Cochise College Student Papers in Geology
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geology historical
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gems
Roger Weller,
geology instructor
wellerr@cochise.edu
Meteor Crater
Nancy Lewis
Historical Geology
Spring 2005
Meteor Crater
For educational purposes only.
Aerial
and rim view of Arizona’s Meteor Crater near Winslow.
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
Official site for
visitors of Meteor Crater
Site of Barringer
Crater Company, owners of Meteor Crater
Meteorite exchange,
short information on Meteor Crater