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Roger Weller, geology instructor
Arizona Meteor Crater
by Katherine A. Smith
Barringer Crater Arizona
The impact of solid bodies on each other is one of the most fundamental of all processes that have taken place on the terrestrial planets. The moon is a great example of such a process, with its crust littered with impact craters from asteroids and meteors of all sizes making its surface appear almost like Swiss cheese with a multitude of holes in an otherwise solid surface. Conveniently for travelers it is not necessary to take an expedition as far as the moon to see magnificently preserved asteroid craters. If you live in United States of America, you have only a short distance to travel to see one of the best preserved craters in the world.
Barringer crater is located 43 miles east of Flagstaff Arizona near the town of Winslow in one of the sandy, flat, arid desert areas of the United States and is easily accessible. The coordinates to the crater are 35 degrees by 1'38 degrees north by 111 degrees 1'21 degrees west. Meteor Crater is located off I-40 at exit 233, then 6 miles south on the paved road. The rocks are made of a mixture of sandstone and a type of hard, sedimentary gravel known as conglomerate. Barringer crater was discovered by the European settlers in the 19th century, in the year of 1891. Although this unique geologic area was so large that it was not recognized as an impact crater by anyone until the year 1920.
The origin of this crater has been a controversy in the scientific community for many years. The first scientist to pay any notable attention to Barringer crater was Grove Gilbert. In 1891 Grove Karl Gilbert postulated that the crater was a result of a volcanic steam explosion. This was a reasonable hypothesis considering there were other volcanic craters in the region, including the still-active Sunset Crater. Yet the absence of any naturally occurring volcanic rock in the vicinity of the crater left a few scientists bewildered by Gilbertís assessments. In 1903, Daniel Barringer suggested that the origination of the crater was a result of a meteorite impact and not the aftermath of any volcanic activity. During the time Barringer was being criticized for his hypothesis, a geologist by the name of George P. Merrill analyzed two new varieties of sandstone discovered by Barringer at the site of the impact crater. During his analysis he concluded that both types of sand must have been produced by a brief but enormous pressure, far greater than any known to occur through terrestrial processes. These conditions could have been created when a meteor crashed into sandstone desert in Arizona. To bring the controversy to a conclusion in the year 1960 another scientist by the name of Eugene Shoemaker confirmed that Barringerís hypothesis was indeed correct.
The discovery of fragments of the Canyon Diablo(or Barringer Crater) meteorite representing about a tenth of the original impactor's mass, were scattered across more than twenty-five square miles surrounding the crater helped to prove that the feature was in fact an impact crater. One of the biggest fragments was found by Samuel Holsinger shown in the picture above. The resolution of the controversy over the organ of this geological wonder was a long and difficult procedure. It confounded the scientific community and 57 years would pass after Barringer presented his first papers before the impact theory was fully accepted by the scientific community.
Barringer Crater is one of the largest and best preserved in the world and measures 4,000 feet in diameter and over 550 feet deep. The rim of the creator rises over 200 feet above the surrounding plain. The meteor is estimated to have hit the earth about 50,000 years ago. This is during the time when Arizona would have been filled with creatures like Woolly Mamoths and Giant Sloths. The flora and fauna was dramatically different instead of the dry arid desert land the modern day population is so used to, it would have been covered in grass and dense vegetation. When the meteorite collided with the Earthís crust it was estimated to be traveling faster than a modern inter-continental missile. It has been calculated that it was hurtling to the earth at approximately 26,000 miles per hour at the time of impact. The geology of the surrounding area of the crater was turned upside down from the impact of the asteroid; which conveniently enough allows scientists, tourists and any other viewer to see all the sediments and rock types exposed from 250million years ago.
Barringer meteor crater is also known as Coon Butte, Canyon Diablo, and/or the Arizona Meteor Crater. When the meteor made contact with the Earthís crust it ejected 175,000,000 tons of rock. Many researches and scientists scoured the dislodged debris for meteorite fragments. As time went on these scientists discovered that the region in and around the crater had quite a large number of nickel-iron fragments scattered in the debris. While many other craters are being discovered and researched, Barringer crater was the first discovered and best preserved meteor crater on Earth.
Today the crater is privately owned by the Barringer family and has become an international tourist attraction. People come from all around the world to take pictures and learn of the geologic history of not only the crater but the region surrounding it. With a gift shop and a visitor center a visitor can find memorabilia, scientific publications, see a 1,406 pound meteorite found in the area, and study meteorite specimens from Meteor Crater. While a fee is required to get into the area, this district is a great spot for a geologic escapade if you ever find yourself in the Flagstaff Arizona region.
(All pictures can be found through the websites below)