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joints more readily than highly oxidized and weathered coal beds do; however, both have <br />undergone similar stresses and have developed similar readjustment features that are apparent <br />in the subsurface. <br />The site specific stratigraphy is described in Exhibit 6, Geological Information, and is <br />graphically shown on the Geologic Cross Section A-A' (Map 8) and the Geologic Cross <br />Section B-B' (Map 9). Three additional geologic cross sections (C-C', D-D', and E-E') that <br />show the coal seam geometry and pit limits are provided in Ivfap 9A. The topographic <br />locations of the geological cross sections are found on the Geology Map (Map 7). <br />The coal seams to be mined. at the Colowyo operation are the <br />"Y3","Y2","X","A2","A3","Bl", "C", "D", "E", and "F" coal seams. These coal seams are <br />found in the Williams Fork Formation and lie within a sequence of sedimentary rocks <br />characterized by sandstones, claystones, siltstones, shales and carbonous and silty shales. <br />This sedimentary sequence is typical of cyclothems deposited along the linear clastic <br />shoreline located at the western edge of an epicontinentai seaway which was located in <br />interior western North America during most of Late Cretaceous time. <br />The analyses of the various coal seams to be mined are shown in Table I, Typical Coal Seam <br />Analyses. <br />Exploration test borings have been conducted within the permit area and have been utilized <br />for the following purposes: <br />• Location of Subsurface Water -_Since the holes were generally dry, the primary circulation <br />medium for most exploration bore holes drilled within the mine plan area was either <br />compressed air or drilling mud when fractures were encountered. Several drill holes <br />throughout the area encountered minor amounts of ground water; however, al! of the data <br />obtained to date by Colowyo and the USGS have indicated that groundwater occurrences in <br />the are not continuous but rather are a series of perched systems. Information on <br />groundwater occurrence is set forth under Section 2.04.7. <br /> <br />2.04.6-6 <br />