The mineral resources survey of Erath County included plane table mapping of Pennsylvanian limestones exposed in the northwest part of the county. Most of the work was on the Goen Limestone and the Santo Limestone. The project was terminated before the Brannon Bridge Limestone could be studied. The outcrops were picked up at the Palo Pinto-Erath County line and mapped southwestward to the Pennsylvanian-Cretaceous contact, 7 miles south of Thurber. In order to show conditions farther west, to the Erath-Eastland County line, some work was done on a sandy limestone 140 feet above the Goen Limestone, in the southern part of the area. The map, which may be consulted at the Bureau of Economic Geology, Main Campus Geology Building, UT-Austin, is on a scale of 1 inch equals 2,000 feet.