I am off to camp for indian tribe weekend with the Growling Bears.
No time for commentary — enjoy!
The Bos, et al.:
LETTER Faulty protocols yield contaminated samples, unconfirmed results
LeCompte et al. (1) reported abundant magnetic microspherules from three
Younger Dryas Boundary (YDB) sites, which they concluded are consistent with
those interpreted by Firestone et al. (2) as markers of extraterrestrial
impacts or airbursts. LeCompte et al. argued that the negative results of
Surovell et al. (3)—who did not observe microspherules—must have been
because of a deviation from an analytical protocol of A. West that is required
to observe them. A. West developed and refined various protocols that enabled
him to prepare samples in which putative impact markers have been reported.
Samples collected by others have failed to reproduce his findings. Magnetic
microspherules are only one of a large suite of professed impact markers found
in samples prepared by A. West, and the LeCompte et al. (1) result must be put
into context. The most celebrated example was the report of hexagonal
nanodiamonds in Greenland ice samples collected for a television program in
2008 (4), prepared by A. West using a nonstandard protocol. This result was
never confirmed, and repeated requests for samples have been denied. A. West
stated that samples were limited and would be provided to other researchers.
However, no other researcher has reported receiving a sample, and no
participants of any subsequent expedition to Greenland have reported locating
the layer or collecting samples. Boslough et al. (5) did acquire carbon
microspherules that A. West prepared from the Gainey site in Michigan, one of
nine key YDB sites for which Firestone et al. (2) presented marker evidence.
One microspherule was dated and yielded a radiocarbon age of 207 ± 87 y BP.
This result suggests that A. West’s protocols and sample preparation methods
do not eliminate contaminants that are unrelated to the YDB or to an impact.
Unfortunately, no samples from the LeCompte et al. (1) study are available for
distribution to test for this possibility. Finally, the protocol for the blind
study was not revealed, nor the identity of the nonparticipating third party
who was responsible for preparing, repackaging, and distributing the blind
samples. The article described itself as an “independent blind
evaluation.” However, there is overlap in the authorship of LeCompte et al.
(1) and Firestone et al. (2). Without full disclosure of individuals and their
involvement, it is not possible to confirm independence. Blind protocols and
techniques can vary, depending on applications that range from drug testing to
high-energy physics. LeCompte et al. (1) did not refer to their study as
doubleblind, which is conventionally applied to research involving human
subjects to control for placebo effects. M. LeCompte revealed that it was
indeed double-blind but failed to provide details. In physical sciences, the
meaning of “double-blind” is ambiguous. Only when all protocols are
precisely defined, all key collaborators identified, and materials made
available, can the LeCompte et al. (1) results be properly evaluated to
determine whether or not they are consistent with and fully independent of
Firestone et al. (2). ACKNOWLEDGMENTS. Sandia is a multiprogram laboratory
operated by Sandia Corporation, a Lockheed Martin Company, for the US
Department of Energy under Contract DE-AC04-94AL85000. Mark Boslough1
Discrete Math and Complex Systems Department, Sandia National Laboratories,
Albuquerque, NM 87185 1 LeCompte MA, et al. (2012) Independent evaluation of
conflicting microspherule results from different investigations of the Younger
Dryas impact hypothesis. Proc Natl Acad Sci USA 109(44): E2960–E2969. 2
Firestone RB, et al. (2007) Evidence for an extraterrestrial impact 12,900
years ago that contributed to the megafaunal extinctions and the Younger Dryas
cooling. Proc Natl Acad Sci USA 104(41): 16016–16021. 3 Surovell TA, et al.
(2009) An independent evaluation of the Younger Dryas extraterrestrial impact
hypothesis. Proc Natl Acad Sci USA 106(43):18155–18158. 4 Kurbatov, et al.
(2010) Discovery of a nanodiamond-rich layer in the Greenland ice sheet. J
Glaciol 56(199):749–759. 5 Boslough M, et al. (2012) Arguments and evidence
against a Younger Dryas impact event. Climate, Landscapes, Civilizations, eds
Goisan L, Fuller DQ, Nicoll K, Flad RK, Clift PD, Geophysical Monograph Series
198:13–16. Author contributions: M.B. designed research, performed research,
and wrote the paper. The author declares no conflict of interest. 1E-mail:
email@example.com. www.pnas.org/cgi/doi/10.1073/pnas.1220567110 PNAS Early Edition |
1 of 1 LETTER
From LeCompte et al.
LETTER Reply to Boslough: Prior studies validating research are ignored In
PNAS, M. Boslough (1) raises issues about carbon spherules and nanodiamonds
unrelated to our magnetic spherule focused research (2). Boslough should
instead address the questions he raises to the appropriate investigators.
Boslough’s letter contains inaccurate and misleading statements, suggesting
he misread our report. Boslough incorrectly states that A. West devised the
spherule protocol, instead of archaeologist W. Topping, who was also
responsible for some of the spherule results reported by Firestone et al. (3).
Boslough then asserts, “Samples collected by others have failed to reproduce
his findings” (1). Boslough continues to overlook our results and others’.
We cite five independent groups that have successfully reproduced magnetic
spherule results and other evidence. Boslough’s “discovery” of a
purportedly “recent” carbon spherule in Younger Dryas Boundary (YDB)
sediment at Gainey, MI, ignores the prior published research of Firestone et
al. (4) that characterizes the problematic nature of carbon spherule dating at
the Gainey site, distinct from any possibility of contamination. Every user,
including Surovell et al. (5), accepted the magnetic spherule protocol’s
efficacy. Boslough too, tacitly accepted its validity until the negative
results of Surovell et al. were challenged, after which Boslough concluded
that the protocol must be “faulty,” rather than Surovell’s conclusions.
Boslough’s position is puzzling at best. Furthermore, one of Surovell’s
coauthors, Vance Haynes, independently validated the correct use of the
protocol by finding thousands of magnetic spherules in YDB sediment at Murray
Springs, Arizona. Thus, Surovell et al.’s conclusions were contraindicated
by one of their own coauthors. Regarding coauthorship, there is no overlap
with Firestone et al. (3), except for the Topper site director, Albert
Goodyear. He designed the important experiment performed at the Topper quarry
and assisted in interpreting its results, but otherwise played no role in
identifying or characterizing magnetic spherules, which was accomplished
independently of his input. We performed an informal “double-blind study”
exactly as described, the procedures of which were tailored to and successfully
accomplished our stated objective: ensuring that sample stratigraphy was
unknown to the examiner. Respecting the requested anonymity of a third-party
facilitator is normal practice and reasonable given the contentious nature of
this debate. We unequivocally affirm the neutrality and independence of our
facilitator with respect to the YDB-impact hypothesis. Our report’s (2)
primary purpose was to resolve the conflicting results of two spherule
studies. Like other investigators, we found Firestone et al.’s (3) results to
be reproducible, whereas Surovell et al.’s (5)were not.We also found it
irrefutable that Surovell et al. did not follow the prescribed protocol, with
fatal results. However, we took a neutral position on the YDB impact
hypothesis: “Our results are consistent with, but do not prove, that a
previously proposed cosmic impact occurred at 12.9 ka BP. The ultimate source
of the magnetic microspherules in YDB sediment remains a mystery warranting
further investigation” (2). Malcolm A. LeComptea,1, Dale Batchelorb, Mark N.
Demitroffc, Edward K. Vogeld, Charles Mooneyb, Barrett N. Rocke, and Alfred W.
Seidelf aCenter of Excellence in Remote Sensing Education and Research,
Elizabeth City State University, Elizabeth City, NC 27921; bAnalytical
Instrumentation Facility, North Carolina State University, Raleigh, NC 27695;
cDepartment of Geography, University of Delaware, Newark, DE 19716; dDepartment
of Psychology, University of Oregon, Eugene, OR 97403; eInstitute for the
Study of Earth, Oceans and Space, University of New Hampshire, Durham, NH
03824; and fSeidel Research, Camden, NC 27921 1 Boslough M (2013) Faulty
protocols yield contaminated samples, unconfirmed results. Proc Natl Acad Sci
USA, 10.1073/ pnas.1220567110. 2 LeCompte MA, et al. (2012) Independent
evaluation of conflicting microspherule results from different investigations
of the Younger Dryas impact hypothesis. Proc Natl Acad Sci USA 109(44):
E2960–E2969. 3 Firestone RB, et al. (2007) Evidence for an extraterrestrial
impact 12,900 years ago that contributed to the megafaunal extinctions and the
Younger Dryas cooling. Proc Natl Acad Sci USA 104(41): 16016–16021. 4
Firestone RB (2009) The case for the Younger Dryas extraterrestrial impact
event: Mammoth, megafauna, and clovis extinction, 12,900 Years Ago. Journal of
Cosmology 2:256–285. 5 Surovell TA, et al. (2009) An independent evaluation
of the Younger Dryas extraterrestrial impact hypothesis. Proc Natl Acad Sci
USA 106(43):18155–18158. Author contributions: M.A.L., D.B., M.N.D., E.K.V.,
C.M., B.N.R., and A.W.S. wrote the paper. The authors declare no conflict of
interest. 1To whom correspondence should be addressed. E-mail: malcolm.
firstname.lastname@example.org. www.pnas.org/cgi/doi/10.1073/pnas.1300425110 PNAS
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