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Meteor crater. Image credit: NASA
The Arizona crater was the first to be identified as an impact crater on Earth. A small asteroid of about 24.5 meters impacted between 20,000 and 50,000 years ago; a relatively recent occurrence when compared to the life of the Earth. The size of this impact crater, 1.2 km around and 170m deep, is how some judged what might happen if the asteroid Apophis were to hit the planet. The origin of this crater had been a source of controversy for many years. The discovery of fragments of the Canyon Diablo meteorite helped to prove that the feature was in fact an impact crater.
The site is formerly known as Canyon Diablo Crater, but scientists commonly refer to it as Barringer Crater after the man who first postulated that it was an impact crater. The crater is now owned by the Barringer family and is promoted as the first proven, best-preserved meteorite crater on earth. One of the interesting features of the crater is its squared-off outline, believed to be caused by pre-existing regional cracks in the strata at the impact site. It’s thought that the impacting meteorite was traveling 7,200 kph when it hit the Earth.
At the time of its creation the area around the Arizona crater would have been an open grassland with occasional stands of trees. The wooly mammoth, giant ground sloth, and perhaps a camel or two would have been the main inhabitants of the area. The meteorite that struck the crater is officially called the Canyon Diablo Meteorite. Every fragment of the meteorite are officially labeled and bear the Canyon Diablo name. The name comes from Canyon Diablo, Arizona, which was the closest community to the crater when scientists began investigating the area in the late 1800s. It’s now a ghost town.
Years of controversy kept the Arizona crater from its true designation.You can visit the site today for a small fee. There is still an old mining shaft at the bottom of the crater and the geology is upside down from the impact, so you can see exposed rock from up to 265 million years ago.
We have written several articles about asteroids for Universe Today. Here’s an article about a new theory on Meteor Crater in Arizona.
Want more resources on asteroids? Here’s NASA’s Lunar and Planetary Science Page on asteroids. And here’s Hubblesite’s News Releases about Asteroids.
We have recorded two episodes of Astronomy Cast about asteroids. There’s Episode 55: The Asteroid Belt, and here’s Episode 29: Asteroids Make Bad Neighbors.
References:
NASA Earth Observatory: Meteor Crater, Arizona
NASA Earth Observatory: Barringer Meteor Crater, Arizona
NASA Solar System Exploration
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