This is one of the best preserved impact craters on Earth, truly unique place where one can learn, what happens when Earth is bombarded by a meteorite.
Meteor crater is located in desert with scarce vegetation cover. It is very impressive. Rims of crater are visible from far away and rise up to 45 m above the surrounding plains.
When one reaches the rim, opens a grand view on approximately 1,200 m wide, up to 170 m deep crater. Crater is not entirely round but rather square, what, possibly, is caused by joints in bedrock.
50,000 years ago the climate in Arizona was more temperate than now. This was ice age – further in the north there were giant glaciers, but here were growing forests, walking large Pleistocene mammals – mammoths, ground sloths and other animals. Most likely this place was devoid of people – they came later.
Impact was almost as fast as lightning.
Some 300 000 tons heavy, 50 m wide iron-nickel meteorite hit the ground with a speed of 12.8 km per second.
Meteorite lost approximately half of its mass before hitting the ground – and the remaining part exploded and evaporated when it blasted in the ground. Most of metal mixed with the blasted rocks.
The force of impact was approximately 2.5 megatons – 150 times more than atomic bomb in Hiroshima. Countless animals and plants died immediately, whole plain turned into lifeless desert.
Meteorite pierced Triassic and Permian sediments – mudstone, dolomite, limestone, sandstone. Depth of crater reached some 400 metres, surroundings of crater were covered with upturned rocks. Total mass of uplifted sediments was 175 million tons.
Nature heals itself fast. Soon after the crater was filled with deep lake. Forest returned, area was full with life again.
210 – 240 m thick layer of sediments formed on the bed of lake.
As the climate changed, lake and forest disappeared, desert environment evolved. This helped to preserve the crater and now Meteor crater is one of the best preserved impact craters on Earth.
Meteorite or volcano?
Area around the crater was well known location to look for pieces of oxidised iron. It is assessed that some 30 tons of raw iron were found here. The largest known piece is Holsinger meteorite – 639 kg heavy, 0.9 m long piece, which was found some 2.5 km north from the crater rim in 1911.
Nevertheless the idea that meteorites can create a large crater was something new for science.
In 1891 chief geologist of US Geological Service Grove Karl Gilbert considered that this crater is created either by the explosion of volcanic gas or by meteorite.
He thought that meteorite should have similar size to the size of crater – and that this giant mass of iron should be buried under the crater. Magnetic measurements did not show any significant mass of iron below the crater – thus he concluded that this is explosion crater caused by volcanic processes.
This hypothesis was widely accepted by the scientific community.
When the enterprising lawyer and mine owner Daniel Moreau Barringer (1860 – 1929) learned about the existence of the giant crater in Arizona and pieces of metal found at it, he was convinced that this is meteorite crater.
He became obsessed with this crater and saw much possibilities in it. If the size of meteorite would be comparable to the size of crater, here could lie 10,000,000 tons of iron – enough to make its finder one of the richest people in the world.
It was also irritating for Barringer to see that scientists blindly disregard many proofs of meteorite impact and support the hypothesis of volcanic explosion without any direct proofs.
Barringer purchased the land (in beforehand managing to obtain the name of local post office – Meteor. This is the formal reason why the crater is oficially called Meteor Crater) and established “Standard Iron Company”.
In 1903 – 1905 there were made first drills which did not bring the desired result. They obtained more and more proofs for meteorite impact – but could not find the giant chunk of iron.
There were made up to 419 m deep drills and Barringer spent most of his fortune and ran in debts. In 1929 he obtained proofs that large meteorites are vaporised during the impact event. Shortly afterwards he died of heart stroke.
Some discussions about the origin of this crater continued until the 1960s, when Eugene Merle Shoemaker added more proofs in favour of impact hypothesis and profoundly described the crater. Here were discovered two rare forms of silica – coesite and stishovite, which are created by extreme overpressure.
Crater is the property of Barringer family up to this day. This inhospitable, alien looking crater has served as a true oasis for the scientific research and popularization of science. There is built Meteor Crater Visitor Center on the north rim – it provides rich information about meteorites around the world, space and astronomy. Access to the bottom of crater though is limited to scientists.
Meteor crater is included in the following list:
- The Barringer Meteorite Crater, official website. Acessed in the 31st December 2012.
|Coordinates:||35.02732 N 111.0228 W|
|Rating:||(5 / 5)|
|Address:||North America, United States, Arizona, Navajo County, 69 km east of Flagstaff|
|Alternate names:||Barringer Meteorite Crater, Canyon Diablo Crater, Coon Mountain, Coon Butte, Franklin’s Hole, Crater Mountain|
|Diameter:||1 180 m|
|Age:||49 000 ± 3 000 years|
This category includes outstanding impact craters – detectable scars on the surface of Earth left by a body coming from outer space. Category includes also meteorites – natural objects from the outer space.