Re: Here We Go Again About Terminal Pleistocene Impact
Paul bristolia at yahoo.comWed Aug 13 23:21:14 EDT 2008
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 noted:
"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.
