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Meteor Crater

Part of Hall of Meteorites.

General view of Meteor Crater section in the Hall of Meteorites, showing meteorites, a model of the crater, text and pictures. M. Shanley/© AMNH

Shocked, Melted And Pulverized Rocks Helped Prove That Meteorite Impacts Can Make Craters.

The first geological report on the gigantic Northern Arizona Crater, in 1891, focused not on the crater itself but on tiny diamonds found in nearby meteorites. Back then, researchers assumed that only an explosive volcanic eruption could make such a large crater. But after more careful study of the meteorites and altered rocks in and around the crater, scientists realized that it must have formed during a massive meteorite impact.

The story of Meteor Crater, also called Barringer Crater, began 50,000 years ago with an asteroid roughly twice as wide as this hall hurtling to Earth at about 50 times the speed of sound. The explosive force of its impact blasted out 175 million tons of limestone and sandstone, sprayed molten rock upward and tossed chunks of meteorite several miles away.

Once the dust and debris settled, the crater sat quietly for tens of thousands of years as the Arizona climate gradually grew drier, helping to preserve evidence of the impact.

Map of Canyon Diablo strewn field at Meteor Crater showing the location of the crater and many clusters of impacts around it.
The Canyon Diablo meteorite, which formed Meteor Crater, broke apart as it passed through Earth's atmosphere. Tens of thousands of fragments were found strewn around the crater.
©AMNH

How Do We Know?

Ejected Evidence

In only six seconds, the Canyon Diablo meteorite excavated Meteor Crater, lifting up 175 million tons of sandstone and limestone, tossing much of it outside the crater. These pieces of rock, some as large as houses, helped to prove that the crater was formed by a meteorite impact.

When mining engineer Daniel Barringer first argued in 1906 that an impact formed the crater, he noted that the meteorites and other rock debris around the crater were randomly mixed together in one layer. This mixing suggested that the meteorite fell at the same time the crater formed. 

In the 1960s, researchers discovered that some pieces of ejected sandstone contained microscopic evidence of the intense impact pressures. Within individual quartz grains, researchers saw criss-crossing sets of parallel lines. These lines show that intense pressure passed through the rock in a fraction of a second, altering the grains' three-dimensional crystal structure. Shocked quartz and other shocked minerals provide crucial evidence that many known craters were formed by meteorite impacts—and have also pointed to impacts in places where no crater survives.

Big formation of limestone on a very arid area with a blue sky.
This block of limestone, as tall as the height of this hall's ceiling, was thrown up during the explosive formation of the crater and landed several feet from the rim.
Jane Murray/© AMNH 
Microscopic image of a quartz grain showing criss-crossing  lines
This quartz grain from Meteor Crater shows the effects of shock in the thin black lines criss-crossing the grain. The presence of shocked quartz confirms that the crater was formed by an impact.
Steven Jaret/© AMNH