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• 4.0 RESULTS AND DISCUSSION <br />4.1 RESULTS APJD DISCUSSIOW OF THE ORIGINAL STUDY <br />4.1.1 Regional Descriptions <br />4.1.1.1 Physiography <br />The physiography of the Hayden Gulch area is seen on Exhibit 2. The <br />Hayden Gulch site lies within the lilliams Fork Mountains at the southern <br />edge of the Wyoming Basin physiographic province and immediately north <br />of the White River plateau, a westward extension of the Southern Rocky <br />Mountains province (Raisz 1972). The 4illiams Fork Mountains range in <br />elevation from 6,500 ft. to 8,500 ft. above sea level. They encompass <br />roughly 150 sq. mi. and are bounded by the Yampa Valley to the north and <br />the Williams Fork to the south. Regional drainage is described in the <br />surface water hydrology report. <br />4.1.1.2 Structure <br />• With. regard to major tectonic units, the Hayden Gulch area is located in <br />the structural limb separating the Sand Wash Basin to the north and the <br />4Jhite River Uplift to the south (Grose 1972). Exhibit 2 shows the signifi- <br />. cant local structural features in the surrounding area. These many folds <br />and faults modify the regional structure, although strata dip predominantly <br />northward in this area. Faulting in the area is northwest trending. The <br />site is situated on the southwestern limb of the small, northwest-plunging <br />Watering Trough syncline (Phillips et. al., 1976). Strata in the irronediate <br />area dip 4° to 8° (Bass et. al., 1955) (see Exhibit 7, 8, and 9). <br />In addition to the larger fault structures shown on Exhibit 2, a fault zone <br />consisting of a number of closely spaced normal faults were found along the <br />Hayden Gulch road (Phillips et. al., 1976). The zone apparently trends west- <br />ward, but the combined displacement is not known. ; <br />~~ <br />5 <br /> <br />