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West Elk Mine(C-1980-007) MT-9 <br /> above the D horizon and contains two coal seams. This horizon has been mined at the <br /> Hawk's Nest Mine and was mined at the Blue Ribbon Mine. The West Elk Mine is <br /> mining the E Seam but did not mine the E seam on Jumbo Mountain because this seam <br /> is split and comprised of several thin (< 5 ft.) coal benches which are separated by rock <br /> partings. The F horizon contains two coal seams and has been mined at the West Elk <br /> Mine. At the mine site, the coal is immediately overlain and underlain by shale. Coal <br /> seams of the F horizon do not exist to the north of the North Fork of the Gunnison <br /> River in thicknesses sufficient for mining. In the Jumbo Mountain area, the F Seam <br /> thins to less than five feet in thickness and is of limited aerial extent. Therefore, MCC <br /> does not plan to mine this seam in Jumbo Mountain. <br /> o Overlying the Upper Coal Member is the Barren Member of the Mesaverde Formation. <br /> This unit consists of interbedded sandstones, siltstones, shales, and coals. The unit is <br /> not thought to be of marine origin and, as a result, the sandstones and the coals are <br /> highly lenticular, discontinuous, and of limited lateral extent in outcrop. This unit <br /> ranges up to 1,500 feet thick and outcrops throughout most of the permit area. <br /> o The Ohio Creek Member is the uppermost member of the Mesaverde Group. This unit <br /> is approximately 700 feet thick and consists primarily of interbedded sandstone, <br /> mudstone, and shale. The sandstones range from a few feet to more than 100 feet in <br /> thickness and are generally lenticular in nature. Although typically fine to coarse <br /> grained, the sandstones may locally be conglomeratic. <br /> • The Mesaverde Formation is unconformably overlain by the Tertiary Age Rudy or Wasatch <br /> Formation. This formation consists of red to buff-colored shales, red sandstones, and red to <br /> gray conglomerates. The sediments of this formation are weathered volcanic rocks. <br /> • Immediately southeast of the permit boundary, igneous intrusives of Tertiary age form the <br /> laccolith of Mt. Gunnison. <br /> • The alluvium of the North Fork of the Gunnison River consists of Quaternary Age deposits of <br /> mixed coarse sand, cobbles and boulders. These coarse sediments are composed primarily of <br /> igneous and metamorphic rock types and have their source area in the headwaters and upper <br /> reaches of the North Fork. This coarse alluvium is capped by finer sands and silts. The North <br /> Fork alluvium in the area of the Hawk's Nest, Bear, West Elk and Elk Creek Mines is fairly <br /> narrow in width and is between 50 and 70 feet thick. About a mile below the town of <br /> Somerset, Colorado, the width of alluvium increases while the thickness of alluvium decreases <br /> to about 35 feet. <br /> Since the three main minable seams (B, E, and F) within the West Elk Mine's permit boundary directly <br /> overlie one another, their structural characteristics are virtually identical. The F Seam strikes north <br /> 60 degrees west and dips three to five degrees northeast across the lease blocks. In the Jumbo <br /> Mountain area, the B Seam has an average dip of 4.6 degrees in a north 25 degrees east direction. <br /> The major cleat orientation within the F and B Seams is north 70 degrees east. This face cleat is <br /> Page 6 of 14 <br />