Posted on 10/25/2006 3:33:16 PM PDT by blam
Source: Geological Society of America
Date: October 24, 2006
Far More Than A Meteor Killed Dinos, Evidence Suggests
There's growing evidence that the dinosaurs and most their contemporaries were not wiped out by the famed Chicxulub meteor impact, according to a paleontologist who says multiple meteor impacts, massive volcanism in India, and climate changes culminated in the end of the Cretaceous Period.
Cottonmouth Creek waterfall over the event deposit with reworked Chicxulub impact spherules. The original Chicxulub ejecta layer was discovered in a yellow clay layer 45 cm below the base of the event deposit. The yellow clay represents a cheto smectite clay consisting of altered Chicxulub impact glass spherules. (Image courtesy of Geological Society of America)
The Chicxulub impact may, in fact, have been the lesser and earlier of a series of meteors and volcanic eruptions that pounded life on Earth for more than 500,000 years, say Princeton University paleontologist Gerta Keller and her collaborators Thierry Adatte from the University of Neuchatel, Switzerland, and Zsolt Berner and Doris Stueben from Karlsruhe University in Germany. A final, much larger and still unidentified impact 65.5 million years ago appears to have been the last straw, exterminating two thirds of all species in one of the largest mass extinction events in the history of life. It's that impact -- not Chicxulub -- which left the famous extraterrestrial iridium layer found in rocks worldwide that marks the impact that finally ended the Age of Reptiles.
"The Chicxulub impact could not have caused the mass extinction," says Princeton University paleontologist Gerta Keller, "because this impact predates the mass extinction and apparently didn't cause any extinctions."
Keller is scheduled to present that evidence at the Annual Meeting of the Geological Society of America in Philadelphia, 22-25 October. The results of her research, which was funded by the National Science Foundation, will be discussed in two technical sessions and a public lecture sponsored by the Philadelphia Geological Survey.
Marine sediments drilled from the Chicxulub crater itself, as well as from a site in Texas along the Brazos River, and from outcrops in northeastern Mexico reveal that Chicxulub hit Earth 300,000 years before the mass extinction. Small marine animal microfossils were left virtually unscathed, says Keller.
"In all these localities we can analyze the marine microfossils in the sediments directly above and below the Chicxulub impact layer and cannot find any significant biotic effect," said Keller. "We cannot attribute any specific extinctions to this impact." No one has ever published this critical survival story before, she said. Keller's research was funded by the National Science Foundation.
The story that seems to be taking shape is that Chicxulub, though violent, actually conspired with the prolonged and gigantic eruptions of the Deccan Flood Basalts in India, as well as with climate change, to nudge species towards the brink. They were then shoved over with a second large impact.
The Deccan volcanism did the nudging by releasing vast amount of greenhouse gases into the atmosphere over a period of more than a million years leading up tothe mass extinction. By the time Chicxulub struck, the oceans were already 3-4 degrees warmer, even at the bottom, she says.
"On land it must have been 7-8 degrees warmer," says Keller. "This greenhouse warming is well documented. The temperature rise was rapid, over about 20,000 years, and it stayed warm for about100,000 years, then cooled back to normal well before the mass extinction."
Marine species at the time suffered from the heat. Most adapted to the stress conditions by dwarfing, growing less than half their normal size and reproducing rapidly with many offspring to increase the chances for survival. The Chicxulub impact coincided with this time. By the time climate cooled back to normal, most tropical species were on the brink of extinction. Then the second large impact hit and pushed them over the brink -- many straight to extinction.
As for how the dinosaurs were affected, that's a bit harder to say specifically, since dinosaurs did not leave a lot of fossils behind to tell the tale.
"Dinosaur fossils are few and far between," Keller said. "People love the dinosaurs but we can only really study what happened to them by looking at microfossils because these little critters are everywhere at all times. In just a pinch of sediment we can tell you the age, the prevailing climate, the environment in which it was deposited and what happened. It's remarkable."
What the microfossils are saying is that Chicxulub probably aided the demise of the dinosaurs, but so did Deccan trap volcanism's greenhouse warming effect and finally a second huge impact that finished them off. So where's the crater?
"I wish I knew," said Keller. "There is some evidence that it may have hit in India, where a crater of about 500 kilometers in diameter is estimated and named Shiva by paleontologist Sankar Chatterjee from the Museum of Texas Tech University in Lubbock. The evidence for it, however, is not very compelling at this time."
"There are lots of things I didn't see for myself. I never saw Thomas Jefferson. I've never seen the pyramids of Egypt, nor heard a single shot fired in the War Between the States. But I have no doubt that those things are/were real."
there were people around to attest to the fact Jefferson existed..plus..he left behind his own evidence to his existance.
The pyramids still exist...and eyewitnesses to the Civil War left behind copious documentation.
I have yet to see an eyewitness account of the extinction of the dinasours.
There are clues...and then there are many different interpretations as to what the clues mean.
meanwhile...more clues are discovered that may contradict previous clues, or show us that previous scenarios are not correct.
And this will continue endlessly because no dinsasaours left behind detailed accounts of what happened to them.
>>Agree, why more people can't take the Bible literally and come to the conclusion that a world-wide flood killed the dinosaurs is beyond me.<<
I'm with you. We know more than we used to, but it is our deductions that seem to always end up being fatally flawed.
The flood account still holds more water than any other explanation/speculation.
Ijust knew those darned Indians were responsible!
Mxytlpyk (sp?) Sounds like MIX IT L PICK.
Don't bet on it. Some things are resolved. It wasn't long ago that Homer's Troy was a mere legend. To say this might continue endlessly might be reasonable, but to say it will continue endlessly discounts the exponential advances of geology.
Geology didn't even get started until the 1800s, and the same for biology. Information is coming in now faster than it can be processed. This is hardly an appropriate time to discourage the young people from careers in science. Give it time. Modern science is barely a century old, which is only two careers end to end: the first rough idea, the second more refined idea--that's it so far. Get more young people interested, don't turn them off before we even look around. Don't kill the SCSC, the Apollo program before birth.
nah. It was Karl Rovestone!
We agree. Our physical laws are like the ultimate infinite puzzle. God wasn't messing around when he made that one.
Dinos and Men existed at the same time
Dont fall for the long time periods lie
"BTW do you happen to know where Noah kept the sharks and all the other salt water fish?"
I asked him but he never gave me an answer.
They say that we are doubling our knowledge every 8 years, and it is accelerating.
I expect a lot of exciting new hypothesis to come from science in the near future, and it is going to change a lot of our ideas on things.
Science is young, but it is maturing quickly, the new tools that are now available, the hypothesis on new evidence, it is a very exciting time in the scientific community.
The new scientists coming up the ranks are going to make all kinds of new and astounding discoveries, our knowledge is just going to grow faster and faster.
It is an exciting time.
The Grand Canyon is an indication of water flow, not flood. If it was caused by flood, why aren't there "Grand Canyons" all over the earth?
I can't recall where I read it but there have been many instances of fossils of sea creatures in mountain ranges throughout the earth. How did they get there?
I don't have to read about fossils of sea creatures in mountain ranges. I've seen them in rocks in the mountains east of Salt Lake City, six or seven thousand feet above sea level. How'd they get there? As grjr21 said, it's tectonic uplift, which is observable and measurable within recent history. The Good Friday earthquake in Alaska raised some land over 30 feet in a few minutes.
Yeah, how about a flood? Look what a little water did to New Orleans.
No, Peter never told us there was an age before, he only said there was a time before the flood and a time after
As for the 1000 years, it is a reference to God's mercy and willingness to forgive
make sure you keep your Biblical references in context with what is being said
Dont just pluck them out and make them mean something they are not talking about
I know you'll go ballistic but noah was a pakistani farmer living in the indus river delta region. He built a 3 layer log raft to ride out a coming river flood. Instead he got washed out to sea during a hurricane(15 cubits = a 22 ft deep storm surge), carried around for a couple of weeks on the CCW gyre of the arabian sea, then back onto a sand bar. They have to wait for low tide to wade to the true shore. He goes back to farming, even parties naked once. His illiterate goat/sheep herding descendents(7 generations later) jazz this old family story up whilst sitting around a campfire in iraq. 7 generations a young boy named ABRAM swallows the whole myth; hook, line and sinker...
Outsourced doomsday.
Could it be that Noah was told to gather all the animals two by two but never made any room for a T-Rex or Brontosaurus because they weren't around?
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