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Roger Weller, geology instructor

wellerr@cochise.edu

Meteor Crater
Nancy Lewis

Historical Geology
Spring 2005

 

Meteor Crater

Northern Arizona

 

For educational purposes only.

Aerial and rim view of Arizona’s Meteor Crater near Winslow.

http://astrosurf.com

 

First mistaken for a volcanic crater, Meteor Crater is also known as Barringer Crater, the most incredible crater site in the world. Created by a meteorite impact estimated to be around 50,000 years ago, the approximate measurements of the crater are about 4,000 feet across and 560 feet deep.  The distinctive look of the crater probably closely resembles the craters of our moon.  The impact of the crater released the equivalent energy of about 20 megatons of TNT, equal to the power of a nuclear weapon.  Inspection of the crater, as well as bore drilling in the center, netted no meteorite evidence.  In the surrounding area of the crater there were several tons of debris located containing metallic meteoritic materials.  This evidence suggested the meteor was iron-nickel, measuring about 200 feet in diameter and weighed in at about one million tons.

 

For educational purposes only

Meteor Crater near Winslow, Arizona

http://www.lpi.usra.edu/science/kiefer/Education

 

There are many crater sites around the world; most of them are between 1 and 50 miles wide.  In most cases the only evidence of the crater site is the disturbed circular area of rocks that were displaced upon impact of the meteor.  Some impacts create a chain of craters, this occurs when an asteroid or a comet breaks up in the atmosphere and the pieces land in the same area within a short range of each other.

 

For educational purposes only.

Meteorite impact sites around the world.

http://euclid.dne.wvfibernet.net

The diameter of the crater varies by the kind of rock or minerals that is impacted.  A crater made in crystalline rock can be twice as big as a crater made in sedimentary rock.  Meteor crater made a deep basin and has a range approximately 2.5 miles in diameter.

 

For educational purposes only.

Rim of Meteor Crater

http://eps.mcgill.ca/~seg/Arizona/pix/MeteorCrater3.jpg

 

            Large meteors traveling at high speeds completely disintegrate upon impact, causing a crater that is generally much large than the meteor itself.  As the meteor burrows itself into the ground, flattening itself in the process, a rim is created by the materials displaced by the impact.  Vaporized rock and shock-melted meteorite are then shot out of the impact area leaving behind a massive crater.  Because the materials are shot out of the impact area the atmosphere is greatly affected by the vapors, thus the atmosphere itself is blown away by the meteor impact.  The vapors and spray from the impact grows into a large plume, spreading several miles at the base and extending high into the disrupted atmosphere.  The plume actually resembles a mushroom cloud created by a nuclear blast.

           

After the plume has reached far into the atmosphere it begins a descent to the earth and partially settles into the crater itself.  The fall-back materials create a level of strata within the crater.  Now the stratigraphy of the crater is a mix of upturned strata from the initial impact, fine sediments in the crater basin and a layer of fall-back materials consisting of broken rock and melted mater.

For educational purposes only.

Rim of Meteor Crater showing displacement of rocks

http://www.56.tok2.com/home/colorado/scene/arizona_meteor_crater

 

Meteor Crater Sites To Investigate

 

  1. www.meteorcrater.com

Official site for visitors of Meteor Crater

  1. www.barringercrater.com

Site of Barringer Crater Company, owners of Meteor Crater

  1. www.meteorite.com/meteor_crater

Meteorite exchange, short information on Meteor Crater

  1. www.solarviews.com/eng/tercrate.htm

Terrestrial Impact Craters