Three facies are recognized in the Catskill clastic wedge: (1) a red bed facies deposited in terrestrial and near-shore marine environments; (2) a gray shale and sandstone facies deposited in a shallow- to moderately-deep marine environment; (3) a dark-gray shale and siltstone facies deposited in the deepest part of the epicontinental sea. Turbidites possibly deposited from storm-generated turbidity currents, are present in facies 2 and 3. Because the rate at which the clastic wedge formed exceeded the rate of subsidence of the basin and the rise in sea level during the late Devonian, the Catskill clastic wedge intertongued with, and prograded inland over, shallow- to moderately-deep platform deposits that consisted of organic-rich black shale, gray and greenish-gray shale, and thin beds of argillaceous limestone. These platform deposits make up the black shale facies. Rocks in the black shale facies formed in marine to brackish water that covered the interior of the continent. Oil and natural gas are now being produced from Devonian shales in the western part of West Virginia and from Upper Devonian sandstones and siltstones in the north-central part of the State. It is suggested that in addition to extending known areas of gas production, that drilling for natural gas be conducted in areas underlain by organic-rich shales and thick zones of interbedded siltstone and shale in the Devonian section in central, and southern, and western West Virginia. The most promising areas for exploration are those areas where fractures are associated with folds, faults, and lineaments.
