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water hydrology, soils, end revegetation sections covered later in this permit application package (PAP): • Structure. The Yoast permit area is situated within the northern portion of the rugged Williams Fork Nounteins. The mining area structurally lies between the Sage Creek and Fish Creek anticlines, two parallel south-southeast trending geologic structures with steeply dipping flanks (Bass et al., 1955). The axis of the Sage Creek Anticline is situated about one to two miles west of the western edge of the Yoast permit area. The axis of the Fish Creek Anticline originates near Scot chman's Draw and extends south-southeasterly dividing the northern first five-year mine block from [he neck portion of the permit (Exhibit 6-1). The rock units in the permit area dip predominantly about 15 to 20 percent to the north in [he north mine block, to the northwest in the neck area, and to the west in the south mine block. More extreme dips of 25 to 35 percent occur locally in [he northwest end northeast parts of the north mine block. The rock units do not appear to be affected by any significant faulting within the Yoast permit area es can be seen on Exhibits 6-2 and 6-5-%1 through 6-5-%9. Exhibit 6-2 is a structural contour map depicting the top of the wolf Creek and wedge coal seams, and Exhibits 6-3-%1 through b-5-%9 are geologic cross sections. The Fish Creek anticline has caused folding between the north mine block and the neck mine block. • Tooograoh v. The study area is located within the Yyoming Basin Physiograph is Province, in northern Colorado (Bass et al., 1955). It is within USDA Major Land Resource Area 48, Southern Rocky Mountains (USDA-SCS, 1978). Elevations within the study area range from about 6530 feet along the northern end of the proposed haul road to about 7,980 feet at summits of ridges within the southeastern portion of the proposed mine area. Slopes range from about 1 percent in Scotthman's Gulch to nearly 100 percent for isolated sandstone bluffs. Prominent ledges are formed by the Twentymile and Trout Creek sandstones, as well as by lesser sandstone units. the study area is dissected by several small, ephemeral drainages which flow into four principal stream systems; Sage Creek on the southwest, Grassy Creek on the southeast, end Scotchman~s Gulch and Annand Draw to the north (Exhibit 6-1). Annand Draw flows into Scotchman's Gulch which empties into Grassy Creek near where the proposed north haul road corridor intersects Twentymile Road (Routt County Road 27). Both Sage Creek and Grassy Creek are tributaries to the Yampa River and join the river about seven miles north of the study area. A detailed discussion of the Yoast surface water system end alluvial valley • 6