Skip to comments.The shifting face of a 200-million-year-old mystery
Posted on 10/14/2011 6:33:24 AM PDT by decimon
Five times in the last half a billion years, tremendous, global-scale extinctions have wiped out a significant fraction of life on Earth - and each of them presents a grand puzzle.
The most recent and the most familiar is the extinction that wiped out the dinosaurs - between the Cretaceous and Tertiary periods, about 65 million years ago.
But before that, 205 million years ago, was the "End-Triassic Event" - it set the stage for the Jurassic Period, which saw the rise to prominence of the dinosaurs.
Just what happened that killed off half the species on the planet, though, remains a mystery.
Once upon a time, Paul Olsen of Columbia University's Lamont-Doherty Earth Observatory was one of the few people who believed that a giant impact of an object from space started the extinction, much like the impact that many people believe caused the demise of the dinosaurs.
But science has moved on. Other workers in the field have found in that same period, enormous lava flows from a flurry of volcanic activity in the then-developing Atlantic Ocean also occurred at exactly the same time.
(Excerpt) Read more at bbc.co.uk ...
Go with the flow ping.
It’s Bush’s ancestors fault.
Heinsohn puts the flood about 3500 years ago.
Lava flows from Bush’s Fault?
Sounds about right.
I don’t want to know - stuff like this makes me dizzy;)
What really happened was that Man (and women) were created when the Earth was created. They started building fires at night to cook the animals that they had killed during the day. The fire put evil carbon dioxide into the new, pristine atmosphere causing the Sun to heat things up which in turn killed the animals. Hence a mass extinction. Thus it has been thru the ages. Man and Woman have polluted the pristine Earth an eventually most of the animals (except those in the deep ocean and those in caves and under rocks) were killed off. We are in the 4th or 5th cycle. But not to worry, the protestors and the aging hippies will save the Earth and turn it into a paradise.
Just what happened that killed off half the species on the planet, though, remains a mystery
Why? I thought scientist had it all figured out.
99% of Scientist blame “Bush” (pear reviewed). However, of those who blame Bush 78% also blame Christians,Conservatives, Tea Partiers,racism and homophobia.
“We are in the 4th or 5th cycle.”
Look up OOPARTS. Out Of Place ARTifactS. Kinda freaky. Many things are listed there, among them, people have found things in solid rock with no reasonable explanation of how they got there.
I have often thought that with the emphasis of late on majority opinion / consensus being accepted as irrefutable fact, why aren't the scientists on the corner evangelizing? After all, clear majority position in the world is that God is real. So the scientists should bow to consensus and make their way to a church, right?
Oh, it doesn't work for God? Hmmmm.
|GGG managers are SunkenCiv, StayAt HomeMother & Ernest_at_the_Beach|
[1999 -- The letter of rejection from Nature for the following article is dated August 28, 1968. At the time most earth scientists would not even accept the fact that meteorites regularly impacted the earth. For example, Barringer Crater in Arizona was still thought by many to be of volcanic origin, as well as the craters on the moon. Bob Dietz had just published his work on shatter cones but I wouldn't say that had been generally accepted. There was not even general agreement on sea floor spreading and plate tectonics outside the radical few at Scripps, Woods Hole, and related institutions.]Possible Formation of the Guatemala Basin by the Impact of an Extraterrestrial BodyThe earth must be as frequently cratered per unit area as the moon. By a relative cross section argument, more than 13 times the number of craters the size of the maria on the moon exist, or existed, on the earth. Whether such events occur with sufficient frequency in recent geologic time to provide tangible evidence today of such cratering is uncertain. From the arguments set forth, and the continuing discovery of meteorite craters on the continents (Short, 1966, Baldwin, 1963, Dietz, 1961, and Prouty, 1952) it seems likely that the importance of the effect of extraterrestrial bodies impacting the earth has been, at least, underestimated (the Alverez's hypothesis concerning the end of the dinosaurs by such a mechanism was more than a decade in the future). Certainly there is as much evidence at present to support our hypothesis for the formation of the Guatemala Basin as other hypotheses advanced to explain the low heat flow found in this basin.
by Charles E. Corry and Miller L. Bell
With the tests for shock processes advanced by Short (1966), our hypothesis should be capable of field verification or rejection.
Why are they spending all that money on finding the answer to this riddle when they could poll the scientists (all type of scientists) and reach a consensus?
If I recall correctly, indications of a very large impact crater partially on antarctica (subglacial today) have been found, the rest would be on the australian plate. Read this a few years ago here.
Maybe we’re kept alive by the luck of Teela Brown.
Two Catastrophe ScenariosAbout 2.2 million years ago, a chunk of space debris about a kilometer in diameter splashed down in the Bellingshausen Sea between Antarctica and South America. It was some splash! The splash zone was about 20 kilometers across, waves 4 kilometers high raced away from Ground Zero, and a column of salt water ascended miles high into the upper atmosphere. The TNT equivalent is estimated at 12 billion tons. Ice clouds formed and shaded the planet, causing severe climate changes. On the floor of the Bellingshausen Sea, 5 kilometers deep, lies the Eltanin Impact Structure.
by William CorlissOcean splashdownAn asteroid between one and four km in diameter that splashed into the Southern Ocean, 1500 km SW of Chile, just over two million years ago, may have worsened a period of global cooling that saw the emergence of modern humans... The impact in question was first discovered during a cruise of the Eltanin in the 1960s: betrayed by anomalously high amounts of iridium in ocean-bed cores... Gersonde and his colleagues have taken another look, their results coming from a cruise in 1995 by the research ship Polarstern. The impact left a distinctive 'signature' of geological layers, very like that of the Chicxulub impact. Lowest in the 'impact' sequence is a thick layer of disordered rubble, full of chunks of rock up to 50 cm across: this layer represents the large-scale disturbance immediately after the impact as the ten-megaton blast ripped up the ocean floor. This layer took around four hours to settle after the blast. Smaller particles, such as grains of sand, took longer to settle, explaining why this layer was found immediately above the rubble layer. Capping the whole sequence is a thin layer of very fine sediment, dispersed over a wide area. This would have contained fine-grained material (including vaporized asteroid) flung high into the air and which took days or months to settle out. This layer contained the iridium.
by Henry Gee
UC Davis Geology Department
Before somebody blames me, it was already like that when I got here.