A VERY UNUSUAL DISCUSSION: A COSMIC IMPACT AND THE YOUNGER DRYAS

The following is a copy of a notice posted in the Cambridge Conference
Network mailing list (CCNET) which I am reposting with the permission
of the author - Professor James P Kennett, University of California
Santa Barbara, Dept. of Earth Science

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A VERY UNUSUAL DISCUSSION: A COSMIC IMPACT AND THE YOUNGER DRYAS

From: Allen7633@xxxxxxx [mailto:Allen7633@xxxxxxx]
Sent: Mon 05/02/2007 22:24
To: Paleoclimate-List@xxxxxxxxxxxxxxxxxx
Subject: A Cosmic Impact and the Younger Dryas

Re: The Younger Dryas Impact Event:

Fellow scientists,

The AGU 2007 Joint Assembly is being held 22-25 May 2007, in Acapulco,
Mexico. Please join us for a very unusual discussion.

Contact; Prof. James Kennett, University of California, SB:
kennett@xxxxxxxxxxxxx
Conference details are at: //:www.agu.org/meetings/ja07/?content=home
Abstract submission is at:
//:submissions5.agu.org/submission/entrance.asp
Deadline: 1 MARCH 2007 23:59 UT

The Younger Dryas Impact Event: The deglaciation that followed the
last ice age was abruptly and dramatically interrupted ~12,900 years
ago by widespread cooling that marks the onset of the Younger Dryas.
Much evidence shows that the Younger Dryas was marked by abrupt
changes in ice *** configuration, the sudden emptying of proglacial
lakes, diversion of North American flood-waters to the northern
Atlantic, and the reorganization of thermohaline circulation.

Nevertheless, significant questions have recently emerged about timing
and direction of major freshwater flows to the oceans, in turn raising
questions about the triggering mechanism for the Younger Dryas. The
onset of the Younger Dryas also appears to have coincided with
massive, widespread, and punctuated changes in animal biota and
Paleolithic cultural development centered in North and South America.
This is represented by the most recent of all mass extinctions, the
disappearance of the megafauna of the Americas, including mammoths,
horses, and ground sloths and the termination of Clovis and other
contemporaneous Paleolithic human cultures. The cause of these changes
is highly controversial and much debated, but is likely tied to the
severe environmental changes that occurred at the beginning of the
Younger Dryas. Another hypothesis attributes the extinctions to
overhunting by Clovis people and other Paleolithic hunters or to
pandemics associated with human migrations. However, all these
hypotheses appear to fall short in satisfactorily explaining much
available evidence.

A new hypothesis posits that Younger Dryas cooling was instead
triggered by extraterrestrial impacts that caused ice ***
destabilization, flood-water rediversion, and changes in ocean
circulation. This work offers newly uncovered evidence for an ET
impact or airbursts at 12.9 ka including end-Clovis-age sediments
throughout North America with high levels of iridium, magnetic and
carbon spherules, glass-like carbon, fullerenes, and ET noble gas
ratios often in association with carbonaceous layers ("black mats")
with unusual biota.

In this session, we invite abstracts that will explore the strengths
and weaknesses of existing and new hypotheses that attempt to explain
the cause of the Younger Dryas, changes in global climate, the
extinctions, and human cultural changes. We are interested in
exploring new perspectives on the chronology, stratigraphic
succession, and potential interconnections between a wide-range of
processes that appear to have been associated with the Younger Dryas.
These include abrupt climatic change, ice-*** deglaciation,
flood-water rerouting, surficial geology, iceberg discharge, ocean
reorganization, including thermohaline circulation, and sea-level
change.

Hope to see you there,

James P Kennett, Prof
University of California Santa Barbara
Dept. of Earth Science
Santa Barbara, CA, USA 93106
805-893-3103
kennett@xxxxxxxxxxxxx

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Eric Stevens
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