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• Member (Dunrud, 1976). Mines recently operating in the various coal seams are as follows: Orchard Valley - D; Bear - E; and west Elk - F. Additional mines have operated in the past including most recently: Tomahawk Strip - A through F; Somerset - B and C; and Blue Ribbon, Hawks Nest - E. Due to the depositional environment of the coal bearing member, individual coal seams are not laterally continuous nor do they maintain uniform thicknesses from differing locations throughout the area. The Barren member of the Mesaverde Formation is lithologically similar to the coal bearing member with the exception of virtually no minable coal seams. In the North Fork area, the barren member is stratigraphically between the F coal seam and the Ohio Creek conglomerate, and was estimated by Lee (1912) to be 1,500 feet thick. The paucity of coal deposits within the barren member probably represents progradation of terrigenous, nonmarine sediments deposited in response to the retreating shoreline. Hail (1972) reports maximum thickness of the entire Mesaverde Formation to be about 2,300 feet. Permit and Adjacent Area Stratigraphy The Mancos shale, of late Cretaceous age, is stratigraphically the lowest and oldest bedrock unit exposed in the study area (Figure 2.00). The Mancos is a sequence of gray to dark gray marine shales • containing several light brown sandstone units. Although the total thickness of this unit over the region is 2,000 to 3,000 feet, only about the upper 600 feet are exposed in the Orchard Valley mine area. The Mesaverde Formation, also of late Cretaceous age, conformably overlies the Mancos shale. Several studies have divided this formation into various members; however, the Dames & Moore Report (1981), appears to be the most useful for the mine area and divided the Mesaverde as follows (in ascending order): the Rollins Sandstone (Kmvr), the Coal Member (Kmvc), and the Barren Member (Kmvb). The Rollins sandstone is the basal unit of the Mesaverde, and represents the transition from the marine environment of the Mancos shale to the fresh and brackish water environments of the Mesaverde Formation. The Rollins is a white to light brown or buff massive cliff-forming sandstone that exhibits some cross bedding. It is conspicuous and easily traceable along the southern boundary of the study area, where it attains a thickness of about 60 to 125 feet. The Coal Member, which contains all the coal seams either being currently mined or targeted for mining in the North Fork Valley, varies regionally in thickness from 500 to 1,000 feet, and in the Orchard Valley Mine area attains an average thickness of about 700 feet. The member is dominated by shales and interbedded shales and • siltstones, interfingered with minor often discontinuous white to - B -