OF-02-03 Geologic Map of the Keystone Quadrangle, Summit County, Colorado


The Keystone Quadrangle is located in Summit County. The map includes cross-section, map unit correlation, shaded-relief map with geology overlay, booklet of extended descriptions of map units, economic geology and selected references. 22 pages. 1 colorado plate (1:24,000). Digital PDF download. OF-02-03D

From the Author’s Notes:

The Keystone quadrangle is located in Summit County on the western margin of the Colorado Front Range. The town of Keystone and the Keystone Ski Area lie at the northern end of the quadrangle and are accessed via U.S. Highway 6, which wraps around Dillon Reservoir before connecting with the Interstate-70 Highway transportation corridor (I-70) about 5 mi west of the quadrangle. Keystone Ski Area has a 6,000 acre permit area with 1,850 acres of trails on Keystone Mountain, which ranges in elevation from about 9,300 ft to 11,661 ft. The Snake River flows westward through the town of Keystone and drains into Dillon Reservoir. The Swan River and its tributaries, the North and Middle Fork, flow generally westward through the southern part of the quadrangle. The highest peaks are Independence Mountain (12,614 ft), Bear Mountain (12,585 ft), and Glacier Mountain (12,443 ft), all of which are located in the eastern part of the quadrangle. Historic metal mining production is from the Brewery Hill area (part of the Breckenridge mining district), the Saints John area (part of the Montezuma mining district), and the Swan River, or Swandyke, mining district located near Wise Mountain.