[meteorite-list] New "Big Impact" Theory

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Wed, 19 Sep 2012 12:54:00 -0500
Message-ID: <D0FED60E485549B298D93CAB0E00DAB7_at_ATARIENGINE2>

New "Big Impact" theory. In case you find the
references to a "new Ice Age" puzzling, I'll remind
you that it's the Ice Age that we in right now. Yes,
friends, we are in an Ice Age, at 5-7 C. below the
long-term norm.

The full text of the article follows.


Sterling K. Webb
-----------------------------------------------------------------
http://www.sciencedaily.com/releases/2012/09/120919103612.htm

Did a 'Forgotten' Meteor
Have a Deadly, Icy Double-Punch?

ScienceDaily (Sep. 19, 2012) - When a huge
meteor collided with Earth about 2.5 million
years ago and fell into the southern Pacific
Ocean it not only could have generated a
massive tsunami but also may have plunged
the world into the Ice Ages, a new study suggests.

A team of Australian researchers says that because
the Eltanin meteor -- which was up to two kilometres
across -- crashed into deep water, most scientists
have not adequately considered either its potential
for immediate catastrophic impacts on coastlines
around the Pacific rim or its capacity to destabilise
the entire planet's climate system.

"This is the only known deep-ocean impact event on
the planet and it's largely been forgotten because
there's no obvious giant crater to investigate, as there
would have been if it had hit a landmass," says Professor
James Goff, lead author of a forthcoming paper in the
Journal of Quaternary Science. Goff is co-director of
UNSW's Australia-Pacific Tsunami Research Centre and
Natural Hazards Research Laboratory.

"But consider that we're talking about something the
size of a small mountain crashing at very high speed
into very deep ocean, between Chile and Antarctica.
Unlike a land impact, where the energy of the collision
is largely absorbed locally, this would have generated
an incredible splash with waves literally hundreds of
metres high near the impact site.

"Some modelling suggests that the ensuing mega-tsunami
could have been unimaginably large -- sweeping across
vast areas of the Pacific and engulfing coastlines far inland.
But it also would have ejected massive amounts of water
vapour, sulphur and dust up into the stratosphere.

"The tsunami alone would have been devastating enough
in the short term, but all that material shot so high into
the atmosphere could have been enough to dim the sun
and dramatically reduce surface temperatures. Earth was
already in a gradual cooling phase, so this might have
been enough to rapidly accelerate and accentuate the
process and kick start the Ice Ages."

In the paper, Goff and colleagues from UNSW and the
Australian Nuclear Science and Technology Organisation,
note that geologists and climatologists have interpreted
geological deposits in Chile, Antarctica, Australia, and
elsewhere as evidence of climatic change, marking the
start of the Quaternary period. An alternative interpretation
is that some or all of these deposits may be the result of
mega-tsunami inundation, the study suggests.

"There's no doubt the world was already cooling through
the mid and late Pliocene," says co-author Professor Mike
Archer. "What we're suggesting is that the Eltanin impact
may have rammed this slow-moving change forward in an
instant -- hurtling the world into the cycle of glaciations
that characterized the next 2.5 million years and triggered
our own evolution as a species.

"As a 'cene' changer -- that is, from the Pliocene to Pleistocene --
Eltanin may have been overall as significant as the meteor
that took out the non-flying dinosaurs 65 million years ago.
We're urging our colleagues to carefully reconsider conventional
interpretations of the sediments we're flagging and consider
whether these could be instead the result of a mega-tsunami
triggered by a meteor."
Received on Wed 19 Sep 2012 01:54:00 PM PDT