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

Trust but Verify: Independent confirmations of the Younger Dryas Impact Boundary

Skeptics of the YDIB hypothesis frequently state that no one can reproduce the YDIB results(Kerr, 2010);nobody has found anything(Kerr, 2010); there is a lack of reproducibility of data (Holliday, 2011); and unique peaks in concentrations at the YD onset have yet to be reproducedPinter (2011). These casual dismissals are hurtful to the investigation, demonstrably false, and irresponsible. That independent researchers have identified materials diagnostic of an event of cosmic proportions at 12.9 before present should not be subject to debate.

To wit, I offer below citations of published research confirming the original findings of Firestone, et. al. in 2007. Note that some of these researchers disagree with an extraterrestrial impact as cause and offered alternate hypotheses, but, in every case, those speculating about causation have not conducted any analytical work to determine if their hypotheses are correct.

INDEPENDENT GROUPS with positive results:



Baker et al. (2008)

Fayek (2008)

Ge et al. (2009, page 1)

Haynes et al. (2010, page 1)

LeCompte et al. (2010)

Mahaney (2010a, page 10)

Wu (2011)

Fayek (2011)


Ge et al. (2009, page 1)

Tankersley (2009)

Tian (2010, page 1)

Van Hoesel (2011)

Bement et al. (2011)


Beets et al. (2008, page 1)

Sharma et al. (2009)

Haynes et al. (2010, page 1)

Mahaney (2010a, page 10)

Marshall (2011)

Wu (2011)

Andronikov (2012)


Mahaney (2010a, page 10)

Tian (2010, page 1)

Courty et al. (2010)

Ge et al. (2009, page 1)

Baker et al. (2008, page 1)

Tankersley (2009)


Mahaney et al. (2010b)

Ge et al. (2009)

Courty et al. (2010)



Schroeder (2009)

Steele (2010)


Higgins, et al. (2011)



Baker DW, Miranda PJ, Gibbs KE. (2008) Montana Evidence for Extra-Terrestrial Impact Event That Caused Ice-Age Mammal Die-Off. American Geophysical Union, Spring Meeting 2008, abstract #P41A-05.

Beets C, Sharma M, Kasse K, Bohncke S. (2008) Search for Extraterrestrial Osmium at the Allerod – Younger Dryas Boundary. American Geophysical Union, Fall Meeting 2008, abstract #V53A-2150.

Bement L, Carter BJ, Simms A, Madden A. (2011) The Bull Creek valley stream terraces, buried soils, and paleo-environment during the Younger Dryas in the Oklahoma Panhandle, USA. Paper #1447, XVIII INQUA-Congress, 21-27 July 2011 in Bern, Switzerland.

Bunch Ted E., James Wittke, Allen West, James Kennett. (2011) Shock-melt Evidence for a Cosmic Impact with Earth during the Younger Dryas at 12.9 ka. Abstract 1606, Session 60, XVIII INQUA-Congress, 21-27 July 2011 in Bern, Switzerland. http://www.inqua2011.ch/?a=programme&subnavi=abstract&id=1606

Courty MA, Fedoroff M. (2010) Soil morphologic indicators of environmental hazards linked to cosmic airburst. 19th World Congress of Soil Science, Brisbane.

Daulton T, Pinter N, Scott A (2010) “No evidence of nanodiamonds in Younger-Dryas sediments to support an impact event”. Proceedings of the National Academy of Sciences of the United States of America 107 (37): 16043–16047

Fayek, M.; Hull, S.; Anovitz, L.; Haynes, V.; Bergen, L. (2008) Evidence of impact material and the extinction of the mega-fauna 12,900 years ago. American Geophysical Union, Fall Meeting 2008, abstract #PP13C-1469.

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 104:16016–16021.

Firestone RB. (2009) The Case for the Younger Dryas Extraterrestrial Impact Event: Mammoth, Megafauna, and Clovis Extinction, 12,900 Years Ago. Journal of Cosmology (journalofcosmology.com)

Ge T, Courty MM, Guichard F (2009) Field-Analytical approach of land-sea records for elucidating the Younger Dryas Boundary syndrome. American Geophysical Union, Fall Meeting 2009, abstract #PP31D-1390.

Haynes CV, Jr, Lauretta DS, Ballenger JAM. (2010) Reply to Firestone et al.: No confirmation of impact at the lower Younger Dryas boundary at Murray Springs, AZ. Proceedings of the National Academy of Sciences, vol. 107, issue 26, pp. E106-E106.

Holliday V. (2011) A Cosmic Catastrophe: the Great Clovis Comet Debate. http://www.argonaut.arizona.edu/Clovis_Comet_Debate.html

Kennett DJ, et al. (2009a) Shock-synthesized hexagonal diamonds in Younger Dryas boundary Sediments, Proc Natl. Acad. Sci. USA, 106 (31): 12623-12628.

Kennett DJ, et al. (2009b) Nanodiamonds in the Younger Dryas boundary sediment layer. Science 323:94.

Kerr RA. (2010) Mammoth-Killer Impact Flunks Out. Science 3 September 2010: 1140-1141.

LeCompte MA, Goodyear AC, Demitroff M, Batchelor D, Mooney C. (2010) An Independent Review of the Younger Dryas Extraterrestrial Impact Hypothesis and its Recent Re-Evaluation by Surovell et al. 21st Biennial Meeting of the American Quaternary Association (AMQUA). Laramie, Wyoming.

Mahaney WC, et al. (2010a) Evidence from the northwestern Venezuelan Andes for extraterrestrial impact: The black mat enigma. Geomorphology, v. 116, iss. 1-2, p. 48-57.

Mahaney WC, Krinsley D, Kalm V (2010b) Evidence for a cosmogenic origin of fired glaciofluvial beds in the northwestern Andes: Correlation with experimentally heated quartz and feldspar. Sedimentary Geology, v. 231, iss. 1-2, p. 31-40.

Mahaney WC, David Krinsley, Kurt Langworthy, Kris Hart, Volli Kalm, Pierre Tricart and Stephane Schwartz. (2011a) Fired glaciofluvial sediment in the northwestern Andes: Biotic aspects of the Black Mat. Sedimentary Geology. 237, (1-2), pp73-83.

Mahaney, WC, Dave Krinsley, James Dohm, Volli Kalm, Kurt Langworthy and J. Ditto. (2011b) Notes on the black mat sediment, Mucunuque Catchment, northern Mérida Andes, Venezuela.. Journal of Advanced Microscopic Research, vol. 6, no. 3.

Marshall W, Head K, Clough R, Fisher A. (2011) Exceptional iridium concentrations found at the Allerød-Younger Dryas transition in sediments from Bodmin Moor in southwest England. Paper #2641, XVIII INQUA-Congress, 21-27 July 2011 in Bern, Switzerland.

McDonough W, Sun S (1995) The composition of the Earth. Chem Geol 120:223–253.

Pinter N, et al. (2011) The Younger Dryas impact hypothesis: A requiem, Earth Science Reviews (in press).

Schroeder KB. (2009) Haplotypic background of a private allele at high frequency in the Americas. Molecular biology and evolution 2009;26(5):995-1016.

Scruggs, MA, Raab LM, Murowchick JS, Stone MW, Niemi TM. (2010) Investigation of Sediment Containing Evidence of the Younger Dryas Boundary (YPB) Impact Event, El Carrizal, Baja California Sur, Mexico. Geological Society of America Abstracts with Programs, Vol. 42, No. 2, p. 101.

Sharma M, Chen C, Jackson BP, Abouchami W. (2009) High resolution Osmium isotopes in deep-sea ferromanganese crusts reveal a large meteorite impact in the Central Pacific at 12 ± 4 ka. American Geophysical Union, Fall Meeting 2009, abstract #PP33B-06.

Steele J. (2010) Radiocarbon dates as data: quantitative strategies for estimating colonization front speeds and event densities. Journal of Archaeological Science 37/8, p. 2017-2030.

Surovell TA, et al. (2009) An Independent Evaluation of the Younger Dryas Extraterrestrial Impact Hypothesis. Proc. Natl. Acad. Sci. USA, 104: 18155–18158.

Tankersley K. (2009) “Evidence of the Clovis Age Comet at Sheriden Cave, Ohio.” Midwest Chapter of the Friends of Mineralogy Symposium and Field Conference (Geology Department of Miami University, Oxford, Ohio, USA), 5 September 2009. http://www1.newark.ohio-state.edu/Professional/OSU/Faculty/jstjohn/Geology-talks/Tankersley-talk.htm

Tian H, Schryvers D, Claeys P (2011) Nanodiamonds do not provide unique evidence for a Younger Dryas impact. Proceedings of the National Academy of Sciences, vol. 108, issue 1, pp. 40-44.

Van der Hammen T., van Geel B. (2008) Charcoal in soils of the Allerød-Younger Dryas transition were the result of natural fires and not necessarily the effect of an extra-terrestrial impact. Netherlands Journal of Geosciences, vol. 87, 4, pp. 359-361.

Van Hoesel A, Hoek W, Braadbaart F, van der Plicht H, Drury MR. (2011) Nanodiamonds and the Usselo layer. Paper #1556, XVIII INQUA-Congress, 21-27 July 2011 in Bern, Switzerland.

Wu Y. (2011) Origin and Provenance of Magnetic Spherules at the Younger Dryas Boundary. Thesis, Dartmouth College.

19 Responses

  1. Hello fo All

    If the Corossol crater is older than 12,900 years it was formed over the ice sheet. It seems to be too small to have an effect beyond just local, it was not likely responsible for the demise of the Ice Age. At most anything sub-continental. It not cause mass extinction in Brazil.

    If the Corossol crater was originated from a fragment of a dying comet, there should be other (fragments) craters. Where were they? A crater appears very little. With a field of craters, the thing would be more interesting, although the craters are smaller in size. At this point, the argument of the craters is still very weak.

    The Corossol structure (big girl) is quite circular, may be the result of a small sporadic asteroid in perpendicular falling. Yes, bigger than that of Berringer.


  2. Thanks Steve

    Hi Pierson – You are correct, but the feature is much younger than 10,900 BCE, as that is the date for its floor. Evidence of the impact mega-tsunami should show up on the resulting land areas, resulting in much more precise dating.

    My guess is that it most likely occurred just prior to 8,350 BCE, the start of the Canadian Maritime Archaic.

    The Canadians have had some luck, as there are likely to be pooled hydrocarbons in the shatter zone around this impact. But my estimate is that it is not part of the Holocene Start Impacts.

    Pierson, we need some dating on the Iltrude and the Loydminster structures. The surface burning seems to have been focused around the northwest of North America.

    That said, this find should raise public awareness as to the severity of the impact hazard.

  3. Hi Pierson –

    Another point that needs to be worked on – the extinctions were caused by the “nuclear winter” following the Holocene Start Impacts.

    The animals starved to death.

    This being the case, which animals died, their food requirements, food storage abilities (fat) and ranges are important. You have the South American data at hand to analyze.

  4. Hi EP

    Yes, there are very interesting myths in this region of Canada, its rock arts are quite similar to other found in other parts of the world, Raven myth:

    I believe that after the great increase of energy in the atmosphere (+10°C), caused by the impacts (oceanic, terrestrial, atmospheric), released large amounts of water in the seas and into the atmosphere. Water that used to be in the form of ice in glaciers.

    Inside the northeastern region of Brazil in the late Pleistocene climate was dry (much of the water was frozen at the poles) and cooler (maybe 8 or 10 degrees less than the current average 25°C), and similar to a savanna, but perhaps with perennial rivers. Yes, “I have nothing to do with it” but, it seemed a paradise, was not the danger of the megafauna.

    Today, the region is semiarid, there is little rain and it is warmer, the rivers are intermit and rainfall is variable. The current vegetation (Caatinga) is denser than the savanna, and vegetation consists of a fully adapted to high temperatures and scarce water.

    I believe that after the meteoritc events, and the large release of dust into the atmosphere, causing a new low in the planet temperature, now associated with the great water in the atmosphere, heavy rain (acid?) fell and rapidly filling the thousands of craters, transforming them into lakes poisoned by gases (CN) which contaminated rocks and soil at these sites.

    Yes, it seems rained a lot here on that abrupt climate transition. Large amount of water condensed in this tropical region.

    The survivors beasts from the blasts, must have died poisoned on these poisoned (CN) lakes. Still others megafauna eventually were exterminated by the ancient and hungry inhabitants, until the arrival (400 years?) of the new ecological stability.


  5. Hi Pierson –

    My current thinking is that the “nuclear winter” was global in scale. Any acid rain effects would have been minor and secondary.

    Immediate starvation was the cause of death, with later predation on the few survivors.

    I’ve gone through the Northern sequence many times. I have not worked out what the cold freshwater release would have done to the South Atlantic currents.

    The northwestern North American forest fires were likely large enough to leave a nice massive geological signal in local glasses.

    Identify pre-Holocene Start Impact phytoliths, compare with post HIS phytoliths, and that should limit the search for these.

  6. Hello

    Ok this or that, no matter the degree of the mix of causes for extinction of the megafauna for each location on the planet. Although overall, it seems reasonable that it was not homogeneous. Of course, the world is not homogeneous. Clusters of comet fragments must have given some aspect heterogeneous at first and even later in many places. And not everything was under the ice in the Pleistocene.

    Too bad no academic research has presented nothing new about craters in North America. I still try to understand the lack of interest, which is not unique to Americans, of course. In many cases it seems to me that science (here and elsewhere) is made so romantic, idealized. In many subjects the pure science goes forgotten.

    Yes, there are many possible techniques for the investigation. I chose the impactites, which are traditionally accessible to anyone, anywhere. I follow in my little canoe with has only a paddle, and trying to do my best.


  7. Hi Pierson –

    Its not this or that, its global simultaneous starvation. Its not local blast effects, its the stop in food production – a nuclear winter.

    That’s why the death dates from recovered mega-fossils show a spike globally.

    The lack of work at Ilturalde and Lloydminster is frustrating.

    We’ll see what the situation is in February of next year.

  8. Hi George –

    There are a whole lot of people who hope I will just shut up.

    I am sorry that Higgins’ et al’s crater does not come from the HSI.

    We all make mistakes, its what we do next that is important.

  9. Sondra Spies and I have been in Imperial Beach, California, 91932, SW of San Diego, near the beach, 3 miles N of Mexico, since Saturday Dec 3 — renting 254-A Donax Avenue — looking for a $ 300 K small house to buy soon — driving here Dec 1 and 2, via 60 and I-8, seems like plenty of geoablation of the landscape a la Cox-Boslough directed air burst jet barrages — hope to start finding glazed rocks nearby — ocean waves toss up interesting SiO2 rocks, including obsidian, with very few shells…

  10. It turns out that the HSI date comes from the sediment filling the crater, and that the crater it is older than the HSI.

    The sediment itself is of great interest.

  11. Here is a 2010 article from Science news that discussed evidence in Greenland of the YD impact:

    New Evidence of Ice Age Comet Found in Ice Cores(Science News, March 30, 2010)
    A new study cites spikes of ammonium in Greenland ice cores as evidence for a giant comet impact at the end of the last ice age, and suggests that the collision may have caused a brief, final cold snap before the climate warmed up for good.
    In the April Geology, researchers describe finding chemical similarities in the cores between a layer corresponding to 1908, when a 50,000-metric-ton extraterrestrial object exploded over Tunguska, Siberia, and a deeper stratum dating to 12,900 years ago. They argue that the similarity is evidence that an object weighing as much as 50 billion metric tons triggered the Younger Dryas, a millennium-long cold spell that began just as the ice age was loosing its grip (SN: 6/2/07, p. 339).
    Precipitation that fell on Greenland during the winter after Tunguska contains a strong, sharp spike in ammonium ions that can’t be explained by other sources such as wildfires sparked by the fiery explosion, says study coauthor Adrian Melott, a physicist of the University of Kansas in Lawrence.
    The presence of ammonium suggests that the Tunguska object was most likely a comet, rather than asteroids or meteoroids, Melott says. Any object slung into the Earth’s atmosphere from space typically moves fast enough to heat the surrounding air to about 100,000° Celsius, says Melott, so hot the nitrogen in the air splits and links up with oxygen to form nitrates. And indeed, nitrates are found in snow around the Tunguska blast. But ammonium, found along with the nitrates, contains hydrogen that most likely came from an incoming object rich in water — like an icy comet.
    More than a century after the impact, scientists are still debating what kind of object blew up over Tunguska in 1908. They also disagree about whether an impact or some other climate event caused the Younger Dryas at the end of the ice age. But the presence of ammonium in Greenland ice cores at both times is accepted.
    “There’s a remarkable peak of ammonium ions in ice cores from Greenland at the beginning of the Younger Dryas,” comments Paul Mayewski, a glaciologist at the University of Maine in Orono who was not involved in the new study. The new findings are “a compelling argument that a major extraterrestrial impact occurred then,” he notes.
    Whenever a comet strikes Earth’s atmosphere, it leaves behind a fingerprint of ammonium, the researchers propose. Immense heat and pressure in the shock wave spark the creation of ammonia, or NH3, from nitrogen in the air and hydrogen in the comet. Some of the ammonium, or NH4+, ions generated during subsequent reactions fall back to Earth in snow and are preserved in ice cores, where they linger as signs of the cataclysmic event.
    Although an impact big enough to trigger the Younger Dryas would have generated around a million times more atmospheric ammonia than the Tunguska blast did, the concentrations of ammonium ions in the Greenland ice of that age aren’t high enough.
    But the relative dearth of ammonium in the ice might simply be a result of how the ice cores were sampled, Melott and his colleagues contend. Samples taken from those ice cores are spaced, on average, about 3.5 years apart, and ammonia could have been cleansed from the atmosphere so quickly that most of the sharp spike might fall between samples.

  12. When I spoke to Dr. Melott he also mentioned that he had calculated that a sharp ammonium spike would also diffuse out of the sharp layer into the surrounding ice, and that these cores had been disposed of and thus he lost interest in it.

    The wiki page has also been updated with a sentence describing the recent framboidal iron paper and the continued debate.

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