Exploring abrupt climate change induced by comets and asteroids during human history

PNAS: Five-Year study rips spear from back of YDB hypothesis

Restored from the library fire 1/11/20



Download the PDF file .

Working on getting the paper. [Update: Got it above}

This appears to be the long hoped for independent, intentional, blind, professional and reproducible confirmation of the original 2007 findings of the Younger Dryas Boundary team.

Independent evaluation of conflicting microspherule results from different investigations of the Younger Dryas impact hypothesis

  1. Malcolm A. LeComptea,1,

  2. Albert C. Goodyearb,
  3. Mark N. Demitroffc,
  4. Dale Batchelord,
  5. Edward K. Vogele,
  6. Charles Mooneyd,
  7. Barrett N. Rockf, and
  8. Alfred W. Seidelg

+Author Affiliations

  1. aCenter of Excellence in Remote Sensing Education and Research, Elizabeth City State University, Elizabeth City, NC 27921
    bSouth Carolina Institute of Archaeology and Anthropology, University of South Carolina, Columbia, SC 29208;cDepartment of Geography, University of Delaware, Newark, DE 19716;dAnalytical Instrumentation Facility, North Carolina State University, Raleigh, NC 27695;eDepartment of Psychology, University of Oregon, Eugene, OR 97403;fInstitute for the Study of Earth, Oceans and Space, University of New Hampshire, Durham, NH 03824; andgSeidel Research, Camden, NC 27921
  1. Edited by* Steven M. Stanley, University of Hawaii, Honolulu, HI, and approved August 7, 2012 (received for review May 22, 2012)


Firestone et al. sampled sedimentary sequences at many sites across North America, Europe, and Asia [Firestone RB, et al. (2007) Proc Natl Acad Sci USA106:16016–16021]. In sediments dated to the Younger Dryas onset or Boundary (YDB) approximately 12,900 calendar years ago, Firestone et al. reported discovery of markers, including nanodiamonds, aciniform soot, high-temperature melt-glass, and magnetic microspherules attributed to cosmic impacts/airbursts. The microspherules were explained as either cosmic material ablation or terrestrial ejecta from a hypothesized North American impact that initiated the abrupt Younger Dryas cooling, contributed to megafaunal extinctions, and triggered human cultural shifts and population declines. A number of independent groups have confirmed the presence of YDB spherules, but two have not. One of them [Surovell TA, et al. (2009) Proc Natl Acad Sci USA 104:18155–18158] collected and analyzed samples from seven YDB sites, purportedly using the same protocol as Firestone et al., but did not find a single spherule in YDB sediments at two previously reported sites. To examine this discrepancy, we conducted an independent blind investigation of two sites common to both studies, and a third site investigated only by Surovell et al. We found abundant YDB microspherules at all three widely separated sites consistent with the results of Firestone et al. and conclude that the analytical protocol employed by Surovell et al. deviated significantly from that of Firestone et al. Morphological and geochemical analyses of YDB spherules suggest they are not cosmic, volcanic, authigenic, or anthropogenic in origin. Instead, they appear to have formed from abrupt melting and quenching of terrestrial materials.


University of South Carolina Press Release

PNAS: Topper site in middle of comet controversy

By Peggy Binette,[email protected], 803-777-7704

Did a massive comet explode over Canada 12,900 years ago, wiping out both beast and man in North America and propelling the earth back into an ice age?

That’s a question that has been hotly debated by scientists since 2007, with the University of South Carolina’s Topper archaeological site right in the middle of the comet impact controversy. However, a new study published today (Sept.17) in the Proceedings of the National Academy of Sciences (PNAS) provides further evidence that it may not be such a far-fetched notion.


Blind Study.

To eliminate potential analytical bias, we participated in a blind test of the sediment samples taken from the two common sites, BWD and TPR. Blind testing was not applicable for the single sample collected from PPC. The eight unprocessed sediment samples, four from each site, were repackaged and distributed by a non-participating third party for blind processing by a member of our group (MAL). The packages were randomly numbered and labeled with the indicated source site, but not with depth or relationship to the YDB layer. At the conclusion of the blind test, we adopted the same chronostratigraphy used by the principal investigators for all of our sites, as well as by Firestone et al. and Surovell et al. YDB depths may vary between studies due to differences in the sampled locations.

7 Responses

  1. Denial is an interesting psychological phenomenon.
    Even though the deviation in the sampling and processing has been identified, and the initial data re-confirmed, you can be sure that the earlier faulty attempts at duplication will be brought up again and again and again.

    That being the case, I’ll repeat what I’ve said before, which is that the only thing which is going to bring this denial to an end is the thorough documentation of one of the HSIE craters.

  2. At 30 micrometers or so they were probably the easiest particle extraction to replicate. It’s too bad these kinds of extractions are so difficult.

    Not sure what this means for my nutty theory, or when anyone will get around to trying to replicate the nanoscale carbon extractions anytime soon.

  3. The study made the science daily web site:


    However, a new study published Sept.17 in the Proceedings of the National Academy of Sciences (PNAS) provides further evidence that it may not be such a far-fetched notion.

    USC archaeologist Albert Goodyear is a co-author on the study that upholds a 2007 PNAS study by Richard Firestone, a staff scientist at the Department of Energy’s Lawrence Berkeley National Laboratory.

    Firestone found concentrations of spherules (micro-sized balls) of metals and nano-sized diamonds in a layer of sediment dating 12,900 years ago at 10 of 12 archaeological sites that his team examined. The mix of particles is thought to be the result of an extraterrestrial object, such as a comet or meteorite, exploding in Earth’s atmosphere. Among the sites examined was USC’s Topper, one of the most pristine U.S. sites for research on Clovis, one of the earliest ancient peoples.

    “This independent study is yet another example of how the Topper site with its various interdisciplinary studies has connected ancient human archaeology with significant studies of the Pleistocene,” said Goodyear, who began excavating Clovis artifacts in 1984 at the Topper site in Allendale, S.C. “It’s both exciting and gratifying.”

  4. From 2 days ago, WattsUpWithThat.com (which in its following post noted that it was ranked #2 of ALL wordpress.com’s millions of blogs) posted this: http://wattsupwiththat.com/2012/09/20/support-comet-impact-may-have-triggered-the-younger-dryas-period/

    This exposure about LeCompte’s paper spreads the word specifically about how sloppy Surovell’s work had been.

    Even for the WUWT readers who only read the headline in passing, another seed is planted: The idea of a YDB impact is being found more probable. That cannot be a bad thing for the cause here at CT.

    See also http://www.sc.edu/news/newsarticle.php?nid=4706#.UF5ho41lSAn

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