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Impacts, Diamonds and the Younger Dryas

The 1300-year cold spell known as the Younger Dryas is back in the news. The sudden climate change, occurring between twelve and thirteen thousand years ago, may be related to the extinction of large species like the saber-tooth tiger and could have something to do with the disappearance of the Clovis culture, a people whose arrival in the Americas can be traced through their distinctive artifacts. Last year a team from sixteen institutions proposed that the climate change was the result of an impact event possibly involving multiple airbursts of cosmic debris.

That theory has been regarded with skepticism, but Douglas Kennett (University of Oregon), who worked with the original team, now says that its research has uncovered billions of nanometer-sized diamonds concentrated in sediments in six locations, ranging from Arizona to Oklahoma, Michigan, South Carolina, Manitoba and Alberta. Such nano-diamonds are produced under the kind of high temperatures and pressures associated with impacts and have been found in meteorites. Says Kennett:

“The nanodiamonds that we found at all six locations exist only in sediments associated with the Younger Dryas Boundary layers, not above it or below it. These discoveries provide strong evidence for a cosmic impact event at approximately 12,900 years ago that would have had enormous environmental consequences for plants, animals and humans across North America.”

The Clovis association is obviously interesting. One of the sediment layers in question was found adjacent to Clovis materials at Murray Springs, AZ. The Clovis culture seems to have lasted no more than 800 years, being replaced by more localized cultures apparently deriving from it. The question is whether we can attribute what may have been gradual cultural change to a sudden impact event and associated climate change.


Image: Nanometer-sized diamonds occur at the base a layer of sediment directly above the remains of extinct animals (mammoths, dire wolves, etc.) and artifacts from Clovis culture at the research site in Murray Springs, Arizona. Credit: University of Oregon.

So how convincing is the theory? I was interested to see that University of Hawaii scientist Gary Huss, who was a reviewer of the paper the team published today in Science, thinks the new work makes the theory more tenable. As quoted in the New York Times, Huss says:

“They have a hypothesis that explains several things that hard to explain any other way. Diamonds are less convincing by themselves, but they strengthen their case considerably.”

And geology consultant Allen West is quoted in the same story to the effect that the team has now traced microscopic diamond deposits to over thirty sites, ranging from offshore California to Germany. The six sites considered in the Science paper show the same pattern: The diamond layer correlates to the date of the supposed impact. Moreover, there’s this, also from the Times article:

…the scientists reported last month at a meeting of the American Geophysical Union in San Francisco, the carbon atoms inside some of the diamonds are lined up in a hexagonal crystal pattern instead of the usual cubic structure. The hexagonal diamonds, formed by extraordinary heat and pressure, have been found only at impact craters and within meteorites and cannot be formed in forest fires or volcanic eruptions, Dr. West said.

But where are the kinds of craters we would expect to find from such events? The lack of such points to how tentative this hypothesis is, but also to the need for continuing to explore it. For the timing of the would-be impact and the disappearance of ice age mammals amidst the sudden cooling makes for a puzzling series of coincidences, one that further field work may help us explain. With thirty sites in play, that could take a considerable amount of time.

The paper is Kennett et al., “Nanodiamonds in the Younger Dryas Boundary Sediment Layer,” Science Vol. 323, No. 5910 (2 January 2009), p. 94 (abstract). A University of Oregon news release is also available.

Comments on this entry are closed.

  • Michael McHugh January 3, 2009, 12:22
  • James M. Essig January 3, 2009, 17:35

    Hi Paul and Michael;

    I wonder if the danger of perhaps a meteor impact with Earth involving some sort of radioactive isotope containing meteor that would result in widspread dangerous levels radioactive fallout to be distributed was ever seriously considered.

    It seems to me that if such had happened in the past, perhaps it happened so long ago such that the radioactive signature of the dust produced by the vaporizing meteor would have since decayed to non-detectable levels.

    One isotope I am thinking of is U-238 which has a half life of roughly 10 billion years. No doubt, if I an not mistaken, one could hold a piece of U-238 in their hands for several hours to no ill effect since its rate of energy release is very low compared to the radioactive fallout produced in nuclear explosions, but with all of the talk of the adverse health effects as a result of the depleated uranium armour piercing rounds used at times during the early 2000s and the resulting dust produced on impact, perhaps we should be concerned not only about tidal waves, and climate changing “dark nights” resulting from impacts, but also from radioactive cantaimination and/or chemical toxins distributed by potential meteor impacts.

    Either way, the study of the possible meteor impact and its effects on the Clovis People is interesting.

    With about 60 percent of Earths population leaving along coastal regions, perhaps tsunami risks along with 1,,000 year long winter based food shortages are enough to worry about.



  • Don Wilkins January 4, 2009, 11:11

    Good morning,

    Last night the History Channel ran a show on the Clovis civilization and its demise in a meteor strike.

    The show supplies two interesting facts. More Clovis sites exist on the East Coast, in Virginia, about 400, than in the Western states, perhaps a dozen. THis indicates a first landing on the East Coast rather than the traditional Siberia to Alaska crossing. Also Clovis points more closely resemble those of Europe than those of Siberia.

    This has led to speculation that the Clovis pepole came from Europe rather than Siberia.

    Unfortunately a meteor strike in the glacier area – therefore no crater – lead to the demise of the Clovis culture and the megafauna of North America.

    One could speculate about how the Americas would have looked if the Clovis civilization had not perished but contimued to advance along with its Eurpoean cousin.


  • George Howard January 11, 2009, 13:15

    Hey Paul,

    You and your readers may be interested in this PNAS paper from May that reveals the synchronous nature of the “Black Mat” across the the US. It’s by C. Vance Haynes, the dean of Clovis Archaeology.

    Here are the pics click to the right for the text:

  • Dennis Cox, Fresno, Ca. January 25, 2009, 14:14

    I am just a high school educated layman but I think this might be the blast structure you folks are talking about.


    Take a look

  • ljk January 29, 2009, 23:43

    BBC 1/29/09: “Mammoth-killing comet questioned”

    “A study of wildfires after the last ice age has cast doubt on the theory that a giant comet impact wiped out woolly mammoths and prehistoric humans.

    Analysis of charcoal and pollen records from around 13,000 years ago showed no evidence of continental-scale fires the cometary impact theory suggests.

    However, the results showed increased fires after periods of climate change.

    The research is published in the Proceedings of the National Academy of Sciences (PNAS).

    The cometary impact hypothesis holds that an enormous comet slammed into or exploded over North America in the Younger Dryas period some 12,900 years ago.”

    More: http://news.bbc.co.uk/2/low/science/nature/7854348.stm

  • Dennis Cox, Fresno, Ca. March 4, 2009, 14:48

    In the mountains of north central Mexico you will find ejecta, impactites, breccias, and miles wide pyroclastic flows. As pristine as the day they first cooled. But there are no volcanoes. And there are no impact craters. If you follow those flows back to their respective sources you find only melted, burned, baron stone. Or strangely shaped bare stone mountains.
    If you want a “Rosetta stone” (no pun intended) for understanding how large clusters of these objects react with the Earth’s atmosphere. And for how the heat and pressure they produce reacts with her geology. you will find it there.
    If you are serious about the science you do. If you really want solve the riddle of the Younger Dryas impact events. And the recent megafaunal extinctions. You will go study that place. Untill you do, you are only students chasing butterflies in the playground.

  • John Hyatt March 1, 2010, 0:24

    The “impact ” craters may be found throughout the South East U S, as so-called “Carolina bays”.

  • Dennis Cox January 21, 2011, 13:44

    From Comets, Catastrophes, and Earth’s History, by W. M. Napier, Phd we read:

    “The evidence that an exceptionally large (50-100 km) comet entered a short-period, Earth- crossing orbit during the upper Paleolithic, and underwent a series of disintegrations, now seems compelling. The idea is not new, but it has been strengthened by an accumulation of evidence from radar studies of the interplanetary environment, from the LDEF experiment, from numerical simulations of the Taurid complex meteoroids and ‘asteroids’, and from the latter’s highly significant orbital clustering around Comet Encke.

    The disintegration of this massive Taurid Complex progenitor over some tens of thousands of years would yield meteoroid swarms which could easily lead to brief, catastrophic episodes of multiple bombardment by sub-kilometre bolides, and it is tempting to see the event at ∼ 12,900 BP as an instance of this. Whether it actually happened is a matter for Earth scientists, but from the astronomical point of view a meteoroid swarm is a much more probable event than a 4 km comet collision.”

    So, if we look to see what a typical fragmented comet looks like, we have images of objects like comets, Linear, or Schwassmann Wachmann 3, (both in short period, Earth crossing, orbits) to give us an idea of the fragment size and distribution we could expect from a meteoroid swarm from the Taurids Look in Google Earth from about 5 km up at the region extending from southeastern New Mexico, to Odessa, and Midland, Texas. If you do, you will see that, liberally scattered among the oil feilds, there are too many small craters averaging 100 meters diameter to count.

    Their numbers, and sizes, are an exact match for the fragment size, and distribution, we see in either of those all too common, ordinary, Taurid family objects. The early Holocene sedimentary deposits of the Red Rock River valley of southwestern Montana are home to a good sized crater field of oval craters from something that hit at a low angle, and coming from the southwest. Should someone have the means to do a little field work there, You will find that one of the ejecta splashes at 44.644033, -112.076880 has fallen across an ancient meander of the Red Rock river. That location should provide an excellent stratigraphic horizon to get a fairly accurate age for that fall of fragments.

    And if we look to the southwest, in the direction those meteors came from, we’ll see that, in a dry lake bed in Nevada at 39.849626, -115.346445 there is another set of oblique impacts with exactly the same trajectory. Those fell into what would have been a shallow lake at the time. And the beach lines from that early Holocene lake are lying across an ejecta splash. So there is a stratigraphic horizon to date that fall by as well. When you quit looking for a large impact structure, and you begin look for the planetary scarring of a very large cluster of small fragments, the signs are everywhere in the American Southwest.