Sometime between 1040 and 1100 A.D., Sunset Crater erupted; the last in a six million year history of volcanic activity in Flagstaff. Forces of the earth created over 600 mountains, hills, and volcanoes in the San Francisco Volcanic Field. The eruption of Sunset Crater started when lava sprayed from cracks in the ground, and slowly built up. Ash was carried by the wind, covering approximately 800 square miles of northern Arizona. Two main lava flows, the Kana-a and Bonito destroyed all living things in their path as they flowed towards the Little Colorado River. A final eruption shot red and yellow cinders into the air where they then fell on the cinder cone. The entire process probably took about 6 months to a year.
Sinagua Indians utilized the fertile soil for their dry farming, but, by the 1300’s, they were forced to move someplace else because of a long drought. John Wesley Powell, who explored the Grand Canyon in 1869, named the volcano for its marvelous red-ish colors along the rim, which just happened to appear as a sunset.
Sunset Crater rises 1000 feet from the ground. The crater is 400 feet deep and has cold ice all year. This ice was used in the 1880’s by saloon managers to keep their customers drinks cold in the summer. Sunset Crater was made a national monument in 1930 and sits north of Flagstaff along the 89. While you are here, consider visiting Wupatki National Monument, just up the road and is free when you purchase a pass to Sunset Crater.
Trimble, Marshall. Roadside History of Arizona. 2nd edition. Missoula, Montana: Mountain Press Publishing Company, 2004. 325. Print.
Informational pamphlet from Sunset Crater Volcano National Monument
Sunset Crater and parts of the Bonito lava flow
San Francisco Peaks and the Bonito Lava Flow. It's thought that the San Francisco Mountains were once large stratovolcano that was over 16,000 feet tall and erupted 200,000 years ago!