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III.D. Human and Natural Resources • 1. Local Topography The leases that make up the Hawk's Nest Mine permit area lie along the North Fork Gunnison River, approximately 1 1/2 miles east of Somerset, Colorado. These leases extend generally north of the North Fork Gunnison River. Eleva- tion varies from 6,140 feet along the North Fork River to over 8,200 feet on the northern edge of the leases, all on the south-facing valley slopes which define the North Fork river drainage. North of this lease line the slopes rise steeply to over 8,600 feet before breaking to uneven park and hill landscape which constitutes the eastern extension of Grand Mesa. Along this portion of the North Fork Gunnison River, the river is narrowly confined by the steep slopes of Grand Mesa to the north and the West Elk Moun- • tains to the south. The permit area lying north of the North Fork consists of a series of east-west trending ridges which are separated by incised gulches or canyons containing ephemeral or intermittent streams. These drain south into the North Fork Gunnison River. The maximum relief on the permit area is generally found along the sand- stone escarpments which form the step-like ridges. Here slopes may reach 90 degrees vertical. The average slope across the lease area is approximately 40 percent (sae 1" = 500' map Appendix D and Figure III.B-1). The landforms present on the permit area are largely the result of the differential erosion of the Mesa Verde Formation (sedimentary rock strata). Thick resistant sandstones form vertical to steep cliffs and escarpments. Shales and other less resistant beds form gentle slopes between the cliffs • and ledges. Because of the predominance of sandstones in the Mesa Verde 42