Volcano's the cause of mass extinction

[southsider2k5]

Scientists are theorizing that the "great dying" was caused by volcanoes and not an asteroid impact.

 

http://www.nzherald.co.nz/index.cfm?c_id=2&ObjectID=10007535

[mreye]

Scientists are theorizing that the "great dying" was caused by volcanoes and not an asteroid impact.

 

http://www.nzherald.co.nz/index.cfm?c_id=2&ObjectID=10007535

 

"theorizing" makes it true, right? Just like the theory of evolution and the theory about global warming.

[FlaSoxxJim]

The article has some good information, but leaves out one very important thing -- they're NOT talking about the mass extinction that did in the dinosaurs!

 

The mass extinction event at the K-T boundary, 65 mya (million years ago) is the one that killed off the dinosaurs. "The geat dying" refers to the Permian extinction event much more extensive and protracted than the K-T event, and occurring 250 mya.

 

volcanism, volcanism induced by asteroid impact, glaciation, and sea level change have long been the competing theories to explain both of these events. When my copy of Science gets here next Tuesday I'll have a better idea of what I think.

 

As regards asteroid impact and the K-T event, the nearly worldwide iridium dust layer in te geological record at the time of the event strongly suggests asteroid impact played a part. Iridium is exceedingly rare in the earth's crust, but can be hundreds of thousands of times more abundant in asteroids and comets. Whether the impact(s) was/were the sole cause, a catylist for massive volcanic events (not a well-defined mechanism for that yet as far as I know), or just the straw that broke the camel's back (ie, a final assault on an already ecologically stressed fauna) is still a subject for debate.

[FlaSoxxJim]

"theorizing" makes it true, right? Just like the theory of evolution and the theory about global warming.

I agree, I would rather see this labeled as hypothesis or conjecture, as elevation to the status of a theory is actually pretty lofty and pretty good scientific vindication.

 

Much like in the case of the ever more coroborated THEORY OF EVOLUTION.

[mreye]

Much like in the case of the ever more coroborated THEORY OF EVOLUTION. 

 

I leave work in 30 minutes. I'll pass.

[FlaSoxxJim]

Actually here's a link to a more complete piece from ABCnews, with some of the sea-level reduction/carbon dioxide release/oxygen reduction hypothetical scenario spelled out a little better:

 

http://abcnews.go.com/Technology/wireStory?id=431119

 

I really like the last part of the excerpt below about absence and evidence. It gets to the heart of the problem regarding the Creation "Science" argument that an incomplete fossil record is sound evidence against biological evolution.

 

The more recent mass extinction that killed the dinosaurs 65 million years ago has been linked to an impact by a large asteroid or comet that struck in an area off the coast of what is now Mexico and left a distinctive layer of dust worldwide.

 

Some researchers have argued that the Great Dying might also have resulted from such an impact, but Ward's team said it could find no evidence for such an event.

 

That doesn't mean there wasn't one, argues Luann Becker of the University of California at Santa Barbara, commenting that "the absence of evidence isn't evidence for absence."

 

The lack of evidence of an iridium layer at the P-T boundary like the one at the K-T doesn't mean an impact event didn't play a part here. Even at the K-T, the layer is only 3 microns (3 millionths of a meter!) thick, so finding iridium traces in 250 million year old strata would make finding a needle in a haystack look easy by comparison.