Note 7 — Chapter II · THE VOLCANIC REGIONS OF NORTH AMERICA.
Reading edition
Powell, Exploration of the Colorado River, p. 177, etc. (1875). Hayden, Rep. U.S. Geol. Survey of the Colorado, etc. (1871-80).
Reading edition
Powell, Exploration of the Colorado River, p. 177, etc. (1875). Hayden, Rep. U.S. Geol. Survey of the Colorado, etc. (1871-80).