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j; <br /> r <br /> x <br /> K�.x yt <br /> Map 1: The 11.294 acre Trapper Mine permit boundary and the area's typical pre mine dendritic drainage pattern <br /> as per the NHD Hydrology Dataset <br /> Physiographic Setting <br /> Trapper Mine extends across the northern slope of the Williams Fork Mountains between elevations <br /> of 6,500 ft. and 7,800 ft. The crest of the Williams Fork Mountains forms a long ridge extending <br /> east/west at elevations between 7,400 and 7,800 ft. The Yampa River flows generally from east to <br /> west a short distance north of the permit area. The Williams Fork River skirts the south side of the <br /> mine site and flows into the Yampa River one mile west of the mine. <br /> Geologic Setting <br /> The bedrock at the ground surface in the Trapper permit area is an interbedded sequence of <br /> sandstones, siltstones, shale, and coals comprised of the Cretaceous-age Williams Fork Formation. <br /> The Williams Fork Formation forms part of the regionally extensive Mesa Verde Group. Younger <br /> unconsolidated alluvial deposits of Quaternary age form a thin mantle over the Williams Fork <br /> Formation in stream drainages. Structurally,the mine is situated on the south limb of the northwest- <br /> plunging Big Bottom syncline. Major faults extend across the region,but none have been found in <br /> the permit area. <br /> Coal Seam Stratigraphy <br /> The Williams Fork Formation is stratigraphically subdivided into three units or members. These, in <br /> ascending order are: <br /> 1. the lower Williams Fork <br /> 2. the Twentymile sandstone <br /> 3. the upper Williams Fork <br /> with individual thicknesses of 920 ft. 100 ft. and 680ft. respectively. The coal seams being mined at <br /> Trapper Mine are all in the upper Williams Fork member and their nomenclature, in descending <br /> order, consists of- <br /> 5 <br />