R
Rick
Guest
It's about time to let the public know, I suppose.
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@geol.ucsb.edu <mailto:kennett@geol.ucsb.edu>_
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 sheet 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 sheet 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-sheet 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@geol.ucsb.edu <mailto:kennett@geol.ucsb.edu>