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u <br />J <br />I• <br />z.oa.s <br />PR-08 <br />/~ P PRovED <br />9~z s/D3 <br />The coal bearing member of the Mesaverde formation locally contains up to nine <br />mineable coal seams in the North Fork Valley, named in ascending alphabetical <br />order, within the stratigraphic interval 500 to 600 ft. above the Rollins Sandstone <br />Member (Dunrud,1976). Mines recently operating in the various coal seams are <br />as follows: Somerset - C & B-2; Sanborn Creek - C & B-2; Bowie No. 1 - D-2; <br />Blue Ribbon and Hawks Nest - E-1; Bear - C & B-2; Mountain Coal Company - <br />F & B-2. Due to the depositional environment of the coal bearing member, <br />individual coal seams are not laterally continuous nor do they maintain uniform <br />thicknesses from differing locations throughout the area. <br />The barren member of the Mesaverde formation is lithologically similar to the <br />coal bearing member with the exception of virtually no mineable coal seams. In <br />the North Fork area, the barren member is stratigraphically between the F coal <br />seam and the Ohio Creek conglomerate, and was estimated by Lee (1912) to <br />be 1500 ft. thick. The scarcity of coal deposits within the barren member <br />probably represents progradation of terrigenous, nonmarine sediments <br />deposited in response to the retreating shoreline. Hail (1972) reports maximum <br />thickness of the entire Mesaverde Formation to be about 2300 ft. <br />The Paleocene Ohio Creek Formation unconformably over lies the Mesaverde <br />formation. The Ohio Creek Formation consists of light-gray, locally <br />conglomeratic sandstone which ranges in thickness from locally 0 ft. to a <br />maximum of 200 ft. Where the conglomeratic facies is lacking or obscured by <br />surficial deposits, the Ohio Creek Formation is mapped within the Mesaverde <br />Formation (Hail, 1972). <br />The Eocene Wasatch Formation consists of variegated mudstone and siltstone <br />with interbedded medium gray lenticular sandstone, which is locally <br />conglomeratic (lunge, 1978). Maximum thickness is reported to be <br />approximately 1600 ft. (Hail, 1972), although exposures are largely obscured by <br />surficial deposits. The Wasatch Formation represents terrestrial sedimentation, <br />dominated by fluvial processes, which preceded the Lacustrine Green River <br />Formation. <br />Structural Geoloov: The Piceance Creek Basin is a typical intermontane basin <br />of the Rocky Mountain region in which coal bearing strata are present. Bounded <br />on the north by the Uintah Uplift, and west by the Douglas Creek Arch, the basin <br />is asymmetric with the synclinal axis trending with the Grand Hogback. The <br />2-04 - 12 - 7/03 <br />