[meteorite-list] 3 INQUA abstracts re Younger Dryas cold era evidence, James P and Douglas J Kennett, July 2011 Bern, Switzerland: Rich Murray 2011.09.17

From: Rich Murray <rmforall_at_meteoritecentral.com>
Date: Sat, 17 Sep 2011 21:28:47 -0700
Message-ID: <CAHqJ8pZVEgTYDJH_WWL-asqBo7JiTeBsoVHv0taKq5xxAnmivA_at_mail.gmail.com>

3 INQUA abstracts re Younger Dryas cold era evidence, James P and
Douglas J Kennett, July 2011 Bern, Switzerland: Rich Murray 2011.09.17
http://rmforall.blogspot.com/2011/09/3-inqua-abstracts-re-younger-dryas-cold.html

http://cosmictusk.com/upcoming-bern-inqua-conference-packed-with-younger-dryas-boundary-studies

[ Put the ID number in place of 1666 to get other abstracts ]

http://www.inqua2011.ch/?a=programme&subnavi=abstract&id=1666&sessionid=60

Abstract
ID: 1666
Title: Younger Dryas Onset Marked by Dramatic Environmental and Biotic Change
Content:
        
The onset of the Younger Dryas (YD) episode was marked by a complex
array of abrupt and potentially linked changes in the Earth's
environmental and biotic systems.

We will broadly review YD changes in atmosphere and ocean circulation,
ice sheets, North American continental hydrosphere, biosphere
including extinctions, and human culture.

The cause of the YD is controversial and currently debated, yet any
causal hypothesis needs to account for these changes.

YD cooling is enigmatic in its timing, magnitude and abruptness at
near-peak insolation.

Such cooling episodes with YD characteristics and timing in earlier
Terminations appear more affiliated with terminal glacial episodes.

YD onset is also outstanding because of close collective association
with major, abrupt continental-scale ecological reorganization,
megafaunal extinction and human adaptive shifts.

The YD climate onset was remarkably abrupt (~one year) suggesting
atmospheric climate response preceded oceanic change.

Maximum cooling was atypically early, near the YD onset and associated
with an abrupt increase in atmospheric dust.

A major North American hydrographic reorganization, apparently
associated with destabilization of ice sheet margins, was marked by
abrupt switch in flow from the south to northern oceans.

This outburst flooding may have coincided with major drainage of Lake Agassiz.

Associated outburst floods affected widely separated areas of the Arctic.

The ocean responded by major change in meridional overturning.

On land, responses include widespread evidence of biomass burning;

change in sediment deposition including a layer with exotic materials
interpreted to be of cosmic impact origin;

broad continental vegetation disruption;

abrupt megafaunal extinction; and

genetic bottlenecks reflecting population declines and/or animal migrations.

The North American human record suggests abrupt disappearance of the
Clovis culture;

a human genetic bottleneck; and

a widespread archeological gap during early YD centuries.

Session: 60 The enigmatic Younger Dryas climatic episode
Authors: James Kennett
Presenter: James Kennett
Type: oral


ID: 1526
Title: Soot as Evidence for Widespread Fires at the Younger Dryas
Onset (YDB, 12.9 ka)
Content:
        
Evidence continues to grow in support of a major extraterrestrial (ET)
impact as a trigger for the late Pleistocene megafaunal extinction in
North America at the onset of the Younger Dryas (YDB, 12.9 ka).

Sediment at the base of a C-rich, dark layer is marked by peaks in
magnetic microspherules, Ir, nanodiamonds, and other materials
consistent with an ET event (Firestone, 2007; Kennett, 2008).

This layer also exhibits spikes in charcoal, C spherules, glass-like
C, and PAHs indicative of continent-wide burning, coeval with evidence
for a major abrupt increase in burning in Greenland (Mayewski, 1993;
Legrand, 1997).

Synchronous, widespread soot in high abundances is a marker for
extensive, impact-related fires.

Soot analysis allowed us to test the possibility that the explosion of
an impactor triggered combustion of biomass or fossil C, as
hypothesized for the Cretaceous-Paleogene (K-P, 65 Ma) (Wolbach, 1985;
Belcher et al., 2009).

Previous analyses of samples from N. America and Europe, yielded YDB
soot (? 10%) at two sites in N. America:
Murray Springs, AZ (20 ppm) and
Blackville, SC (2000 ppm) (Wolbach, 2007).

We now report results from analysis of six more sites:
Arlington Canyon and nearby Arlington Springs, CA;
Bull Creek, OK;
Hall's Cave, TX;
Murray Springs (new sampling); and
Lommel, Belgium.

Soot concentrations spike in the YDB layer at four of these sites:
2000 ppm at Arlington Canyon, CA;
500 ppm at Bull Creek;
2000 ppm at Hall's Cave, TX; and
6000 ppm at Murray Springs, 30x higher than previously observed there.

Significant YDB soot at five locations up to 3500 km apart across
North America, combined with other wildfire evidence, suggests
widespread burning and aeolian transport of soot across North America
~12.9 ka ago.

These results support an impact sufficient to ignite continental-scale fires.

Session: 60 The enigmatic Younger Dryas climatic episode
Authors: Adrienne Stich
Charles Kinzie
James Kennett
Allen West
Wendy Wolbach
Presenter: James Kennett
Type: poster


ID: 1584
Title: Human Population Decline across Parts of the Northern
Hemisphere during the Younger Dryas Cooling Period
Content:
        
There is an ongoing debate about a possible human population decline
or contraction at the onset of the Younger Dryas (YD) at 12.9 ka.

We used three methods to test whether YD climate change affected human
population levels.


FREQUENCY ANALYSES.

This method employed lithic projectile point data from the Paleoindian
Database of the Americas
(PIDBA, http://pidba.utk.edu ).

We tallied diagnostic projectile points used by North American
Paleoindian cultures, such as Clovis, that existed prior to about 12.9
ka, and obtained point totals that were larger than those of
immediately post-Clovis cultures.

For the SE U.S., the ratio of Clovis points (n=1993) to post-Clovis
points (n=947) reveals a point decline of 52%.

For the Great Plains, a comparison of Clovis and fluted points
(n=4020) to Folsom points (n=2527) shows a point decline of 37%,
suggesting a population contraction of similar magnitude.

QUARRY USAGE.

Eleven major Clovis-age lithic quarry sites in the Southeastern U.S.
exhibit either limited usage or total abandonment just after the YD
onset, only to resume normal usage hundreds of years later.

Those usage patterns imply a severe population decline or
reorganization around 12.9 ka.

SUMMED PROBABILITIES.

This method involved calibrating relevant 14C dates from across the
Northern Hemisphere and combining the probabilities, after which major
peaks and troughs in the trends were assumed to reflect changes in
human demographics.

We found an abrupt, statistically significant decline at 12.9 ka,
followed by a rebound 200 to 900 years later.

The overall decline was more than 50%, similar in magnitude to the
decline in Clovis-Folsom point ratios.

The coeval YD declines in projectile points, quarry usage, and 14C
dates appear linked to significant changes in climate and biota.

While the causes of the YD remain controversial, evidence suggests
that human population declines occurred nearly simultaneously across
the Northern Hemisphere around 12.9 ka.

Session: 60 The enigmatic Younger Dryas climatic episode
Authors: David G. Anderson
Albert C. Goodyear
James Kennett
Allen West
Presenter: James Kennett
Type: poster


http://www.geol.ucsb.edu/faculty/kennett/Home.html

[ photo ]
Professor: Marine Geology, Paleoceanography, Stratigraphy,
Micropaleontology, Paleobiology

Office: Webb Hall 1037A
Phone: (805) 893-3103 or
805-893-4187
FAX: 805-893-2314
E-mail: kennett at geol.ucsb.edu
         
Research Interests
         
Research largely deals with earth system history during the Cenozoic
based on the analyses of the deep sea sedimentary record and the
uplifted marine record on land.
A variety of paleoenvironmental proxies are used (stable isotopes,
fossils, sediments) to reconstruct paleoclimatic, oceanographic and
biotic changes in the sedimentary record.
Of greatest interest is to help develop better understanding of past
global changes; to evaluate the dynamic interactions that constantly
occurred in the past between the several global spheres (lithosphere,
oceansphere, atmosphere, cryosphere and biosphere).

The kinds of questions we think about include the following:
What is the climate evolution of the polar regions?
When and how did the major ice sheets form?
How have changes in ocean circulation affected global climate development?
How did the oceans circulate during times of global warming?
How tight are the linkages between climate change and thermohaline circulation?
How rapidly do climate and oceans switch between different states and
what processes drive these changes?
How has the global climate changed during the classic ice-age period
and how has this affected North American climate? What is the record
of biological evolution in the oceans and how does this help with the
understanding of evolutionary processes?
Data related to this and other questions are generated in light stable
isotope mass spectrometry and micropaleontological laboratories.


http://pages.uoregon.edu/dkennett/

Department of Anthropology
University of Oregon
Eugene, OR 97403-1218
Phone (Office): 541-346-5106
E-mail: dkennett at uoregon.edu



Abstracts for Session 60 ?The enigmatic Younger Dryas climatic episode?
Oral Presentations July 20-27, 2011 INQUA Conference, Bern, Switzerland

ID Title Presenter Talknbr. Invited
1666 Younger Dryas Onset Marked by Dramatic Environmental and Biotic
Change James Kennett 1 x
835 The Younger-Dryas Cold reversal: Ice-Earth-Ocean Intercations
During a Period of Rapid Climate Change Richard Peltier 2 x
366 Assessing the effectiveness of different freshwater drainage
routes at triggering the Younger Dryas Alan Condron 3
2964 Reduced Atlantic Meridional Overturning Circulation (AMOC) and
Regional Climate Change During the Younger Dryas Jerry McManus 4 x
3138 Oceanic Variability in the Gulf of Alaska during the Younger
Dryas Summer K. Praetorius 5
1514 Abrupt changes in runoff from North America during the Younger
Dryas James Teller 6 x
262 Younger Dryas glaciation of Scandinavia ? the type area for the
Younger Dryas Jan Mangerud 7 x
1813 Unusual material in early Younger Dryas age sediments and their
potential relevance to the YD Cosmic Impact Hypothesis Malcolm
LeCompte 8 x
2641 Exceptional iridium concentrations found at the Aller?d-Younger
Dryas transition in sediments from Bodmin Moor in southwest England
William Marshall 9
1556 Nanodiamonds and the Usselo layer Annelies van Hoesel 10
2768 Vegetation change and the Younger Dryas: a continental-scale
perspective Matthew Peros 11 x
209 The Younger Dryas in the Neotropics: paleoecological evidence from
Venezuela Encarni Montoya 12 x

Posters

ID Title Presenter

583 New paleoclimatic reconstruction for the Aller?d and Young Dryas
of the plain part of Ukraine (based on palynological data) Lyudmila
Bezusko
997 Vegetation dynamics during Younger Dryas climatic episode (12600 ?
11500 yr. cal. B.P.) in Northwest Lithuania Eugenija Rudnickaite
1177 Effective moisture during the late glacial to Holocene transition
from mainland eastern Australia John Tibby
1181 The boundary phenomenon of the Pleistocene ? Holocene in the
Baikal Siberia (Russia) Natalia Berdnikova
1184 A review on the radiocarbon and absolute chronologies bracketing
the Younger Dryas climatic event Edouard Bard
1294 Individual and community responses of diatoms to the Younger
Dryas climatic reversal in a South Carpathian glacial lake Krisztina
Buczk?
1378 North Atlantic reservoir ages linked to high Younger Dryas
atmospheric radiocarbon concentrations William Austin
1447 The Bull Creek valley stream terraces, buried soils, and
paleo-environment during the Younger Dryas in the Oklahoma Panhandle,
USA Alexander Simms
1526 Soot as Evidence for Widespread Fires at the Younger Dryas Onset
(YDB, 12.9 ka) James Kennett
1584 Human Population Decline across Parts of the Northern Hemisphere
during the Younger Dryas Cooling Period James Kennett
1587 Eastward Drainage of Glacial Lake Agassiz: The Perspective from
the Lake Superior Basin Steve M. Colman
1591 Nanodiamonds as Evidence for a Younger Dryas Cosmic Impact Event Allen West
1606 Shock-melt Evidence for a Cosmic Impact with Earth during the
Younger Dryas at 12.9 ka Allen West
1619 Evidence for Widespread Biomass-Burning at the Younger Dryas
Boundary at 12.9 ka Allen West
2667 Greater-than-present wet conditions from 14.6 to 10.2 cal ka yr
BP in the southwestern Great Lakes area, North America Brandon Curry
2765 Evidence of Younger Dryas aridity in dune-paleosol successions in
the Midwest of U.S.A. Hong Wang
2853 Pedogenic Climate Signals in the Great Plains (USA) during the
Pleistocene-Holocene Transition (B?lling/Aller?d ? Boreal) William C
Johnson
2875 The Aller?d-Younger Dryas Transition in lake sediments from The
Netherlands Wim Hoek
3116 Megafaunal Extinction at the Younger Dryas Onset in North America
Douglas Kennett
3134 Carolina Bays: Younger Dryas Time Capsules Malcolm LeCompte


Pierson Barretto gives best amateur site for worldwide evidence for
Holocene impacts: Rich Murray 2011.09.06
http://rmforall.blogspot.com/2011/09/pierson-barretto-gives-best-amateur.html


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Boston University Graduate School 1967 psychology,
BS MIT 1964, history and physics,
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Received on Sun 18 Sep 2011 12:28:47 AM PDT