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State Reg. <br />• (1973), and are characterized by carbonaceous shale and impure <br />coal with lessor airounts of interbedded sandstone and silt- <br />stone. Basically, these coals are high BTU, low sulfur bitu- <br />minous coals that show goal lateral continuity. Each seam <br />shows a well-defined system of vertical to near vertical joints <br />(coal "cleats") at the outcrop. These joints are less evident <br />in core samples indicating a lower porosity than would be ex- <br />pected by outcrop etiamiu~ation. Fractures of this sort are <br />highly anisotropic. <br />The Upper Dakota (#1) seam averages from 1.6 to 3.3 feet in <br />thickness and lies approximately 100 feet from the base of the <br />Dakota. The Iffier Dakota (#2) seam averages fran 5.9 to 7.9 <br />feet in thickness and lies approximately 83 feet from the base <br />of the Dakota. There is roughly 7 feet of interburden sepa- <br />rating these seams at the mine site. A 1 foot laterally dis- <br />continuous "rider" coal seam is fourrl 8 feet above the Upper <br />• Dakota coal seam in sere parts of the permit. In the under- <br />burden, t4ro additional coal seams, the Nucla (#3) seam and <br />an unnamed seam, are observable in the Nucla area. They occur <br />approximately 52 feet and 23 feet, respectively, above tl:e <br />base of the Dakota. <br />Shale and sandy shale are the predominant lithologies in over- <br />burden msterial at the Nucla Mine site. These shales are <br />characterized by their extremely fine-grained nature, fria- <br />bility, high carbon content, and exceedingly low vertical and <br />horizontal permeabilities. Tcn thin clay (kaolinite?) beds <br />are widely traceable in the northwest part of the permit. <br />These clays average 1 to 2 feet in thickness and are found <br />approximately 42 feet arx3 52 feet above the Upper Dakota Coal <br />Seam. <br />6-15 <br />