2013-04-10_PERMIT FILE - C1981019 (75)

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Class III Inventoiy, Colowyo's Collorn Mine Project 7 2.0 PROJECT SETTING This section presents the environmental overview of the project area and the cultural setting. 2.1 ENVIRONMENT The project area occurs within the Southern Rocky Mountain physiographic province (Fenneman 1931; Thornbury 1965). The mountainous areas were formed by repeated uplifting that began as early as 300 million years ago, with the present configuration of the Rockies formed by about 60 million years ago. The project area occurs along the northwestern margin of the Southern Rockies. Specifically, it is located among a series of long, broad, northeast/southwest - trending ridges that originate in the Danforth Hills to the south and then slope gently northeast to Axial Basin, which lies below the ridges and borders the northern portion of the project area. This region includes several perennial and ephemeral drainages. Elevations above mean sea level within the project area range from 6,500 ft (1,981 m) in the northern portion of the project area to as high as 8,567 ft (2,611 m) in the extreme southern portion within the Danforth Hills. Axial Basin lies in the southernmost portion of the Wyoming Basin that extends into northwestern Colorado. It is developed on an anticlinal trough whose axis has been deeply eroded, and it connects the White River Plateau to the south with the Uinta Mountains to the north. The Yampa River follows the western half of this trough, while the eastern half of the basin is crossed by several streams. The Danforth Hills consist of uplifted folds that rise 2,000 ft (610 m) above the surrounding valleys and are intermediate in character between the Mountain and Plateau provinces. Structurally, they are a connecting link between the Uinta Mountains and the Southern Rocky Mountains (Fenneman 1931; Thornbury 1965). The entire area of broad ridges and gulches within the project area is composed of Williams Fork formation sandstone, shale, and major coal beds. There is a linear band of Iles formation sandstone and shale that lies along the foothills adjacent to the southern margin of Axial Basin. The eastern 47599 TRC Mariah Associates Inc.