METEOR CRATER

also called Barringer Crater, Coon Butte, Arizona Meteor Crater, or Canyon Diablo, rimmed, bowl-shaped pit produced by a large meteorite in the rolling plain of the Canyon Diablo region, 19 miles (30 km) west of Winslow, Ariz., U.S. It is 4,000 feet (1,200 m) in diameter and about 600 feet (180 m) deep inside its rim, which rises nearly 200 feet (60 m) above the plain. Drillings reveal undisturbed rock beneath 700800 feet of fill. The strata forming the rim of the crater are upturned and covered with the debris of the same bedrock, which shows an inverted stratigraphy. Discovered in 1891, its age has been variously estimated at between 5,000 and 50,000 years. Large numbers of nickeliron fragments from gravel size to 1,400 pounds (640 kg) have been found in a 100-square-mile (260-square-kilometre) area. The distribution and composition of several thousand tons of sand-grain size nickeliron droplets indicate that they condensed from a cloud of metallic vapours. Surveys show only fragments within the pit, but the 1960 discovery there of coesite and stishovite, which are high-pressure modifications of silica, helped to confirm the crater's meteoritic origin.