Posted on 06/01/2006 2:26:58 PM PDT by PatrickHenry
Ancient mega-catastrophe paved way for the dinosaurs, spawned Australian continent.
Planetary scientists have found evidence of a meteor impact much larger and earlier than the one that killed the dinosaurs -- an impact that they believe caused the biggest mass extinction in Earth's history.
The 300-mile-wide crater lies hidden more than a mile beneath the East Antarctic Ice Sheet. And the gravity measurements that reveal its existence suggest that it could date back about 250 million years -- the time of the Permian-Triassic extinction, when almost all animal life on Earth died out.
Its size and location -- in the Wilkes Land region of East Antarctica, south of Australia -- also suggest that it could have begun the breakup of the Gondwana supercontinent by creating the tectonic rift that pushed Australia northward.
Scientists believe that the Permian-Triassic extinction paved the way for the dinosaurs to rise to prominence. The Wilkes Land crater is more than twice the size of the Chicxulub crater in the Yucatan peninsula, which marks the impact that may have ultimately killed the dinosaurs 65 million years ago. The Chicxulub meteor is thought to have been 6 miles wide, while the Wilkes Land meteor could have been up to 30 miles wide -- four or five times wider.
"This Wilkes Land impact is much bigger than the impact that killed the dinosaurs, and probably would have caused catastrophic damage at the time," said Ralph von Frese, a professor of geological sciences at Ohio State University.
He and Laramie Potts, a postdoctoral researcher in geological sciences, led the team that discovered the crater. They collaborated with other Ohio State and NASA scientists, as well as international partners from Russia and Korea. They reported their preliminary results in a recent poster session at the American Geophysical Union Joint Assembly meeting in Baltimore.
The scientists used gravity fluctuations measured by NASA's GRACE satellites to peer beneath Antarctica's icy surface, and found a 200-mile-wide plug of mantle material -- a mass concentration, or "mascon" in geological parlance -- that had risen up into the Earth's crust.
Mascons are the planetary equivalent of a bump on the head. They form where large objects slam into a planet's surface. Upon impact, the denser mantle layer bounces up into the overlying crust, which holds it in place beneath the crater.
When the scientists overlaid their gravity image with airborne radar images of the ground beneath the ice, they found the mascon perfectly centered inside a circular ridge some 300 miles wide -- a crater easily large enough to hold the state of Ohio.
Taken alone, the ridge structure wouldn't prove anything. But to von Frese, the addition of the mascon means "impact." Years of studying similar impacts on the moon have honed his ability to find them.
"If I saw this same mascon signal on the moon, I'd expect to see a crater around it," he said. "And when we looked at the ice-probing airborne radar, there it was."
"There are at least 20 impact craters this size or larger on the moon, so it is not surprising to find one here," he continued. "The active geology of the Earth likely scrubbed its surface clean of many more."
He and Potts admitted that such signals are open to interpretation. Even with radar and gravity measurements, scientists are only just beginning to understand what's happening inside the planet. Still, von Frese said that the circumstances of the radar and mascon signals support their interpretation.
"We compared two completely different data sets taken under different conditions, and they matched up," he said.
To estimate when the impact took place, the scientists took a clue from the fact that the mascon is still visible.
"On the moon, you can look at craters, and the mascons are still there," von Frese said. "But on Earth, it's unusual to find mascons, because the planet is geologically active. The interior eventually recovers and the mascon goes away." He cited the very large and much older Vredefort crater in South Africa that must have once had a mascon, but no evidence of it can be seen now.
"Based on what we know about the geologic history of the region, this Wilkes Land mascon formed recently by geologic standards -- probably about 250 million years ago," he said. "In another half a billion years, the Wilkes Land mascon will probably disappear, too."
Approximately 100 million years ago, Australia split from the ancient Gondwana supercontinent and began drifting north, pushed away by the expansion of a rift valley into the eastern Indian Ocean. The rift cuts directly through the crater, so the impact may have helped the rift to form, von Frese said.
But the more immediate effects of the impact would have devastated life on Earth.
"All the environmental changes that would have resulted from the impact would have created a highly caustic environment that was really hard to endure. So it makes sense that a lot of life went extinct at that time," he said.
He and Potts would like to go to Antarctica to confirm the finding. The best evidence would come from the rocks within the crater. Since the cost of drilling through more than a mile of ice to reach these rocks directly is prohibitive, they want to hunt for them at the base of the ice along the coast where the ice streams are pushing scoured rock into the sea. Airborne gravity and magnetic surveys would also be very useful for testing their interpretation of the satellite data, they said.
NSF and NASA funded this work. Collaborators included Stuart Wells and Orlando Hernandez, graduate students in geological sciences at Ohio State; Luis Gaya-Piqué and Hyung Rae Kim, both of NASA's Goddard Space Flight Center; Alexander Golynsky of the All-Russia Research Institute for Geology and Mineral Resources of the World Ocean; and Jeong Woo Kim and Jong Sun Hwang, both of Sejong University in Korea.
Not sure I understand what you're asking. Can you explain?
The Russian-born scholar was a friend and colleague of Albert Einstein, a student of Freud's first pupil Wilhelm Stekel, and Israel's first practicing psychoanalyst. Some of his writings appeared in Freud's Imago. In 1930 he published the first paper to suggest that epileptics would be characterized by abnormal encephalograms. He was the founder and editor of the scholarly publication, Scripta Universitatis, the physics and mathematics section being prepared by Einstein.
It was while researching a book on Freud and his heroes that Velikovsky first wondered about the catastrophes said to have accompanied the Hebrew Exodus, when fire and hailstones rained upon Egypt, earthquakes decimated the nation, and a pillar of fire and smoke moved in the sky. Biblical and other traditional Hebrew sources speak so vividly that Velikovsky began to wonder if some extraordinary natural event might have played a part in the Exodus.
To explore this possibility, Velikovsky sought out a corresponding account in ancient Egyptian records, finding a remarkable parallel in a papyrus kept at the University of Leyden Museum, called the Papyrus Ipuwer. The document contains the lamentations of an Egyptian sage in response to a great catastrophe overwhelming Egypt, when the rivers ran red, fire blazed in the sky, and pestilence ravaged the land.
Velikovsky also encountered surprising parallels in Babylonian and Assyrian clay tablets, Vedic poems, Chinese epics, and North American Indian, Maya, Aztec, and Peruvian legends. From these remarkably similar accounts, he constructed a thesis of celestial catastrophe. He concluded that a very large body -- apparently a "comet" -- passed close enough to Earth to violently perturb its axis, as global earthquakes, wind and falling stone decimated early civilizations.
http://www.thunderbolts.info/velikovsky-ghost.htm
I think we'll just have to settle for disagreement.
So...what do you think about the 75 million year old T-Rex tissue hydrated and plastic enough to BBQ?
IIRC, few of the members of the Affiliation of Christian Geoscientists are Young Earthers.
Close. Not a bullet, but blunt (non-penetrating) trauma. The medical condition is caused by the brain bouncing off the opposite side of the skull from the impact.
In this case imagine you are standing at the antipodes of a major impact. The shock-wave travels through the surface rocks in a a wave like the ripples from a stone in a pool, except the earth isn't flat! At some point the shock waves have traveled half way around the world, to where you are standing. They come at you simultaneously from all points of the compass, and as the leading edge of the shock-waves go from a full planet's diameter at the quarter way around point, they are re-compressed and concentrated to that little bit of land you are standing on.
This refocusing dumps a goodly fraction of the energy of the impact into a small area. as the rock gets slapped from all sides at the same time it crushes and shatters. The energy gets squirted down into the mantle, and up into space.
Not that you get to appreciate the ride, because somewhere along the way (in the first few milliseconds or so) the bottoms of you feet have been driven through the top of your skull...
Think of the Sudbury irruptive...it's not UNDER the crust, but penetrating it.
T-Rex. It's what's for dinner...
It's too bad it wasn't anything like meat to BBQ. I'd love a T-Rex steak! But the material didn't have DNA or even cell structures... they were just able to soften the material that was there. :-(
It was nothing like what you described too. Not *I*.
"Science' is nothing more than another human agency and prone to hubris the same as any other. "
From "The Experts Speak: The Definitive Compendium of Authoritative Misinformation", by Christopher Cerf and Victor Navasky.
Men might as well project a voyage to the Moon as attempt to employ steam navigation against the stormy North Atlantic Ocean.
-- Dr. Dionysus Lardner, 1838
That birds can be taught to talk better than other animals is explained by the fact that their mouths are Nordic in structure....
-- Professor Hermann Gauch, 1933
We need not hesitate to admit that the Sun is richly stored with inhabitants.
-- Sir William Herschel
X-rays are a hoax.
-- Lord Kelvin, ca. 1900
Shades of that other kook, medved the Silly.
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