2013-10-05_REVISION - C1982056 - Laserfiche WebLink

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EFFECTIVE ENVIRONMENT This project is located along the west side of Twentymile Park in the middle of the Fish Creek valley along the eastern foothills of the Williams Fork Mountains approximately six miles south of the Yampa River in Northwest Colorado. In general the area is a high plateau with rugged mountainous areas, broad valleys, and rolling upland parks. The area is drained by a dendritic pattern of seasonal drainages flowing generally east and south to Fish Creek, a tributary of Trout Creek which flows north to the Yampa River. Quaternary deposition in the project area is mostly alluvial with some areas of colluvium. Dark brown silts and sandy silts up to several meters thick have accumulated in the drainage bottoms. Holocene deposits on the tops and upper slopes of the low ridges are thin and consist of light to medium brown silty loams. Alluvium has accumulated in the drainage bottoms and thin aeolian deposits have accumulated in the hills, especially on the leeward sides of ridges. The project area is situated at the west edge of a structural syncline underlain by Cretaceous age Lewis Shales and sandstones, coal beds and shales of the Williams Fork Formation (Tweto 1979). The tops of the high ridges, knobs and hills surrounding Twentymile Park are capped by the thick, light colored Twentymile sandstone. Outcroppings of the Twentymile sandstone in the area are the frequent locations of rock art panels and rockshelters (Pool 1997). Although there are sandstone outcrops in the project area, no cliff faces suitable for rock shelters or rock art occur. Sagebrush, grasses, and mixed forbs are found in the park and along drainages. Vegetation cover in the project varied from 100% to 40 %. Both water wells and the vast majority of the access roads are in areas of improved range lands where the native sagebrush has been replaced by a mix of native and non - native livestock forage. Area fauna includes a variety of large ungulates, black bear, coyote, fox, and several species of small and medium -sized mammals. Numerous avian species also inhabit or utilize the area. At present, the area is used predominantly for ranching, agriculture, and coal mining. Large portions of the park and valley appears to have been mowed and/or plowed in the past and cattle grazing is ongoing. The project area is rich in natural resources that would have been attractive to the Native American inhabitants during prehistory. CULTURE HISTORY AND PREVIOUS WORK Prehistoric Overview A variety of site types are present in the general project area, representing most of the thematic contexts outlined in the original RP3 documents for Northwest Colorado (Grady 1984; Mehls 1984) and in the more recent prehistoric contexts for the area by LaPoint (1987), and Reed and Metcalf (1999). Prehistoric sites in the general area include lithic scatters, open campsites, quarry sites, rockshelters, and rock art panels. Evidence of Paleoindian inhabitants in the area For Official Use Only: Disclosure of Site Locations Prohibited (43 CFR §7.18)