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Re: Why was Earth a fiery hell 55 million years ago?

On the other hand, this article, http://www.washingtonpost.com/wp-srv/national/horizon/sept98/sea.htm


One day in the Caribbean Sea, at the end of the Paleocene epoch 55 million years ago, a volcano blew, spewing a climate-altering parasol of tiny particles high into the atmosphere. Such events are hardly rare. But this was no ordinary volcano: It was huge. And this was no ordinary time in the planet's history: The environment already was on the threshold of profound change.

According to a new theory proposed by marine geologist Timothy Bralower of the University of North Carolina at Chapel Hill, climatic fallout from the Caribbean eruption pushed Earth beyond that threshold, triggering what has been identified in the last 10 years as one of the most remarkable worldwide transformations known.

In the dry argot of earth scientists, this event is called the Late Paleocene Thermal Maximum, or LPTM. In the language the rest of us speak, it is simply unbelievable.

Its prelude, innocuously enough, was a long-term global warming trend that began about 60 million years ago and weakened the circulatory system of the world's oceans. Five million years of that warming seems to have left Earth's environment vulnerable to catastrophic change.

Then, at the very end of the Paleocene, the circulation system experienced the oceanic equivalent of a heart attack. The global network of ocean currents stopped doing its vital job of delivering cold, oxygen-rich water to the deep ocean. As a result, the abyss warmed and stagnated.

This shock caused a mass extinction of marine organisms, including as many as half of all species of deep-sea foraminifera. This family of ubiquitous one-celled sea animals forms one of the primary links in the oceanic food chain. The mass killings of forams and other species, Bralower says, represent "the biggest extinction event in the deep sea in the last 90 million years. Nothing else even comes close."

When the oceanic heart attack struck, Earth was considerably warmer than today, thanks to the 5-million-year global warming trend. Global average air temperature was several degrees higher than now, chiefly because the poles were far warmer.

I guess I'll have to contact him and find out what he's talking about.

Dora Smith
Austin, TX
----- Original Message ----- From: "Dora Smith" <villandra@austin.rr.com>
To: <villandra@austin.rr.com>
Sent: Saturday, January 26, 2008 2:27 PM
Subject: Re: Why was Earth a fiery hell 55 million years ago?

Actually, closer reading of these articles betrays possible confusion.

First of all, the Caribbean large igneous province isn't even in teh Caribbean; it's in the Pacific.

Second, that event ended 69 million years ago, and the articles in question appear to link it to an ocean die-off 94 million years ago, which is a different event. This and a string of flood basalt volcanoes from Greenland to Great Britain that did occur at 55 to 56 million years ago, just happen to sometimes get discussed together.

So I don't know if there is any evidence for a Caribbean eruption of that magnitude at 55 mya, or not.

Dora Smith
Austin, TX

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