Aerial view of Meteor Crater, color, Coconino County, Arizona

Meteor Crater formed approximately 50,000 years ago by the impact of a 100,000-ton iron-nickel meteorite, ~30 m in diameter, which struck at an approximate speed of 12-20 km/sec. The Canyon Diablo meteorite, so named for the small canyon to the west of the crater, exploded with the force of over 2 million tons of TNT (or about 150 times the force of the atomic bomb detonated over Hiroshima). The impact blasted millions of tons of sandstone and limestone out of the crater, and this pulverized rock was redeposited on the plain around the crater along with fragments of the Canyon Diablo meteorite, impact melt (shock-melted sandstone and limestone), and metallic spherules (ballistically dispersed droplets of melted meteorite). This redeposited material is the crater’s ejecta blanket. Geologic and petrologic studies of Meteor Crater, especially the works of Daniel Barringer and Eugene Shoemaker, have demonstrated conclusive evidence for the impact origin of the crater and provided diagnostic scientific tools needed to recognize impact structures throughout the Solar System.