Skip to comments.Meteor shards linked to massive extinction
Posted on 11/21/2003 12:16:33 PM PST by balrog666
Fragments may be 250 million years old
About three dozen microscopic shards of rock unearthed in Antarctica may be the fragments of a meteor that killed most of life on earth 250 million years ago, scientists reported Friday. .
The shards bolster theories that meteors caused several of the mass extinctions in earth's history when large numbers of species died out almost simultaneously. Most scientists agree that the most recent major mass extinction 65 million years ago, which killed off the dinosaurs, was caused when a meteor struck the earth near the Yucatán Peninsula of Mexico. .
The extinction 250 million years ago, known as the Permian-Triassic boundary, was the largest extinction of all. More than 90 percent of species living in the oceans and 70 percent of those on land disappeared. .
At present, the primary suspected cause for the Permian-Triassic extinction is giant volcanic eruptions in Siberia, which might have induced catastrophic ecological changes. .
Writing in Friday's issue of the journal Science, the researchers report that they found the meteorite fragments in rocks in Antarctica that date to the Permian-Triassic boundary. The mineral composition of the fragments, each less than one-fiftieth of an inch, or roughly half a millimeter, wide, correspond to that of certain meteorites and is like nothing found naturally on earth, they reported. .
In addition, the scientists said, the same rocks had previously yielded soccer-ball-shaped molecules known as buckyballs containing extraterrestrial gases as well as grains of quartz with fractures that indicate they had been hit with a tremendous shock. .
"Clearly, this evidence points toward a major impact at the Permian-Triassic boundary," said Asish Basu, a professor of earth and environmental sciences at the University of Rochester in New York and lead author of the Science paper. That, he said, is "the most reasonable interpretation." .
The same researchers will report at a American Geological Union meeting next week in San Francisco that they have also found tiny metal spheres they believe were part of the earth's crust and melted by the impact. .
Others are not yet convinced. Eldridge Moores, an emeritus professor of geology at the University of California at Davis, described the meteorite fragments as "the most interesting evidence for a meteorite event at this boundary that I've seen so far." .
But, he added, while the evidence for the dinosaur-killing meteor 65 million years ago is a convincing 10 on a 1-to-10 scale, the evidence for a killer meteor at the Permian-Triassic boundary is not nearly as solid. "I think it's now up to 3 or 4," he said. "It's not 9 or 10." .
Douglas Erwin of the National Museum of Natural History in Washington said, "It's suggestive, but it's hardly compelling." Each piece of evidence offered so far has not by itself been compelling. .
The description of shocked quartz, he said, was tentative, even by the researcher who reported it, and other scientists have failed to reproduce the findings of buckyballs and extraterrestrial gases. If a meteor caused this largest of all extinctions, "I find it remarkable that there's so little evidence," Erwin said. .
If the evidence for an impact does become more compelling, that would raise another geological mystery: whether meteor impacts can set off gigantic volcanic eruptions. Huge eruptions in India coincided with the Yucatán meteor impact 65 million years ago. .
To date, most geologists have argued that meteors are not powerful enough to crack the earth's crust. Basu, who is strongly convinced that a meteor struck the Earth 250 million years ago, believes coincidence is not likely. "There has to be a connection," he said.
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Calderists, cometists, and asteroidists too?
I'm surprised they didn't find shards of prehistoric SUV's during their research.
That was Wesley Clark's presidential campaign re-entering the atmosphere.
Haw! Craterism is as much a religion as Christianity. How dare you hide behind "science!"
1. Meteor craters are not observed to be happening now.
2. Meteor craters have not been observed to happen in the past.
3. Thomas Jefferson said: "Gentlemen, I would rather believe that two Yankee professors would lie than believe that stones fall from heaven."
4. The odds against a rock falling from the sky in a random fashion and making a crater are astronomical.
5. The second law of thermodynamics prohibits meteor craters.
6. Meteor craters are not mentioned in the bible, and are thus blasphemy.
7. Meteor craters have never been reproduced in the lab, and are thus not scientific.
8. Belief that rocks can fall from the sky promotes hedonism and animalistic, amoral behavior.
9. Craterism is a product of materialism and a naturalistic worldview.
10. Craterism makes no predictions and is untestable; it is therefore not scientific.
11. Craterists point to evidence of micro-cratering, but have no evidence of macro-cratering.
12. Scientists are abandoning craterism because they know it is not supported by evidence.
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Joking? I borrowed as a template the highly respected (and much quoted) arguments that are constantly presented against evolution, which can be found at the website of the Institute for Creation Research.