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42,04 APPLICATION FOR PERMIT FOR SURFACE OR UNDERGROUND MINING ACTIVITIES -- <br />MINIMOM REQUIREMENTS FOR INFORMATION ON ENVIRONMENTAL RESOURCES. <br />2,04.6 Geology Description. <br />(2) (a) (Cont'd.) <br />of the permit area suggests a modification of the den- <br />dridic drainage pattern by inferred antecedent geologic <br />structures. Map 2-8 portrays knocm geologic structures <br />and suspected structures inferred on the basis of <br />abrupt straight portions of stream drainages. The sig- <br />nificance of these drainage lineaments has not been de- <br />termined with confidence. They may represent faults, <br />zones of unstable roof, and abundant jointing, or may <br />not persist into the "D" coal horizon. The nature of <br />the lineaments will be determined when undermined. <br />The face cleat of the "D" coal seam trends N60°E with <br />the lesser developed butt cleat trending N30°W, with <br />local undulations common. The spacing of the cleat is <br />variable, ranging from a minimum of 2 to 3 inches to an <br />observed maximum of 2 to 3 ft. Generally, the deeper <br />overburden thicknesses result in closer spaced cleats. <br />Although not widespread, jointing follows the same <br />trends. <br />The geologic structure of the Permit Area may be fur- <br />ther modified by the nearby location of igneous intru- <br />sive bodies in the extreme northeastern portion of <br />Lease ~~C-37210. Coal seams in this area surrounding <br />DH-51 have been coked and devolitized by suspected <br />sills, undoubtedly related to the Miocene Iron Point <br />Pluton (Junge, 1976). The combined effect of extension <br />type structural features, nearby igneous activity, and <br />frequency of inferred structures may indicate the pres- <br />ence of an igneous complex at depth beneath the area. <br />Regional geophysical studies or deep drilling would be <br />required to confirm this idea. <br />The "D" coal seam overburden ranges in thickness from <br />less than 100 feet to greater than 2,000 ft ., and is <br />characterized by alternating claystone, siltstone, <br />sandstone, and minor carbonaceous horizons. The lith- <br />ologies comprising the barren member of the Mesaverde <br />formation are typically laterally discontinuous and un- <br />dergo abrupt facies changes within short distances. <br />The stratigraphic interval between recognizable <br />. Revised 08/01/84 <br />Revised 10/01/87 <br />19 <br />