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The Iles Formation is divided into three members. The basal Tow Creek Sandstone is a massive, <br />fine grained, well sorted sand. The Tow Creek varies from 35 to 125 feet thick. Overlying the Tow <br />Creek are 1200 feet of interbedded shales, sandstones, and coals. The coals, while mined in the <br />vicinity, are too deep to be considered economically recoverable at the Seneca II-W Mine. The <br />massive, fine grained, 100 feet thick Trout Creek Sandstone is the uppermost unit of the Iles <br />Formation. <br />Conformably overlying the Iles is the Williams Fork Formation. The lower unit of the Williams <br />Fork Formation is a series of interbedded shales, sandstones, sandy shales and coal. The middle coal <br />group contains the seams of economic importance. Four coal seams of economic importance are <br />found in the Williams Fork Formation. These seams are, in ascending order, the Wolf Creek, Sage <br />Creek, Wadge, and Lennox coals. Due to discontinuous occurrence of the Sage Creek seam, and <br />excessive overburden cover relative to seam thickness over much of the permit area, the operator <br />proposes to extract Wolf Creek and Sage Creek coals within only selected areas of the South <br />Extension Area. The Wadge coal will continue to be mined as part of this operation. The Lennox <br />seam is locally present in the Wadge overburden. It is usually two to five feet thick, but has been <br />eroded away in some areas, and is not recovered by mining operations. <br />The Wolf Creek coal is split into an upper and lower unit. The lower seam is about 16 feet thick, <br />while the upper is about 7.5 feet thick. Above the Wolf Creek seam within portions of the permit <br />area, and separated by 100 to 150 feet of interburden is the Sage Creek seam. The Sage Creek seam <br />ranges from 2 to 5 feet thick where it occurs in the permit area. SCC initiated mining of selected <br />areas of both the Wolf Creek seam and the Sage Creek Seam in the South Extension Area, upon <br />approval of PR-3, in 2003. Neither seam was previously mined at Seneca IIW. Overlying the Sage <br />Creek seam is a 50 to 65 foot thick zone of sandstone interbedded with shales and siltstones. <br />Immediately above this sequence is the Wadge coal seam. The Wadge coal seam is the most <br />continuous in the area and is the only seam that was extracted prior to 2003. The outcrop strikes <br />about north-south, and dips 8 to 14 degrees. The Wadge is also split into upper and lower seams. <br />The lower is two to three feet thick, and is separated from the 10 foot thick upper seam by two to five <br />feet of shales and sandstones. Overlying the Wadge is about 560 feet of sandstones, shales, and coal, <br />including the Lennox Coal Seam, which has been eroded away in places. Overlying this lower unit <br />of the Williams Fork Formation is the 130 feet thick Twenty Mile Sandstone. The upper most unit <br />of the Williams Fork Formation consists of interbedded sandstones, shales, and thin coals. <br />The surficial geology of the area is composed chiefly of sedimentary rocks, of marine and <br />non-marine origin. These sedimentary rocks were formed through the transgression and regression <br />of an epicontinental sea. <br />Alluvial deposits are locally present in stream valleys, particularly along the larger streams. <br />Colluvial slides and slumps are also present in canyons and gullies throughout the area. Slide bodies <br />which could potentially affect the stability of mining related structures in the northern portion of the <br />permit area have been identified, and mitigation measures are addressed in Section VII., "Backfilling <br />and Grading" of this document. <br />Seneca II-W Findings Document 9 C1982057 <br />Permit Renewal No. 5 December 9, 2010