S P Volcano and Lava Flow
January 20, 2004
Cinder cones in the San Francisco Peaks volcanic field of northern Arizona have been active as recently as 1,000 years ago. Nearby Sunset Crater erupted in 1064 CE. With an average historic interval of several thousand years, future eruptions seem likely. One of the most symmetrical cinder cones is labeled S P Volcano, about 40 km (25 miles) due north of Flagstaff, Arizona. It rises approximately 300 m (1,000 ft) above the high desert of the Colorado Plateau. Composed primarily of cinders and volcanic ejecta, the rim of the crater is hardened lava rock. A lava flow from the base of the volcano extends to the north toward the Grand Canyon. The S P Volcano is featured in John S. Shelton's classic 1966 book, "Geology Illustrated," recently cited as one of 100 books that shaped the century.