2022-02-22_PERMIT FILE - C1980007 (5)

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West Elk Mine 2.04-16 Rev. 11/04- PR10; 07/18- PR15; 01/22- MR459 generally lenticular in nature. Although typically fine to coarse -grained, the sandstones may locally be conglomeritic. Tertiary Wasatch Formation The Wasatch Formation of Tertiary age lies unconformably atop the Upper Cretaceous Mesaverde Formation. Rocks of the Wasatch Formation are only exposed in the easternmost portions of the West Elk Mine coal lease area where they cap the highest mesas, including West Flatiron in the Box Canyon permit revision area. Atop West Flatiron Mesa, the Wasatch Formation is represented by brownish-gray to reddish mudstone and its characteristic basal conglomerate of sandstone, chert, and volcanic rocks. Other Rocks and Deposits Further to the south and east, igneous intrusives of Tertiary age form the laccoliths of Mt. Gunnison and West Beckwith Peak. There is a low probability of intrusive dikes/sills within the permit area, based on an aerial magnetic survey completed in 1997. Unconsolidated deposits of sand, gravels, and boulders (Pleistocene age) derived from the tertiary intrusives and Wasatch Formation may cover the Barren and Ohio Creek Members of the Mesaverde locally. These deposits are the result of more recent erosion and mass-gravity movements. Coal Seams and Related Strata B Seam The B Seam is the lowermost mineable coal seam within the lease area. This seam constitutes a portion of the recoverable reserves and is of economic importance. Multiple rock partings and subsequent thinning of mineable B Seam coal benches cause challenging mining conditions in the South of Divide permit area. With the Coal Preparation Plant constructed in 2010, these B Seam reserves can be efficiently recovered. The B Seam and adjacent strata gently dip to the northeast at approximately 3.5 degrees (Map 11). In the South of Divide permit area the strike is southeast to northwest. In the Box Canyon lease area, the strike swung to nearly east-west and the dip flattened to approximately two degrees to the north. This change of strike and lessening of the dip was significant because it reduced the concern about block glide instability over the Oliver No. 2 Mine and bedding plane failures in the Box Canyon area. Photo mapping by Intrasearch indicated numerous flat and even some gentle south dips of surface outcrops in the Box Canyon area. B Seam outcrops occur along the North Fork of the Gunnison River to the north and west of the mine portal and along Minnesota Creek. Some burning of the B Seam has occurred along outcrops on Jumbo Mountain and in the Minnesota Creek drainage, predominantly on south and west-facing slopes.