Barringer Meteor Crater of Arizona
- 10 years ago
Meteor Crater is a meteorite impact crater approximately 43 miles (69 km) east of Flagstaff, near Winslow in the northern Arizona desert of the United States. Because the United States Board on Geographic Names commonly recognizes names of natural features derived from the nearest post office, the feature acquired the name of "Meteor Crater" from the nearby post office named Meteor. The site was formerly known as the Canyon Diablo Crater, and fragments of the meteorite are officially called the Canyon Diablo Meteorite. Scientists refer to the crater as Barringer Crater in honor of Daniel Barringer, who was first to suggest that it was produced by meteorite impact. The crater is privately owned by the Barringer family through their Barringer Crater Company, which proclaims it to be "best preserved meteorite crater on Earth"
The crater was created about 50,000 years ago during the Pleistocene epoch when the local climate on the Colorado Plateau was much cooler and damper. At the time, the area was an open grassland dotted with woodlands inhabited by woolly mammoths and giant ground sloths. The crater was over 10,000 years old when the first humans saw it, at the earliest, 40,000 years ago.
The object that excavated the crater was a nickel--iron meteorite about 50 meters (55 yards) across. The speed of the impact has been a subject of some debate. Modeling initially suggested that the meteorite struck at up to 20 kilometers per second (45,000 mph), but more recent research suggests the impact was substantially slower, at 12.8 kilometers per second (28,600 mph). It is believed that about half of the impactor's bulk was vaporized during its descent before it hit the ground.Impact energy has been estimated at about 10 megatons.
The meteorite was mostly vaporized upon impact, leaving little in the crater
In 1891, Grove Karl Gilbert, chief geologist for the U.S. Geological Survey, investigated the crater and concluded that it was the result of a volcanic steam explosion. Gilbert had assumed that if it were an impact crater then the volume of the crater, as well as meteoritic material, should be present on the rim. Gilbert also assumed a large portion of the meteorite should be buried in the crater and that this would generate a large magnetic anomaly. Gilbert's calculations showed that the volume of the crater and the debris on the rim were roughly equivalent, so that the mass of the hypothetical impactor was missing, nor were there any magnetic anomalies. Gilbert argued that the meteorite fragments found on the rim were coincidental. Gilbert would publicize these conclusions in a series of lectures. In 1892, Gilbert would be among the first to propose that the Moon's craters were caused by impact rather than volcanism.
The crater was created about 50,000 years ago during the Pleistocene epoch when the local climate on the Colorado Plateau was much cooler and damper. At the time, the area was an open grassland dotted with woodlands inhabited by woolly mammoths and giant ground sloths. The crater was over 10,000 years old when the first humans saw it, at the earliest, 40,000 years ago.
The object that excavated the crater was a nickel--iron meteorite about 50 meters (55 yards) across. The speed of the impact has been a subject of some debate. Modeling initially suggested that the meteorite struck at up to 20 kilometers per second (45,000 mph), but more recent research suggests the impact was substantially slower, at 12.8 kilometers per second (28,600 mph). It is believed that about half of the impactor's bulk was vaporized during its descent before it hit the ground.Impact energy has been estimated at about 10 megatons.
The meteorite was mostly vaporized upon impact, leaving little in the crater
In 1891, Grove Karl Gilbert, chief geologist for the U.S. Geological Survey, investigated the crater and concluded that it was the result of a volcanic steam explosion. Gilbert had assumed that if it were an impact crater then the volume of the crater, as well as meteoritic material, should be present on the rim. Gilbert also assumed a large portion of the meteorite should be buried in the crater and that this would generate a large magnetic anomaly. Gilbert's calculations showed that the volume of the crater and the debris on the rim were roughly equivalent, so that the mass of the hypothetical impactor was missing, nor were there any magnetic anomalies. Gilbert argued that the meteorite fragments found on the rim were coincidental. Gilbert would publicize these conclusions in a series of lectures. In 1892, Gilbert would be among the first to propose that the Moon's craters were caused by impact rather than volcanism.