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-28- <br /> The Upper Bowie shale submember overlies the Middle sandstone suomember. <br /> This submember contains the Uutch Creek or ;diddle bed seam, which is <br /> mined only at the Coal Basin No. 2 Mine. <br /> The Middle and 'Upper sandstone submembers are deltaic beach front <br /> sandstones. These sandstones are fine to medium-grained and poor to <br /> moderately well sorted. The Upper sandstone member is slightly coarser <br /> in texture. <br /> The Paonia member is about 600 feet thick in the area of the mines, and <br /> consists of interbedded sandstone, siltstone, shale and coal beds. The <br /> sandstones of this member are more lenticular and discontinuous, and <br /> their deposition represents a more terrestrial origin than the sandstones <br /> of the Bowie member. There are six irregularly distributed coal seams <br /> within the general area of the mines. These seams are, in ascending <br /> order, the Placita, the Sunshine, the Anderson, the Lake Ridge, the <br /> Thompson, and the Stony Ridge seams. <br /> The North Thompson Creek No. 3 Mine is located in the Anderson seam. <br /> This is the only active mine in a Paonia member coal . In addition to <br /> these minable seams, the Paonia member contains several thin, lenticular <br /> seams. <br /> The Upper Barren member consists of between 2,000 and 2,500 feet of <br /> lenticular sandstones and gray shales. The lenticular sandstones <br /> represent terrestrial stream channel deposits. <br /> The Tertiary Age Wasatch Formation - Ohio Creek conglomerate, <br /> unconformably overlies the Mesaverde Group. This formation outcrops west <br /> of the permit areas of the mines. The Wasatch consists of up to 5,800 <br /> feet of interbedded claystone, siltstone, sandstone, and conglomerate. <br /> The Ohio Creek conglomerate consists of about 400 feet of sandstone and <br /> conglomerate unconformably overlying the Mesaverde Group. <br /> The sedimentary strata in the southern end of the Grand Hogback Monocline <br /> have been injected by igneous dikes, sills, and a laccolith. The coal <br /> beds in the Coal Basin iviines have been naturally coked as a result of <br /> this igneous activity. <br /> Unconsolidated Pleistocene gravel deposits occur as glacial remnants <br /> capping some of the ridge tops. <br /> The alluvia of the tributaries to the roaring Fork River (e.g. , Founnile <br /> Creek, Thompson Creek, and Uoal Creek) are generally thin, inte"ittent <br /> and, for the most part, restricted to the immediate stream channels. The <br /> most extensive alluvium occurs 1L! the confluence of two or more <br /> tributaries. <br /> The alluvium of the Roaring Fork River consist of young stream, terrace, <br /> and ouzwash ;ravels. The thickness of these ;gravels r?noe ub to 1G0 f=-t. <br />