[meteorite-list] Re Here We Go Again About Terminal Plesitocene Impact

[Paul]

In http://six.pairlist.net/pipermail/meteorite-list/2008-August/046148.html ,
Darren Garrison noted the article “Comet strike would be cataclysmic” at:

http://www.thisiswesternmorningnews.co.uk/news/Comet-strike-end-world-scenario/article-265193-detail/article.html

The article states:

“Fiery debris from the comet also melted 
huge portions of the ice sheet, which
drastically altered the planet's climate. 
Massive volumes of fresh water found
their way into the oceans and changed 
their currents, plunging the Earth into 
an Ice Age for 1,000 years.”

It is interesting to note that Dyke (2004) made a detailed study of 
the deglaciation of North America. As a part of this study, he 
constructed and published in this paper a series of detailed 
paleogeographic maps showing the extent of ice starting at 18,000 
C14 BP and ending at 5,000 C14 BP. for time periods ranging from 
500 to 100 years. 

From calculating ice volumes using these paleogeographic
maps Dyke (2004) states:

“The world’s largest ice sheet complex lost 
<10% of its area prior to 14 ka BP. It then 
retreated nearly linearly until 7 ka BP, by 
which time only 10% of the area remained
more glaciated than today. This linear 
reduction of area, as currently understood, 
was interrupted by two events: a reduced 
rate of recession during the later half of the
Younger Dryas, and an increased rate as ice 
was clearing from Hudson Bay (Fig. 5). 
These events are clearer when plotted on 
the calendar time scale, because the 
radiocarbon time scale abbreviates the 
duration of the impact of the Younger Dryas 
effect in North America (Fig. 5b).”

At the beginning of the Younger Dryas, Dyke (2004) shows a lack 
of any abrupt increase in the retreat (melting) of the North American 
ice sheet. So far, the proponents of this theory have provided  a 
single shred of evidence that massive melting of the ice sheets, as 
described in the newspaper article, actually occurred. 

There is significance evidence of the discharge of large amounts 
of freshwater from either Lake Agassiz, the melting of the Keewatin 
ice dome, or combination of both sufficient to shut down 
thermohaline circulation within the Atlantic Ocean, i.e. Alley (2000), 
Broecker (2003), and Tarasov and Peltier (2006). The water 
contained by Lake Agassiz was already there and was simply 
released, not created, abruptly.

References:

Alley, R.B., 2000, The Younger Dryas cold interval as 
viewed from central Greenland. Quaternary Science 
Reviews. vol. 19, no. 1-5, pp. 213-226.

Broecker, W.S., 2003, Does the Trigger for Abrupt 
Climate Change Reside in the Ocean or in the Atmosphere? 
Science. vol. 300, pp. 1519-1522.

Dyke, 2004 A.S. Dyke, An outline of North American 
deglaciation with emphasis on central and northern Canada. 
In: J. Ehlers and P.L. Gibbard, EDS., pp. 373–424, 
Quaternary Glaciations—Extent and Chronology, Part II 
vol. 2b, Elsevier, Amsterdam.

Tarasov , L., and W.R. Peltier, 2005, A calibrated deglacial 
drainage chronology for the North American continent: 
evidence of an Arctic trigger for the Younger Dryas. 
Quaternary Science Reviews. vol. 25, pp. 659–688

Also, look at:

States and Stability of Climate System, PDF file at:

http://www.iac.ethz.ch/education/bachelor/climate_systems/notizen/Climate-States-and-Stability.pdf.

The newspaper article also stated:

“It left no impact crater but sparked the 
biggest wildfires in history, which stretched
 across the continent and suffocated humans 
and animals with overwhelming amounts 
of soot and smoke, leaving the few survivors 
with no vegetation or prey to live on.

The just published paper, which I mention in my previous post
comments on this claims. The paper is;

Buchanan, B., M. Collard, and K. Edinborough, 2008,
Paleoindian demography and the extraterrestrial impact
hypothesis. Proceedings of the National Academy of
Sciences. Published online before print August 12,
2008, doi: 10.1073/pnas.0803762105

http://www.pnas.org/content/early/2008/08/11/0803762105.abstract

They fnoted:

"Given that the ET impact is proposed to have 
occurred north of the Great Lakes, if the trough 
represents a population decline, there should be 
significantly fewer Paleoindian radiocarbon dates in 
northern latitudes during the second time period 
compared with the first and third time periods. 
This is not the case."

They concluded:

"The results of our analysis are consistent with recent 
comments by Pinter and Ishman (13) and Haynes (14). 
Pinter and Ishman reject Firestone et al.’s (1) claim 
that there was a devastating ET impact north of the 
Great Lakes at 12,900+/-100 calBP."

and

“The results of the analyses were not consistent 
with the predictions of extraterrestrial impact 
hypothesis. No evidence of a population decline 
among the Paleoindians at 12,900 ± 100 cal BP 
was found.”

Note:

"Pinter and Ishman (13)" = Pinter, N., and S. E. Ishman, 2007,
Impacts, mega-tsunami, and other extraordinary claims. GSA
Today. vol. 18, no. 1, pp. 37-38.

http://www.gsajournals.org/archive/1052-5173/18/1/pdf/i1052-5173-18-1-37.pdf

Also look at figure 4 at:

http://www.hallofmaat.com/images/004Fig.jpg

Notice there were three major periods of rapid vegetational change
in the northeast Midwest and southeast United States as indicated 
by the green lines, None of them correspond to Firestone’s 
hypothesized impact. There is a complete lack of any evidence in 
the paleovegetation records from numerous lake cores in these 
areas for Firestone’s hypothesized impacts. Given the claims 
made for the size, magnitude, and devastation of his hypothesize 
impact, it is impossible for entire ecosystems to have been 
devastated by continent-wide wildfires and not significantly changed
the vegetation in an abrupt manner  The lack of any apparent effect 
on vegetation in North America as illustrated by Jacobson et al. 
(1987) grossly contradicts, if not refutes, the geopoetry, which 
appears in this newspaper article, about continent-wide 
devastating wildfires.

References cited:

Jacobson, George L., Jr., Webb, Thompson, III, and Grimm, 
Eric E., 1987, Patterns and rates of vegetational change 
during the deglaciation of North America. in W. F. Ruddiman 
and H. E. Wright, Jr., eds., pp. 277-287. North America 
Adjacent Oceans During the Last Deglaciation. The Geology 
of North America. vol. K-3. Geological Society of America, 
Boulder, Colorado.

Yours,

Paul H.