Undersea volcanic activity blamed for mass extinction 93 million years ago 

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Undersea volcanic activity blamed for mass extinction 93 million years ago


16 Jul 08 - Researchers from the University of Alberta, Canada, found a tell-tale signature of underwater volcanism in rocks dating to a mass extinction 93 million years ago.

At the time of the event, average temperatures were higher than today’s, the researchers say.

               How could that possibly happen without humans around?
               You don’t suppose that ocean warming is a natural
               occurrence, do you?

Palm trees grew in what would later become Alaska and large reptiles roamed northern Canada. The Arctic Ocean was ice-free and scientists think it would have had a temperature we might describe today as lukewarm.

However, the oceans were also hit by a mass extinction which wiped out a type of large clam common at the time as well as foraminifera, tiny ocean creatures that live on the sea floor.

After the extinction, the earth lurched into a sudden, but short-lived, period of cooling.

               Which, as you probably know, is where I think we’re
               headed right now.

According to Steve Turgeon and Robert Creaser from Alberta's department of Earth and atmospheric sciences, whose findings were recently published in Nature, volcanic eruptions on the ocean floor appear to have altered the chemistry of the sea and possibly of the atmosphere also.

A lava bed of the present-day Caribbean was formed by the huge lava flows thought to have been involved. However, the researchers say the flows would have preceded the extinction by up to 23,000 years.

               Huge lava flows and lukewarm oceans.

               Hey guys, do you suppose that those huge lava flows –
               pumping 2,150-degree lava into the seas -  might have
               had anything to do with the lukewarm water?

Two theories, which are not mutually exclusive, have emerged to explain the chemistry of what happened next, says Tim Bralower, a geologist at Pennsylvania State University, US, who reviewed the paper.

One possibility is that the volcanoes … disgorged clouds of CO2 to the atmosphere, warming the climate to the extent that Earth's ocean circulation system ground to a near-halt.

               So …ancient underwater volcanoes “disgorged clouds
               of CO2 into the atmosphere.”

               Wouldn’t it make sense that that’s where the CO2 in
               our atmosphere is coming from today?

Thanks to Tim Rian and Steven Ehrlich for this link




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