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Elevation of the general mine site varies from approximately 6400 to 8350 feet. Slopes range from about 2 percent to nearly 100 percent. Prominent ledges are formed by the Twen[ymile sandstone in the western permit area and the Trout Creek sandstone ledge in the eastern permit boundary. Many of the drainages are deeply incised. The Seneca II-W Mine is situated in the southeastern synclinal portion of the Sand Wash Structural Basin of northwestern Colorado and south central Wyoming. Exposed strata near the mine site vary in age from Late Cretaceous to Quaternary. Most units in the area are sedimentary. However, some Miocene ex[rusives are locally present. Many faults and folds modify the regional synclinal structure, however, no faults have been identified at the site. The most significant local fold is the Sage Creek Anticline, located just east of the mine. Rock units dip 8 to 14 degrees to the west. The Seneca II-W Mine lies on the western flank of this anticline. The largest local structure is the Tow Creek Anticline, located about 10 miles northeast of the permit area. The local stratigraphic sequence, in ascending order, is the Mancos Shale; the Mesaverde Group, which is subdivided into the Iles and Williams Fork Formations; and the Lewis Shale. See Figure 2 for further detail. The Iles Formation is divided into three members. The basal Tow Creek Sandstone is a massive, fine grained, well sorted sand. The Tow Creek varies from 35 to 125 feet thick. Overlying the Tow Creek are 1200 feet of interbedded shales, sandstones, and coals. The coals, while mined in the vicinity, are too deep to be considered economically recoverable at the Seneca II-W Mine. The massive, fine grained, 100 feet thick Trout Creek Sandstone is the uppermost unit of the Iles Formation. Conformably overlying the Iles is the Williams Fork Formation. The lower unit of the Williams Fork Formation is a series of interbedded shales, sandstones, sandy shales and coal. The middle coal group contains the seams of economic importance. Lowermost is the Wolf Creek coal, which is split into an upper and lower unit. The lower seam is about 16 feet thick, while the upper is about 7.5 feet thick. This coal lies too deep within the permit area to be mined by surface methods. 100 feet above the Wolf Creek coal is the Wadge coal. The two seams are separated by interbedded sandstones, shales, siltstones and thin coals. The Wadge coal seam is the most continuous in the area and is the seam which will be extracted. The outcrop strikes about north-south, and dips 8 [0 14 degrees. The Wadge is also split into upper and lower seams. The lower is two to three feet thick, and is separated from the 10 foot thick upper seam by two to five feet of shales and sandstones. Overlying the Wadge is about 560 feet of sandstones, shales, and coal, including the Lermox Coal Seam, which has been eroded away in places. Overlying this lower unit of the Williams Fork Formation is the 130 feet thick Twenty Mile Sandstone. The upper most unit of the Williams Fork Formation consists of interbedded sandstones, shales, and thin coals. Three coal seams of economic importance are found in the Williams Fork Formation. These seams are, in ascending order, the Wolf Creek, Wadge and Lennox coals. The Wolf Creek coal Seneca II-W Findings Document 5 June 15, 2001 Permit Renewal No. 3