Meteor Crater is a
meteoriteA meteorite is a natural object originating in outer space that survives impact with the Earth's surface. Meteorites can be big or small. Most meteorites derive from small astronomical objects called meteoroids, but they are also sometimes produced by impacts of asteroids...
impact craterIn the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...
located approximately 43 miles (69.2 km) east of
FlagstaffFlagstaff is a city located in northern Arizona, in the southwestern United States. In 2010, the city's population was 65,870. The population of the Metropolitan Statistical Area was at 134,421 in 2010. It is the county seat of Coconino County...
, near
Winslow-Demographics:As of the census of 2000, there were 9,520 people, 2,754 households, and 1,991 families residing in the city. The population density was 773.1 people per square mile . There were 3,198 housing units at an average density of 259.7 per square mile...
in the northern
ArizonaArizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
desert of the
United StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
. Because the US Department of the Interior Division of Names commonly recognizes names of natural features derived from the nearest
post officeA post office is a facility forming part of a postal system for the posting, receipt, sorting, handling, transmission or delivery of mail.Post offices offer mail-related services such as post office boxes, postage and packaging supplies...
, the feature acquired the name of "Meteor Crater" from the nearby post office named Meteor. The site was formerly known as the
Canyon Diablo Crater, and fragments of the meteorite are officially called the Canyon Diablo Meteorite. Scientists refer to the crater as
Barringer Crater in honor of
Daniel BarringerDaniel Moreau Barringer was a geologist best known as the first person to prove the existence of a meteorite crater on the Earth, the Meteor Crater in Arizona...
who was first to suggest that it was produced by meteorite impact. The crater is privately owned by the Barringer family through their Barringer Crater Company, which proclaims it to be "the first proven, best-preserved meteorite crater on earth."
Despite its importance as a geological site, the crater is not protected as a
national monumentA National Monument in the United States is a protected area that is similar to a National Park except that the President of the United States can quickly declare an area of the United States to be a National Monument without the approval of Congress. National monuments receive less funding and...
, a status that would require federal ownership. It was designated a
National Natural LandmarkThe National Natural Landmark program recognizes and encourages the conservation of outstanding examples of the natural history of the United States. It is the only natural areas program of national scope that identifies and recognizes the best examples of biological and geological features in...
in November 1967.
Meteor Crater lies at an elevation of about 1,740 m (5,709 ft) above sea level. It is about 1,200 m (4,000 ft) in diameter, some 170 m deep (570 ft), and is surrounded by a rim that rises 45 m (150 ft) above the surrounding plains. The center of the crater is filled with 210–240 m (700–800 ft) of rubble lying above crater bedrock. One of the interesting features of the crater is its squared-off outline, believed to be caused by pre-existing regional jointing (cracks) in the strata at the impact site.
Formation of the crater
The crater was created about 50,000 years ago during the
PleistoceneThe Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
epochIn the fields of chronology and periodization, an epoch is an instance in time chosen as the origin of a particular era. The "epoch" then serves as a reference point from which time is measured...
when the local climate on the
Colorado PlateauThe Colorado Plateau, also called the Colorado Plateau Province, is a physiographic region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. The province covers an area of 337,000 km2 within western Colorado, northwestern New Mexico,...
was much cooler and damper. At the time, the area was an open grassland dotted with woodlands inhabited by
woolly mammothThe woolly mammoth , also called the tundra mammoth, is a species of mammoth. This animal is known from bones and frozen carcasses from northern North America and northern Eurasia with the best preserved carcasses in Siberia...
s and
giant ground slothGround sloths are a diverse group of extinct sloths, in the mammalian superorder Xenarthra. Their most recent survivors lived in the Antilles, where it has been proposed they may have survived until 1550 CE; however, the youngest AMS radiocarbon date reported is 4190 BP, calibrated to c. 4700 BP...
s. It was probably not inhabited by humans; the earliest confirmed record of human habitation in the Americas dates from long after this impact.
The object that excavated the crater was a
nickelNickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
-
ironIron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
meteorite about 50 meters (54 yards) across, which impacted the plain at a speed of several kilometers per second. Impact energy has been estimated at about 10
megatonTNT equivalent is a method of quantifying the energy released in explosions. The ton of TNT is a unit of energy equal to 4.184 gigajoules, which is approximately the amount of energy released in the detonation of one ton of TNT...
s. The speed of the impact has been a subject of some debate. Modeling initially suggested that the meteorite struck at a speed of up to 20 kilometers per second (45,000 mph), but more recent research suggests the impact was substantially slower, at 12.8 kilometers per second (28,600 mph). It is believed that about half of the impactor's 300,000 metric tons (330,000 short tons) bulk was vaporized during its descent, before it hit the ground.
The impactor itself was mostly vaporized; very little of the meteorite remained within the pit that it had excavated.
Discovery and investigation
The crater came to the attention of scientists following its discovery by European settlers in the 19th century. Dubbed the Canyon Diablo crater – from
Canyon Diablo, ArizonaCanyon Diablo is a ghost town on the Navajo Reservation in Coconino County, Arizona, United States on the edge of the arroyo Canyon Diablo.-History:...
, the closest community to the crater in the late 19th century, 12 miles (19.3 km) northwest of the crater, but now a
ghost townA ghost town is an abandoned town or city. A town often becomes a ghost town because the economic activity that supported it has failed, or due to natural or human-caused disasters such as floods, government actions, uncontrolled lawlessness, war, or nuclear disasters...
– it had initially been ascribed to the actions of a
volcano2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...
. This was not an unreasonable assumption, as the
San Francisco volcanic fieldThe San Francisco volcanic field is an area of volcanoes in northern Arizona, north of Flagstaff, USA. The field covers 1,800 square miles of the southern boundary of the Colorado Plateau. The field contains 600 volcanoes ranging in age from less than 6 million years old to less than 1,000 years ,...
lies only about 40 miles (64.4 km) to the west.
Grove Karl Gilbert
In 1891
Grove Karl GilbertGrove Karl Gilbert , known by the abbreviated name G. K. Gilbert in academic literature, was an American geologist....
, chief geologist for the U.S. Geological Survey, investigated the crater and concluded that it was the result of a
volcanic steam explosionA maar is a broad, low-relief volcanic crater that is caused by a phreatomagmatic eruption, an explosion caused by groundwater coming into contact with hot lava or magma. A maar characteristically fills with water to form a relatively shallow crater lake. The name comes from the local Moselle...
. Gilbert had assumed that if it were an impact crater then the volume of the crater, as well as meteoritic material, should be present on the rim. Gilbert also assumed a large portion of the meteorite should be buried in the crater and that this would generate a large magnetic anomaly. Gilbert's calculations showed that the volume of the crater and the debris on the rim were roughly equivalent, so that the mass of the hypothetical impactor was missing. Further there were no magnetic anomalies. Gilbert argued that the meteorite fragments found on the rim were coincidental. Gilbert would publicize these conclusions in a series of lectures in 1895. In 1892 Gilbert would be among the first to propose that the moon's craters were caused by impact rather than volcanism.
Daniel Barringer
In 1903, mining engineer and businessman Daniel M. Barringer suggested that the crater had been produced by the impact of a large iron-metallic meteorite. Barringer's company, the Standard Iron Company, received a
patentA patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....
signed by
Theodore RooseveltTheodore "Teddy" Roosevelt was the 26th President of the United States . He is noted for his exuberant personality, range of interests and achievements, and his leadership of the Progressive Movement, as well as his "cowboy" persona and robust masculinity...
for 640 acres (2.6 km²) around the center of the crater in 1903. The claim was divided into four quadrants coming from the center clockwise from northwest named Venus, Mars, Jupiter and Saturn. In 1906 Roosevelt authorized the establishment of a newly named Meteor, Arizona post office (the closest post office before was 30 miles (48.3 km) away in
Winslow, Arizona-Demographics:As of the census of 2000, there were 9,520 people, 2,754 households, and 1,991 families residing in the city. The population density was 773.1 people per square mile . There were 3,198 housing units at an average density of 259.7 per square mile...
).
Standard Iron Company conducted research on the crater's origins between 1903 and 1905. It concluded that the crater had indeed been caused by an impact. Barringer and his partner, the
mathematicianA mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....
and
physicistA physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...
Benjamin Chew TilghmanBenjamin Chew Tilghman was an American soldier and inventor. He is best known as the inventor of the process of sandblasting.-Early life:...
, documented evidence for the impact theory in papers presented to the U.S. Geological Survey in 1906 and published in the
Proceedings of the Academy of Natural Sciences in Philadelphia.
Barringer's arguments were met with skepticism, as there was a reluctance at the time to consider the role of meteorites in terrestrial geology. He persisted and sought to bolster his theory by locating the remains of the meteorite. At the time of first discovery by Europeans, the surrounding plains were covered with about 30 tons of large oxidized iron meteorite fragments. This led Barringer to believe that the bulk of the impactor could still be found under the crater floor. Impact physics was poorly understood at the time and Barringer was unaware that most of the meteorite vaporized on impact. He spent 27 years trying to locate a large deposit of meteoric iron, and drilled to a depth of 419 m (1,376 ft), but no significant deposit was ever found.
Barringer, who in 1894 was one of the investors who made $15 million in the Commonwealth silver mine in
Pearce, ArizonaPearce, Arizona and Sunsites, Arizona are adjacent unincorporated communities in the Sulphur Springs Valley of Cochise County, Arizona, United States. The two communities are referred to as Pearce-Sunsites, Pearce/Sunsites, or Pearce Sunsites. Pearce is best known as a historic ghost town...
in
Cochise County, Arizona-2010:Whereas according to the 2010 U.S. Census Bureau:*78.5% White*4.2% Black*1.2% Native American*1.9% Asian*0.3% Native Hawaiian or Pacific Islander*4.0% Two or more races*9.6% Other races*32.4% Hispanic or Latino -2000:...
, had ambitious plans for the iron ore. He estimated from the size of the crater that the meteorite had a mass of 100 million tons. The current estimate of 300,000 tons for the impactor is only three-tenths of one percent of Barringer's estimate. Iron ore of the type found at the crater was valued at the time at $125/ton so Barringer believed he was searching for lode worth more than a billion 1903 dollars.
Despite Barringer's findings and other excavations in the early 20th century, geologists' skepticism continued until the 1950s when
planetary sciencePlanetary science is the scientific study of planets , moons, and planetary systems, in particular those of the Solar System and the processes that form them. It studies objects ranging in size from micrometeoroids to gas giants, aiming to determine their composition, dynamics, formation,...
gained in maturity and understanding of cratering processes increased. Professor
Herman Leroy FairchildHerman Le Roy Fairchild was an American educator and geologist. He was an early proponent of the theory of meteorite impact causing craters such as that of Meteor Crater, Arizona....
, an early promoter of impact cratering, argued Barringer's case in an article in
ScienceScience is the academic journal of the American Association for the Advancement of Science and is one of the world's top scientific journals....
in 1930.
Eugene M. Shoemaker
It was not until 1960 that later research by
Eugene Merle ShoemakerEugene Merle Shoemaker , American geologist, was one of the founders of the fields of planetary science....
would confirm Barringer's hypothesis. The key discovery was the presence in the crater of the minerals
coesiteCoesite[p] is a form of silicon dioxide SiO2 that is formed when very high pressure , and moderately high temperature , are applied to quartz. Coesite was first synthesized by Loring Coes, Jr., a chemist at the Norton Company, in 1953. In 1960, coesite was found by Edward C. T...
and
stishoviteStishovite is an extremely hard, dense tetragonal form of silicon dioxide. It was long considered the hardest known oxide; however, boron suboxide has recently been discovered to be much harder...
, rare forms of silica found only where
quartzQuartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
-bearing rocks have been severely
shockedShocked quartz is a form of quartz that has a microscopic structure that is different from normal quartz. Under intense pressure , the crystalline structure of quartz will be deformed along planes inside the crystal...
by an instantaneous overpressure. It cannot be created by volcanic action; the only known mechanism of creating it is through an impact event (or artificially through a
nuclear explosionA nuclear explosion occurs as a result of the rapid release of energy from an intentionally high-speed nuclear reaction. The driving reaction may be nuclear fission, nuclear fusion or a multistage cascading combination of the two, though to date all fusion based weapons have used a fission device...
).
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 due to its size, young age and lack of vegetative cover.
Geology
The impact created an
inverted topographyInverted topography or topographic inversion refers to landscape features that have reversed their elevation relative to other features. It most often occurs when low areas of a landscape become filled with lava or sediment that hardens into material that is more resistant to erosion than the...
so that the layers immediately exterior to the rim are stacked in opposite order in which they normally occur; the impact overturned and inverted the layers to a distance of one to two kilometers outward from the crater's edge. Specifically, climbing the rim of the crater from outside, one finds:
- Coconino Sandstone
Coconino Sandstone is a geologic formation named after its exposure in Coconino County, Arizona. This formation spreads across the Colorado Plateau province of the United States, including northern Arizona, northwest Colorado, Nevada, and Utah....
(sandstoneSandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
formed 265 million years ago) nearest the top of the rim
- Toroweap Formation (limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
formed 255 million years ago)
- Kaibab Formation (dolomite
Dolomite is a carbonate mineral composed of calcium magnesium carbonate CaMg2. The term is also used to describe the sedimentary carbonate rock dolostone....
formed 250 million years ago)
- Moenkopi Formation
The Moenkopi is a geological formation that is spread across the U.S. states of New Mexico, northern Arizona, Nevada, southeastern California, eastern Utah and western Colorado. This unit is considered to be a group in Arizona. Part of the Colorado Plateau and Basin and Range, this formation was...
(mudstoneMudstone is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the...
formed 200 million years ago) nearest the outer foot of the rim
Meteor Crater today
Meteor Crater is today a popular
tourist attractionA tourist attraction is a place of interest where tourists visit, typically for its inherent or exhibited cultural value, historical significance, natural or built beauty, or amusement opportunities....
privately owned by the Barringer family, with an admission fee charged to see the crater. The Meteor Crater Visitor Center on the north rim features interactive exhibits and displays about meteorites and asteroids,
spaceSpace is the boundless, three-dimensional extent in which objects and events occur and have relative position and direction. Physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of a boundless four-dimensional continuum...
, the
solar systemThe Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
and comets. It features the American Astronaut Wall of Fame, and such artifacts on display as an Apollo boilerplate command module (BP-29), a 1,406 pound meteorite found in the area, and meteorite specimens from Meteor Crater that can be touched. Formerly known as the Museum of Astrogeology, the Visitor Center includes a movie theater, a gift shop, and observation areas with views inside the rim of the crater. Guided tours of the rim are offered daily.
Recent history
- During the 1960s, NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
astronautAn astronaut or cosmonaut is a person trained by a human spaceflight program to command, pilot, or serve as a crew member of a spacecraft....
s trained in the crater to prepare for the Apollo missions to the MoonThe Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
.
- On August 8, 1964, a pair of commercial pilots in a Cessna 150
The Cessna 150 is a two-seat tricycle gear general aviation airplane, that was designed for flight training, touring and personal use.The Cessna 150 is the seventh most produced civilian plane ever, with 23,839 aircraft produced...
flew low over the crater. On crossing the rim, they could not maintain level flight. The pilot attempted to build up speed by circling in the crater to climb over the rim. During the attempted climb out, the aircraft stalled, crashed, and caught fire. It is commonly reported that the plane ran out out of fuel, but this is incorrect. Both occupants were severely injured but survived their ordeal. A small portion of the wreckage not removed from the crash site remains visible to this day.
External links