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chiefly of well sorted, fine grain quartz minerals with admixtures of fine feldspathic minerals and <br />some clay. Together the Williams Fork and Iles formations comprise the Mesaverde Group. • <br />The Mesaverde Group forms steep slopes and cliffs with bare ledges of sandstone. Long dip <br />slopes are formed in many areas by interbedded thin soft sandstones and sandy shales. The <br />steeper slopes are generally covered by thick deposits of fine textured colluvium. Areas of soft <br />shale generally form gently rounded grass-covered ridges and knobs. <br />The Cretaceous Lewis shale outcrops northeast of the mine study area and occurs in the <br />proposed north haul road corridor area where it forms broad-undulating ridge and slope <br />topography. In the survey area, the Lewis shale is composed of tan to brown clay marine <br />shales. <br />2.3 Geomorphology <br />The study area is in an area of high relief, having eroded in Cretaceous sedimentary rocks (Bass <br />et al., 1955). The center of the study area (mine site) is located about 4 miles southwest of the <br />Seneca II Mine, and 3.5 miles east of the Seneca II-W permit area. The study area is located <br />about 8.5 miles southeast of Hayden, Colorado. <br />The study area is dissected by several small, ephemeral drainages which flow into four principal <br />stream systems; Sage Creek on the southwest, Grassy Creek on the southeast, and <br />Scotchman's Gulch and Annand Draw to the north. Annand Draw flows into Scotchman's Gulch <br />which empties into Grassy Creek near where the proposed north haul road corridor intersects <br />Twentymile Road (Routt County Road 27). Both Sage Creek and Grassy Creek are tributaries <br />to the Yampa River and join the river about 7 miles north of the study area. A detailed <br />discussion of the Yoast surface water system and alluvial valley floors is presented in Tabs 7 <br />and 16 of this PAP. <br />The terrain is characterized by barren and sparsely brush covered southwestward facing cliffs <br />where the more resistant sandstone outcrops and broad west- and northeast-facing moderately <br />sloping sideslope benches and ridges that are deeply incised. The long sloping landfonns of <br />these areas roughly coincide with the strike and dip of the underlying bedrock. Rounded shale <br />knobs, ridges, and benches are common in the west central and northern third of the mine site <br />area and along the northem haulroad (Exhibit 9-1, Sheets 1 and 2 of 2). Deeply incised long, <br />north-south trending drainages surrounded by very steep sideslopes and escarpments bisect the <br />central portion of the study area. Shorter, deeply incised northwest-southeast trending drainages <br />dissect steeply sloping sandstone bedrock controlled topography in the southwest, northwest, <br />and eastern portions of the study area. <br />• <br />4 <br />