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The structure contour map, Map 2.04.6 -2, and the overburden map, Map 2.04.6 -3 were prepared <br />by using the "QuickSurf' modeling program that operates inside of AutoCad. The structure map <br />utilized the elevations to top of the LDx Seam from the drillhole data. The overburden map was <br />prepared by subtracting the "grid model" of the structure from the digital model of the new <br />topography. <br />Stratigraphy With the exception of unconsolidated Quaternary deposits, the only exposed <br />formation at the mine site is the Dakota Formation. The general lithologic characteristics of this <br />formation were described in the section on Regional Geology. This section discusses the site - <br />specific stratigraphy as derived from: drillhole cuttings /core sample descriptions; geophysical <br />logs; field observations of highwalls at both the adjacent "old" Peabody Nucla Mine and WFC's <br />New Horizon Mine; as well as local road cuts. <br />Figure 2.04.6 -1 is a columnar section showing the general stratigraphy of the Dakota Formation <br />lithology in the NHN permit area. Two cross sections, A -A' and B -B', have been prepared <br />demonstrating in more detail the permit area stratigraphy, (see Map 2.04.6 -1 for locations of the <br />cross sections). Cross Section A -A' is presented as Map 2.04.6 -4 and was constructed along the <br />strike of the strata from the northwest corner of the area to the southeast corner of the area. Cross <br />Section B -B', Map 2.04.6 -5, was constructed along the dip of the strata and is oriented from the <br />southwest to the northeast. <br />The Cretaceous Dakota Formation unconformably overlies the Jurassic Morrison Formation and <br />has been divided into three units or members, (Young, 1973). The base of the Dakota is marked <br />by the top of a green shale /mudstone in the permit area. The "Lower Member" (about 36 ft. <br />thick) consists of interbedded gray to white, fine to medium grained sandstone, gray shale and <br />thin light gray siltstone. The "Middle Carbonaceous Shale and Coal Member" of the Dakota <br />Formation contains 3 coal seams, in ascending order: the Nucla Seam, the LDx Seam and the <br />UD1 Seam. <br />The Nucla Seam is less than 5 feet thick in the permit area which includes parting material <br />(carbonaceous shale) that can be one to several feet thick. The net coal thickness is generally <br />about 3.0 ft. or less and the seam is high in ash and sulfur content. Due to low thickness, low <br />quality, and depth, the Nucla Seam will not be mined in the proposed permit area. The Nucla <br />Seam is overlain by the LDx Seam and is separated from it by about 32 ft of interburden. The <br />interburden consists of interbedded carbonaceous shale, gray shale, white fine to medium grained <br />sandstone and white siltstone laminated with carbonaceous material. A white, fine to medium <br />grained, hard (sideritic) sandstone of variable thickness lies immediately to several feet below <br />the LDx Seam. <br />The LDx Seam is of primary interest in the NHN permit area where the net coal thickness varies <br />from about 8.0 feet in the southern part of the area to less than 3.0 ft. in the northwest corner. <br />While the LDx Seam has been described as lenticular it has, however, demonstrated continuity <br />from the startup of the New Horizon Mine to the north side of the NHN permit area, a distance of <br />about 3.5 miles. Cross Section A -A' (Map 2.04.6 -4) shows that the LDx Seam is beginning to <br />Section 2.04.6 Page 3 April 2011 <br />