2013-04-10_PERMIT FILE - C1981019 (78)

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Collom Area Geology Pre - Feasibility Report 3.0 Regional Geology, Coal Seam Development and Structural Geology 3.1 Regional Geology The CMA is located in the northern extent of the Danforth Hills Region of the Uinta Basin. The Danforth Hills Region is comprised of coal deposits on the northeast flank of the Piceance Creek Basin and is defined to the north by the Axial Basin Anticline. All significant coal resources and reserves for the CMA are located to the south of the Axial Basin Anticline, with the major structural feature north of the current and proposed mining areas being the asymmetrical Collom Syncline. Coal resources and reserves lie on the southern, less steeply dipping southern flank of the syncline. In northwest Colorado, the Williams Fork Formation is the predominant coal bearing formation of the Mesa Verde Group in the Upper Cretaceous. The top of the Williams Fork Formation is characterized by thin, lenticular coal seams exposed at surface. The Lewis Shale overlies the Williams Fork Formation, but has been eroded throughout the Colowyo /Collom resource and reserve areas. The lower sequence of the coal bearing Williams Fork Formation is characterized by thick and rather continuous coal seams deposited during a major regressive marine sequence. The massive Trout Creek Sandstone lies conformably beneath the Williams Fork Formation and constitutes the upper -most unit of the Iles Formation. The Trout Creek Sandstone consists of a white, fine grained, massive, marine sandstone. The Trout Creek Sandstone occurs regionally throughout northwestern Colorado and can be continuously mapped for more than 40 miles. All coal beds within the CMA reside above the Trout Creek. While more than 100 separate coal seams occur within the Williams Fork Formation, approximately 68 correlatable coal seams occur across the area. Additional correlatable seam splits also occur across the area. August 2005 Page 5 of 38