Signs of an ancient impact could help to explain a mass extinction. Mark Peplow
A dense bit of rock in the Antarctic (orange circle) seems to be circled by a crater.
Posted on 06/05/2006 9:07:10 AM PDT by S0122017
Does a giant crater lie beneath the Antarctic ice?
Signs of an ancient impact could help to explain a mass extinction. Mark Peplow
A dense bit of rock in the Antarctic (orange circle) seems to be circled by a crater.
© Ohio State University
Evidence of a cataclysmic meteorite impact has been unearthed in Antarctica, according to researchers who say the collision could possibly explain the greatest mass extinction ever seen on our planet. But scientists contacted by news@nature.com say they are sceptical, as no signs of such an enormous impact have been found in other, well-studied areas of Antarctica.
The first sign of this possible impact was spotted by NASA's GRACE satellites, a pair of orbiting probes that sense slight variations in the Earth's gravity field. They revealed a 320-kilometre-wide plug of dense mantle material more than 1.6 kilometres beneath the East Antarctic ice sheet in an area known as Wilkes Land.
This mass concentration, or 'mascon', can be caused by the upwelling of denser material from the Earth's mantle after a massive impact. "If I saw this mascon signal on the Moon, I'd expect to see a crater around it," says Ralph von Frese, a geophysicist at Ohio State University, Columbus, who led the team that made the find.
When they looked at airborne radar images of the area, they found what they say looks like a crater — a circular ridge some 500 kilometres wide running around the mascon. "It could be the biggest impact ever found on Earth," says von Frese.
Incoming!
"It's possible, but it's not the interpretation that would top your list," says Ian Dalziel, a geologist at the University of Texas at Austin. The region of dense rock is certainly circular, he says, but it could easily be volcanic rock that had welled up during normal geological activity: "You can find a lot of gravity anomalies like this." The roughly circular feature thought to be the rim of the crater may just be part of the normal variation in terrain in the area, he adds.
If an incoming asteroid did gouge out the hole it must have been up to 50 kilometres across, says von Frese. That's four or five times larger than the object thought to have created the Chicxulub crater on the Yucatan peninsula in Mexico, which was probably responsible for wiping out the dinosaurs some 65 million years ago.
But that's peanuts compared with the Permian-Triassic extinction, which destroyed more than three-quarters of all species on Earth about 250 million years ago. The cause of this mass extinction is still hotly debated by scientists.
Most think that the extinction started when a vast volcanic eruption released a flood of lava to create the Siberian Traps — an area of basalt that covers an area larger than Europe. "They represent the biggest volcanic event of all time, and coincide precisely with the extinction," says Paul Wignall, a palaeontologist at the University of Leeds, UK, who studies mass-extinction events. Such an eruption would have belched huge amounts of gas, including sulphur dioxide and carbon dioxide, into the atmosphere, causing acid rain and greenhouse warming.
Other scientists have argued that a massive impact, like that at Chicxulub, could be responsible instead (see 'Comet impact theory faces repeat analysis'). "But nobody's been convinced of that," says Wignall.
Von Frese notes that the explanations aren't mutually exclusive: the shockwaves from a huge impact could have travelled through the planet to trigger the eruptions in Siberia, delivering a devastating combination of disasters.
Hot topic
Von Frese presented the discovery at an American Geophysical Union meeting in Baltimore, Maryland in late May. He admits that it was greeted with "a lot of scepticism", largely because there's no direct evidence that the feature is 250 million years old.
An impact of that size should also have melted and twisted nearby rock. Yet rocks in the Transantarctic Mountains of the same age show no evidence of the collision, says Jane Francis, a geologist also at the University of Leeds. "That sequence has been worked on before, and no one has found evidence to support a massive impact like this," she says.
Wignall says that few scientists will be convinced by the hypothesis until the team can precisely date their crater directly, and find rocks there that have been altered by the searing heat of the explosion. "Then we'll all sit up and take notice," he says.
Too much ice covers the putative crater for a drilling expedition. But Von Frese hopes to make a research trip to Antarctica to look for rocks at the base of the ice sheet along the continent's coast that could attest to an impact.
ping
How can we speed up global warming so this theory can be proven (or disproven)?
Yet people say global warming is all bad.
BIG BANG IN ANTARCTICA -- KILLER CRATER FOUND UNDER ICE
Ohio State University | 01 June 2006 | Staff (press release)
Posted on 06/01/2006 5:26:58 PM EDT by PatrickHenry
http://www.freerepublic.com/focus/f-news/1641966/posts
Giant Crater Found [in Antarctica]:
Tied to Worst Mass Extinction Ever [Permo-Triassic]
SPACE.com | June 2, 2006 | Robert Roy Britt
Posted on 06/02/2006 2:44:43 PM EDT by cogitator
http://www.freerepublic.com/focus/f-news/1642426/posts
Meteor mega-hit spawned Australian continent: researchers
AFP on Yahoo | 6/2/06 | AFP
Posted on 06/03/2006 6:23:27 PM EDT by NormsRevenge
http://www.freerepublic.com/focus/f-news/1642946/posts
The headline sez Australia, but the event described is in Antarctica. :')
http://www.freerepublic.com/focus/f-news/1641966/posts?page=76#76
http://www.freerepublic.com/focus/f-news/1641966/posts?page=147#147
http://www.freerepublic.com/focus/f-news/1641966/posts?page=148#148
http://www.freerepublic.com/focus/f-news/1641966/posts?page=149#149
But the size of the comet is described as only twice as that that wiped out the dinos. In my article it was described as 4-5 times.
It's the Nazi flying saucer base...
Al Gore is probably confused over how a meteor could hit the South Pole since to his "scientific" mind it would have to fall up.
Perhaps it was merely a matter of what was meant by size. :') An increase in diameter of twice pushes up the volume eightfold.
ALgore is a giant creator.
What is Happening at the South Pole?
(from Richard Hoaxland's website)
http://www.enterprisemission.com/antarctica.htm
...Almost immediately after the discovery of the Columbia "Vostok magnetic anomaly," word began to leak out that JPL was inexplicably "pulling back from its Vostok exploration program." The reason given was the previously stated "environmental concerns." This was all well and good, until unconfirmed reports began to surface that a JPL spokesperson had admitted at a February press conference that the National Security Agency (NSA) had literally taken over the JPL polar research program at Lake Vostok. It was this report which created something of a firestorm on the Internet.
Several sources immediately pointed to the fact that the location of the "Vostok anomaly" is quite close to coordinates shown in the "X-Files" movie regarding the fictional location of a massive, "buried alien spacecraft." In fact, the Russian Vostok Base is the closest base of any kind to the coordinates given in the movie. (All this reminded us, of course, of our own previous suspicions about the true source of some of X-Files creator Chris Carter's story ideas ....)
The discovery of the peculiar Vostok anomaly underneath the ice -- encompassing an area almost 3,000 miles in area -- was also eerily reminiscent of a French novel, "Subterranean," in which Antarctic scientists discover an inhabited "Lost City" under the ice.
Antarctica's underground Lake Vostok could be teeming with life
News/Current Events News
Source: New Scientist
Published: 2/21/01
Posted on 02/20/2001 09:34:30 PST by dead
http://www.freerepublic.com/forum/a3a92aaa62f16.htm
What is Happening at the South Pole?
News/Current Events News Keywords: THE LAKE VOSTOK MOSTERS
Source: The Enterprise Mission
Published: April 2001 Author: Richard Hoagland and Associates
Posted on 04/23/2001 23:11:12 PDT by ravinson
http://www.freerepublic.com/forum/a3ae519000490.htm
What is Happening at the South Pole?
Miscellaneous Miscellaneous Keywords: ANTARTICA UFO ATLANTIS
Source: The Enterprise Mission
Published: 4/23/2001 Author: Michael Bara and Richard Hoagland
Posted on 04/24/2001 17:46:16 PDT by Yo-Yo
http://www.freerepublic.com/forum/a3ae61e5820ba.htm
Vostok: The Lake of Shadows
FATE Magazine | Cover Story FATE Magazine 2002-06-01 00:00:00 | by Scott Corrales
Posted on 06/25/2002 8:46:51 PM EDT by vannrox
http://freerepublic.com/focus/news/705933/posts
Warning: Well in Antarctica may pop like a can of Coke
Knight-Ridder Tribune News | August 14, 2003 | JOSHUA L. KWAN
Posted on 08/14/2003 11:46:58 AM EDT by Dog Gone
http://www.freerepublic.com/focus/f-news/964070/posts
Human tools found in Antarctica
Early morning Today show | 1/20/2004 | NBC
Posted on 01/20/2004 8:03:51 AM EST by djf
http://freerepublic.com/focus/f-news/1061409/posts
New plant finds in andes foretell of ancient climate change (It's a natural cycle, people!)
EurekAlert | September 14, 2005 | Staff
Posted on 09/15/2005 10:44:16 AM EDT by DaveLoneRanger
http://www.freerepublic.com/focus/f-news/1485041/posts
<< But the size of the comet is described as only twice as that that wiped out the dinos. In my article it was described as 4-5 times. >>
Mine's bigger than yours.
a list of similar, earlier topics:
http://www.freerepublic.com/focus/f-chat/1643681/posts?
page=6#6
SECOND IMPACT
The Human Instrumentality Project is almost complete. When Third Impact comes, there will be no place to hide.
Eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee!
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