Posted on 12/22/2006 11:19:39 AM PST by blam
Mysterious Egyptian Glass Formed by Meteorite Strike, Study Says
Stefan Lovgren
for National Geographic News
December 21, 2006
Strange specimens of natural glass found in the Egyptian desert are products of a meteorite slamming into Earth between 100,000 and 200,000 years ago, scientists have concluded.
The glass—known locally as Dakhla glass—represents the first clear evidence of a meteorite striking an area populated by humans.
At the time of the impact, the Dakhla Oasis, located in the western part of modern-day Egypt, resembled the African savanna and was inhabited by early humans, according to archaeological evidence (see Egypt map.)
"This meteorite event would have been catastrophic for all living things," said Maxine Kleindienst, an anthropologist at the University of Toronto in Canada.
"Even a relatively small impact would have exterminated all life for [several] miles."
Crater Mystery
The origin of the glass had puzzled scientists since Kleindienst discovered it in 1987.
Some researchers had suggested the Stone Age glass may have been produced by burning vegetation or lightning strikes.
But a chemical analysis showed that the glass was created in temperatures so high that they could only have been the result of a meteorite impact.
Gordon Osinski, a geologist at the Canadian Space Agency in Saint-Hubert who conducted the analysis, found that the glass samples contain strands of molten quartz, a signature of meteorite impacts.
"We can now say for definite that they were caused by a meteorite impact," he said.
Osinski is the lead author of the paper detailing the findings, which was published online in ScienceDirect. The glass deposits have been found in desert locations separated by tens of kilometers, suggesting a massive event.
But scientists have found no signs of an impact crater in the area.
Enlarge Photo
"Usually from an impact like this, we should have a crater at least a kilometer [0.6 mile] across," Osinski said.
The absence of a crater, the scientists believe, suggests that the large space rock may have disintegrated upon entering Earth's atmosphere.
What happened may have been similar to the so-called Tunguska event, in which an asteroid exploded miles above the Earth's surface in a remote area of Siberia in 1908. That explosion felled an estimated 60 million trees over 830 square miles (2,150 square kilometers).
"There was no hole in the ground at Tunguska either," said Albert Haldemann, a planetary scientist at the Jet Propulsion Laboratory in Pasadena, California, who has been using radar to scour the Egyptian desert for impact signs.
"In an air burst like that, contents of the explosion continue to travel downward … providing a gas pulse across the [Earth's] surface that could vitrify sediments," Haldemann explained.
Life-Forms Killed
Scientists know much more about what happens when meteorites hit hard rock than when they impact sand and sedimentary rock, as would have been the case in the Egyptian desert.
At the time, there was a large lake in the area, the researchers say.
"If there was an impact at the surface and it happened to hit the lake, it wouldn't be surprising if the [crater] was filled in," Haldemann said.
"Did the event boil the entire lake away, or did it just cause a really big wave to go across the lake? Maybe we can figure that out from the sediments."
Kleindienst, the anthropologist, has been excavating the site for more than 20 years as part of the Dakhla Oasis project.
(Her research has been partially funded by the National Geographic Committee for Research and Exploration. The committee and National Geographic News are both divisions of the National Geographic Society.)
Kleindienst has obtained a large amount of evidence, including spears and scrapers, to show that humans continually inhabited this region of Egypt's Western Desert during the Middle Stone Age, from about 200,000 to 30,000 years ago.
She has even found glass in lake sediments with archaeological evidence of human habitation in the soil layers below and above it.
"There is no reason to suspect that humans were not there at the time that this catastrophe happened," she said.
The meteorite research has important implications for understanding the environmental and human history at the time, Kleindienst added.
"Calculations at Meteor Crater [in Arizona] give some idea of what the effect of a [relatively small] impact would be," she said.
"Life-forms are killed or seriously injured for many tens of kilometers away from the impact."
"If this event happened during a humid period, the area might have been ecologically repopulated fairly quickly from surrounding areas," she added.
"But if it happened during a dry period, it might have taken a considerable period for life to be re-established in the oasis region."
Haldemann, who is also the deputy project scientist on NASA's Mars Exploration Rover project, says the meteorite strike underlines the interconnectedness between Earth and the rest of the solar system.
"We already know the environment of the whole Earth is tied together," he said.
"What we've been learning more and more in the last 20 years or so is that we're also tied to the solar system as a whole over longer time periods and that this interaction tends to be punctuated by these catastrophic events."
"Here we have evidence in the [Early Stone Age] records that this kind of thing can really happen to us."
:)
more on Dakhla Oasis and environs:
Swallowed by the Sands
Discovering Archaeology (Wayback Machine) | August 2000 | Michael A. Stowe
Posted on 08/21/2004 11:26:26 AM EDT by SunkenCiv
http://www.freerepublic.com/focus/f-chat/1196256/posts
by Norbert Brügge, Germany
http://hometown.aol.de/SLVehicles4/LDG/LDG.htm
Gilf Kebir 'clayton craters'
Remarks to the origin of the craters around Gilf Kebir and Djebel Uweinat (Egypt) and the supposed impact craters of Libya
Publication at the end of the year 2004 by Norbert Brügge, Germany
http://hometown.aol.de/SLVehicles4/Clayton%20Craters/Clayton-Craters.htm
Brilliant site, heaps of images!
http://web.archive.org/web/20041210145800/http://www.star.ucl.ac.uk/~apod/solarsys/cap/comet/hb10.htm
I remember reading somewhere the ancient arab (before islam) tradition is the 'angel gabriel' had six hundred (or was it six thousand) wings...
Just like this one!
COMET WHISKERS:
This enhanced composite image detailing structure in the coma and dust tail of Hale-Bopp was recorded one day before the comet's passage from north to south across the plane of Earth's orbit. Whisker-like structures, probably part of the ion tail, are visible above extending from the lower left of the bright coma. Along with Southern Hemisphere observers, astronomers and a fleet of spacecraft of the International Solar-Terrestrial Physics program had been anxiously awaiting this north/south crossing. The comet's interaction with the changing equatorial solar wind and magnetic field during this crossing was expected to produce distortions and disconnections of Hale-Bopp's ion tail. (Image: T. Puckett)
King Tut's Necklace Shaped By Fireball
The Australian | 6-26-2006
Posted on 06/26/2006 7:32:58 PM EDT by blam
http://www.freerepublic.com/focus/f-news/1656059/posts
Tut's gem hints at space impact
bbc | Last Updated: Wednesday, 19 July 2006, 19:09 GMT 20:09 UK
Posted on 07/20/2006 8:48:59 AM EDT by BenLurkin
http://www.freerepublic.com/focus/f-chat/1669079/posts
Please FREEPMAIL me if you want on or off the
"Gods, Graves, Glyphs" PING list or GGG weekly digest
-- Archaeology/Anthropology/Ancient Cultures/Artifacts/Antiquities, etc.
Gods, Graves, Glyphs (alpha order)
For the description of a trek to the Libyan location follow "Meteorite Man" Bob Haag here: Libya Those wishing to learn more can find lots of good info at Tektites and Tektite Lore
Thanks.
Thanks Fred.
Yup. Tektites. IIRC, there was a SciAm article about it years back.
The study of glass is actually a very interesting part of geology. Turns out every volcano produces as part of the ash, it's own very, very specific kind of glass particles.
I forget the fellows name, but he is an expert in just about every ash-producing eruption for the last 5 centuries or so... and it was his work, in part, that identified Toba as the event it was.
There's a great deal of fascinating information about obsidian here: OBSIDIAN
"But a chemical analysis showed that the glass was created in temperatures so high that they could only have been the result of a meteorite impact."
As you can see this glass "could only" have been the "result" of a "meteorite impact".
"only" rules out nuclear. In other words, according to the article, a nuclear event could not create the glass at issue.
Are you saying that this fundamental fact, as affirmatively asserted by the author of this pience, is not true.
Why would they lie?
Nope, you must be wrong. A nuclear event could not create such glass otherwise this respected, established, academically acclaimed, thorough study of the subject would be laughable to the extent it fails to get even the most basic of facts correct.
Therefore, I submit, that you, Non VAlue Added, are misleading people and misinforming people.
Now, I've given you a lead. Have at it.
For those you you in Rio Linda, post #5 was projecting today's events of scientists trying to divine what happened 100,000 to 200,000 years ago from bits of glass in the sand against future events 100,000 to 200,000 years hence, with scientints tying to divine from similar clues what will surely happen within the remainder of the current decade. The 12 Monkeys tag is the lead.
"Can't you recognize cynical prophesy"
Nam Drol Doog,
I was in fact agreeing with your sentiments and in so agreeing thought to give you a straw man to use as a platform for further explanation of your 12 Monkey take.
Additionally, I thought the article's assertion that it could only have been a meteorite was irresponsible and patently untrue. I thought to use cynical sarcasm to make this point.
Perhaps this bundling of narrative styles amalgamated as "cynically prophetic sarcasm" and resulted in a complete "failure to communicate".
Hope xmas was good to you.
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Just updating the GGG info, not sending a general distribution. |
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