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End of the "Lone Asteroid" Theory?
hussar writes "This BBC article reports on research that suggests the dinosaurs were not killed off by the Chicxulub asteroid's immediate effects but ultimately fell to evironmental stresses caused by a second asteroid that hit about 300,000 years later. The second impact may have been in the Indian Ocean."
Kellers findings are pretty well founded. The idea is that the Chicxulub impact occurred during this warming period with severe environmental effects but the extinction of the dinosaurs - When the second impact finally occurred, it hit an already stressed community which was the straw that broke the camel's back. Almost anything could have wiped them out at that point. Jan Smits doesn't refute this very clearly - but I would accept that the theory is less sensational that it appears from the headline.
Please help publicise swpat.org - the software patents wiki
Ah.... The great K-T extinction debate continues....
For those interested in reading about the supporting data and possible causes of the K-T extinction,
here's a good discussion" by Dewey M. McLean of the Department of Geological Sciences,
Virginia Polytechnic Institute and State University.
>...fossil fuel carbon still on the surface (where we're presently putting it again...
Land vegetation, oceans, and volcanoes put about 200 billion tons of CO2 into the air, compared to 6 billion tons from humans. If we're going to avoid the fate of the dinos, somebody needs to get Monntserrat and Krakatau to ratify Kyoto.
"Give a man a fish and he will ask for tartar sauce and French fries!"
Check out his reply to the original article.
There's a picture of the soil sample he's talking about, too.
"The best evidence in favour of a single impact, I repeat, is in the K/T record from the US western interior. In numerous outcrops from Alberta in Canada, through Dogie Creek in Wyoming to the Raton Basin in New Mexico an iridium-enriched clay layer occurs in coal swamp deposits at the palynological K/T boundary. This clay layer has a dual nature (Izett, 1990), and consist of two layers: a lower layer that contains spherules (best seen in Dogie creek (Fig. 7) morphologicaly indistinguishable from the Chicxulub spherules from the Gulf.
The upper layer is strongly enriched in iridium and shocked minerals, such as quartz, feldspar and zircons. The shocked zircons are shown (Krogh, 1993) to have the isotopic properties (Sm/Nd) of the pan-African basement of the Chicxulub crater. In all the mentioned localities the two layers are in contact with each other, without an intervening layer. Not even a single layer of one fall season of leaves or plant material occurs between the two layers. If the upper, iridium-rich, layer is from another impact than the Chicxulub impact, they have to be simultaneous, and have to occur on the same pan-African basement - in itself highly unlikely, but not impossible. A 300Ka separation between the two layers in all the localities, as Keller posits for the separation between the Chicxulub impact and the iridium producing impact, is therefore excluded - barring a miracle."
Could it be that this second meteorite was rich in poisonous metals, tainting the soil world-wide for years to come? This article is interesting, but I have not seen mention of the theory elsewhere.
"I'm looking for a theory that says the earth was a warmer place with most of that fossil fuel carbon still on the surface"
Wouldn't that be contrary to existing theories about the carboniferous period, which occured more than 250 million years prior to the K-T bounday? Maybe not.
Limestones and other sedimentary rocks high in calcium lock away a lot of carbon and oxygen in the form of CaCO3. I wonder how much impact the periods of high limestone production had on the environment including surface level CO2. Of course, right before the Tertiary period we had the Cretaceous - a period of high sea levels and warm temperatures, and distinctively marked in many places by chalk beds.
He has one of the samples of this study was based on (and (acording to above mentioned radioshow) the who divided up the original). In the end of the radiointerview he sugests letting all the original drill samples be tested by a third party for magnesium or calcium to prove if what Kellar has found are actual organism or just cristaline structures (as Smit seem to think). Sounds good to me, but then IANAPaleontologist.
The model I always think of is Krakatoa's eruption in 535 AD. Global climate change kicked in just after that -- years without any harvest in Europe, extreme volatility.
For people interested in following that up, the hypothesis was proposed by David Keys, who speculates in his book and BBC program Catastrophe (1999) that several events in world history in the 6th century AD were all linked to a volcanic eruption, which he feels is most probably Krakatoa.
There is some scepticism towards this theory, specifically the fact that Antarctic ice cores don't have any record of volcano-related climate change in the 6th century. But the jury's still out, and there is no evidence yet to prove or disprove David Keys's hypothesis conclusively.
Time flies like an arrow. Fruit flies like a banana.
It's either a fact that Noah's flood was not global, refuting the Bible; or a fact that Chinese written history is a fraud, refuting the legitimacy of any ancient written document such as the Bible. The only thing that separates the Bible from other ancient texts is the belief that it was authored by God which is an obvious fallacy. Take Old Testament 101 in any college and you'll spend a great amount of time studying the ample evidence that the OT has been edited, by whom, when, where, and how many times.
And as I've said elsewhere, even the notion that the Bible is a historically accurate document is brand new - less than 150 years old. The idea itself is not consistent and can only be supported by countless leaps of "faith", known to educated people as "pseudo science", "fallacy", and "make believe".
The Bible is an infinitely valuable document and an irreplaceable component of many people's spirituality, but a history text it is not.