G. Reid Fisher Jr. Barbara J. Waugh David S. Harwood 1995 This map covers an area of 123 km² on the west slope of the Sierra Nevada, an uplifted and west-tilted range in eastern California (fig. 1). The area is located 20 km west of Donner Pass, which lies on the east escarpment of the range, and about 80 km east of the Great Valley Province. Interstate Highway 80 is the major route over the range at this latitude and secondary roads, which spur off from this highway, provide access to the northern part of the area. None of the secondary roads crosses the deep canyon cut by the North Fork of the American River, however, and access to the southern part of the area is provided by logging roads that spur off from the Foresthill Divide Road that extends east from Auburn to the Donner Pass area (fig. 1). application/pdf 10.3133/i2341 en U.S. Geological Survey Geologic map of the Duncan Peak and southern part of the Cisco Grove 7 1/2' quadrangles, Placer and Nevada Counties, California reports