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_~ <br />J <br />J <br />J <br />J <br />_~ <br />I <br />1 <br />Soils, Vegetation, and Climate <br />The proposed mine site is on a very steep hillside with a western facing aspect ranging from <br />about 7,800 to 8,400 ft above sea level. The average slope across the various rock slides is 27° <br />(2H:1 V), and there is no soil cover present. The average slopes on the outcrop areas above the <br />slides ranges from 75° (1H:3.SV) to 30°. There is soil and sparse vegetative cover on areas <br />adjacent to the rock slides and outcrops, but [he slides and outcrops are bare of vegetation. The <br />soil adjacent to the rock slides and outcrops is mapped by the Soil Conservation Service as <br />Nagitsy channery loam (Soil Survey of Rio Blanco County Area, May 1982). It is a typical soil <br />unit for mountainsides, ridges, and hills in the area (see enclosed soils map). The native <br />vegetation growing on the Nagitsy soil is mainly shrubs and grasses. The average annual <br />precipitation is l8 to 22 inches, the average annual air temperature is 37 to 39 degrees F, and the <br />average frost free period is 45 to 75 days. <br />The Nagitsy soil is moderately deep and well drained. I[ formed in residuum and colluvium <br />derived front sandstone and shale bedrock. The upper part of the surface layer is typically very <br />dark grayish brown channery loam about 7 inches thick. The lower part is dazk grayish brown <br />channery loans up to 16 inches thick. The subsoil is brown very channery loam ] 0 inches thick. <br />Rock fragments make up 15 to 35 % of the A horizon and 35 to 65 % of the deeper section. <br />Hard sandstone is generally present at depths ranging from 20 to 40 inches. A closely related <br />soil unit present in the area is the Tomorthents rock outcrop complex. The unit consists of thin <br />well drained soils and rock outcrops with slopes ranging from 35 to 90 %. The rock slides and <br />outcrops to be mined are considered a subunit of the Tomorthents. Livestock grazing and <br />wildlife utilization on the Tomorthents are limited by loose rock, sparse vegetation, and steep <br />slopes. <br />The permeability of the Nagitsy soil is moderate and so is the available water capacity. Effective <br />rooting depth is 20 to 40 inches. Runoff is medium, and the hazard of water erosion is slight to <br />high depending on slope and vegetation. The unit is primarily used for livestock grazing and <br />wildlife habitat. The plant community consists mainly of Gambel oak, serviceberry, mountain <br />6 <br />