.

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