Arizona might not be the first place you think of when it comes to volcanoes, but it actually has some of the most mysterious ...

The San Francisco volcanic fields cover about 3,000 square miles of northern Arizona and is one of the more well-known areas. More than 600 volcanoes can be found in this volcanic field.

Arizona Bureau of Geology and Mineral Technology. Rasmussen, Jan C. Geologic History of Arizona published in Rocks & Minerals, v. 87, no.1, p. 56-63, Jan.-Feb. 2012.