Barringer Meteorite Crater rises 150 feet above the Colorado Plateau in northern Arizona. It is nearly a mile wide and 570 feet deep. The nickel-iron meteorite is estimated to have been only 150 feet across and 300,000 tons. The meteorite traveled at 40,000 miles per hour when it struck the earth approximately 49,000 years ago. The force of the impact was the equivalent of 20 million tons of TNT, more than 1000 times the force of the blast at Hiroshima and Nagasaki.
Approximately 175 million tons of rock was excavated by the impact. Bedrock was ejected up to 1.2 miles away. The explosion produced a shock wave and airblast which spread across the landscape. Winds exceeding 1200 miles per hour scoured the terrain. Parts of this meteorite may still be found scattered throughout nearby Canyon Diablo.
Northern Arizona at that time was a forested terrain, with mastodons, mammoths, giant ground sloths and bison. Plants and animals within 6 miles would have been seared by the fireball produced by the impact. All animals within 12 miles would have been killed or severely injured by the airblast. Hurricane force winds would have been felt as far as 24 miles away.
Barringer Crater is named after Daniel Barringer, a mining engineer who concluded that the crater was the result of an iron meteor, and worth mining. He presented his proofs that the crater was the result of a meteorite encounter to the Academy of Natural Sciences in Philadelphia in 1906 and 1909. Geologist George P Merrill presented further evidence to support Barringers theory.
In 1963, Eugene Shoemaker (of the Shoemaker-Levy comet fame) analyzed the similarities between Barringer crater and the craters left by nuclear tests in Nevada. Both Barringer crater and the nuclear test explosion craters deposited ejected rocky material in identical manner, proving the crater was the result of an impact and not volcanic in origin. Shoemaker also discovered a new mineral called coesite at the crater. This mineral is found only at impact craters.
Barringer Meteorite Crater is the first proven meteorite crater in the world. From this crater, criteria has been established that aids in the identification of other meteorite craters in the world today. The crater has been mined for iron, studied, and served as a training ground for NASA astronauts in preparation for Apollo moon landings.
Currently it is a privately owned attraction. A rim trail takes you to 4 viewing locations along the edge of the crater.
There are over 150 identified meteorite impact craters in the world. Specific criteria is used to identify such craters. The most important criteria fall into 4 major categories: morphology, evidence of shock metamorphism, geochemical evidence and presence of geophysical anomalies.
Morphology is the study of landforms and topographical features of the crater. Barringer crater is a simple crater. It is circular, bowl shaped with a well defined rim. Ejecta deposits radiate outward from the rim.
Coesite and stishovite, 2 mineral pseudomorphs of quartz that form at extremely high pressures, are found only at impact craters. These minerals provide evidence of shock metamorphism, proving that the craters are the result of impact rather than having volcanic origins. Another shock indicator is the presence of shattercones. Shattercones are distinctive striated conical fragments of rock along which fracturing has occurred.
Meteorites contain elements rarely found on earth. Most meteorites vaporize on impact. Elements in the meteorites can chemically interact with the surrounding rocks to produce geochemical anomalies. Iridium in large quantities is one such example.
Geophysical anomalies can be any unusual measurement of such things as gravitational or magnetic properties, reflection or refraction seismic activity, or electrical resistivity. Such anomalies are often found at an impact crater.
When a meteorite hits the ground, several things occur. At first there is the contact or compression stage. Material is pushed downwards and out the sides of the impact area. This action of pushing material out the sides is called jetting.
The next stage is the crater excavation stage. This is rapid crater expansion. Material can leave either ballistically or plastically. Surface material is thrown upwards, while deeper material is shoved outwards. This results in a reverse stratigraphy of ejecta than is evident in the untouched material in the ground. Rock may be melted, partially melted, brecciated, or vaporized.
The final stage is post impact crater modification. Simple craters, such as Barringer crater do not have much crater modification. Complex craters may have raised centers or double rings.
More than a hole in the ground visible from miles away, Barringer Crater historically played a large role in our understanding of the processes involved at impact craters. Today, the crater is preserved and accessible to those who go there.
Somewhere along the way, my original proof of visit requirements got dropped. A gps photo along the rim trail is required to log this earthcache. In addition, you must email me how deep the crater is or looks like it is from where you took the photo. 11/5/2011 Lately some folks are not emailing me the required answer to the question above. Anyone not contacting me with said answer will have their log deleted.