Studies of water well yields, of three roadcuts, and of field observations indicate that the Parsons lineament in eastern West Virginia is a broad, cross-strike zone of unusually intense jointing. To test this hypothesis, strike, dip, exposed length, exposed depth, and spacing of 1594 joints were measured in interbedded siltstones, mudstones, and shales in the Upper Devonian Chemung facies. Joint sets were determined to strike N 35 to 55/sup 0/ W, N 25 to 45/sup 0/ E, and N 80/sup 0/ E - N 80/sup 0/ W. SYMAPS show more intense jointing within the Parsons lineament with the northeast-trending set contributing most to the increase. Identification of zones of intense jointing could be useful in hydrocarbon exploration, mine design, construction, and water-well siting. 8 figures, 1 table.