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Re: Report Sez Volcanic Gases Killed The Dinosaurs

I have to check out some of the rest of this. I want to verify that there was an ice age in the Cretaceous, because that could point the way to the rest of the data.

However, on whether the Deccan traps heated the climate or cooled it off, I'd agree with you that one would expect it to get hot, but maybe it got cold instead. I'd actually expect it to do some of both. It's just that the climate record we just saw evidence about says it got cold, not hot. That was just one piece of mussel evidence, however.

Dora Smith
Austin, TX
----- Original Message ----- From: "David Marjanovic" <david.marjanovic@gmx.at>
To: "DML" <dinosaur@usc.edu>
Sent: Sunday, November 04, 2007 1:59 PM
Subject: Re: Report Sez Volcanic Gases Killed The Dinosaurs

Was the climate fluctuating during this 100,000 year period?

Not detectably, it seems.

I think that the first ice age was before the end of the Cretaceous,

Within the Phanerozoic, there were ice ages at the end of the Ordovician, in the Late Carboniferous through Early Permian, in the Late Permian, and then never again till the late Pliocene, unless you count the existence of inland ice in eastern Antarctica since the late Eocene. There was none in the Mesozoic.

If Deccan traps actually cooled off the oceans, they could have brought on a volcanic winter and helped trigger an ice age.

No, as mentioned, they heated the Earth. That's because only explosive eruptions blow ash into the atmosphere; the Deccan eruptions were effusive -- imagine a crack where basalt flows out. This pumps lots of gases like carbon dioxide into the air, but nothing to counteract that greenhouse effect.

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