All Paleozoic systems are represented in the contiguous states of West Virginia, Virginia, and Maryland, and constitute a section ranging up to more than 25,000 ft (7,620 m) in thickness. The regional dip on the basement is southeastward, but the numerous folds and faults increase in intensity toward the southeast.

Production is mainly gas, and most is from the Appalachian Plateau province. Trapping is predominantly structural in the east and combined stratigraphic-structural in the west. Reservoirs are usually sandstone, but some production is from chert, limestone-dolomite, and shale.

Pennsylvanian and Upper Mississippian rocks add to the prospects of the deeper objectives. The Greenbrier has limited potential. The prolific "Big Injun" still has good possibilities for increased reserves with the application of new completion techniques. Additional reserves can be expected in the Berea, and there are secondary possibilities in the Weir. The Devonian shale section, very productive in eastern Kentucky, has numerous possibilities in adjacent West Virginia. Extensions of production from the Benson can be expected principally northwest of the present producing area. The Oriskany and associated Huntersville and Helderberg still have good prospects in the eastern part of the area and in east-central West Virginia. Additional discoveries can be expected in the "Newburg"-Wil iamsport. The Keefer is a secondary target for wells projected to the Tuscarora. The Tuscarora, although generally containing low-Btu gas, is still an exploratory target in many areas. The poorly explored Cambrian-Ordovician, comprising a large volume of sedimentary rock, is believed to have numerous prospects in the area. Although the deep Paleozoic exploration will be costly, a single discovery of economic size in these rocks would be a development of major importance to the industry.