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<br />• ENVIRONMENTAL SETTING <br />This section provides information concerning the topography, geology, <br />soils, climate, flora, and fauna of the study area. A general environ- <br />mental assessment discusses present and historic land use in light of these <br />environmental parameters. <br />Topography <br />The Sheridan Coal Lease lies in the Book Cliffs/Roan Cliffs area of <br />the Canyonlands section of the major physiographic province known as the <br />Colorado Plateau. The Book Cliffs are a linear series of south-facing, <br />steep escarpments which have been carved by the Colorado River and rise <br />to heights of 1500 to 2000 feet above the Grand Valley floor. North of <br />the Book Cliffs rise the Roan Cliffs, an equally rugged expanse of south- <br />. facing cliffs which form the southern edge of the Uinta Basin. Elevations <br />within the study area range from 5320 feet along the western edge (East <br />Salt Creek) to 7820 feet along the eastern ridges. <br />Numerous steep-walled intermittent drainages dissect the study area. <br />Most of those in the southern portion flow southward into Big Salt Wash, <br />while those in the northern portion generally flow westward into East <br />Salt Creek. Both Big Salt Wash and East Salt Creek are tributary to the <br />Colorado River and are designated as permanent streams on the U.S.G.S. <br />topographic maps. Important side canyons of these drainages include Mun- <br />ger and Mac Lane Canyons (which empty into East Salt Creek) and Stove and <br />Buniger Canyons (which empty into Big Salt Wash). <br />Geology <br />The study area is underlain by Tertiary and Upper Cretaceous sedi- <br />. ments. Along the ridges, the Douglas Creek member of the Green River <br />6 <br />