When you think of Arizona, do you think "Volcanoes"? Of course not. However, volcanoes have left massive craters in the Colorado Plateau Region and Sun Set Crater is the best known example. Many of the sharp peaks in the central highlands are made of volcanic ash. The San Francisco volcanic field is dotted with volcanic cones. Red Mountain has an unusual cinder cone. Also, the Arizona Meteor Crater is called the best preserved meteor crater in the world. Google the names in red for more information. BTW. I watched Mt. St. Helens erupt in the state of Washington.