About 50,000 years ago, a rock fragment broke away from the asteroid belt and hurtled towards earth. The rock, composed of nickel and iron, was about 50 meters across and weighed 300,000 tons. It was travelling at 12.8 kilometers per second. Upon entering the earth’s atmosphere it became a giant fireball that streaked across the North American sky. When it crashed into the plains of Arizona, it exploded with a force equal to 10 megatons or about 150 times the force of the atomic bomb that destroyed Hiroshima.
The violence of the impact vaporized the meteorite leaving little residue, but millions of tons of limestone and sandstone were blasted out covering the ground for a mile in every direction. When the dust settled, what remained was a crater over a kilometer across and 750 feet deep. The impact occurred during the last ice age, a time when the Arizona landscape was cooler and wetter. The area was an open grassland dotted with woodlands inhabited by woolly mammoths and giant ground sloths. The force of the impact leveled the forest for miles around, hurling the mammoths across the plain and killing or severely injuring any animals unfortunate enough to be nearby.
As the landscape recovered, a lake formed in the bottom of the crater, and sediments accumulated until the bowl was only 550 feet deep. When the ice age ended, the climate changed and dried, preserving the crater from further erosion.
The crater has been named the Barringer Crater in honor of Daniel Barringer, who was first to suggest that it was produced by meteorite impact. It is also referred to simply as "Meteor Crater". The crater is located approximately 69 km east of Flagstaff, near Winslow in the northern Arizona desert of the United States. It is the largest impact crater yet discovered in the United States, and one of the best preserved on earth. Today the crater is about 1,200 meters in diameter, some 170 meters deep and is surrounded by a rim that rises 45 meter above the surrounding plains.
The origin of this crater has been a source of controversy for many years. Initially, the scientist community believed that such a crater cannot exist arguing that all natural landforms had been created slowly, over thousands or even millions of years, rather than in a single catastrophic moment.
Barringer, a mining engineer and businessman, was one of the first people to claim that the crater was the result of an impact, contradicting the most eminent scientists of his time. He was convinced that an iron-nickel core over 10 million tons lay beneath the floor of the crater, and in 1928, raised $200,000 from an investor promising a profit of $250 million on a mere half million dollar investment. But when the mine shaft hit nothing but water, an astronomer was consulted for his opinion on the size of the meteorite.
The astronomer F. R. Moulton calculated that the size of the meteorite to be 300,000 tons, or only 3% of the amount claimed by Barringer, and too small to justify any further drilling. In addition, Moulton argued that the energy of the impact would have resulted in the total vaporization of the meteorite itself.
Work on the mine was halted. Barringer lost nearly all of his own fortune, along with hundreds of thousands entrusted to him by his investors. Devastated by the loss, Daniel Barringer died of a massive heart attack on November 30, 1929.
It was not until 1960 that later research by Eugene Merle Shoemaker confirmed Barringer's hypothesis. The key discovery was the presence in the crater of the minerals coesite and stishovite, rare forms of silica found only where quartz-bearing rocks have been severely shocked by an instantaneous overpressure. It cannot be created by volcanic action; the only known mechanism of creating it is through an impact event.
Shoemaker's discovery is considered the first definitive proof of an extraterrestrial impact on the Earth's surface. Since then, numerous impact craters have been identified around the world, though Meteor Crater remains one of the most visually impressive owing to its size, young age, and lack of vegetative cover.
Meteor Crater is today a popular tourist attraction privately owned by the Barringer family through the Barringer Crater Company. There is a Visitor Center on the north rim that features interactive exhibits and displays about meteorites and asteroids, space, the solar system and comets. It also features a 1,406 pound meteorite found in the area, and meteorite specimens from Meteor Crater that can be touched.
The largest fragment discovered from the meteorite that formed Meteor Crater, exhibited at the tourist center in Meteor Crater, Flagstaff, Arizona. Photo credit
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