Posted on 03/09/2005 10:19:19 AM PST by ZGuy
It's a mystery that has puzzled scientists for years but researchers said Wednesday they have discovered why there isn't much melted rock at the famous Meteor Crater in northern Arizona.
An iron meteorite traveling up to 12 miles per second was thought to have blasted out the huge hole measuring three-quarters of a mile across in the desert.
The impact of an object at that speed should have left large volumes of melted rock at the site. But British and American scientists said the reason it didn't was because the meteorite was traveling slower than previously estimated.
"We conclude that the fragmented iron projectile probably struck the surface at a velocity of about 12 km (7.5 miles) (per second)," said Professor H. Jay Melosh, of the University of Arizona, in a report in the science journal Nature.
Meteor Crater, which was formed about 50,000 years ago, was the first terrestrial crater identified as a meteorite impact scar.
Melosh and Gareth Collins, of Imperial College London, used a simple model to calculate the speed on impact. They showed the meteorite had slowed when it hit the Earth's atmosphere and broke into fragments before it struck the Earth.
They calculated the impact velocity was about 26,800 miles per hour.
"Even though iron is very strong, the meteorite had probably been cracked from collisions in space," Melosh said in a statement.
"The weakened pieces began to come apart and shower down from about 8.5 miles high. As they came apart, atmospheric drag slowed them down, increasing the forces that crushed them so that they crumbled and slowed more," he added.
The scientists said that at about 3 miles altitude, most of the meteorite was spread in a large cloud.
Sure that's not Amboy Crater in CA?
It truly is an impressive sight.
Near Winslow, AZ I believe.
Which ones?
A "Craterism" ping.
Map Quest "Meteor Crater, AZ"
http://www.mapquest.com/maps/map.adp?searchtype=address&country=US&addtohistory=&searchtab=home&address=&city=meteor+Crater+&state=az&zipcode=
Uh, that's not Meteor crater... it's a cinder cone (volcanic). Don't know where. From a distance, Meteor crater has a much lower, more subtle topographic profile.
I think it one of the natural wonders, a geological "must see". Definitely worth a half day side trip when seeing the Grand Canyon.
Look it up. You know what Google is.
It's a matter of faith.
Good luck getting them to admit it, though.
The site I pulled the pic from identifies it as Meteor Crater in Arizona. I've never been there so I'm just taking him at his word. It does look a little tall and not as wide in that shot compared to the others though...
My thoughts too, if it was mostly vaporized (in cloud form) then why is there a big 'ol hole in the ground? and the article did not really explain what happened to the iron either, seems like they would have found more.....
I already know what most of the "geochronical indicators" are. I want to know which ones they relied on in this case.
They never tell you in the popular press, they always leave that out.
Another extremely interesting feature your son might get into is called Upheaval Dome in Arches National Park, Utah. It is a large circular anomaly that for a century was thought to be the surface expression of a salt diapir (a large blob of salt that migrates upward due to bouyancy). A few years ago grad student reexamined it and determined it to be a meteor impact feature. It is easy to get to, and their is a nearby topographic high so you can get a good view of the thing.
It was wearing a Timex. It didn't stop ticking.
Shalom.
That's Amboy Crater. We used to ride dirtbikes out there back in the 60's and 70's. Had my first tangle with a rattlesnake within view of that crater.
>>The scientists said that at about 3 miles altitude, most of the meteorite was spread in a large cloud.<<
So it was a shotgun blast?
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