[meteorite-list] New PNAS Paper About Firestone’s Impact Hypothesis

[Paul]

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

The abstract is at 

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

Jaconson et al. (1987) did a study of the rate at which the 
vegetation of North America changed during the last 15,000
years. They found from the examination of sevreal well-dated 
and continuous paleovegetational records that there were
only three major periods of rapid vegetational change in the 
northeast Midwest and southeast United States during this 
time. None of them correspond to the time of Firestone’s 
hypothesized impact. There is a complete lack of any 
evidence of significant vegetation changes in the 
paleovegetation records from numerous lake cores for 
Firestone’s hypothesized impacts. These times are shown 
as green lines in Figure 4 at:

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

Given the claims made for the size, magnitude, and
devastation of his hypothesize impact, the complete lack of 
any significant effect, which can be seen the paleovegetational
records in cores from any of numerous lakes within the 
Midwestern and eastern North America, as summarized
by Jaconson et al. (1987), raises the same questions about
Firestone’s hypothesis that the analysis of radiocarbon
dates by Buchanan et al. (2008) does.

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.