Aerial view looking northeast across Berthoud Pass. Grand County, Colorado. 1932.

Aerial view looking northeast across Berthoud Pass, from an altitude of 16, 200 feet, the position of the Berthoud Pass fault, which is responsible for the heavy ground in the Moffat tunnel 6 miles to the north is shown. Two cirques of Wisconsin age, which are cut into the Flattop peneplain at an altitude of slightly more than 12,000 feet, appear in the foreground and middle distance. Grand County, Colorado. Circa 1932. Figure 15, with sketch, in U.S.Geological Survey Professional paper 223. 1950.