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RULE 2 PERMITS <br /> -"40",Pa :3$Qid F:W�bFa01'vi_z�iqw w1. ..�r.\d� '.'dgP:�a.l•,,M00`,e ." 1N.•s,•4 4'°'S+.4.4. AY ,4,.. .b ,+`i.*n,,, iPf444-...�v�....n« <br /> Both the "adjacent area" and the "permit area", as defined in Rule 1.04, lie within the "general <br /> area" as previously described. Specifically, the "general area" includes the drainages of <br /> Goodspring Creek and Wilson Creek, perennial streams; and Taylor Creek and Streeter Gulch, <br /> intermittent and ephemeral streams,respectively. <br /> Groundwater resources within the "general area" are delineated by these major basins and are a <br /> function of the stratigraphy and local climate conditions. <br /> The geological information for the "permit area" and the "general area" are discussed and <br /> described in detail in Section 2.04.6. Groundwater information for the general area, adjacent area <br /> and permit area is set forth in the discussion under Section 2.04.7. <br /> The location of wells and surface water sites located within and within one mile of the Permit <br /> Boundary is provided on Map 10B. The cross-reference for these sites can be found in Exhibit 7. <br /> 2.04.6 Geology Description <br /> The coal mined at the Colowyo operation is located in the northern extent of the Danforth Hills <br /> coal field of the Uinta Region.The Danforth Hills field comprises the coal deposits on the northeast <br /> flank of the Piceance Creek basin and is defined to the northeast by the Axial Basin Anticline. <br /> Stratigraphy <br /> The area is underlain by as much as 13,500 feet of sedimentary rock consisting of approximately <br /> 4,500 feet of Paleozoic (570 million to 225 million years old) quartzite, limestone, shale, <br /> sandstone,and gypsum and 9,000 feet of Mesozoic(225 million to 70 million years old)limestone, <br /> shale, mudstone, sandstone, and conglomerate. The coal seams mined at the Colowyo operation <br /> are of upper Cretaceous Age. <br /> The generalized geological structural setting is outlined in Figure 2.04.6-1 Geologic Structural <br /> Setting. The stratigraphic position of the coals mined by Colowyo are graphically illustrated in <br /> Figure 2.04.6-2, Generalized Stratigraphic Column. <br /> The two most important geologic formations within the permit area are the upper Cretaceous Iles <br /> and Williams Fork Formations of the Mesa Verde Group. Details of each formation are set forth <br /> below. <br /> Iles Formation - In general, the Iles Formation consists of light brown-to white, fine-to medium- <br /> grained,poorly-sorted calcareous sandstone interbedded with red and dark maroon sandy and silty <br /> carbonaceous shale. Thin lenticular coal beds are found in this formation. The uppermost <br /> sandstone of the Iles Formation,the Trout Creek Sandstone Member,appears to be reliable marker <br /> horizon at the base of the principal coal beds within the Williams Fork Formation. The 75 foot <br /> thick Trout Creek member is a white, fine-grained, well-sorted, massive sandstone that is fairly <br /> uniform in thickness over a large area. The Trout Creek Sandstone Member, a common ridge- <br /> Rule 2 Permits 2.04-8 Revision Date: 12/20/19 <br /> Revision No.: TR-135 <br />