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_11_ <br />Several sites were recommended for further testing in the first survey. <br />Subsequently, thdse sites have been cleared. The second survey (in the <br />U.S.F.S. Special Use area proposed in Permit Revision No. 2) identified two <br />isolated artifacts, neither of which were eligible for consideration for <br />listing on the National Register of Historic Places. <br />The proposed operations are in compliance with the requirements of this <br />section. <br />IV. Geology - Rules 2.04.5 and 2.04.6 <br />Details of the chemical characteristics of the overburden, interburden, and <br />coal, as well as detail on the geology of the area, can be found in Section <br />2.04.6 in Volume I of the approved permit application. <br />The proposed operation lies on the northern rim of the San Juan Basin in <br />southwestern Colorado. The San Juan Basin is an asymmetric structural basin <br />containing sedimentary rocks ranging in age from Cambrian to Holocene. <br />Mining operations will extract two coal seams from the Lower Fruitland <br />Formation, which dips 6° to 8° to the southwest and strikes N60°W. No <br />large displacement faults have been identified in the Permit Revision No. 2 <br />area. <br />The Fruitland Formation, which is up to 220 feet thick, is composed of <br />interbeded sandstone, siltstone, shale, carbonaceous shale, and coal. The <br />coal seams appear to be the most continuous stratigraphic units in the <br />Fruitland Formation. The coal bearing zone is approximately 82 feet thick. <br />In the Fruitland, the "A" seam is the first mineable coal seam encountered. <br />It is generally 4 to 5 feet thick with intermittent shale partings. The "B" <br />seam is about 6 to 12 feet below the "A" seam, and has an average thickness of <br />11 feet. Twenty to thirty feet below the "B" seam is the "C", which has an <br />average thickness of 9 feet. The "C" seam, extracted in the original permit, <br />Revision 1 and Barren Ridge areas will not be disturbed in the Permit Revision <br />No. 2 Area. <br />The Kirtland Shale which overlies the Fruitland Formation, is composed of gray <br />shales interbedded with thin layers of siltstone and sandstone. This <br />formation is highly erodable. <br />Underlying the Fruitland Formation is the Pictured Cliffs Sandstone. The <br />upper Pictured Cliffs is a massive fine to medium grained, yellowish-gray <br />sandstone, while the lower portion is composed of thinly interbedded <br />sandstones and shales. The Pictured Cliffs ranges in thickness from 200 feet <br />to 250 feet. <br />The Pictured Cliffs Sandstone, Fruitland Formation and Kirtland Shale are all <br />Cretaceous in age, and conformably overlie each other. <br />