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Pre-Renewal4 Renewal4 Chan e Total 7,402.5 7,531.05 + 129.05 3.2.3 Coal Resources to be Mined Eight major coal seams are mined in the Colowyo operation. These are the "I"', "X," "A", "B", "C", "D", "E" and "F" seams (PAP, page 5). The seams vary in thickness from 2.5 to 15 feet, and overburden thickness varies as a function of structural geology and topography. 3.2.4 Topography The active mining sites lie just west of the northward flowing Goodspring (also referred to as Good Spring) Creek, which is paralleled by Colorado Highway 13. The azea is a gently sloping upland ranging from about 7,640 feet near the sautltwest comer to 6,560 feet near the northeast comer of the pemut area. Valleys that cut into the upland surface are generally narrow, ~/-shaped, and about 250 to 500 feet deep. The topographic surface north of the proposed active mine site is dominated by two ridges about two miles Ions, trending north-northeast, bounded by Goodspring, Taylor and Wilson Creeks. 32S Geology .- . _ Geologic information is found in Sections 2.04.6, Maps 7 through 9A, and Exhibit 6 of the PAP. The permit area lies about six miles south of the axis of the Axial Basin Anticline, a lazge northwest-treadmgfulcffixnrd irr ~e smrthercr Eiirrta regioFr o€ the Pieearree. Basis. The a~ielirre structure and corresponding syncline (Cullum Syncline) to the south consist of thousands o€feet of marine deposited sediments of Cretaceous age. To the south of the anticline, the axis of the Cullum Syncline, a downwazd fold, passes directly through the permit azea, trendingnarth 7Q degrees west and phrasing from 0 to 20 degrees to the North. In the southeastern comerofthe pemrit area, near Streeter Fill, the Collura Syncline is influenced'by the Elkhorn Syncline which results in strata having an eastwazd dip and north-south strike (see Map 7 and Figure 1 in the PAP). There appears to be no evidence of.faulting in the permit area; however, linear features that may befault-related have been observed from aerial photographs. These lineations trend approximately north 70 degrees west, north 45 degrees west and north 30 degrees east, with near vertical inclinations. The coal-bearing strata of interest to the Colowyo operation aze stratigraphicallylucated in the Mesaverde Group within the Williams Fork Formation of upper Cretaceous age. The Williams Fork consists of alternating beds of sandstone, sandy shale, carbonaceous shale and coal. The coal to be mined lies within a 392-foot interval in the Fairfield Member of the Williams Fork Formation. The quality of the coal seams is midway between bituminous and sub-bituminous. October 21, 2002 13