2008-08-11_GENERAL DOCUMENTS - C1992080

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Geology The pen-nit application describes the geology of the permit area and adjacent area (permit application Sections 2.04.5, 2.04.6; Table 4-1; Map 4-2; and Appendix 4-2). The permit area is located on the northern rim of the San Juan structural basin in southwestern Colorado. A sequence of Cretaceous-aged sandstones, siltstones, shales, and coals is exposed in the outcrop belt on the rim of the basin. These strata dip between 26 and 30 degrees to the southeast (into the basin), and strike North 45° West. There are no mapped faults within the permit and adjacent areas. Folding within the general area, however, has fractured the more brittle sandstone and coal strata. The sandstones are resistant to erosion and form prominent ridges and cliffs at outcrops. Stream valleys in the vicinity of the Carbon Junction Mine are controlled by geologic structure. The Animas River has cut a steep-sided valley perpendicular to bedding of the strata, and may be related to a fracture or fault zone in Carbon Junction Canyon. Stratigraphic units exposed in the area include (in ascending stratigraphic order): the Lewis Shale, the Pictured Cliffs Sandstone, the Fruitland Formation and the Kirtland Shale. The following coal seams in the Fruitland Formation underlie the Carbon Junction Mine: the Lewis coal seam ("C" seam), Carbonero seam ("B" seam) and the Shamrock seam ("A" seam). The Lewis Shale is the lowermost formation exposed in the vicinity. This formation consists of between 1600 and 1800 feet of light to dark gray and black shales that contain interbeds of light brown sandstone, sandy to silty limestones, calcareous concretions, and bentonite. This formation is erosive and wide valleys have formed within this unit to the north. The Pictured Cliffs Sandstone conformably overlies the Lewis Shale, is 200 feet thick, and consists of two members. The lower member consists of 80 feet of interbedded shales and sandstones. The Upper Pictured Cliffs Sandstone consists of 120 feet of massive sandstone with some thin interbeds of shale and siltstone. The sandstone is white to light gray, well sorted (uniform grain size), fine to medium grained, and contains silica and calcareous cement. This sandstone is resistant to erosion and forms prominent ridges, cliffs, and steep sided stream valleys (water gaps) in the area. (Fassett and Hind, 1971 and Shomaker, et. al., 1971.) The Upper Pictured Cliffs Sandstone locally intertongues with the overlying Fruitland Formation. The Fruitland Formation is coal-bearing. The Lewis or "C" coal seam is in the Fruitland Formation. The Lewis coal seam is the lowest coal seam that was to be mined. The Fruitland Formation is the coal bearing formation in the permit and adjacent areas. This formation is composed of laterally discontinuous interbedded and lenticular sandstones, siltstones, shales and coals. The formation is a terrestrial deltaic deposit and is gray to brown and black with greenish shale and gray- green fine grained dense feldspathic sandstones in the upper parts. The Fruitland Formation contains three minable coal seams. In ascending stratigraphic order, the seams are the Lewis or "C" seam, the Carbonero or "B" seam, and the Shamrock or "A" seam. The Lewis seam is approximately 17 feet thick and consists of high volatile C bituminous coal. The Carbonero or "B" seam is approximately 28 feet thick, contains a five-foot parting of shale and bone, lies 105 feet above the Lewis seam, and is a high volatile C bituminous coal. The Shamrock or " A" seam is located about 87 feet above the Carbonero seam, is about 21 feet thick, and is classified as a high volatile C bituminous coal. The Shamrock seam is overlain by 0 to 120 feet of overburden strata in the permit area. The entire overburden section is in the Fruitland Formation. 4