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III. SITE SPECIFIC GEOLOGY <br /> A. INTRODUCTION. For a period of more than 23 years, Peabody <br /> Coal Company has gathered and analyzed detailed information on <br /> the geology of the mine plan area. This information includes a <br /> program of high density exploration drilling, geologic mapping, <br /> topographic mapping, aerial photography, field investigations <br /> and ground water quantity and quality data. A comprehensive <br /> description and analysis of this information will provide <br /> background information for ground water and surface water <br /> hydrology, soils and revegetation sections covered later in the <br /> permit. <br /> B. RECORDS OF DRILL HOLES. Appendices 6-1 and 7-4 contain <br /> numerous lithologic and geophysical drill logs for the permit <br /> area which show and describe the lithologic characteristics and <br /> thickness for each coal seam and associated strata. The <br /> location and elevation of these drilling sites are provided in <br /> Tables 6-2 through 6-4. The locations of these drill holes are <br /> shown on Exhibits 6-3, 6-3A and/or 7-2. <br /> 2.04.6(1) <br /> (a) (i )(ii) C. STRUCTURE. The mine site is located a few miles north <br /> of the axis of the structurally simple Nucla Syncline. <br /> Structure contours drawn as the top of the Lower Dakota <br /> (#2) coal seam indicate that the coal dips 10 to 20 southwest <br /> and strike N. 250 W to N. 45' W (see Exhibit 6-3) . Minor <br /> local variations in the attitude of these coals occur due <br /> to spuriously trending small folds and penecontemporaneous <br /> depositional features. These slight undulations are best <br /> seen in the highwalls and mine floors of active and <br /> abandoned mine pits in the northwest part of the permit <br /> area. The outcrop patterns and configuration of <br /> overburden thicknesses are determined by a combination of <br /> topography and geologic structure. Overburden isopach contours <br /> are shown in Exhibit 6-3. Three geologic cross sections, <br /> 6-9 Revised 11/01/86 <br />