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<br />The coal seam which is being mined at the Golden Eagle Mine is the <br />Maxwell seam; the New Elk Mine is located in the A11en seam. Both the <br />Allen and fdaxwell seams are located in the middle of the Raton Formation <br />of Cretaceous age. The Allen seam lies stratigraphically beneath the <br />Maxwell coal seam. The seams are separated by a thin interburden strata <br />which varies in thickness from a few feet in the New Elk Mine to a few <br />tens of feet in the Golden Eagle Mine. <br />The Paleocene Poison Canyon formation unconformably overlies the Raton <br />Formation and has a thickness of approximately 600 feet in the study <br />area. It occurs as small isolated outcrops, probably no thicker than 200 <br />feet near the study area. This formation consists of massive, very <br />coarse arkosic sandstone, pebble conglomerates, and thick shales. <br />Sills and dikes associated with Tertiary volcanism intrude the Vermejo <br />and Raton Formations and are visible in the Picketwire Valley. They <br />range in thickness from a few inches to greater than 20 feet and are <br />primarily composed of basalt. <br />Quaternary deposits consist primarily of river terrace and floodplain <br />deposits associated with the Purgatoire River and its tributaries. The <br />study area contains two levels of rock benches that formerly may have <br />been referred to in the literature as Beshoar and Barilla pediments. The <br />applicant's consultant has interpreted these as strath terraces with an <br />alluvial veneer. These strath terraces are located approximately 90 to <br />170 feet above the river in the study area. They have been eroded from <br />shale and siltstone containing thin lnterbeds of fine to very fine, silty <br />sandstone. The overlying alluvium has a maximum thickness of <br />approximately 35 feet and is composed of predominantly silt and sand <br />containing pebbles and occasional boulders. <br />Two levels of alluvial terraces were identified adjacent to the <br />Purgatoire River. These terraces are located 5 to 10 feet and 40 to 50 <br />feet above the river in the study area and have been investigated by <br />Powell, 1952. They are composed of relatively unweathered, gray to light <br />tan alluvium overlain by medium to dark brown sandy overbook deposits. <br />These terraces support typical hydrophytic vegetation characteristic of <br />floodplains and contain ground water hydrologically connected to the <br />river. Absolute dates on the alluvial deposits are not available; <br />however, in analogous areas of the Rocky Mountain Region, the strath <br />terraces are of Pleistocene age and the alluvial terraces of Holocene age. <br />B. Ground Water -Bedrock Aquifers <br />The Trinidad Sandstone is a significant regional aquifer, given its 250 <br />feet thickness and regional extent. This sandstone is the first major <br />aquifer below the lowest coal seam to be mined and is separated from the <br />coal seam by up to 900 feet of interbedded and lenticular shales, <br />siltstones, and sandstones. The Trinidad Sandstone, however, may be <br />impacted by the Golden Eagle Mine. Early in 1988, a substantial artesian <br />flow of water was encountered in conjunction with a fracture zone in the <br />Second Right entry area of the mine. The source of this water is <br />uncertain, but the Trinidad Sandstone is a possibility. <br />-13- <br />