Microscopic Diamonds Suggest Cosmic Impact Responsible for Major Period of Climate Change

WUWT previously covered this story on August 29th, and also on September 20th, 2012. This is a new press release from the University of Chicago today. A new study published in The Journal of Geology provides support for the theory that a cosmic impact event over North America some 13,000 years ago caused a major period of climate change known as the Younger Dryas stadial, or “Big Freeze.”


Around 12,800 years ago, a sudden, catastrophic event plunged much of the Earth into a period of cold climatic conditions and drought. This drastic climate change—the Younger Dryas—coincided with the extinction of Pleistocene megafauna, such as the saber-tooth cats and the mastodon, and resulted in major declines in prehistoric human populations, including the termination of the Clovis culture.

With limited evidence, several rival theories have been proposed about the event that sparked this period, such as a collapse of the North American ice sheets, a major volcanic eruption, or a solar flare.

However, in a study published in The Journal of Geology, an international group of scientists analyzing existing and new evidence have determined a cosmic impact event, such as a comet or meteorite, to be the only plausible hypothesis to explain all the unusual occurrences at the onset of the Younger Dryas period.

Researchers from 21 universities in 6 countries believe the key to the mystery of the Big Freeze lies in nanodiamonds scattered across Europe, North America, and portions of South America, in a 50-million-square-kilometer area known as the Younger Dryas Boundary (YDB) field.

Microscopic nanodiamonds, melt-glass, carbon spherules, and other high-temperature materials are found in abundance throughout the YDB field, in a thin layer located only meters from the Earth’s surface. Because these materials formed at temperatures in excess of 2200 degrees Celsius, the fact they are present together so near to the surface suggests they were likely created by a major extraterrestrial impact event.

In addition to providing support for the cosmic impact event hypothesis, the study also offers evidence to reject alternate hypotheses for the formation of the YDB nanodiamonds, such as by wildfires, volcanism, or meteoric flux.

The team’s findings serve to settle the debate about the presence of nanodiamonds in the YDB field and challenge existing paradigms across multiple disciplines, including impact dynamics, archaeology, paleontology, limnology, and palynology.


C. R. Kinzie, et al., “Nanodiamond-Rich Layer across Three Continents Consistent with Major Cosmic Impact at 12,800 Cal BP,” The Journal of Geology 2014, 122(5). http://www.jstor.org/stable/10.1086/677046

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186 thoughts on “Microscopic Diamonds Suggest Cosmic Impact Responsible for Major Period of Climate Change

  1. The interesting thing is to draw a continuous warming from before the Younger Dryas as though it never occurred, and then connect it about horizontally to the post YD peak warming, and the curve you get looks a whole lot like the Eemian.

    • And all the interglacials have pointy heads, while the Holocene has the appearance of a plateau. Fascinating to speculate whether civilisation got a leg-up because of the YD, which appeared to put a damper on the Holocene and give homo sapiens a chance to make something of themselves.

      • The resolution of the ice core data decreases the farther back we go. If we were able to examine the previous Pleistocene interglacials in as much detail I’m sure we’d find them equally ‘up/down’ temperature-wise as the Holocene. For example, take the Eemian (130-115ka):
        http://en.wikipedia.org/wiki/Eemian#mediaviewer/File:EPICA_delta_D_plot.svg
        Are you suggesting that had the YD not occurred the Holocene would have come and gone more quickly and thus civilization would not have had sufficient time to develop before the onset of the next glacial max? I don’t see much evidence for that. It has taken humanity about 12k years to get from stone-age hunter gatherers to where we are now. Previous interglacials lasted as long or longer. If anything, the YD almost stopped the Holocene in its infancy. Now that would have been a real climate catastrophe!
        I think you could make a much stronger case for humans being evolutionarilly more advanced and thus more able to take advantage of the Holocene interglacial climate than previous interglacials. You might even make the case that the Eemian was the ‘garden of eden’: a species memory of a distant past when the land was warm and fruitful, and filled with abundance. 😉

      • In the absence of evidence of an extraterrestrial impact, all manner of theories attempting to explain simultaneous extinctions could be considered.
        Now, we have evidence of one or more continents burning about the time these extinctions are thought to have occurred. Judging from the geologic record, entire continents don’t burn often. Or multiple continents at burning at the same time, not often either.
        So did the circumstances that created a 50,000,000 sq. km. burn layer have anything to do with the extinctions? Doesn’t seem an unreasonable possibility.

  2. Nanodiamonds? Maybe. Meteor? Maybe. But a climate changing meteor? A meteor that wipes out big game while stirring not a mouse? Or climate that does the same? Or disease? The comet theory and the overkill theory are best kept separate. –AGF

    • Where did you ever read that mice weren’t also killed? You didn’t.
      As to the comet theory and the overkill theory not being kept separate, you are either misstating the state of affairs or misinterpreting. The two hypotheses (not theories) are mutually pretty much exclusive.
      It is quite ironic that at least two of the skeptics to the YD impact hypothesis (YDIH) – Surovell and Melzer – are researchers who seriously seem to question the exclusive hunting of megafauna. Surovell even has a paper entitled, “How many elephant kills are 14?: Clovis mammoth and mastodon kills in context” (Surovell and Waguespack 2008) http://uwacadweb.uwyo.edu/nmwhomepage/pdfs/QI%202008.pdf. Melzer also authors papers counting the number of Clovis-mammoth/mastodon sites, and there are only those 14.

      • Mr. Garcia, have you ever seen a list of Pleistocone extinctions–species by weight? Did mice go extinct? The K/T extinctions were pretty much size-didn’t-matter, unless you were small enough to live in burrows. The Pleistocen extinctions are typically labeled “Pleistocen Megafauna Extictions.” Now of course the “overkill” theory is opposed to all other explanations, including comet/climate. The distinction I am attempting to make is that between the possibility of a meteor event which is not blamed for Pleistocene extinctions and one that is. See, you could conceivable have ET nanodiamonds and still have overkill.
        Now one poster links some papers that show the nano-diamond evidence is bunk: some three of some 40 supposed sites have anything close to reliable dating. Strike one.
        It would take an enormous ET object to cool the climate for more than a year or two. That would do more than wipe out a few large species. Strike two.
        Megafauna disappear everywhere humans show–beginning with Australia and continuing with New Zealand, Madagascar, Mauritius, and every other island with animal land lubbers, big and small. North America was no different. Strike three.

      • Mr. Garcia, have you ever seen a list of Pleistocone extinctions–species by weight? Did mice go extinct? The K/T extinctions were pretty much size-didn’t-matter, unless you were small enough to live in burrows. The Pleistocen extinctions are typically labeled “Pleistocen Megafauna Extictions.” Now of course the “overkill” theory is opposed to all other explanations, including comet/climate. The distinction I am attempting to make is that between the possibility of a meteor event which is not blamed for Pleistocene extinctions and one that is. See, you could conceivable have ET nanodiamonds and still have overkill.
        Now one poster links some papers that show the nano-diamond evidence is bunk: some three of some 40 supposed sites have anything close to reliable dating. Strike one.
        It would take an enormous ET object to cool the climate for more than a year or two. That would do more than wipe out a few large species. Strike two.
        Megafauna disappear everywhere humans show–beginning with Australia and continuing with New Zealand, Madagascar, Mauritius, and every other island with animal land lubbers, big and small. North America was no different. Strike three.

      • [Hmm, posted double and wasn’t even done–using an old browser.] Continued:
        And of course there are all those pesky problems with the meteor/climate theory, like why did mammoths persist on Wrangel Island and elsewhere–far to the north where climate was coldest. And of course the scientific answer is that humans were late arriving there (4.7kya). In fact why did all the most northern species survive? Because they were safe from humans, not climate change.
        So, multiplying improbabilities: nanodiamond evidence? 1% maybe.
        Comet caused climate change? Ditto.
        Climate caused extinctions? Highly unlikely.
        Product (comet killed mammoths)? This whole theory is on the order of creationism and CACC. Very, very bad science. –AGF

      • agfosterjr says @September 12, 2014 at 8:22 am

        And of course there are all those pesky problems with the meteor/climate theory, like why did mammoths persist on Wrangel Island …

        Although it is not currently a popular explanation, disease hasn’t really disappeared as a potential cause of population & even species-losses. And it would ‘cover’ why island-populations etc persisted after continental eradication.
        Disease-problems can also be more difficult for larger animals to withstand.
        Like the formerly laughable idea that Modern humans are connected to Neanderthals, questions about ancient diseases may soon become more answerable than we have heretofore thought.

      • The terminal Pleistocene extinctions are likely a camel-straw situation where no single “cause” can or should be singled out. The most obvious primary issue is a changing climate. The YD punctuates a period of rapid change with another period of extremely rapid change in an opposite direction. With a “predictable” shift in life zones plants and animals can adapt through population redistribution or other means. But two such shifts would be a profound stress. Another point is that if you take a graph of the Late Pleistocene that shows the YD, the late YD warming rate is a very close match to that of the Bolling-Allerod immediately prior to the YD. That implies that whatever processes were set in motion to warm the planet at the end of the LGM continued to act throughout the YD, implying that the cause of the YD literally overpowered the climate system. Life would have been very difficult.
        The LP extinctions were not universal nor are all the “extinctions” true extinctions. Elephants survived quite well in Africa and southern Asia, as did rhino. Horses vanished from the Americas but not from anywhere else on the planet. Bison seem to have changed by fairly minor biological adaptations to body size and body conformation. They aren’t extinct. They just look different. Musk Ox survived just fine as did caribou. They simply moved northward.
        It is important to remember also that the perigalcial environments south of the great ice sheets have no modern analogs. It is a profound mistake to consider modern tundra and taiga as equivalents since they are not, and can not be. Insolation for instance was much higher. While the “climate” might have been colder, the incoming light was more intense in the lower latitudes than can be found in tundra or taiga today, meaning the primary productivity was much higher in these periglacial zones during the Pleistocene. The primary extinctions are almost all among animals that were occupants of those environments and they evidently vanished along with the environments. In North America the situation may have been complicated as the Bering land bridge opened allowing diseases to move somewhat more freely between the major land masses.
        Since a human population was present in the Americas by as early as 17,000 BP, it seems unlikely that “overhunting” was a serious problem. It is important to remember too that there are immensely many more elephants, dire wolves, sabertooths and Alaskan lion in the la Brea Tar Pits than there are known to be victims of human predation.

      • agfostrjr –
        Just because ALL mice didn’t die doesn’t mean at all that MOST mice could have died. Did you ever take allogic course? An event that kills 100% of one or more species but only 80% of others can leave those 80% species still around, enough to repopulate. It’s called a bottleneck. The event, whatever it was – climate or impact (or some OTHER cause no one has thought of) – that caused the YD onset killed ALL of some. Because SOME of the others made it though the bottleneck you can’t read that as a “selective”.
        Because SOME survived in no way means that every individual in that species was spared.
        SOME small animals – including small mammals – made it through the K-T. You said it yourself.
        It doesn’t matter that we LABEL the event the “Pleistocene megafauna extinction.” Labels don’t mean anything.. Warmists call the current climate “global warming”. That label doesn’t make it so.
        As to your strike one… Are you going to conclude that because someone presented THEIR one side of the case, that the issue is over without hearing the rebuttals? If so, holy crap! If you judge before hearing both sides, you would make a terrible jury member. Look at my post of 6:10 pm yesterday (reply to ob at 1:14 pm) that includes rebuttals of the earlier assertions of “bunk”. You can see that just because the skeptics state something that that is not the end of the discussion. Scratch strike one.
        As to your strike three, have you noticed that every place you mentioned is an ISLAND? read up on extinctions, and you will find that islands are specifically easy places to make a species go extinct. It’s part of the reality of extinctions and WELL discussed in the literature. You can’t equate an 8 million square mile continent to an island. Different realities exist and must be considered. Try cornering the last 1,000 mammoths in one corner of N America with a few thousand hunters – without the mammoths doing an end run and escaping back out into the other 7.9 million square miles. Scratch strike three.
        As to strike three, what do YOU consider “an enormous ET object”? Have you read any of the literature, or do we get to just pick our own nebulous number range – say 100 feet to 7000 miles? “Enormous” is so vague it means nothing.
        You got nothing.

      • Duster –
        All good points.
        “It is important to remember too that there are immensely many more elephants, dire wolves, sabertooths and Alaskan lion in the la Brea Tar Pits than there are known to be victims of human predation.”
        Along those lines, are you aware that there are only 12 Clovis-mammoth kill sites and 2 Clovis-Mastodon kill sites? That’s it. That’s all the evidence for overkill. 14 sites. Surovell himself wrote a paper entitled, “How many elephant kills are 14?: Clovis mammoth and mastodon kills in context”. http://uwacadweb.uwyo.edu/nmwhomepage/pdfs/QI%202008.pdf

      • Steve:
        I took a quick look at the Surovell/Melzer paper (I skipped the math stuff…way above my pay grade). The paper attempted to analyze the known Clovis-mammoth/mastodon sites in the context of similar known sites in the “Old World”. The authors of the paper, rather refreshingly, are blunt about the fact that they are making a range of assumptions (identifying them as they go along), that there is much that is not known and that the way the evidence has been preserved may bias the results (factors like time span between the different comparators, geology/climate, etc.). However, based on the examination that they conducted, they feel that the better view is that (p. 94 of the article):
        “[…] we suspect that a strong behavioral signal is coming through our sample, biased or not. In other words, the abundance of mammoth and mastodon kills known from Clovis contexts relative to Old World contexts is largely a product of past human behavior. Does this mean that mammoth meat was served on the dinner table every night in the latest Pleistocene of North America? Absolutely not. From our analysis, we cannot estimate an absolute frequency of elephant hunting. All we can say is that in comparison to the Old World record, Clovis peoples seem to have exploited elephants with much greater frequency than in any other time and place.”
        Now, they are not claiming (in this paper, at least) to link this possibly greater predilection for hunting of big game with the extinction of those animals – rather, they merely are noting that, based on their assessment of the available evidence, it was a greater part of Clovis culture than elsewhere, in the older comparator cultures that were analyzed. However, it seems to me that this paper does not itself undercut the “hunting to extinction” thesis, and potentially could be used to support it.
        (I’m taking no view on the hunted-to-extinction hypothesis: merely noting that the paper itself does not contradict it, and potentially could support it.)
        I found that the way you’ve stated the issue is perhaps a bit different what is actually being considered. You note that they are “researchers who seriously seem to question the exclusive hunting of megafauna”. I’m not sure what you mean by “exclusive” and certainly Surovell/Melzer expressly seem to note that they are not suggesting that the Clovis ran a Flintstones’ style drive-in for mammoth ribs. As noted above, however, they do appear to conclude that such hunting was more frequent in Clovis than comparable cultures in the Old World (though they are not positing the absolute extent of such hunting).

      • ian005 –
        Amazing – someone who actually DOES go and read papers linked. . .LOL
        Yeah, that is not the only paper they’ve done on this general angle. In another paper Meltzer goes into depth on other types of game that Clovis likely killed. This paper as I read it at LEAST considers that it WASN’T mammoth meat drive through – which is more than I can say for many. And this thinking they’ve done for about 20 years now.
        I am actually giving them credit for objectivity, even though they are on the opposite side of the impact fence.
        To me, it is an open question of their dietary choices. But if you go to the maps on the PIDBA-org site, you will see that where most Clovis sites are there are no mammoth kill sites, except way up in Wisconsin and Michigan, in the northern reaches. Not many Clovis sites exist out west. Most are east of the Mississippi River. This is one of the points Dennis Stanford makes in his Solutrean-Clovis hypothesis. Considering the amount of plant matter elephants eat (and mammoths, by inference), it is amazing that no mammoth kill sites are where most Clovis points have been found – where the forests were densest. (Especially when one considers that the most reasonable place for points to be lost is at kill sites.) In Africa elephant ranges are mixed, but in India and SE Asia their main range has been forests, so one would tend to think that mammoths also would prefer forests. So if we have Clovis in forests mainly and proboscideans preferring forests, why do we find Clovis points at mammoth kill sites almost exclusively in regions that were not forested?
        I am beginning to think that Clovis point sites are not necessarily Clovis PEOPLE sites. I am beginning to think that Clovis knappers traded their points and the points got used by all sorts of people. I think that is a thought Melzer had in one of his papers, too. If so, that would mean that Clovis points are not necessarily a good proxy for Clovis people.
        Time will tell on that. As to the overkill, it’s a tough sell for me, because N America is REALLY big, and tracking down all those megafauna to every corner of the continent, by a few thousand hunters in a few hundred years – that seems illogical to me, to even START down that logical path.
        If 14 kill sites doesn’t refute – and I agree it doesn’t – it also lends VERY little support to the overkill hypothesis.

      • Ian005 –
        One more response, if I may…
        You said “However, based on the examination that they conducted, they [Surovell and Meltzer] feel that the better view is that (p. 94 of the article):
        ‘[…] we suspect that a strong behavioral signal is coming through our sample, biased or not. In other words, the abundance of mammoth and mastodon kills known from Clovis contexts relative to Old World contexts is largely a product of past human behavior. Does this mean that mammoth meat was served on the dinner table every night in the latest Pleistocene of North America? Absolutely not. From our analysis, we cannot estimate an absolute frequency of elephant hunting. All we can say is that in comparison to the Old World record, Clovis peoples seem to have exploited elephants with much greater frequency than in any other time and place.’
        While I can probably respond on every one of those points that they made, I would rather make a different point.
        I often remind people that science is NOT the accumulation of evidence, but the INTERPRETATION of the evidence. To whit, science has often been described as the attempt to understand and explain the natural world. Such understanding and explanation is what they are paid to do – not to just assemble data and walk away. There is always the attempt to put the evidence in some context, and that is where interpretation comes in.
        As those authors phrased it (very honestly, I will credit), “…we suspect that…” and “…From our analysis we cannot estimate an absolute…” and “…All we can say is that . . . Clovis peoples seem to have exploited…”
        All of this is their interpretation. I don’t say that to demean them. I say it to shine a light on the element of interpretation. THESE scientist weigh the evidence in their particular way. And each other researcher into this area has interpretations weighed in various other ways. This happens in other areas of inquiry, too, not just this one – that different weighings of mostly the same body of evidence yields several (if not many) different interpretations.
        As I’ve noted in these comments already, there are FOUR scenarios for megafauna extinctions out in the academic world right now – climate change, overkill, plague/illness, and impact. You and I both know that all of them can’t be correct, not as the main forcing. Yet each one each year or so has papers weighing evidence preferentially toward ONE of these four, and these aer done in all seriousness. The authors of each paper sincerely think that their interpretation should be favored above the other three. Are three of the four groups of scientists simple-minded? Of course not. But the way they select which evidence to include and which to exclude, PLUS the relative weight given to the particular bits of evidence, gives an almost unlimited panoply of overall interpretations.
        It appears that “science” gives these variously interpreting authors very broad authority to weigh evidence, I would say. To me, this only serves to obfuscate the entire field of study (this and perhaps many others), by not having sufficiently tight standards that are applied to evidence and treatment of evidence. And by not even having HIERARCHIES of evidence as courts do. (In courts, forensics are #1, documents #2, and on down to eye witness evidence, which is last on the totem pole.)
        As mr lorax said at 12:24 pm yesterday:
        …The researchers leading the “impact skeptics” are anthropologists. In their field of anthropology, truth is somewhat subjective, as in whatever you can convince the other anthropologists of, without a lot of actual definitive physical evidence. They are hoping by making a lot of nice sounding arguments they can establish their theory of “something not an impact” being responsible for the black mat layer. Unfortunately for them, this is a topic with substantial physical evidence.
        In science, empirical (measured physical) evidence should be #1, the equivalent of forensics in court – which forensics are, in fact, actually empirical and physical and measured. Mr lorax’s “convinc[ing] of others” arguments sans physical evidence should be put much farther down the totem pole. “Reasonableness” or reason itself, should never be put ahead of physical evidence, measured and organized. Reason is, when you come down to it, one of two things – a guess, or an interpretation. And one could argue that all interpretations are themselves guesses, so perhaps reason needs to be piled down at the bottom of the evidence hierarchy with eyewitness evidence.
        Perhaps 70-95% of the comments here on this thread are wrapped up in pretty-sounding “reasonable” ideas. But supposedly science replaced that Aristotlean approach long ago, replaced by quantified physical evidence. As mr lorax calls it here, “substantial physical evidence.”
        Mr lorax understands the hierarchy that SHOULD exist in this debate about a hypothesis in the Earth Sciences. Surovell, Pinter, and Holliday, etc, somehow don’t. The amount of interpretation should be as SMALL as possible. (In that sense, Occam’s razor perhaps should be ruling here.) But since Surovell, et al, do not seem to understand the hierarchy of evidence in science, they don’t know when they’ve been bested. They think that more talk will win the day.
        But when physical evidence says that temps over 2200°C are required, and 2200°C is far above what forest fires and the fermentation of insect poop can produce, they just don’t get it. And if they DO NOT, how in the world can they ever be convinced that they are wrong? So, Wittke, and Kinsie, and Kennett, and Le Compte, and Israde keep on putting the highest evidence in front of them, and what is the reaction? Surovell keeps having his eyes glaze over.

      • Steve Garcia
        September 12, 2014 at 3:20 pm
        ….
        Along those lines, are you aware that there are only 12 Clovis-mammoth kill sites and 2 Clovis-Mastodon kill sites?

        Actually, I believe there have been another couple of kill sites identified within the last two years. Another problem with the “overkill” concept is the vanishing of other mega predators. The short faced bear, sabertooth, Alaskan lion and direwolf all vanished from America along with mammoth. Other herbivores also vanished including mastodon, horse, camel, and ground sloth, though the latter may have hung around several millennia. No overkill account handles these collective extinctions well. The argument is silly at best.
        When you discuss Clovis one thing most people are unaware of is that there are only a handful of Clovis occupation sites, of which the best is probably the Gault site in Texas. That site yielded lots of smaller mammals, birds and even evidence of pond turtles in the Clovis diet. The site was evidently placed to take advantage of a good water supply and abundant Edwards Plateau chert. I believe it may be the only long-term, Clovis occupation site known. The archaeological debate about Clovis is far louder than the evidence justifies.

      • Mammoths did not go extinct during the YD either in North America or Siberia.
        Mastodon populations show clear evidence of human hunting pressure and its effects before going extinct.
        The YD was no different climatically than the onset of other interglacials and other cold events during the transition and the Holocene. The null hypothesis has not been rejected, and there is in any case no clear evidence of an impact.

  3. As for the possibility of a Younger Dryas magnetic reversal, core/mantle coupling should not be ruled out. Probably no event incurs as much core/mantle torque as rapid polar ice sheet melting. That is to say, magnetic reversal does not affect climate, but the reverse. –AGF

      • ok smart guy I’ll bite would like your thoughts on mine ten thousand years ago enough ice pressed down on the core through the Hudson bay to make Florida rise above what the ocean had dropped from ice displacement with Hawie as my example and a couple of miles of ice pressing down on the crust my magma core would wear the crust thin at which time the ice would melt from the heat at the bottom melting the ice from center out giving us a huge lake thousands of feet above ocean level just like now with mankind having 95% of its population living within 50 feet of ocean level the ice dam would eventually collapse and I would suggest to you that the crust would rebound dumping all of the displaced water back into the ocean lifting that level one to two hundred feet in as little as 24 hours the loss would be as huge as to the speed in which the ocean rose and the flood would spread outward depending on which ocean the water got dumped into your thoughts sir

    • There is an immense amount of data collected on geomagnetic reversals now spanning about 250 MY, IIRC my Historical Geology properly. There is no regularity of spacing or clear periodicity to chrons, some have lasted more than 10 MY many others are as short as several tens of thousands of years. Frequency does appear to increase toward the present and many, many more reversals have occurred in the Cenozoic than have been found in the Mesozoic. There is no correlation that I can see between reversals and “climate.” Also, since climate appears to be an emergent property of weather, and possibly only real in the minds of climatologists, I am dubious that there would be real correlations.

  4. I have been avidly watching the development of this theory since it was first proposed in 2006 and have seen many counter studies, and counter-counter studies. As a biologist mass extinction events are bread and butter of punctuated equilibrium that helps define our understanding of speciation. Some of the challenge to the theory are from the vocal environmental “Man is the cause of the extinction” crowd, who, much like their warmist cohorts crow about protecting the planet from humanity because of the “ongoing” extinction event by pointing to it.
    Here’s a prediction, in a month to six months, yet another counter study will say there is insufficient evidence for the impact event, and yes those dastardly Paleo-Indians ate their way all the way to Patagonia.

    • Ah, but those Paleo-Indians would have crossed the continent the same way that … Lewis and Clarke did: By walking across mountains, and valleys, and hills and dales. (True, they started from the east coast with horses using well-established roads as least as far as Pittsburgh (Ohio River) but even the settlers leaving the Mississippi from St Louis got all the way to the Wilmette Valley in less than 6 months. Washington DC to Washington state’s Pacific Coast took two years, then least than two years to get back.)
      So, from the Bering Strait to Patagonia? Less than 10 years … If they wanted to. To settle? Look at the Mongol hordes sweeping across the steppes with entire tribe in arms.

      • Well, according to the people in the know, those Paleo-Indians didn’t ride horses. Obviously they had voracious appetites and set fires to the grasslands to stampede hundred of animals over cliffs (so the reasoning goes). Hey, all that CO2 they produced not only destroys the noble savage myth, but implies they should have stupided themselves into extinction. Biologists make no such assumptions, anthropologists seem to. Of course I am paraphrasing the eco-enviro-anthropologists I’ve run into in my many years of getting degrees, and now with me working in an educational position now.

      • One of the very curious facts about Clovis sites is that the vast majority of them are in the EAST, not the west. It is amazing how many Clovis finds are mapped in the east on PIDBA.org – and how FEW were out west. And yet, there are ZERO Clovis-mammoth/mastodon kill sites in the east.
        In addition, the “point technology” up and over the Bering Strait has absolutely NOTHING in common with the Clovis points. Instead of one long and graceful blade, like Clovis, the Siberian spear points are serrated – mainly wood or ivory with many small flakes embedded in them. In addition, no Clovis sites exist up at the northern end of the “ice-free corridor). The tech there matches Siberia. But not Clovis.
        Yes, SOME people came to America via Beringia. No one argues that. The real question is: Was Clovis part of that?


      • Steve Garcia
        September 11, 2014 at 5:42 pm

        Yes, SOME people came to America via Beringia. No one argues that. The real question is: Was Clovis part of that?

        Since we really don’t know when or how humans first colonized the Americas, we can’t say. The best archaeological evidence is that it happened before 17,000 years ago. In fact what we do know now is that Clovis (as in the classical, early percussion-fluted technology) is an American development made by populations already resident. Archaeology like all science is subject to the hazard presented by Occam’s Razor. The simplest explanation is usually the best (but,it is also the easiest to remember, to think about, to imagine, and presents the greatest temptation to disregard contradictory or complicating data). The idea that CO2 is the “control knob” for climate is a good example of over-simple explanatory hypotheses.

      • Duster –
        We see more or less the same things about the peopling of the Americas, as far as we’ve opened that door.
        On Occam’s razor and the “simplest is usually right” meme, yeah, you caught some of its failings there. My experience in science and engineering is that you START with the simplest explanation/approach, and then all sorts of complications DO come in. I am virtually certain that some form of the impact hypothesis will win out here, but I think it will have numerous complications added in. Right now, it is simple and straightforward. But as the need comes in (probably fairly quickly) to cover things like the other spikes in the D-O record, and the duration of the YD at 1300 years, the hypothesis will get more complex. Hey, the topic covers about 5 or 10 areas of inquiry, so it needs to address things all over the map, so it would be amazing if its simplest version is the final one.
        People here bring up good points – but I know for a fact that the scientists involved have thought of all of those and many more. It kind of amazes me that people will assume scientists overlooked the obvious candidates (and most of the ideas here are the obvious ones – no offense to anyone intended). That doesn’t mean “Trust the scientists blindly”, though. People here SHOULD be asking those questions. But the ridicule on some comments is silly, and for the most part uninformed, or – like warmists – .informed of only one side of the story.
        This is a VERY complex hypothesis. That is why all those scientists’ names are listed (I count 26). Each one or two is covering his/her area of expertise. That is a lot of disciplines.

    • The human cause for the obliteration of the New Zealand moas is well-established. The major facilitator of that extinction was that the moas had no evolutionary experience of humans, didn’t fear them, and didn’t know to avoid encounters. Paleo-Maoris could just walk up to a moa and club it death. And they apparently did so. Bone yards show they often killed more moa than they needed for food.
      It’s likely that the large fauna of Australia were likewise killed off by the paleo-Aborigines. Mega-fauna disappeared from Australia, after the arrival of the Aborigines, at the same time as they thrived on New Zealand.
      The evidence does not support the extinction of Australian fauna due to climate change, or to a sudden impact.
      A similar case can be made for North American mega-fauna, in that they had no evolutionary experience of humans. In analogy with the New Zealand moas, it is likely true that they had no response to avoid humans and that humans could kill them after almost trivially easy stalking. There’s no reason to think that paleo-Americans were reticent about mass-killing prey animals or that they were conscious stewards of their environment.
      Buffalo jumps all across the US and Canadian midwest show that native Americans killed far more bison than they could eat or use. Two larger species of bison had already been driven to extinction in pre-Columbian times. So, there is good circumstantial evidence at least, that north American mega fauna were driven to extinction by predatory competition from humans. The hunting hypothesis is made stronger by the fact that virtually all mega-fauna disappeared during this time. A climate extinction event might be expected to make extinct some suite of non-adaptive species. Not all species.
      Also, why shouldn’t an impact that obliterated animals obliterate humans, as well? But humans weren’t obliterated. David Meltzer and Vance Holliday say (pdf) that, “conditions during the Younger Dryas interval may not have measurably added to the challenge routinely faced by Paleoindian groups who, during this interval, successfully (and perhaps rapidly) dispersed across the diverse habitats of Late Glacial North America.” J. World Prehist. (2010) 23, 1–41.

      • You are not ever going to hear one thing from Melzer or Holliday in harmony with the impact hypothesis. They are firmly entrenched in the small skeptics group. So, no matter how many papers or how many other scientists find support for it, Holliday and Melzer will be among the last to agree. So, you will always find some paper of theirs kibitzing negatively. Right now they are basically doing Op-Eds, with almost NO actual science, just commentary.
        Notice that while the TONE of that passage is negative, they waffle on it with “may not have”. So, they have their “may not haves”, while the YDIH scientists keep putting out paper after paper with all sorts of empirical evidence at the “forensic” level. Lab tests of actual physical samples taken carefully in the field.
        In other words, one side is doing physical science and the other side is doing play-by-play with a negative twist.

      • Paleo-Maoris ? Paleo-English ?
        We are talking about around 1000 years ago.
        However there is no doubt that Maoris killed off the moa.
        And killed more than they could eat ?
        Certainly, because they used the feathers for cloaks.
        Fur trappers in 18th-19th century North America killed more animals than they needed for food as well.

      • Your comment reads to me as confirmation bias. Decide the outcome, decide the events to the outome, decide the perpetrators which is of course always man…
        The moa extinction event is a very long way away from causing the extinction of the megafauna.
        Or are you going to argue that the short faced bear didn’t know to fear man? Ditto for the saber tooth and the poor innocent lamb loving dire wolf.
        Very few small field finds are stretched far beyond their evidence to fault man as the cause.
        Did mankind drive animals over a cliff when possible for enough food for a tribe over a very long winter? Quite likely.
        Now explain how mankind drove the largest most dangerous creatures of the age miles and miles till they found a convenient cliff? Or did they dig pit traps for the mastodons? Perhaps they rode the backs of the dire wolf and saber tooth till they found a tall enough hill? Maybe they ran them up and down manmade mounds till the beasts died of exhaustion?
        The blunt truth is that the concept for man caused the mega fauna extinctions is based on little real evidence and has major holes in the whole premise. Much like the climate crowd, when their concept is questioned they scream louder and point to research echoes, identical including the lack of proof.

      • “The major facilitator of that extinction was that the moas had no evolutionary experience of humans, didn’t fear them, and didn’t know to avoid encounters.”
        Most prey animals learn very quickly to avoid predators and how and where to avoid them. Perhaps small island populations might be seriuosly depleted but the concept of lack of “evolutionary experience of humans” would seem to be very unlikely as a reason for poor adaptability to predators, at least to this hunter.

      • Steve G, notice the citation at the end of the quote: (2010) Journal of World Prehistory.
        Meltzer and Holliday published their data and conclusions in a bona-fide science journal. You mischaracterized their venue as an op-ed, and your general criticism is fact-free.
        A Google Scholar search turned up a 2012 book chapter criticizing the impact hypothesis, in which Meltzer is joined by 15 co-authors: “Arguments and Evidence Against a Younger Dryas Impact Event,” in Climates, Landscapes, and Civilizations (eds L. Giosan, D. Q. Fuller, K. Nicoll, R. K. Flad and P. D. Clift), American Geophysical Union, Washington, D. C.. doi: 10.1029/2012GM001209.
        It may be he’s wrong, but his criticisms deserve to be heard without personal dismissals merely because he may be in a minority position and insists on arguing his case. After all, he may be right. The rational debate, in any case, is only to the betterment of science because it forces everyone’s investigation to be most thorough.
        For myself, I don’t see any necessary contradiction between climate change following a Younger Dryas impact, but most mega-faunal extinctions due to other causes such as human competition.

      • ATheoK, early humans didn’t have to ride dire wolves. They only had to out-compete them for prey.
        And yes, without direct evolutionary experience, dire wolves, mastodons, saber-tooths, and all the rest would not have had an avoidance response for humans. Predators might have seen humans as a new sort of prey. Humans do not take kindly to members of their family (or tribe) being attacked and eaten. When predated, humans generally respond by hunting down the predators.
        The population of predators is generally fairly thin in any case. It wouldn’t take an overlong period of strong human competition, plus direct predation for fur and self-defense, to drive an animal predator population into extinction.

      • Jim G, when they inhabit the same geography predators and prey generally co-evolve.
        They first evolve into that relationship, and they then evolve within that relationship. All of that occurs over tens of thousands of years.
        The capacity to catch prey evolutionarily improves in response to an evolutionary improvement of prey to escape — a kind of co-evolutionary arms race. Predator and prey start naive and jointly move towards sophistication.
        Your experience as a hunter is with animals that have a long evolutionary experience of humans. In North America, it’s now been at least 14,000 years of experience. Their avoidance of humans (you) has been bred into their genome by systematic culling (predation).
        The introduction of rats into island populations exemplifies a sophisticated predator encountering naive prey. This has been well-investigated. Rats can walk up to ground-nesting birds and start chewing on a bird’s legs, while the bird evidences no alarm at all.

      • Pat Frank –
        “Meltzer and Holliday published their data and conclusions in a bona-fide science journal. You mischaracterized their venue as an op-ed, and your general criticism is fact-free.”
        NO, you misunderstood, so I must have misstated myself. What I MEANT to say was that the CONTENT of Holliday’s and Melzer’s work is the Op-Ed. Basically, they have published about half as many papers as the YD proponents. And their papers tend to have a lot of comment and editorializing and very little empirical science in them. Seriously, not much. I refer to them as “the Kibitzers” sometimes. Monday morning quarterbacks. Surovell’s oft-quoted 2009 paper is loaded with errors that their team made in failing to replicate the work of the YD proponents.
        See my comment of 6:10 pm last night, in reply to ob at 1:14 pm. I pasted in Israde’s shredding of Surovell’s genuinely sloppy work.
        As to calling certain journals nasty things, Surovell and Melzer and Holliday actually tried to make debate points by saying that the PNAS editors were giving the YD proponents an easy pass, and that the YD proponents were taking advantage of that. This in spite of the fact that the skeptics themselves have used PNAS for several of their own papers. The skeptics have gotten really immature at times, actually.

      • Sorry about all that bold at the end of that comment. I mis-typed the closing brackets after the word “editorializing.”
        [Fixed. Remember to tip the mods. 8<) .mod]

      • Steve G. the link to Meltzer’s book chapter summary is here. Note the section headings: Introduction; Fundamental Flaws (in the impact hypothesis); Evidence-Based Arguments (concerning the YD); Conclusions.
        They appear to deploy a large amount of empirical science throughout.
        I’m not saying I agree with them. I’m saying they have an argument and they should be allowed to make it so long as they stick to scientific arguments.
        From what I have seen of their papers — I’ve not made a close study — they seem to be contextually valid and to argue their point by reference to data.
        As to the PNAS editors, given the easy pass they’ve given to pretty fatuous papers promoting AGW, I wouldn’t put other sorts of bias beyond them.

    • From the Supplemental materials in Israde’s 2010 paper “”, she shreds the Surovell inability to follow well-spelled out sampling and testing protocols laid out by Firestone 1007:

      SUROVELL et al. (2009). Those authors claimed to have closely followed the Firestone et al. protocol (2007a, 2007b) for quantification of MSp. LeCompte et al. (2011) compared their protocol with that of Firestone et al., and this comparison revealed that the methods of Surovell et al. differed substantially in several critical ways, as described below. For two sites common to both studies, Surovell did not observe a single MSp in the YDB and, therefore, claimed to refute the results of Firestone et al. However, LeCompte et al., an independent group, retested those two sites and reported MSp values ranging from ~100 to >1000 MSp/kg, confirming the results of Firestone et al. and refuting the results of Surovell et al. They concluded that the changes in protocol introduced by Surovell et al. led to fatal flaws in their extraction, identification, and quantification of YDB MSp, all of which invalidate that group’s conclusions, as follows:
      Deficiency #1: YDB Samples Too Thick Stratigraphically. A) Quote from Firestone et al. (2007a) regarding the YDB interval: “we found a thin, sedimentary layer (usually <5 cm).” B) Source, Table S1 in Surovell et al. (2009) shows that the candidate YDB interval at 7 sites was sampled at a resolution ranging from 5-28 cm, averaging 11 cm. Problem: Firestone et al. collected sediment samples at 7 sites at which they discovered high abundances of YDB markers in a thin layer with vertical thicknesses ranging from 0.5 to 5 cm and averaging 2.3 cm, as illustrated in their Fig. 1 in Firestone et al. Surovell et al. collected some samples that were sufficiently thin, but also collected much thicker samples, ranging up to 28 cm thick (averaging 11 cm), much wider than the average YDB layer averaging 2.3 cm where the MSp are concentrated. The thickest sample (28 cm) collected by Surovell et al. diluted the markers by an average of ~5× and up to ~60×, masking. Although we do not consider this to be a fatal deficiency, it does make spherule detection more difficult.
      Deficiency #2; Inadequate Aliquot Size. A) Quote from Firestone Protocol (2007b), who analyzed “one or more ~100-200 mg aliquots….Microspherules are usually rare, often making it necessary to inspect the entire magnetic fraction.” B) Quote from Surovell et al. (2009): they “examined 10–40 mg … per sample,” and never examined the entire magnetic fraction. Problem: This deficiency means that Surovell et al. examined up to 20× fewer magnetic grains than Firestone et al., further reducing the resolution necessary to find the MSp.
      Deficiency #3: Size-Sorting. A) Quote from Firestone Protocol (2007b): “We used ASTM sieves to screen the magnetic grains into separate fractions and worked mostly with the <150-μm samples.” B) Source, Surovell et al. (2009): They utilized only a “1-mm sieve.” Problem: Adequate size-sorting is essential in order to overcome the difficulty in detecting rare MSp among other, more abundant magnetic grains. Also, during normal handling of the magnetic fraction, the grains tend to separate by size, meaning that the fine grains tend to move to the bottom of the container. Hence, drawing test samples from the upper layers results in preferential selection of coarser detrital magnetic grains, potentially missing the smaller MSp that become concentrated in the finer material beneath. Failure to size-sort represents a fatal flaw in their analyses. Furthermore, in those instances where the entire sample is not examined, it is critically important to work with well-mixed representative aliquots to assure an even distribution of MSp. A mechanical sample splitter is the preferred instrument for splitting the magnetic fraction, although careful manual splitting will suffice.
      Deficiency #4: Perfect Sphericity. A) Source, Fig. 2 in Firestone et al. (2007a): two of the four MSp shown in Fig. 2 are highly spherical, but the other two are not. B) Quote from Surovell et al. (2009): they elected to “eliminate a number of particles that at first glance appeared to be highly spherical but were not.” Problem: The approach of Surovell et al. differed from that of Firestone et al. by only counting those candidate spherules with a high degree of sphericity, even though it is well recognized that cosmic and impact microspherules often are non-spherical (Taylor, 2000, 2002). Such non-spherical objects occur frequently in Lake Cuitzeo, where such an overly rigorous protocol would have meant not counting the MSp shown in Figs. 5D, 5F, SI Figs. 6A, 6C, and 6D, resulting in an undercount in YDB MSp by ~50%.
      Deficiency #5: No SEM/EDS Analyses. A) Quote from Firestone Protocol (2007b): “Selected microspherules were mounted, sectioned, and analyzed by XRF [SEM-EDS] and/or laser ablation.” B) Source, Surovell et al. (2009): no MSp were reported to have been analyzed. Problem: Firestone et al. analyzed MSp using SEM-EDS, as in the present study. Both investigations indicate that the observed YDB MSp are not of anthropogenic, volcanic, or cosmic origin, but instead match quench-textured spherules from known impact events. Furthermore, while detrital magnetic grains and framboidal spherules may appear to be MSp under a light microscope, examination by SEM/EDS can show that they are not. The Surovell et al. group did not conduct any SEM analyses, resulting in potentially counting apparent spherules that were not impact-produced, and thereby leading to erroneous values, especially outside the YDB. In our experience, most candidate “spherules” outside the YDB tend to be detrital grains or framboidal spherules, rather than true MSp. Regarding this, Pinter et al. (2011) did not to recognize the difference between quench-melted MSp as compared to rounded detrital grains and framboidal spherules, which are readily differentiated using SEM/EDS.

      So, just like in junior high science lab, if you don’t follow the protocol, you results are meaningless. Surovell couldn’t follow protocol, but he and his group expect the world to weigh their evidence equally with the properly taken samples and the properly tested samples.
      If the above is over your head (some of it is over mine, certainly), the more you learn about what it says, the more you realize that this evidence of Surovell’s is pretty bad.
      Then, since then, they’ve done little besides snipe and run to their favorite science editors around the country and scream bloody murder.

      • Above, you say “small skeptics group”. That would include the AGU, which published a devastating analysis of this evidence-free, cockamamie conjecture. Had its proponents any evidence, there would be a basis for debate, but there isn’t. Its advocates just keep changing their scenarios and presenting over and over again the same thoroughly debunked junk science.

  5. The drop in temperature was very fast. When the period was over the temperature rise was very fast too but not as fast as the drop to start the Younger Dryas. A drop this fast suggests something truly out of the ordinary happened.

  6. This story seems to have more lives than a cat! As Anthony points out, it has been in earlier articles making the same claim–a cosmic impact caused the Younger Dryas. Five of these have appeared on WUWT (some with comments from me) at the dates listed below: You can read the articles in the WUWT archives by searching for ‘cosmic Younger Dryas.’
    May 21, 2013 — (my comment) There are several compelling lines of evidence showing that the Younger Dryas (YD) was NOT caused by a cosmic impact or other single event. Aside from the fact that cosmic material in YD sediments doesn’t prove a cause-and-effect relationship (correlation isn’t proof of causation), the YD lasted for about 1,300 years, which is far too long for atmospheric dust not to have fallen to the ground. Even more compelling evidence is that the YD is not a simple, single climatic event–it was a series of repeated oscillations of climate each lasting several hundred years. In Scotland, Washington state, and various other places, glaciers advanced and retreated not only during the YD, but also during the preceding late Allerod cold period. The glaciers advanced and retreated as many as 8-12 times during Allerod/YD period and is thus not explainable by a single cosmic event. There were also a number of similar glacial oscillations during the preceding several thousand years. A cosmic event cannot explain the long duration (1,300 years) of the YD nor the multiple oscillations.
    June 13, 2012 — (my comment) Before jumping on the comet bandwagon, a number of dots need to be connected and some critical questions need to be addressed. For example, how could a single event, even with multiple projectiles, cause an ice age that lasted for more than 1,000 years? Surely not from atmospheric dust and if not that, then what? The Younger Dryas is not the only climatic event during the post glacial maximum period—there are also a number of others spanning the time from 14,500 radiocarbon years (about 17,500 calendar years) to 10,000 14C years (about 11,500 calendar years). These are well known, well dated, and well documented in ice cores and in the global glacial record. So the question is, how could an impact event cause both multiple warming and cooling events over a 3,000 year period? Doesn’t seem logical at all for either impact or volcanic events.
    Some other questions pertain to the evidence for the proposed cosmic event. Geologists are used to studying micro-images of rocks and looking at the two samples shown in the paper, it is obvious that both show definite flow structures that closely resemble glass flows from volcanic lava. The statement “Morphological and geochemical evidence of the melt-glass confirms that the material is not cosmic, volcanic, or of human-made origin. “The very high temperature melt-glass appears identical to that produced in known cosmic impact events such as Meteor Crater in Arizona, and the Australasian tektite field,” is very vague. What morphological and geochemical evidence? As for these specimens being identical to trinitite from atomic blasts, there is surely no flow structure in the photos shown so how can they be identical?
    The bottom line here is—a lot more dots need to be connected and these critical questions (as well as a number of others) need to be addressed before concluding that the Younger Dryas was caused by a cosmic impact.
    March 12, 2012 –(my comment) Before jumping on this bandwagon, consider the following:
    1. There may well have been a meteorite impact near the beginning of the Younger Dryas (YD), but that doesn’t prove it was the CAUSE of the YDs. It’s the same logic as saying the cause of the 1978-1998 warming coincided with rise in CO2 so the cause must be CO2. Bad logic.
    2. The YD is just the most prominent of many Dansgard-Oerscher abrupt climatic events.
    3. The YD ended just as abruptly as it began a little over 1000 years later.
    4. The YD corresponds with changes in 10Be and 14C production rates, suggesting changes in incoming radiation and pointing toward a Svensmark type cause.
    5. The problem with single event causes (e.g., volcanic eruption) is that they cannot be sustained for the length of time of the climate change. If the idea is that the cooling was caused by ejection of dust into the atmosphere, that wouldn’t last for more than 1000 years.
    6. If the YD was caused by dust in the atmosphere, it should show up in the Greenland ice cores (where even very small, annual accumulations of dust from summer ablation are well preserved). There is no such evidence of dust from an impact event throughout any of the well preserved YD ice core record.
    7. The list goes on and on–too many to include them all here. Perhaps a longer response later. The bottom line is that a single event, meteorite impact event doesn’t prove the origin of the YD.
    I also wrote two articles explaining the issues (posted on WUWT).
    http://wattsupwiththat.com/2013/06/02/multiple-intense-abrupt-late-pleisitocene-warming-and-cooling-implications-for-understanding-the-cause-of-global-climate-change/
    http://wattsupwiththat.com/2012/06/19/the-intriguing-problem-of-the-younger-dryaswhat-does-it-mean-and-what-caused-it/
    The issues are clear cut and spelled out in these comments and articles. In a nutshell, the Younger Dryas includes so many very sudden, intense climate changes over a period of several thousand years that it couldn’t be related to a single cosmic event. Even if there was a cosmic event as the authors postulate, it certainly didn’t cause the Younger Dryas.
    September 1, 2014 at 8:47 am
    Three issues seem apparent here:
    1. Is evidence of a cosmic impact about the time of the Younger Dryas (YD) conclusive?
    2. What caused the extinction of mammoths, saber-toothed tigers, sloths, etc. in the late Pleistocene?
    3. What caused the Younger Dryas.
    Each of these is an independent question that may or may not bear on the other issues. If there was indeed a cosmic event near the YD, that doesn’t prove that it was the cause of the YD nor the cause of extinctions. Many of the discussions above mix these issues. In order for the impact hypothesis to be a credible cause of the YD, it must account for all of the distinctive features of the YD. (Remember Richard Feynman’s and Albert Einstein’s caution that it only takes one negative piece of evidence to kill a hypothesis). Well, take a look at the number and magnitude of well documented YD temperature changes and the duration of the YD (1000 years), which cannot be explained by any single or even multiple cosmic events (there are too many climatic fluctuations over too long a time). These effectively kill the cosmic event hypothesis as a cause of the YD.
    A comment on the temperature fluctuations and the validity of the Greenland ice cores. Be aware that the abrupt warming and cooling of the late Pleistocene was not confined to the YD but began about two thousand years before the YD and well before the postulated cosmic impact event. These earlier temperature fluctuations were as large or larger than those of the YD. These large, abrupt temp fluctuations do not depend only on the ice core evidence. The ice core data is confirmed by well documented advances and retreats of glaciers on a global scale, the CET temp records, and a host of other temp proxies.
    The bottom line remains that you cannot explain the multiple, intense temp fluctuations of the late Pleistocene (YD and older) by cosmic impact.

    • Yep, fully with Don on this one. There were some outstanding comments on this topic 2 weeks ago:
      http://wattsupwiththat.com/2014/08/29/younger-dryas-climate-event-solved-via-nanodiamonds-it-was-a-planetary-impact-event/ by “milodonharlani” in particular, and my own modest contribution was the idea that the YD represented the time it took to melt out a frozen-solid 5 mile thick arctic ice cap — like a Greenland on steroids. However, Anthony seems to favor the impact hypothesis and it’s his blog, so there you go.

    • Why couldn’t the impact induce a precipitous descent into cold, followed by a thousand years of oscillation between relatively warmer and colder climates? These followed by a final return to the pre-impact climate attractor.
      One might expect to see rapid oscillations in a dynamically coupled system following a sudden energetic perturbation away from a quasi-equilibrium state.

      • There have been other meteor impacts documented, and yet those meteors didn’t bring about anything like YD. What’s so special about this particular meteor that triggered the YD cooling?

      • Maybe the impact, coupled with solar changes, coupled with some human caused extinctions?? It does not have to be all of one or the other.

      • That’s my guess. Only slight changes in regional isolation precipitated massive glacier growth/recession w/the help of Gulf-stream-current, albedo and ice-shelf changes amplifying the effects. Seems quite plausible a comet-strike causing a decades-long “nuclear winter” could change the above-mentioned conditions back to glacial for a thousand yrs.
        Whether this caused mega fauna extinctions is another question — much harder to determine. But the evidence for a catastrophic comet strike seems pretty conclusive IMO. I really don’t understand why there is so much vitriol about the possibility of a comet-strike, given the ample evidence. Only thing that comes to mind is defending the “humans did it” meme?

    • Don “Each of these is an independent question that may or may not bear on the other issues. If there was indeed a cosmic event near the YD, that doesn’t prove that it was the cause of the YD nor the cause of extinctions. Many of the discussions above mix these issues.”
      Yes, they do, but SO ARE YOU.
      Right now, the involved researchers are focusing on ONE time period and on the “forensic” evidence – in order to even ascertain that, yes, an impact occurred – or no, it didn’t. The full suite of impact materials they’ve studied argue that, yes, it appears that one happened. They are LOOKING for that one piece of evidence to falsify it – as Einstein and Feynman argue should be done. IN specific areas where they have found something doesn’t FIT, they’ve abandoned that line of inquiry (e.g., the Carolina bays), as they SHOULD. But removing the Carolina bays hasn’t left the rest of it wanting for evidence.
      The researchers are focusing on THAT time period and THAT evidence. So they are not working on the corollary parts of the bigger picture. THAT would be “mixing the issues.” Actually, the points you bring up ARE in themselves mixing the issues, because they are not in position to answer the 1,000 length of the YD until long after they have determined for certain that the impact even happened. First they have to determine if the microscopic evidence shows positive. And it certainly does – which you would know id you go reading the actual papers instead of Survell’s and Melzer’s and Holliday’s sniping op-ed papers. Se for yourself if there are holes in their evidence – as far as they have taken the evidence.
      Just like the evidence for evolution had to have many, many naturalists go out and find butterfly samples and birds and shrew,, etc., in order to establish a foundation of BASIC evidence, these researchers are trying to lay the groundwork at the micro level, before moving on to the macro level.
      Are they going to have some big conundrums when they GET to the macro lecvel? Yes, of course – on just those points you make. But if the micro evidence tells them that a big event happened which spewed impact materials over a 50 million square km area, are they to NOT try to see what it actually MEANS? Of course not. Are they going to stop looking because the conflagrations on 3 continents made it hard to find out which materials are terrestrial and which are not, and which are impact-related and which are not? Of course not. If an impact occurred, it would have a complex suite of evidence, in many disciplines. They have to go where the evidence leads them. There are some questions that can’t be answered with today’s level of evidence. So they have to go ADD to today’s evidence, so that the picture can become clearer. And if that evidence is THERE, and if it is microscopic, they sure as hell aren’t going to find it by starting at the (inappropriate) macro level.
      “In order for the impact hypothesis to be a credible cause of the YD, it must account for all of the distinctive features of the YD. (Remember Richard Feynman’s and Albert Einstein’s caution that it only takes one negative piece of evidence to kill a hypothesis).”
      Don, it doesn’t matter one whit whether YOU think the evidence is credible or not. YOU are not in there, in the labs and in the field with them. They are all competent scientists and they are doing the science that they have in front of them. What you think is credible – WHO CARES? Have you agreed with every scientist out there, on every topic ever studied? And lets’ look at the mammoth extinction for a moment. WIUth FOUR – count ’em, FOUR – current hypotheses out there, and only ONE of them can be correct, can YOU tell all of us which one is correct? Each one of them has competent scientists arguing that HIS hypothesis is correct. At least three of them must be wrong, but that doesn’t mean that they should stop their research, does it?
      “Well, take a look at the number and magnitude of well documented YD temperature changes and the duration of the YD (1000 years), which cannot be explained by any single or even multiple cosmic events (there are too many climatic fluctuations over too long a time).”
      THIS POINT I agree with you on, 100%. If there was an impact at one point, but not at the others, that poses a big problem, doesn’t it? OR there is something we all aren’t seeing right now.
      If the late paleontologist Stephen J Gould had come out with his “Punctuated Equilibrium” in, say, 1785, everyone would have thought he was crazy. Science had to grow into the point where he could see that extinctions and species explosions are the reality, not the gradual mutational story of Darwin. If Gould had come out with it in 1885, he would have been laughed out of town, too. But in 1985, the science was well enough along to have his idea make SOME sense to some people.
      Don’t forget that when Agassiz was finding evidence in the Jura Alps about ice ages, no one else was up with him. And when Darwin was hiking around near the coasts of S America and having ideas that didn’t include a Creator, there were a LOT of people who wouldn’t agree with him in a million years. In fact, he was so intimidated by them that it took him over 20 years – and Alfrred Russel Wallace – to publish “On the Origin of Sepeices”.
      MUCH of the science of that year 1885 has gone by the boards, replaced with newer ideas, and – we hope – more correct ideas. In 2085 or 2114, will today’s science all still be around? OF COURSE NOT.
      So, just because we can’t see an answer to those spikes in the Greenland ice core evidence doesn’t mean that THAT idea is the wrong one. (For example: Is there ANY chance at all that they are actually artifacts of the methodology of studying ice cores? We KNOW, from the animal and plant record that at the YDB, that THAT was a real climate change – but how about the others? Do we have that solid, or do the ice cores stand out as the only – or almost only – evidence that those are real?) Do YOU have an explanation for those spikes, within gradualist climatology, with its micro-forcings that have trouble raising the temperature by 1°C? Is there ANYTHING in that to explain rises and falls of 13°C? 14°C?
      And if 14°C cooling at one point didn’t kill off the mammoths, why did the YDB?
      So, so WHAT, if you don’t see that this has legs? Some people do.
      Or do we have to toe a line of consensus on this, even before all the evidence is in?
      Are folks like you going to go up and tell them, “STOP! You aren’t real scientists if you believe in this evidence” – are you?

      • beng
        September 12, 2014 at 7:13 am
        The evidence for a YD impact is so far from ample as to be nonexistent. There is not a single shred of incontrovertible evidence in favor of this hypothesis. All its proponents are left with is supposed hexagonal nanodiamonds (lonsdaleite), which have repeatedly been shown by independent investigators to be graphene, and the same material has been found at other sites going back at least to 40,000 years ago.
        No less an expert that the father of impact theories, Walter Alvarez, thoroughly debunked this evidence-free conjecture.
        http://www.usgs.gov/newsroom/article.asp?ID=3180&from=rss#.VBedRVcqlPk
        Technical Announcement:
        New Evidence Argues Against Prehistoric Extraterrestrial Impact Event
        Younger Dryas “Impact Markers” are the Result of Natural Processes
        Released: 4/23/2012 3:00:00 PM
        Contact Information:
        U.S. Department of the Interior, U.S. Geological Survey
        Office of Communications and Publishing
        12201 Sunrise Valley Dr, MS 119
        Reston, VA 20192
        It’s not just the USGS. Please read this AGU monograph on the YDIH in full. It’s more devastating than its bland abstract suggests:
        http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&ved=0CC8QFjAC&url=http%3A%2F%2Fwww.agu.org%2Fbooks%2Fgm%2Fv198%2F2012gm001209%2F2012gm001209.pdf&ei=7ZsXVOuyGeKrigL11YH4BA&usg=AFQjCNERJCPDRNT01nhPsMC2B8Sf36JVQg&sig2=cnF60Eoe5X-gRM8piLEI5g&bvm=bv.75097201,d.cGE
        Climates, Landscapes, and Civilizations
        Geophysical Monograph Series 198
        © 2012. American Geophysical Union. All Rights Reserved.
        10.1029/2012GM001209
        Arguments and Evidence Against a Younger Dryas Impact Event
        M. Boslough,1 K. Nicoll,2 V. Holliday,3 T. L. Daulton,4 D. Meltzer,5 N. Pinter,6 A. C. Scott,7 T. Surovell,8 P. Claeys,9 J. Gill,10 F. Paquay,11 J. Marlon,10 P. Bartlein,12 C. Whitlock,13 D. Grayson,14 and A. J. T. Jull15
        1Sandia National Laboratories, Albuquerque, New Mexico, USA.
        2Department of Geography, University of Utah, Salt Lake City,
        Utah, USA.
        3School of Anthropology and Department of Geosciences, University
        of Arizona, Tucson, Arizona, USA.
        4Department of Physics and Center for Materials Innovation,
        Washington University, St. Louis, Missouri, USA.
        5Department of Anthropology, Southern Methodist University,
        Dallas, Texas, USA.
        6Department of Geology, Southern Illinois University, Carbondale,
        Illinois, USA.
        7Department of Earth Sciences, Royal Holloway University of
        London, Egham, UK.
        8Department of Anthropology, University of Wyoming, Laramie,
        Wyoming, USA.
        9Earth System Science, Vrije Universiteit Brussel, Brussels,
        Belgium.
        10Department of Geography, University of Wisconsin-Madison,
        Madison, Wisconsin, USA.
        11Department of Geology and Geophysics, University of Hawai‘i
        at Mānoa, Honolulu, Hawaii, USA.
        12Department of Geography, University of Oregon, Eugene, Oregon,
        USA.
        13Department of Earth Sciences, Montana State University, Bozeman,
        Montana, USA.
        14Department of Anthropology, University of Washington, Seattle,
        Washington, USA.
        15AMS Radiocarbon Facility, University of Arizona, Tucson,
        Arizona, USA.
        We present arguments and evidence against the hypothesis that a large impact or airburst caused a significant abrupt climate change, extinction event, and termination of the Clovis culture at 12.9 ka. It should be noted that there is not one single Younger Dryas (YD) impact hypothesis but several that conflict with one another regarding many significant details. Fragmentation and explosion mechanisms proposed for some of the versions do not conserve energy or momentum, no physics-based model has been presented to support the various concepts, and existing physical models contradict them. In addition, the a priori odds of the impact of a >4 km comet in the prescribed configuration on the Laurentide Ice Sheet during the specified time period are infinitesimal, about one in 1015. There are three broad classes of counterarguments. First, evidence for an impact is lacking. No impact craters of the appropriate size and age are known, and no unambiguously
        shocked material or other features diagnostic of impact have been found in
        YD sediments. Second, the climatological, paleontological, and archeological
        events that the YD impact proponents are attempting to explain are not unique, are arguably misinterpreted by the proponents, have large chronological uncertainties, are not necessarily coupled, and do not require an impact. Third, we believe that proponents have misinterpreted some of the evidence used to argue for an impact, and several independent researchers have been unable to reproduce reported results. This is compounded by the observation of contamination in a purported YD sample with modern carbon.

    • Don Easterbrook September 11, 2014 at 1:39 pm
      6. If the YD was caused by dust in the atmosphere, it should show up in the Greenland ice cores (where even very small, annual accumulations of dust from summer ablation are well preserved). There is no such evidence of dust from an impact event throughout any of the well preserved YD ice core record.

      Oops.
      Journal of Glaciology Volume 56, Number 199, December 2010
      DOI: http://dx.doi.org/10.3189/002214310794457191
      Discovery of a nanodiamond-rich layer in the Greenland ice sheet
      Kurbatov, Andrei V.; Mayewski, Paul A.; Steffensen, Jorgen P.; West, Allen; Kennett, Douglas J.; Kennett, James P.; Bunch, Ted E.; Handley, Mike; Introne, Douglas S.; Que Hee, Shane S.; Mercer, Christopher; Sellers, Marilee; Shen, Feng; Sneed, Sharon B.; Weaver, James C.; Wittke, James H.; Stafford, Thomas W.; Donovan, John J.; Xie, Sujing; Razink, Joshua J.; Stich, Adrienne; Kinzie, Charles R.; Wolbach, Wendy S.

      • I won’t get drawn into this fight, but will point out that the Kurbatov 2010 paper was a preliminary finding to be followed by a full paper which however has never appeared. Critics have re-analyzed their “nanodiamonds” and found them to be (1) industrial soot from the 1700s, and (2) insect dander (trying not to trigger the moderation bot here). So who’s right? Beats me, but for me it’s clear that an impact event isn’t needed. The big extinctions were very obviously caused by human hunting, so who needs a meteor?

      • You missed Don’s point BP…. He was indicating that there would be 1300 years of dust in an ice core…. not just a single layer deposited over a couple of years…. Once the dust settled there would be an end to its cooling effect on the climate…… He wasn’t denying a dust layer, just that the dust was not in the atmosphere long enough to cause a 1300 year cooling.
        If there was continued cooling then it must be from another mechanism…. and probably separate from the impact event….. I would posit that the impact probably put paid to the Clovis culture… but had little impact on the global climate of YD period.

      • Greenland ND abundances are found at up to 5 × 10⁶ times above background

        Well, suppose NDs they’ve found are in fact soot or insect product or whatever. Still, it is a narrow peak, with concentrations some 5 million times above background, never occurring at any other depth in ice cores. Anything that abundant and only once demands explanation. And yes, there is much dust right above that thin layer. It is obviously not a direct consequence of an impact, just the usual high dust level of glacial times. So much so, that “dust age” is a more accurate term than “ice age”, because in cold epochs there was a hundred times more airborne dust while continental ice volume was only several times above its current level.

      • J.H. –
        No, Berenyi didn’t miss Don’s point. Don didn’t MAKE the point you say he did. Don said, “If the YD was caused by dust in the atmosphere, it should show up in the Greenland ice cores”. As written, Don was wrong. There IS dust in Greenland – and right at the 12,800 year mark. Beréyni’s reply is correct and a direct rebuttal.
        Don makes a point based on what we know now about dust in the atmosphere. But is what we know now actually correct? Probably, but not necessarily. If I had a dime for every time a scientist admits that, “Well, THAT was a surprise. Now we will have to rethink what we thought we knew about this phenomenon.” Scientists make such admissions several times a year, usually. (I point to Shoemaker-Levy 9 as a nice example…)
        Don likes to quote Einstein. I will go with Arthur C. Clarke and #1 of his laws:
        When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.
        Berényi Péter –
        This is a very perceptive comment. There IS all that un-consolidated loess deposited on top of that black layer in so many places, and yes, though loess is usually seen to be wind-blown, it COULD be seen as you say.
        Do I myself have an answer for that 1300 years? No. But I am keeping an open mind about it. That loess so common on top of the black layer has not been paid enough attention to – especially when it was evidently laid down in EXACTLY the time period when so may point to the 1300 years and argue that dust doesn’t stay up for 1300 years. As I recall, the loess in at least some places is just about 1300 years deep. Is there a connection? Are we missing anything?
        Based on so many comments here, hardly anyone here seems to have actually read the paper at all. Those spikes are VERY important. The spikes mean something, and the scientists involved are trying to ascertain what. And the answer keeps coming back: impact. Everything else at this time is secondary to that.

    • We could well be looking at a highly improbable concatenation of events. The improbability does not make it impossible. In fact, every impact event is precisely that unlikely all by itself. But consider the planet is also pulling out of glacial epoch, which happens once about every 100 ky during the Pleistocene. So now there are to rare, but profound, events on the table happening simultaneously in geological terms. If the YD was in fact a Daansgard-Oeschger event, they happen at irregular intervals but are usually seperated by millennia, that piles a third unlikely event on. The YD may have been a rather tight knot hole that terrestrial life dragged itself through. Also, as I mentioned in an early note, the actual environments around the periphery of the great ice sheets have no modern ecological analogs and that definitely includes both tundra and taiga. They ceased to exist with the ice sheets. So did the faunal associations.

  7. My explanation is first of all the state of the climate at that time was near boarder line threshold values of glacial versus non glacial conditions. This would then lend itself to given changes in items that exert influence on the climate to have a much greater influence. I think the ice dynamic plays a big part in all of this.
    That said I think much smaller changes were needed in given items that control the climate to set a cascade of things in motion which could then shift the climate from one regime to another. Today it can still happen but the changes will probably have to be more substancial and last longer in duration.
    My candidates are solar variability and associated primary and secondary effects, changes in the earth’s magnetic field which can either enhance or moderate solar variability , the initial state of the climate( which I just explained), and Milankovitch Cycles . However in regards to Milankovitch Cycles they were less favorable for glaciation then today’s parameters which include the tilt of the earth’s axis(less today then 12000 years ago ), eccentricity of the earth’s orbit(more eccentricity)more favorable if N.H. aphelion back then occurred in summer instead of winter(not favorable), and precession of the equinoxes(aphelion today now in N.H. summer) all favorable for cooling.
    This leads me to conclude it is the initial state of the climate (the ice dynamic) moderated by solar variability (primary and secondary effects) further moderated by the weak earth magnetic field at that time. Gothenburg reversal or at least excursion taking place 11500 years ago. This then could bring the climate to threshold values both for rapid warming and rapid cooling.
    It had nothing to do with co2 concentrations which are a by-product of the climate not a cause.
    It had absolutely nothing to do with some cosmic impact due to the simple but compelling fact that the YD event was by no means unique . Similar events took place many times before. Also the climate within the YD was also very variable.

    • Impacts can have huge and immediate, to an unlimited degree, effects on a planet. Magnetic fields changes, etc., not so much.
      The other apparent temperature changes in the millennia preceding the proposed YD event do indeed suggest a non-impact explanation, since the YD event is of similar, if larger, magnitude. Otherwise, you need multiple impacts, which obviously would be unlikely.
      However the mere existence of a 50M sq. km. soot layer demands explanation, irregardless of all else.
      Do the circumstances that created a 50M sq. km. soot layer have anything to do with the extinctions and temperature change? Doesn’t seem an unreasonable possibility.

      • I agree with all that you say here. I have myself considered the possibility of all of those down-spikes as being impactors, and, of course, that seems a VERY unlikely scenario – but a reasonable one to at least consider before tossing it out. (Sometimes the crazy sounding idea is the one that turns out to be true. Witness the Scablands of Harlan Bretz and the tectonic plates of Wegener. The YD seems to be the only one of them with the “soot layer”, as you call it. (The very lowest part of that soot layer is where the impact markers are being found – so don’t forget to include the impact markers in your thinking, too.) That unique soot layer kind of rules that multiple impacts idea out.
        However, FYI someone here commented that some NEW Greenland ice cores now exist, and that those show that the spikes in the GISP2 ice cores evidence some extremes that maybe are not so extreme. That seems to me to be an important development.
        In addition, researchers are beginning to become aware that impacts do occur quite a bit more frequently than was thought not so very long ago. The thinking about the frequency of big impacts has come down from tens of millions of years to about 5,000 to 10,000 year intervals. There is nothing precise about the numbers, but the more evidence we’ve acquired over the decades, the clearer it has become that big impact intervals are considerably less than once thought. One of the big events, later even than the YD onset, is one called the “8.2 kya event”. It even has it’s own Wiki page. Was it an impact? Some say yes. Some say no. But they’ve barely scratched the surface as far as evidence goes, so who knows?

    • Who knows?
      FYI, the suspected duration between big impacts isn’t what it used to be. In his 1999 book “Impact!: The Threat of Comets and Asteroids”, astronomer Gerrit Verschuur has this to say about that:

      Odds on comet impact, in the form of estimates of the period between such events, have been published for two centuries. Each generation no doubt felt that the latest estimates were superior to those that went before. For example, in 1861 James Watson, in A Popular Treatise on Comets, said that “it has been found by actual calculation, from the theory of probabilities, that if the nucleus of a comet having a diameter equal to only one fourth part of that of the earth… the probability of receiving a shock from it, is only one in two hundred and eighty-one millions”…
      …In 1897 Herbert Howe . . . went on to estimate the chance of a collision and thought that the chance of an impact in the next 100,000 years was “exceedingly slight.”…
      …Specific odds were offered by Sir Richard Gregory in 1893: “about once in about twenty million years.” In 1897 David Todd offered an estimate of an impact every 15 million years…
      …The famous textbook of Russell, Dugan, and Stewart in 1926 stated flatly that comet collisions would happen once in 80 million years…
      …Clark Chapman and David Morrison published their odds in Nature in January 1994. In “Impacts on the Earth by Asteroids and Comets: Assessing the Hazard,” they concluded that the chance that a large (2-kilometer diameter) object will slam into the planet and terminate civilization during the next century is I in 10,000…
      …there has been a lot of debate about whether it would take a 2-kilometer object to plunge us back into a dark age, or whether a smaller one would do, something like a half-kilometer object. Based on what was seen after the comet impacts on Jupiter in 1994, it now seems fairly certain that a half-kilometer object would do nicely. That immediately ups the ante to something like once every 100,000 years…
      …For example, an object 1 kilometer across traveling at about 40,000 kilometers per hour would produce a 15,000-megaton explosion, or thereabouts, depending on the density of the object […the largest H-Bomb tested was 50 megatons (the Tsar Bomba in 1961). See, so this would be 300 times that, yet so many people here seem to think it would be much smaller of an impact. But look at the mushroom clouds in that link. Now imagine a mushroom cloud 300 times bigger than the Tsar Bomba. Notice how SMALL Hiroshima is in that image.]…
      …In July 1994 an interesting article appeared in Scientific American on what was learned from the Apollo moon landings. The author, G. Jeffrey Taylor, a geophysicist at the University of Hawaii in Honolulu, pointed our that for every impact crater you see on the moon there would be 20 expected on the earth, because of the earth’s larger size. He added that Frederick Horz of the Johnson Space Center estimates that there are 5000 craters on the moon larger than 5 kilometers across which were produced in the past 600 million years. Putting these numbers together implies that half-kilometer objects, which are potentially civilization-destroying, are expected on average every 6,000 years…
      …Duncan Steel suggests that the comet impacts on Jupiter (chapter 14) may even have something to offer as regards calculating odds. Jupiter is likely to be struck about 1000 times as often as the earth and there is tantalizing evidence for dark markings such as followed the July 1994 impacts having been seen on at least four previous occasions: in 1885, 1928, 1939, and 1948, or five collision events per century. That would imply that earth might be hit every 20,000 years. [Two other comets have impacted Jupiter since 1994.]…
      …our conception of what the future holds depends so intimately on our knowledge base. In two centuries, the typical estimated time between comet impacts (from old books) to impacts capable of producing global catastrophe (from new research) has decreased from once every 281 million years (which held for most of the 19th century) to about once ever 5 to 10,000 years in the past year…
      …A spate of at least nine estimates appeared in early 1995, four of which independently set the interval between such collisions at close to 5,000 years…
      …This also ties in to the suggestion made by Clube and Napier that impacts affected the evolution of civilization about 5,000 years ago.

      Today’s figures are not the final ones in this. The more we learn, the more we think the intervals are smaller, rather than larger. As of 15 years ago the number was 5,000 to 10,000 between whacks. If that shortens by another 50-75% what are we talking about? And would that tell us anything about those spikes in the ice cores? ANY connection at all? Not even possible?
      We’ve lived in a very tame portion of human history. We don’t have an ice age, for one. For another, there are lots of tales from early human societies that speak of things that sound an awfully lot like impacts. Is our Comfy Chair mentality any kind of protection?
      I am not saying let’s take the several trillion dollars from global warming in the next 85 years and turn it over to space lasers and such? NO. But looking into the matter may not be a stupid thing to do. And part of that is to look in the past to determine what risk we are under. And that is certainly the cheap part.

      • I’d say ‘yes’ to taking the several trillion dollars from global warming in the next 85 years, and turning it over to space lasers and such.
        With that sort of investment, by 2100 we’d have an industrial ring in near space, another on the moon, and hotels going up on Mars.
        We’d capture any comet or asteroid that approached Earth and turn it into raw materials. Productive industry: the ultimate protection against terrestrial bolide impact.

      • Ironically, you have hit on something pretty close to one of the now discarded parts of the YD hypothesis – that there were a LOT of small iron balls embedded in mammoth tusks. It is one of the first things that drew Firestone’s attention to this event/period. But eventually they had to drop that aspect, while pursuing other, less sexy, lines of evidence.

    • Robertvd – Yes, you understand EXACTLY what biologists have been wondering about for a LONG time, enough to give the period beginning right then a name – the Younger Dryas. The biologists still after several decades are scratching their heads – nothing in gradualism so far has been able to explain it. But WOE unto those who conjure up ideas of catastrophes!…LOL
      Obviously, since those other 13-14°C ups and downs didn’t kill off the mammoths and giant sloths, etc. – plus the Clovis points stopped appearing in the fossil record, there was something unique about the YD onset.
      Amazingly, this microscopic evidence keeps on pointing at 12,800 years ago, too.
      So, the REAL question is how to connect the dots. That is what the YD scientists are trying to do. There are a lot of folks here hip-shooting and second-guessing the scientists – and mostly without ever having even read the paper.

    • Slow change is adapted to. Fast change is not. What matters is not the magnitude of the event, but the magnitude of its first differential.
      If you dont have time to walk to a better feeding ground, you are dead.
      A slowly rising sea level is far less of an issue than a tsunami.

  8. These deposits are always buried.
    Buried under what ?
    Where does the top-cover come from ?
    I’m sure there is a simple explanation, such as: wind drift, erosion, plants decaying, etc.
    But, why does everything become buried, all else being equal ?

    • They don’t in general, but it is only where they do that we can find them today. Same with cave men who did not live in caves, but we can only find their traces in caves because their wooden and thatched dwellings are gone gone gone…

      • uk(us) September 11, 2014 at 4:08 pm
        The ‘fossil fuels’ are deep because their initial biological components are buried by orogenic processes. Due to heat and pressure, gases and liquids tend to rise after formation unless/until they encounter an impermeable layer that stops the upwards migration. The Alberta oil sands are a good example of oil that has migrated all the way to the surface.

    • uk(us), Stuff gets buried to a large extent from plants catalyzing a slow “rain” of converted carbon dioxide into dead plant material. I suppose dust also gets accumulated. That also assumes the location is not dominated by sedimentation. I think it is a very interesting area to study, and I’m sure lots of folks have, but not me.

      • Indeed. my back garden featured about 50 years of scrub – thorn and tree – and very little grew under it. When I cleared that there as a couple of inches of highly fertile topsoil composed of mainly leaf litter, overlying the glacial moraine clay, which is what lies underneath, and under that is chalk.
        So many processes deposit solids on top of stuff – erosion of mountains and hills, and organic sediments.
        I have actually seen derelict houses less than 100 years old in the process of being overlaid with plant growth and soil.
        I’d say an inch every 20 years is probably about the way it goes. Round here. YMMV.

    • Fist there is the YDB layer.
      That is immediately – as in part of and touching – the black layer. That has several names, such as “The Black Mat” and the “Bradley soils” in the USA. THAT layer is varying thicknesses. In Belgium/Holland it is about 10 cm thick.
      What some here may not realize is that the black layer is acknowledged by all to be from some major, MAJOR conflagration, and it is made up pretty much entirely of burned plants. Over an area stretching from Syria to Belgium, to Holland, to Alberta, to Arizona, to Michigan, and to South Carolina, and then into the northern reaches of the Andes. And there is a layer in the glaciers of Greenland, too.
      So, whatever happened, it was bigger than your back yard barbecue.
      Above the black layer, it varies, depending on the location. In Belgium and Holland it is sand – mostly un-stratified, but not always. It is also sand below – also un-stratified – and called the “Usselo horizon”. In Nebraska the Bradley soils have mostly loess above – which is also un-stratified.
      In case you aren’t aware, at at least one of the YD sites, there was found a mammoth skeleton with the YD layer AND the black lying right ON the bone, and staining it. So in at least one location the last mammoth known and the YD were right at the same time.

  9. Of course the temperatures over the glaciers during the Younger Dryas had to be warm enough to melt them rapidly and generate the copious flows of meltwater that blanketed the North Atlantic, meltwater that was depleted in O18 from the freezing process and then further depleted by evaporation before being deposited as snow on Greenland. I think the purported cooling during the YD probably never happened.

    • pochas – Not right. First of all, the YD was a real period, noted first of all by the biologists, who noticed that the plants had all changed, and around the world it all happened at the same time.
      Also, the YD was not warmer, as you are thinking. The melting of the last glacial period before the YD cold was the Wisconsinan glacial period, and between the two were two warm periods (the Bolling and the Allerod) separated by the Older Dryas, a short cool period.
      Yes, these things really happened. The biologists have never been able to explain the sudden cold. And they’ve been on this for several decades, scratching their heads. The impact hypothesizers didn’t make it up.

    • Of course they do. They are not idiots. They made a conscious choice about where to start. They chose to make sure they had the microscopic stuff well in hand before they try to tackle the macro issues.
      It is called “doing due diligence”, and it is a BIG part of good science. They are, in fact, trying to falsify the hypothesis. Don’t blame them if the evidence keeps telling them that there was an impact, and that there was a BIG planetary reaction to it.

    • Ah, and you haven’t hard the certainty on the OTHER side, about “Requiems” and such.
      At least one side – the authors of this paper – is actually doing SCIENCE, collecting empirical samples and lab testing them with every test known to man.
      If YOU had 7 years of lab results coming back positive, what would YOU be saying?

  10. For a rebuttal of this theory having to do with the radiocarbon dating of the supposed YD impact layer–a fundamental problem for the hypothesis and a lot more date certain than the KT iridium layer dating from the Chixilub impact that helped wipe out dinosaurs and eventually resulted in this blog and all of its commentators–see Meltzer from SMU, published in PNAS. Easy multiple Google finds using comet Meltzer Younger Dryas.
    Nano diamonds are also produced in candle flames. Just the way nano stuff works, when surface properties dominate over bulk properties. Think lightning sparked forest fires spread out in time. No comet needed.

    • Yes, forest fires making a ONE time layer 4″ think and more on 4 continents – all at the same time.
      And did you even bother reading the paper?
      If you should be made aware that there are at least four kinds of nano-diamonds. Which ones are YOU talking about? If you don’t know, you are hardly in a position to cast aspersions. As to the quality of work done by Melzer and Surovell and Holliday, see my comment above at 6:10 pm in response to Ob at 1:14 pm. If you can’t understand it, it points out how they didn’t even understand how to follow proper protocols.

  11. The new high resolution NEEM ice core has temperatures in Greenland increasing by 16C in just 240 years from 15,737 bp to 15,494 bp.
    And then temperatures fell again by 12C in the next 300 years.
    There were significant swings in the climate well before the Younger Dryas. It was tough going for any non-technological non-adaptive animal in those times.

    • Yes, and the YD people will address that in time. Right now they are doing due diligence, making sure the evidence is correct at the microscopic level, the most fundamental level. As they should. If that is not done, they aren’t scientists, but hip shooters.

  12. Cosmic impact and the resulting cold/freezing conditions: After each meteor impact,
    the global temps go steeply down, rebounce at the same velocity to higher than at
    impact date and stabilize again at the previous level ….this is a multicentennial
    event. The temp evolution forms a GISP2 Z-syimbol or high voltage-symbol. This is
    evidenced EMPIRICALLY for all (more than 10) Holocene meteor impacts over the:
    entire Holocene…..
    Literature: http://www.knowledgeminer.eu/climate_papers.html
    The argument:””ME know nothing” — therefore “for ME not true” is constantly repeated by
    the worst ignorant types…..JS…

  13. “In a nutshell, the Younger Dryas includes so many very sudden, intense climate changes over a period of several thousand years that it couldn’t be related to a single cosmic event. ”
    that’s funny.
    now one could argue multiple causes.
    but the presence of rapid change cant PRECLUDE a cosmic event.
    keep up the fight against plate tectonics.

    • Steven –
      Very humorous.
      But correct.
      The climate folks have a really hard time with causes for such huge swings. Even with global warming, there doesn’t seem to be any capacity for the internal system to account for such huge swings – only perhaps a degree or two. (Never mind the models.).
      If this one pans out, what does that imply for some of the others – ones for which there is no black layer? They are in the ice cores, those spikes. If this spike means an impactor, there is a LOT that will have to be re-thought out.

    • “…Fight against plate tectonics.”?
      I must’ve missed that comment; though the hypothesis for plate tectonics has as little proof as the other hypotheses for ice ages.
      Lots of freeze/thaw hypotheses, little proof; but the evidence of impacts is interesting. There is enough evidence to a very dramatic event, but it does lack evidence for all of the Younger Dryas fluctuations.
      One thing is certain, those climate models are not proof; even when coupled to plate tectonics models.

  14. This press release makes the same errors as UCSB’s. Mastodons did not go extinct at the YD, for starters.

  15. Like others I’ve kept an eye on this idea but it keeps hitting the same evidence wall. Time. An impact event is quite a reasonable explanation for the entry into the YD era but not for its continuation or exit.
    Meteoric ash, like volcanic ash doesn’t hang around in the atmosphere for 1,000 years and then suddenly vanish.

    • JohnB – Your points are well made. Yes, those conundrums exist. The researchers on this are primarily working on the microscopic evidence so far, doing due diligence, getting their feet on the ground with the impact materials. That is the first step, as they see it. The rest they will have to deal with later.
      Right now it is certain that there are impact markers that are almost always accepted as such. But this time there is a group arguing that the markers are not impact related, even though there is a suite of them, all pointing at an impact. The point they make about the extent of the effects is important – 50 million sq km with conflagrations on 4 continents – obviously something out of the ordinary happened and it was big. And all the dates come back right around 12,800 years ago. The skeptical group is quibbling about the dates being off on some. Their other quibbles have been rebutted, over and over, and those will be, too. See my comment at 6:10 pm above, in response to ob (1:14 pm).

  16. A recent study at Oregon State may indicate that the Younger Dryas temperature variations did not occur, or at least were much less intense. The study used N2 diffusion from gas bubbles in three new Greenland ice cores to determine temperature and obtained a much more steady increase through this time period. The authors suggest that the older temperature variations, obtained using 18O/16O, were artificially produced by changes in the moisture source of snow fall on GL over this time. To a large degree, this O isotopic ratio reflects the temperature of the water source, and any ice temperature profile must be calibrated to a known entity.

    • I am going to agree with you, Don, and I am GLAD that the new ice cores are coming into play.
      I have never been satisfied that the GISP2 and GRIP ice cores are telling the story quite right. I DO think that it is logical that the swings were less than the O18 proxies show in the previous ice cores. And my thinking has been that the high temps and low temps were artifacts of something in the processing of the ice cores and data.
      It is kind of funny. Someone above argued that there were “only” 6 carbon-14 dates from Lake Cuitzeo – but there were only TWO ice cores, and basically only one sample from each ice core, at that particular 12,800 ya level. With a resolution of 200 years, do ice cores weigh more heavily than carbon-14?

  17. I know from my industry days that diamond exploration in Northern Australia based on regional surface samples was significantly affected by the widespread distribution of microdiamonds (nanodiamonds) over the continent, so much so as to render some sampling methods almost useless. Microdiamond sampling of gravels/soils etc is a standard exploration technique where a bulk sample is completely dissolved in HF and the resistant residue is microscopically examined.
    With such a stable continent, its likely the 12,800 yr surface is right at the present-day surface. (In fact, in parts of Australia the Cambrian-Pre Cambrian 600Myr surface corresponds with the present day surface).
    Explanations for this widespread distribution of microdiamonds that I am aware of included aggressive kimberlite volcanism (diamond bearing), and cosmic sources.

    • FYI – Most of the YD layer has been found about 1 meter below the surface, though the Bradley soils are about 6-7 meters below, with loess above.
      These researchers are examining mostly with SEM/EDS.

    • Dave
      Can you please supply some references for your statement: ‘Explanations for this widespread distributions of microdiamons that I am aware of included aggressive kimberlite volcanism (diamond bearing), and cosmic sources.’
      Ciao
      John

  18. People, people, you are playing right into their hands of your own tormentors by playing skeptic to the Younger Dryas Impact Hypothesis! See Eric Steig’s of Real Climate’s comments in 2009:
    “Think about it. If it turned out that rapid climate change events are caused by comets, it would imply the climate system is far more stable than we thought, that abrupt climate change events are not part of the inherent variability of climate during glacial periods. That would perhaps allay fears that we could be pushing the system towards an abrupt climate change in the future. On the other hand, it would also suggest that cometary impacts are far far more common than we thought. Now that would be news. Perhaps further research by Kennett, Firestone and others will indeed show that to be the case. We’re not, however, holding our breath.” – See more at: http://www.realclimate.org/index.php/archives/2009/01/the-younger-dryas-comet-impact-hypothesis-gem-of-an-idea-or-fools-gold/#sthash.GVWPk1xj.dpuf
    It is no coincidence that the chief antagonist of the YDHI theory, Mark Boslough, is also a fundamentalist preacher of climate change alarm — the YDIH theory is suggest a serious threat to their “message.” If the YDHI is allowed to be true — The current level of attention and anxiety over climate change is akin to fretting over the radio station as your car sits on the train tracks.
    The enemy of your enemy is your friend!

    • Good points.
      DO, though, expect the default position here to be skepticism. But you make good points about being on guard about the mainstream trying to buffalo people into one way of thinking.
      Boslough siding with where the big money comes from? Oh my! What a shocker.

    • Rubbish. Science is replete with cases of throwing out the baby with the bathwater. Jefferson refused to accept high and dry fossils as oceanic since for him that would be tantamount to accepting Noah’s flood. Galileo rejected a causal connection between the moon and tides, indifferent or oblivious to centuries of record keeping by English monks establishing a strong correlation. To him this was all menstrual nonsense. Skeptics have no need of grasping at straws of third party junk science to refute the junk science of climate alarm. –AGF

      • You increase your credibility when you identify the false basis of your antagonists’ claims. Al Gore laid the first modern brick of public fear of AGW with the “tipping point” meme — based on the Younger Dryas. Pull that block out — and the Jenga tower crumbles.

  19. > Robertvd
    > September 11, 2014 at 3:49 pm
    >
    > http://www.youtube.com/watch?v=zS7Adv3DFXg
    Let’s just say that when it comes to “Ancient Aliens”, I’m a skeptic. To see the History Channel “Ancient Aliens” series debunked, it’s well worth spending 3 hours on

    Zachariah Sitchin was another major name in the ancient aliens area. For a detailed point-by-point destruction of his theories (almost 2 hours long) see

    • NO. This is NOT Zechariah Sitchin in lab coats. Sitchin was a bunch of silly conclusions, a house of cards, and a lot of people with poor discernment skills fell for it..
      He is a classic case of what I see in terms of translations of ancient cultures’ accounts – if the translator isn’t a native, he misses a lot. And how does one become a native of ancient Sumer? You don’t.
      People riding in on a big-ass comet that goes out into deepest space, out beyond Neptune and Pluto – how silly is THAT? They leave their slaves here on the planet in the Goldilocks zone, while they go out where it is minus 200 degrees?
      Ri-i-i-ight. That makes a lot of sense. /snarc

      • It was Robertvd who first posted the clip from the “Ancient Aliens” series. Ask him why he posted it. I was simply trying to cover the major variants of “Ancient Aliens” in the rebuttal post.

    • I never said I believe in Aliens. I think it is all about changes in incoming radiation . That’s why I use the picture of the plasma figure seen all over the world in rock art. There must have been a plasma event in the sky. There is no other explanation for finding the same figure all over the Earth. This plasma event must have taken a long time with sometimes dramatic results. That could be the reason why people started living underground (video Derinkuyu) to be save from the incoming radiation.

  20. Lets be clear – finding evidence of an impact e.g. nanodiamonds is one thing. But evidence that such an impact changed climate profoundly is something else altogether. Folks may find evidence of the first that could be valid. But going from the first to the second – impact changing climate – is usually evidence-free, mechanism-free speculation at best, fantasy at worst.
    It should also be crystal clear that those who argue that major climate shifts can only be caused by atmospheric forcing such as comets or CO2, stand squarely shoulder to shoulder with the CO2 AGW alarmists.
    Its a very simple game. It’s called the “lets pretend the oceans don’t exist” game.
    There is rock solid body of science with abundant evidence from ocean sediment geology and knowledge of oceanographic processes detailing how interactions between the NH and SH oceans, involving deep, intermediate and surface water currents, driveglobal climate shifts on timescales of centuries and millenia.
    Of course oceans are forced from outside by e.g. Milankovitch and (possibly) other solar variations. And its hard to imagine the Chixilub dinosaur-terminatong meteor not affecting ocean currents.
    The most destructive source of militant talebanic climate ignorance are those who wave the black flag of atmosphere-only. This CO2-comet-volcano camp either ignores the ocean entirely – where 99% of climate heat is located – or like Gavin Schmidt they dismiss the ocean as a passive puddle responding in mild obedience in real time to atmospheric (CO2) forcing.
    But the ocean drives the atmosphere more than the other way around. For instance it is well known that the Atlantic Meridional Overturning Circulation (AMOC) has nonlinear instability due to the positive salinity feedback. This means that on century-millenial timescales the AMOC is prone to abruptly switching on and off. 12 kya under the influence of Antarctic drived ocean circulation changes the AMOC turned off. This caused the YD.
    It’s deeply ironic tha

    • Its deeply ironic that the AGW camp is now appealing to the ocean to explain the “pause” in global warming. Are they waking up to the existence of the ocean? Or just playing games to keep their fraudulent show on the road. Here’s the thing – the oceans don’t only explain the pause. They explain all climate change.

  21. > agfosterjr
    > September 11, 2014 at 1:07 pm
    >
    > Nanodiamonds? Maybe. Meteor? Maybe. But a climate
    > changing meteor? A meteor that wipes out big game
    > while stirring not a mouse? Or climate that does the same?
    > Or disease? The comet theory and the overkill theory are
    > best kept separate. -AGF
    > Pat Frank
    > September 11, 2014 at 3:59 pm
    >
    > The hunting hypothesis is made stronger by the fact
    > that virtually all mega-fauna disappeared during this
    > time. A climate extinction event might be expected to
    > make extinct some suite of non-adaptive species. Not
    > all species.
    Both posts mention *MEGA*fauna. Remember that “the big one” 65 million years ago wiped out megafauna, leaving only smaller creatures as the survivors
    1) It’s now widely believed that ***ALMOST ALL*** dinosaurs were feathered. See http://news.nationalgeographic.com/news/2014/07/140724-feathered-siberia-dinosaur-scales-science/ The asteroid/comet drastically changed climate, and destroyed the feeding grounds, starving to death any large herbivores that the asteroid impact didn’t immediately kill. This, in turn, led to the death by starvation of any large carnivores that the asteroid impact didn’t immediately kill. The only surviving feathered dinosaurs were the small, omnivorous types, aka birds.
    2) Due to competition from dinosaurs, there weren’t any large mammals 65 million years ago. The small omnivorous mammals went on to take over.
    3) Insects, also small, also survived.
    Given that the dino-killer comet/asteroid selectively wiped out large land animals, why the surprise that YD comet/asteroid selectively wiped out large land animals. Note also, that the YD comet/asteroid was much smaller and seemed to affect mostly North America, so the extintion event was regional, not global.

    • No comparison. The K/T event wiped out almost everything, large or small. Birds, fish, mammals, reptiles, amphibians, microbes. The reason small mammals survived is probably that they lived underground with a supply of roots, filtered air and probably warmth. Same for amphibians. Birds and reptiles may have survived as eggs, but very few birds survived. Snakes survived like mammals. Crocodiles, your guess is as good as mine; maybe as eggs, maybe fasting in the water; reptiles can go long without food. Dinos were warm blooded with high metabolism, needed constant feeding. At any rate, the K/T event was indeed catastrophic, and though habitat gave small creatures an advantage, most small species disappeared. The K/T event was not a megafauna extinction event.
      Pleistocene extinctions on the other hand involved megafauna exclusively, even in historic times: the great auk is gone; the lesser auk survives. Why? Hunting. Humans consistently hunt big prey to extinction, from mammoths to seals and whales. And ancient man, without agriculture, without winter fruit, what do you think they depended on? What kept their population in check? If it wasn’t fast or scared it was doomed.
      –AGF

  22. Michael Wassil
    September 11, 2014 at 4:59 pm
    The resolution of the ice core data decreases the farther back we go. If we were able to examine the previous Pleistocene interglacials in as much detail I’m sure we’d find them equally ‘up/down’ temperature-wise as the Holocene.

    But the YD was different. There’s a meter or more layer of wind-blown soil-dust laid down during the YD in the Chesapeake Bay (Maryland) area . None of the dozens of earlier cold excursions (D/O, Heinrich events or even the LGM itself) in drilled sediment layers show this deep dust layer. It’s unique to the YD.

    • The post to which I responded suggested that the YD was responsible for creating a more “plateaued” Holocene that enabled human civilization to arise. He said that previous interglacials appeared to reach a quick temperature peak then subside into the next glacial max, unlike the Holocene.
      I countered that assertion. I pointed out that were the ice core resolution sufficient we’d likely see that previous Pleistocene interglacials had temperature ups and downs similar to what we’ve seen in the Holocene. I linked to the Eemian timeline, for which we have quite a bit of resolution. My thought is that human beings were not sufficiently evolved to take advantage of previous interglacials and create civilizations.
      I did not address the cause of the YD, nor how or why it might be different from other cooling phases. My only comment was that it almost killed the Holocene right from the start and had it done so would have been a real climate catastrophe.

  23. I might go hide after this but,
    supernova close by that disrupted the entire geo-magnetism of our solar system.
    Or sumpin like dat.

    • No don’t go hide. You are talking about a gamma ray burst, don’t know about the geo-magnetism thing (I’m a biologist, but one of my colleagues is a physicist who is working towards his astronomy masters and I’ll ask him Monday) and gamma ray bursts are theoretically the cause of the Permian–Triassic Mass extinction event. I have read something about evidence of a gamma ray burst presenting itself as high levels of radioactive compounds in tree ring analysis about 775 CE, further I have read about old logs recovered (in lakes in New England associated with Mastodon or Mammoth fossils, I’d have to search for it, I read way too many studies) and now wonder if they fall in the time frame of the younger dryas. Would be interesting if they had a go at them if they fell in the right time frame.
      Well, IMHO anyhoo

  24. From the U Chicago press release/post:

    In addition to providing support for the cosmic impact event hypothesis, the study also offers evidence to reject alternate hypotheses for the formation of the YDB nanodiamonds, such as by wildfires, volcanism, or meteoric flux.

    Lightning.
    Lightning will easily provide the necessary high-energy conditions for exotic particle-formation, which advocates of the YDIH say can only be provided by a cosmic impact.
    How is it that we are overlooking lightning? Large-scale ectrical arc-discharge phenomena exceed the conditions created in cosmic impacts.

    • Sadly The Electric Universe is not on the menu list of this blog. But then as long as we believe the Sun is heated from the inside out by nuclear explosions in its core making the Corona the hottest place of this plasma body little will change.

    • Arc-discharge is the key search-term that leads to extensive academic, industrial, and US Patent Office activity making tiny exotic particles from ordinary gases, etc. Add qualifiers to the root-term, like diamond, nanodiamond, diamond-like, etc.
      Lightning is powerful, intense, and common. Certain kinds of storms churn up impressive lightning-displays, including dry and dusty environments that prevailed during and after the Ice Age.
      It’s fallacious, to claim that only a cosmic impact can supply the kinds of conditions needed to create these unusual particles. Ordinary, familiar lightning does the trick nicely.

  25. The bottom line is and it is BIG is the YD period was not UNIQUE. That is all the evidence needed to show the cosmic ray theory is not valid. If it were valid then they would have to explain all the other similar climatic events to the YD due to a cosmic impact, which they can not do.
    These one item climatic explanations do not cut it.
    As I have said in my earlier post it was likely the ice dynamic and the state of the climate through out that time being close to boarder line glacial/inter – glacial conditions to begin with which made the climate very vulnerable to any changes in the various items which control the climate. The sun being a prime candidate.

    • The YD IS unique. Ask the biologists who have puzzled over the huge change in flora at that time. It was the biologists who discovered the YD cold period and who named it and who have not found an answer as to why it happened. The same sort of change only happened at the Older Dryas, but that one was very short.
      ALL of the other temperature excursions since the Wisconsin ice age were short. The YD lasted 1300 years. THAT is unique.
      The megafauna in N America went extinct. THAT is unique.
      Clovis points disappeared from the fossil record. THAT is unique.
      The mammoths in Siberia (except for the pygmy mammoth, which was a different species) went extinct. THAT is unique.
      And now, they find spikes in SEVERAL materials that have ALWAYS been seen as impact markers. THAT is unique.
      As explained in the Abstract, this paper focuses only on nanodiamonds and the spikes in the nanodiamonds. And yes, they know the difference between the various forms of nanodiamonds – which anyone who actually READ the paper would know. Other papers discuss the other materials normally seen as impact markers.

      • Agreed. There are only two identified large-scale impact-suggestive geologic boundaries (soot, trace-metals, nano-diamonds, etc) — the K-T boundary (65 Mya) and the YD boundary.

        • Agreed. There are only two identified large-scale impact-suggestive geologic boundaries (soot, trace-metals, nano-diamonds, etc) — the K-T boundary (65 Mya) and the YD boundary.
          An interesting thing about it is that very often the K-T boundary layer is THINNER. Reason suggests that at 65 Mya there is more overburden and thus more compression.
          Whereas Iridium was pretty a conclusive “tell” for the K-T, notice that the skeptics avoid mentioning the Iridium found in the YDB layer that shows up at some sites.
          I liken the skeptics – not just here, but especially the academics – to a pack of dogs sorting out the weakest member of a herd – the weakest points of the YD proponents’ papers and completely avoid the strong points – the male bulls of the herd. They THINK they’ve got a weak point in the nanodiamonds, but keep an eye on this over time. The proponents will win out.
          In design engineering, it is IMPERATIVE to find the weak points, the tough areas, and to put the most initial effort into those, so that they were no longer weak points. So, though the skeptics are a nuisance to the YDIH proponents, the proponents actually appreciate having to solidify their position on those weakest points. As Michael Jordan used to do, he would work on his weaknesses and turn them into strengths.
          For SCIENCE it is better to deal with those weak points, certainly. If the hypothesis is no good, the proponents want to know that as soon as possible. Well, 7 years on now, and they have REAMS of evidence that supports the hypothesis IN THE WEAK AREAS.
          That is the main thrust of this paper – to solidify the nanodiamond evidence (AGAIN), which the skeptic pack dogs have latched onto as the weak member of the herd. The skeptics are actually HELPING the YDIH proponents.
          But myself, sometimes I wonder how many different times, how many different WAYS, do the proponents have to produce solid empirical evidence against hollow, NON-empirical blather – so the whole issue can move onto the next level. The skeptics are just yak yak yak yak yak.

    • While it would be nice to have a comprehensive theory that explains all features, it is not realistic in this case, since there is such a dearth of actual physical evidence from 10k to 20k years ago.
      What is central here is the large black layer at 12800. And 40 studies finding nano diamonds embedded. The layer alone is unexplained, not to mention the diamonds. Any process capable of creating such a layer , diamonds or not, should be a prime suspect in any extinctions nearby in time.
      Evidence such as ice cores is interesting, but as it is subject to melting and loss of years it can hardly be relied on, like you can, say, on a layer in the sediment over a 50M km in area.
      The researchers leading the “impact skeptics” are anthropologists. In their field of anthropology, truth is somewhat subjective, as in whatever you can convince the other anthropologists of, without a lot of actual definitive physical evidence. They are hoping by making a lot of nice sounding arguments they can establish their theory of “something not an impact” being responsible for the black mat layer. Unfortunately for them, this is a topic with substantial physical evidence.

  26. Take the 8200 year ago cold event similar to the YD. Abrupt although shorter in duration and less in degree of magnitude but still extreme. They need to explain that event among many others in relation to their cosmic impact theory which they can’t do.

    • YES, Salvatore, the 8.2 kya event is also on the table. Right now these scientists are wrapped up in this event. Will they get to the 8.2 kya event some day? I hope so. But none of THESE scientists are talking about looking into that event at this time.
      But eventually it will need to be addressed.

  27. Ted Clayton
    September 12, 2014 at 9:02 am
    “Although it is not currently a popular explanation, disease hasn’t really disappeared as a potential cause of population & even species-losses. And it would ‘cover’ why island-populations etc persisted after continental eradication.”
    ========================================================================
    As with other non-hunting extinction explanations, microbes care less about the size of the host than its physiology. Cameloids of all sizes would be expected to share similar physiology and susceptibility to particular microbial parasites, yet the giant camels disappeared, not the llama, alpaca, or vicuña (other South American megafauna did bite the dust: GIANT ground sloths, GIANT armadillos, etc). (BTW, several species of GIANT ground sloths survived on various islands of the West Indies till 5kya–when humans arrived). So no, disease as an extinction agent is as spurious a cause as was ever suggested–like climate, comets, etc. Only if humans were the disease carriers could you blame island survival on disease, and humans would then be the megafauna carriers of a megafauna specific microbe. Will you buy that? –AGF

    • One of the few suggestions seemingly more-dubious than that microbes would have selectively exterminated the more-select cuts of big-game out from under freshly-arriving (and surely Eco-attuned) First Americans, is that Neanderthal might be in our direct line of ancestry.
      That is, Neanderthal ancestry remained a topic of creative argument (among the certifiable idiotic and intellectually-irresponsible), after the point at which it became quite clear that we had acquired the basic tools that would sooner rather than later lay the question to rest once and for all. Why argue – the answer is just around the corner.
      And the comparison is more than figurative, since it is further-enhancements of the same tool-kit that dropped the Neander-Denisova-comeonecomeall bombshell, that will resolve questions about microbes in paleoecology.
      I’m of course not really a champion of Germs Dunnit. What I am is chagrined at the archaeological losses we suffer, because of poor relations with Native Americans. The Overkill Hypothesis promises to make an unfortunate situation, worse. That it remains a (mere) circumstantial case, which nonetheless strongly affects the ‘accused’, encourages me to go the extra mile on behalf of each of the available alternative explanations.
      Investigation of fossil microbes, and their associations with bygone individuals, populations and species is set to make explosive advances. There’s nothing particularly time-sensitive in the Late Pleistocene Extinction, or the Overkill Hypothesis.
      Overkill is admittedly a fairly obvious possibility (which may ultimately be proven), but asserting it makes a hefty impact on key sets of peoples. Adverse impacts experienced by those communities, seemingly at the hand of science, then reduces the opportunity of investigators to pursue avenues & questions.
      =====
      I have personal knowledge of the Manis Mastodon site, and its immediate & wider ecological contexts, throughout the Holocene. ‘What was going on there’, appears to weigh pointedly against a “pursuit” hunting-culture, and thus weakens the scenario in which hunters scour the landscape for every last game-animal.
      Likewise, supporters of Overkill are known to point to ‘jumps’, and link wasteful killing to extinction. Yet, using jumps suggests a more-sedentary, certainly site-dependent means of acquisition. Let the game wander by, then run ’em off the bluff. We stay right here, and make sure nobody else claims our bluff.
      Subarctic cultures are rather well-known for sitting in place, waiting for game-movements to bring the resource to them. Indeed, exciting things are happening, investigating high-north ‘fences’ erected to better-channel those movements, at much-early dates than we used to think.
      There appears to be, actually, fairly abundant opportunity to question whether the practices of early-Holocene cultures really support the high-energy, chase-centered scenario that is implicit in Overkill.

  28. Duster
    September 12, 2014 at 11:57 am
    Not much there I can agree with. The extinctions occurred throughout the Americas, first on continents, then on islands. That includes polar islands and tropical islands. What sort of climate mechanism applies from tropics to poles? Climate as a general extinction agent is as absurd as disease. As is a natural ET agent. –AGF

  29. Ted Clayton
    September 12, 2014 at 1:26 pm
    ===================================
    You are politically correct. Native American ancestors (excluding the the more recently arrived Dine people, were surely more noble ecological caretakers than my most recent ancestors who killed the dodo, the great auk, Steller’s sea cow, the passenger pigeon, and so on. To attribute to their ancient ancestors the same disregard for nature that I and my grandfathers show is surely a crime against that same nature. Indigenous peoples were noble, generous, peaceful, and benevolent to man, woman, child and beast. They were most likely vegans. War, slavery and murder were unknown; infanticide, unthinkable.
    That’s why we shouldn’t celebrate Columbus day: Europeans brought nothing but Christian misery to the New World. I just finished reading 1493; read 1491 a few years back. Vermont could have done with out English worms and Arabian horses. It certainly could have done without a dozen Eurasian diseases. Because of Colon the New World population was literally decimated–victimized by…us. We…are…evil. Therefore it is wrong to blame not only survivors of this great onslaught for any animal deprivations, but their ancient ancestors as well! Absolve them all, science be damned. –AGF

    • agfosterjr says@September 12, 2014 at 1:45 pm

      To attribute to their ancient ancestors the same disregard for nature that I and my grandfathers show is surely a crime against that same nature. Indigenous peoples were noble, generous, peaceful, and benevolent to man, woman, child and beast.

      28 generations back, we spoke French on the upper Seine. Then we tended a manor directly under King William for 500 years, and eventually dropped the “de Clayton”.
      Here on the Olympic Peninsula, there are 9 Federally listed Tribes. Olympic Nat’l is the only Park with it’s own staff anthropologist. I was born and went to grade school in Forks, with the La Push (Quilleyute) kids, who were then bussed. Yes, that Forks.
      At Port Angeles (Elwha (yes, that Elwha) Klallam country, with whom I came of age), a “graving dock” excavation (for assembling floating-bridge sections) uncovered what is certainly a seminal site. The Klallam tribe required it be covered, and the dock-construction was cancelled. I believe this would have become a dig of global importance, lasting decades. The Klallam would have been elevated, past their Makah neighbors & competitors (who had grabbed the torch & ran with it, by reasserting whaling-rights).
      But the problem for them and others, is that the fabulous remains at Port Angeles do not tell the story that they believe they have to stick to: That We were the First, have always been Here, and are the Only Ones.
      Late in the evening of January 29, 1700, we now believe the offshore Cascadia Fault yielded in a megathrust earthquake. The shaking was probably still throwing initial survivors around on the ground, or even through the air, when the monster tsunami came ashore. Virtually everyone along the outer coastal regions was surely smote … from northern California to central British Columbia.
      Less-apocalyptic but still-severe tsunamis thrashed coastlines – leaping up suddenly in the dark of the night – for additional 100s if not 1,000s of miles.
      Social chaos ensued. The only thing that ‘saved it’ for many peoples & cultures, is that everyone along a huge stretch of the West Coast was severely affected (and ‘some’ members lived back from the beach). Still, it looks like there was a lot of tribal ‘turn-over’, as anyone that could, took every advantage while the taking was good.
      It really ‘throws’ me, that the Native need to maintain exclusivity stands in face of the reality that they are here, they are who they are, that have the status that they have … and there is absolutely nothing to be found in the ground or in their DNA that is going to take what they have away from them.
      So yeah, I’m able to work with the Politically Correct hegemony, even though I know it’s a story.
      =====
      As the reservoirs drained, as the dams were taken off the Elwha River, another important site came to light … 9K yo, establishing a very early presence at an inland small-river setting. This is very important, for the early Holocene cultural context. The Elwha claimed they formerly had a village there … presumably before the diseases made their way their up the coast from Mexico, say around 1530.

  30. What really happened to the passenger pigeon?
    The main insult is said to have been market or commercial hunting.
    Like the Late Pleistocene or Early Holocene megafauna extinction, it’s a problem that other sources of game existed, as the lost species became difficult to procure, “economically”. Sensible hunters just shift to something else, if possible.
    There are several dodo-species that sailors and Empire plainly rubbed-out. Mainly because they were dodos, and the invaders were moving fast.
    Passenger pigeons, though, were not dodos, and neither were the market-hunters. Not in the sense that they would waste their time going after a particular, increasingly-scarce bird, not when they would be able to fill the wagon with other species.
    In the late 1800s, the continent was ‘settled’, but there was still a lot of country that mostly just ran wild. In settled places, there was plenty of habitat for birds, and species with needs similar to the passenger pigeon carried on.
    Actively exterminating the last of a successful, mobile, adaptable bird-species is … a surprise. This particular robust bird did die out, though, and events seemed to demand an explanation. We ‘found’ one.
    Today, quickie and fairly facile accounting of the demise of this pigeon is secular Gospel. Ecologically, though, the passenger pigeon story sounds more like a story … really, someone’s Chapter & Verse, more than science … or even competent Game Management.
    There’s a chance that what actually continued to make life difficult for passenger pigeons, as they became hard to find (which probably was not humans, or their landscape-modifications), will prove more interesting that our ‘story’. Scientifically.
    =====
    Similarly, that humans at the beginning of the Holocene would become so fixated upon particular game-animal species, that they would continue to invest extra effort harvesting them, when easier & richer food-sources were at-hand, at the very least raises questions.
    In fact, we know better. From the middens, we know across long spans that hunter-gatherers were opportunistic, flexible and adaptive in their game-species.
    =====
    More-generally, in the same way that appealing to cosmic impact to explain events, comes up against the problem that there have really been a lot of events, and we end up invoking a lot of comets … statistically all species that have ever lived, are extinct, and humans obviously didn’t have anything to do with it, because they weren’t there.
    Extinction is a major fact of Nature. Nature has exterminated nearly every species that every lived. Just as radical climate fluctuations throughout the Pleistocene, are natural.
    There can be “exceptions”, but there is no need or requirement for a special accounting for the Younger Dryas … or for the extinctions that took place before, during & after the YD.
    ====
    Humans might have done it. I won’t go down, fighting good evidence. But all we have so far is circumstantial suggestions … and that I don’t think is quite worth the asking-price.

    • What a bunch of words! How the passenger pigeon met its end is well documented — google it. They nested en masse and the last flock descended in a place in Illinois or Ohio, and teams of passenger pigeon slaughterers descended on them and wiped the whole flock out — about 250,000 birds all slaughtered and dressed and sent on a train to New York for consumption, but the train derailed and the whole load went to the maggots. End of the passenger pigeon. Look it up!

      • NZ Willy @September 12, 2014 at 5:56 pm
        Yeah, a lotta words, but we have enough skinny-Twiggy comments… 😉
        The oft seen line goes;

        The last great nesting flock came together in 1896 near Bowling Green Ohio. Hunters descended from afar and out of 250,000 birds 200,000 were taken. Shipped in boxcars the train derailed and the wasted birds were dumped into a ravine.

        The bit about the train is not incidental. In the later 19th C, large flocks of pigeons were tracked by telegraph, hunters etc brought in by train, and the train then took the meat to market.
        In fact, only with the train, could the large-scale meat-hunts of the era serve large city markets of the era.
        And therefore, only sites rather close to the tracks were suitable hunting-grounds. Although railroads were ‘extensive’, by no means was all the habitat suitable for passenger pigeons handy to transportation (or communication) of the day.
        And, often presented as [hankies now!] the last pitiful flock of the doomed birds … it really says it’s the last_great_nesting flock. It was firstly a GREAT flock, and a NESTING flock, and purportedly it was the LAST of the great nesting flocks. *Large* nesting flocks filled the available nest-sites in the trees, and then spilled over onto the ground … making them easy to take. Smaller flocks might be able to all nest in the trees, and thus were commercially nonviable.
        So this was the last of the big pigeon-hunting hurrahs … but we have very little basis on which to conjecture about the status of passenger pigeons at that time, across very extensive parts of Eastern America. That’s what banding of birds was about, years later … it is really tough to know about the movements & locations of migratory birds.

  31. OK .. An open question for the assembled masses.
    If microscopic diamonds could be formed from the energy released/transferred from a collision between a rapidly moving extra-terrestial object and (either) the earth’s atmosphere OR the earth itself, then
    (1) how much microscopic diamond remnants are expected to be formed from the (very much smaller) energy released from last year’s comet/asteroid/meteor explosion over Siberia?
    (2) How much more would have been formed over the much more massive Tunguska “non-impact” 100 years ago?
    (3) How many micro-dimonds formed over Tunguska would be recoverable today (impact + 100 years)?
    (4) How many micro-diamonds – if any! – have been found today in that area?
    Why are we not confirming/checking this micro-diamond formation theory against the one impact that we KNOW happened (even if smaller than the Y-D “impact”) only a few years ago?

    • RACookPE1978 asks @September 12, 2014 at 5:31 pm;

      If microscopic diamonds could be formed from the energy released/transferred from a collision between a rapidly moving extra-terrestial object and (either) the earth’s atmosphere OR the earth itself … [let’s assess their possible deposition patterns.]

      Practically all incoming cosmic objects vaporize in the atmosphere. The high-temperature vapors then condense into particles of various sizes.
      Tunguska is said to have caused unusual red sunsets around the globe. Obviously, the floating particles causing that effect drifted away from the vicinity of the impact … and so won’t be found there.
      In nuclear weapons bursts, early fallout is granular and sandy. In warfare training, breathing radioactive fallout (it’s bad to have ‘hot’ particles stuck to the living lung-tissue), inhalation is not a big concern, because the condensed vapor products that fall are too big to breath in. Meanwhile, the really small stuff is circling the global, distributing itself very thinly.
      Generally, meteor-dust hangs in the atmosphere, and circulates, for rather long periods. Any kind of stuff that would be called ‘nano’ [ie, nanometer-scale], is presumably off & gone for parts unknown … not on the ground surface beneath the locale of the original entry.
      Off the cuff, I understand that the smallest “particles” are a few nanometers. At the other end of the range, objects of about a micron, or one micrometer (1,000 nanometers), are the biggest sizes of “dust”. Pragmatically, dust observationally remains suspended and travels well … probably being removed by specific processes & under certain conditions … rather than ‘gradually’ settling-out in an even distribution over earth’s surface.

      • Perhaps the smallest particles of the extra T object, but some stuff from the ground would be coarser. The diamonds could be from carbon in vegetation or even limestones, although the literature insists that carbonado diamond in Brazil has an extra T origin. The largest carbonado found was almost a kilogram weight. It is full of vesicles (bubbles) that I fancy were the result of a meteoric impact of a carbonate or carbonaceous sedimentary rock. They have been mining carbonado for ~150 years in Bahia – no small particles these. The fact such a volume of the stuff existed suggested a concentrated source of carbon on earth. I don’t believe meteorites have such a high carbon content – they do have nanodiamonds though.
        http://www.meteoritestudies.com/protected_CARBONAD.HTM

      • RACookPE1978 @September 12, 2014 at 5:31 pm

        Why are we not confirming/checking this micro-diamond formation theory against the one impact that we KNOW happened (even if smaller than the Y-D “impact”) only a few years ago?

        It really is a valid & important point, that we should be broadly investigating the nature & origin of any nanodiamonds and any other anomalous particles and layers associated with the onset of the Younger Dryas … and testing the proposed impact-mechanism. I apologize to RACookPE1978 for being only negative, when the underlying point being made is actually very good.
        Certainly, from nuclear weapons bursts, we know that vaporized solids also condense into larger sand-like particles, which do fall out nearby, as well as dusts that drift away***. This kind of coarse condensation-product could be produced in meteor bursts, too, and would be near the site of the impact. These would not be the nanodiamonds per se, but these residues would help fill out the picture.
        =====
        Gary Pearse @September 13, 2014 at 10:46 am,

        The diamonds could be from carbon in vegetation or even limestones … The fact such a volume of the stuff existed suggested a concentrated source of carbon on earth.

        Yes, the sheer volume being claimed is a problem. But stuff actually on the ground is going to be hard to heat to the prescribed temperatures. If an impact-explosion is very spread-out, and blows burning ground-vegetation high into the sky, where extreme temperatures are sustained, then a high-production diamond-factory might result.
        But whether it’s an unholy volume of ET diamond-production directly from the impactor, or an unholy wallop of broad-spread high-intensity energy to diamondize roiled ground-carbon … either way there is the problem of being lured into ever-larger sizes for the putative object.
        As the supposed object gets bigger, the easier its other proxy calling-cards should be to spot. It looks like trouble for the general hypothesis, that advocates keep amping up how much of the earth was affect, and how big this thing had to be…
        *** The Bikini Atoll hydrogen bomb was detonated at the surface, excavated a large crater in underlying coral limestone, which was lofted into the fireball and became a major part the fallout, both large & small.

  32. North African locusts had nothing over passenger pigeons. Quoting my autographed copy of David Quammen’s, “The Song of the Dodo” (p.304): “In Virginia, around 1614, one man reported pigeons ‘beyond number or imagination,’ adding that ‘my self have seene three or four houres together flockes in the Aire, so thicke that even they have shadowed the Skie from us.’ A Dutch settler in Manhattan wrote in 1625, ‘The Birds most common are wild Pigeons; these are so numerous that they shut out the sunshine.'”
    Same page: “Around 1810, the ornithologist Alexander Wilson made a meticulous but dizzying estimate of 2,230,272,000 birds in a single flock [a few too many significant figures; let’s round that off to 2 billion]. (Daily food intake; about seventeen million bushels of acorns.)”
    They nested on the ground in flocks of billions, so numerous that predators could never make a dent in the reproductive rate. Crows and (introduced later) starlings were benign by comparison; the pigeons could eat a crop of grain or fruit in hours. Farmers battled them for a couple of centuries, loading shotguns with anything they could find, blowing the birds out of the sky by the millions, smoking them, netting them, trapping them, feeding people and pigs. Eventually the farmers did make a dent in their numbers, sufficient to reduce their nesting flocks to numbers where predators could kill them faster than they could reproduce. So the most numerous bird species in North America–in fact in the world–was reduced to a critical threshold beyond which it could not reproduce at a rate sufficient for survival. The most successful avian ecological strategy could not exist alongside the agriculture and technology of the Industrial Age. They’ve gone the way of the mammoth and dodo, and we did it, sure enough.
    We’re better off without the passenger pigeon (falcons and foxes aren’t), but it would be nice to have some in cages. Dodos too. –AGF

    • agfosterjr @September 12, 2014 at 6:15 pm
      The most successful avian ecological strategy could not exist alongside the agriculture and technology of the Industrial Age.
      It is said of the Eastern deciduous forests as settlers moved west, that a wagon could be drawn by teams all day long through the trees, without impediment. They were that park-like.
      But in truth they were actively managed forests, until not very long before the early settlers arrived (at least, not long by the standards of trees & forests). They weren’t exactly or even ‘very’ natural. The reason they were so park-like, is the tribes who mostly-vanished not long ahead of western emigration, tended them. To a fair degree, these were agricultural plantations, the product of indigenous technology.
      The “great passenger pigeon flocks” developed on the fat of the vast stands of acorn & nut-bearing trees … which were artificially uniform, spaced and abnormally large & productive.
      The Indians created the enormous passenger pigeon populations. This is why the species was not ‘notable’ in Western America; why no ‘great’ flocks were reported in the Far West. Conditions there did not support the kind of forest-management seen in the East. (Natives of the West did also ‘intensively’ manage landscapes there, but they used a different approach, with different results. Lewis & Clark, eg, marveled at the fabulous game-loads they encounter, and remarked upon the condition of vegetation.)
      Variation of flocking and nesting behavior of birds, occurs with opportunities and adversities in the environment. For example, we used to have a major seagull presence along the West Coast shorelines. People who lived along the beach threw household garbage out for the tide to dispose of. Port Angles backed city garbage trucks to the lip of our 200′ tall Quaternary bluffs, and tumbled megatons of refuse directly onto the overflowing narrow beach, and ‘landfilling’ out into the surf. [Yellowstone National Park kept bleachers at the park dump, into the 1970s, where tourists sat to watch as dump trucks unloaded for the waiting, and often fighting grizzlies. They posted dump-times in campgrounds, etc.]
      Seagulls responded. Maybe not quite passenger pigeon-esque, but impressively, to be sure. Then private dumping was banned, city dumps were modernized … bald eagles made a strong comeback, and seagulls are now very sparse. They get along as loners and in tiny flocks, after looking for decades like an obligate mega-flock & nest-colony species.

  33. Glass from the event is still vitrified? I doubt it. Or are they able to find recrystallized spherical shapes that were likely once glass? Devitrification results in the surface spallling off in layers. Glass of optimal composition may last, perhaps, a millennium or two but poorly formulated glass can begin to devitrify more quickly. Desert conditions preserve glass best since in moist soil conditions, the alkalis dissolve out of the surface, frosting the surface, but eventually it flakes into pieces. 13,000years ago, I don’t think the glass survives as such. By the way, I do believe in the strength of the evidence for the impact, though.

  34. Die-offs of band-tailed pigeons connected to newly discovered parasite

    Scientists were able to implicate this new parasite, along with the ancient parasite Trichomonas gallinae, in the recent deaths of thousands of Pacific Coast band-tailed pigeons. The die-offs occurred during multiple epidemics in California’s Central Coast and Sierra Nevada mountain ranges.

    The disease may also have contributed to the decline of the passenger pigeon, whose extinction occurred exactly 100 years ago.
    Epidemics of the disease can result in the death of thousands of birds in a short amount of time. An outbreak in Carmel Valley killed an estimated 43,000 birds in 2007.

    There are links to further articles on this topics, on this page

  35. Ted Clayton: “The Indians created the enormous passenger pigeon populations.”
    A few problems with that:
    1) Natural forest fires have always been able to provide wide open spaces. In the early 20th century there was far less forest than now in such places as South Dakota’s Black Hills forest and elsewhere. Were Lakotas and Dakotas still clearing forests?
    2) Is it not established that the bird nested exclusively on the ground? Is there any extant species which nests both in trees and on the ground?
    3) If it is true that the birds required predator proof nesting populations, requiring large areas of Amerind provided open space, how would they have survived before human arrival?
    Sea birds typically nest on islands, and their populations are not limited as much by food availability as by nesting space. I don’t live far from the Great Salt Lake, and we have gulls and pelicans here by virtue of islands in the lake that provide nesting sites (vulnerable to fluctuating lake levels). These birds never nest anywhere else. So the question arises: how did the passenger pigeon evolve such a nesting strategy if small flocks lead to extinction?
    I propose that it evolved soon after the K/T event when there were no predators extant, and persisted till September 1, 1914, when Martha, the last passenger pigeon died in the Cincinnati Zoological Garden:
    http://www.si.edu/encyclopedia_Si/nmnh/passpig.htm
    That is to say, passenger pigeon populations were greater 60mya than 400 years ago. As I recall, it was passerines that survived the K/T event, from which all modern birds descended.
    But I could be wrong. –AGF

    • Not passerines but landfowl and waterfowl are known from across the K/T boundary.
      Passerines did however evolve within five to ten million years of the K/T event. By about 55 Ma, in the Early Eocene, perching birds were recognizably distinct.

  36. agfosterjr @September 13, 2014 at 9:46 am

    1) Natural forest fires have always been able to provide wide open spaces. In the early 20th century there was far less forest than now in such places as South Dakota’s Black Hills forest and elsewhere. Were Lakotas and Dakotas still clearing forests?

    Wikipedia says in its Black Hills Nat’l Forest entry: “After a series of devastating wildfires in 1893, U.S. President Grover Cleveland created the Black Hills Forest Reserve on February 22, 1897.” I’d have to do much more research, to know what the deal was with Lakotas & Dakotas, at that time, in that setting.
    Especially for nesting, it was the Eastern Hardwood Forest that supported & enabled the passenger pigeon, and which the tribes there had modified & managed. Further west on the Plains, it was marginal for the big flocks. Smaller & sparser flocks would be able to forage successfully on semiarid landscapes, but maybe not nest in huge flocks.

    2) Is it not established that the bird nested exclusively on the ground? Is there any extant species which nests both in trees and on the ground?

    Wikipedia’s passenger pigeon entry says; “The passenger pigeon was one of the most social land birds.[35] It lived in colonies stretching over hundreds of square miles and practiced communal breeding with up to a hundred nests in a single tree.” “Nearly every tree capable of supporting nests had them, often more than 50 per tree; one hemlock was recorded as holding 317 nests.[47]”
    The egg was white, whereas ground nesters typically have camouflaged eggs. This is a hint, that actually this bird did not ‘naturally’ nest on the ground, and the behavior was an artifact of unusual flock-sizes … which likewise were not usual for the species.
    Sorry – I don’t know birds thoroughly enough to say quickly whether we have ‘dual’ ground & tree nesters or not. But as I say, and especially as the white egg suggests, passenger pigeons were operating outside their normal parameters.

    3) If it is true that the birds required predator proof nesting populations, requiring large areas of Amerind provided open space, how would they have survived before human arrival?

    From what fragmentary fossil evidence we have, this species was not dramatically abundant, before humans arrived. It presumably lived similarly to other pigeons & doves.
    The Eastern Hardwood Forest which Amerinds optimized, were park-like and the ground was clear & open, beneath the closed canopy. The very large flocks that confer predator-tolerance, appear to have been an outgrowth of the Amerind habitat-modification, followed perhaps by benefits that arose from European settlement – especially creating forest & open-space mosaics.
    The Eastern Hardwoods upon which the sky-darkening pigeon relied, are themselves a phenomenon of the latter part of the Holocene, only some thousands of years. The family to which pigeons belong, is first seen in the Miocene fossil record (~20 mya).
    Ecological adjustments following the K/T event must have been fascinating…

    So the question arises: how did the passenger pigeon evolve such a nesting strategy if small flocks lead to extinction?

    The capacity to express both large flock & herd, as well as small-group habits is not unusual. Bison have a large-herd Plains form, and a small-group Woods Buffalo form. Elk come in forms that disperse thinly, and others that herd strongly. Birds show ranges of such behavior too. Animals are generally good at ‘covering the bases’; the variations enable adaptation, selection, and evolution.
    Passenger pigeons local to the Plains and other ‘marginal’ places are thought to have gotten along without large-flock strategies.

  37. Well, I read Wiki and went back and reread my old sources and found no claim of ground nesting–my memory must have invented it. The only thing that comes close is the three-day mass fledgling, which would certainly attract a load of predators. Accordingly we don’t need any post K/T evolution of a nesting habit that didn’t exist.
    Returning to your claim: “The Indians created the enormous passenger pigeon populations,” Charles Mann in “1491” has a different take. There seems to be no archeological evidence that Amerinds ate them. Even when many species of bird bones are found at a site, the pigeons are not included. Yet Europeans found them eating them with relish, together with appertaining lore and ritual. Mann suggests that it was in fact the disappearance of the Amerinds due to European disease that led to forest recovery and pigeon and bison population booms. Much to discovered and learned.
    Thanks for the chat! –AGF

  38. agfosterjr said @September 14, 2014 at 7:46 am

    Returning to your claim: “The Indians created the enormous passenger pigeon populations,” Charles Mann in “1491” has a different take. There seems to be no archeological evidence that Amerinds ate them.

    Yeah … I indulged a little ‘rhetorical flourish’. A bit of artistic license. 😉
    It was by managing the forest, that Amerinds established the conditions that eventually supported & drove the hypertrophied passenger pigeon flocks.
    Originally, the Natives were interested in foods produced by trees, like acorns, for their own direct benefit. There would be other pay-offs, too, in an upgraded-forest program.
    Actually, during the days when acorns etc were crucially important to the indigenous cultures, the pigeons would have been a pest, an enemy, since they competed for – preferred – the same vital food-source that people wanted for themselves.
    However, by the time Europeans showed up, eastern seaboard American Native cultures were newly but well-along to becoming agriculturalists. Indians famously saved our early Colonists, by giving them corn (maize) and other cultivated crops. Amerinds had become farmers; they made popcorn around the winter-fire, instead of roasting those old-fashioned acorns. Great-grandma still roasted a few of the bitter wild nuts … but with-it youngsters snacked on mild-flavored & deliciously-oily roasted pumpkin-seeds … which they ‘slaved’ to raise in gardens & fields, during the summer.
    “The Three Sisters” based farming lifestyle – corn, beans & pumpkin/squash – had originated in Southwest and Central America long ago, but steadily migrated north and especially Northeast, over a span of centuries. Mississippian cultures had waxed fat on the new food-sources, earlier, and it was just getting established good in the far-Eastern reaches of America, when the Colonists arrived.
    So … the importance of forest-foods had declined. Villages no longer had to defend vital acorn crops from pigeons, because they had recently adopted & committed themselves to other, better crops. I would imagine that in their own ‘old days’ when the acorns were their staple food, the Indians skillfully deployed efficient means to suppress the pigeons, all of whom seek acorns preferentially.
    Amerind cultures were not uniform or egalitarian. They had hierarchies & one-up-man-ship that were often intense & merciless. Some uncouth groups, and various kinds of lowly individuals, still collected acorns and depended on them, and might not be welcome to share cornbread in the upper-class villages, even if things got tough. But the cool people and the with-it groups had shifted to domesticated agricultural crops … and didn’t care much about the acorns anymore.
    And so … the pigeons went ‘hog-wild’ … the more nomadic-flocking passenger-type going into ‘perfect storm-mode’.
    It would be a decent guess that the old-timer Indians had viewed pigeons the way we do rats – a scourge to be destroyed. You wouldn’t eat the awful things. But Three Sisters Amerinds didn’t need to worry anymore about pigeons gobbling the acorns, since they had cornmeal-dumplings instead. At that point, the taboo against eating pigeons went the way of pounded & leached acorn-meal.

  39. Black Mat Layers are Buried Vegetation, not Fire Residue
    Fires don’t typically leave a black mat layer. These ‘mats’ are composed of fine vegetation; grasses, leaves, needles, twigs – and these are the first fuel-component that the fire completely consumes.
    Black mat horizons on terrestrial surfaces result from the sudden burial of normal ‘ground-vegetation’. Sealed off from the air by an over-burden, fine vegetable materials blacken and compress into a mat.
    If forest fires commonly left black layers, we would see them super-abundantly, since such fires big & small, high & low intensity, are frequent. Actually, forest fires do not normally leave anything resembling a ‘black mat layer’.
    The phenomenon of buried fine vegetation producing a ‘black mat’ is very familiar, around residential properties where grading & filling has previously covered the former ground-surface (to level the site). Subsequently, we go back in with equipment to work on septic systems, excavate new foundations … and we see in our cut-banks these striking ‘black layers’. Inspected closely, the blackened individual grass blades and other small vegetable detritus can be identified. Casual observers very common perceive these layers as having been ‘burned’; it looks like char.
    Black mats are also very common in natural fluvial deposits. Light floating (and sinking) debris is windrowed or eddied or ‘tide-lined’ at places along water-bodies … and then quickly buried in the next flood.
    Black mat layers are very striking. They grab the eye and demand attention & investigation. But they aren’t black, because they were charred in fire. It’s a chemical reaction that results from having been quickly buried … the same reaction and color-effect we see in coal-deposits, which were built up from repeated quick (swamp) burial of mostly fine organic materials.
    In the case of the onset of the Younger Dryas, the obvious culprit for buried landscapes, is windblown soil, sand and dust. There was an intense drought. The glaciers & ice sheets had been melting. ‘Sand storms’ were a huge feature of this era, laying down “loess” soils sometimes 100s of feet thick, hundreds of miles away from the source.
    We shouldn’t think ‘fire’, when we see a black-mat layer in the ground. We should think, ‘abrupt burial’. Intense fires may leave a reddened or yellowish mineral-layer, but the “fine” fuels (that would become a mat) are the first to be incinerated.
    Drought promotes fires, and small charcoal fragments are very lightweight and wind-transport very well. Char-particles much larger than the sand-particles will be found in wind-blown deposits. Strongly wind-blown fires can produce lots of airborne char-particles, and charcoal-residue (and ashes) at ‘dead’ fire-sites is readily lofted in subsequent wind-storms.
    Black mat layers at the onset of the Younger Dryas may have been fundamentally misidentified.

    • “Fires don’t typically leave a black mat layer”
      The details of the circumstances that produced this black mat is obviously a key question. Although fire has been discussed for the Younger Dryas onset layer, I don’t think there is a consensus.
      Certainly, one could imagine a major impact producing one or more years with very little sunlight, resulting in the demise of everything except fungus and the like.
      What about a fire followed ten years of darkness? Black mat? Is it possible to prove that an major impact would not result in a black mat layer in the geologic record? Probably not.
      “Black mat layers at the onset of the Younger Dryas may have been fundamentally misidentified.”
      Perhaps, but the real question is if the black mat layers in question contain markers unique to a major impact. That is what the paper discussed here is appropariatly focused on.
      But on the subject of black mat layers generally, one could consider a number of questions, such as how frequently in the past do black mat layers appear? And are known prior layers that are synchronized in time on different continents?
      And specific to 12800, what was happening in the geologic record in the southern hemisphere?

      • What about a fire followed ten years of darkness? Black mat? Is it possible to prove that an major impact would not result in a black mat layer in the geologic record? Probably not.

        Fire burns the fine materials that black mats are made of, first. Only if the fine ground-cover is buried good, do we get a black mat (it’s an anaerobic preserving process, which also blackens). Darkness won’t halt normal decay processes.

        “Black mat layers at the onset of the Younger Dryas may have been fundamentally misidentified.”
        Perhaps, but the real question is if the black mat layers in question contain markers unique to a major impact. That is what the paper discussed here is appropariatly focused on.

        The presence of a black mat layer means there wasn’t a fire, at that site. If the sample-sites are usually or always black mats, then there was no generalized fire. That seems inconsistent with the “major impact” proposal.
        No chain is any stronger than its weakest link. Tawdry facts routinely fall exhilarating theories. 😉

  40. Search this press-release post, and the previous press-release post, linked at the top of this one, for the term “black mat”. Note that it does not occur in either press-release.
    The term that does occur, is “black layer”. The previous release also uses the term “carbon-rich”. Both terms are vague, and could be many different things.
    Impact-proponents strongly suggest they are dealing with a char-layer; invoking continent-scale Tunguska-style aerial bursts and general environmental devastation. A char-layer is an easy type of feature to identify; we know what char & soot is, and can tell if a horizon resulted from a scorching heat-application. Junior High kids can ID fossil charcoal and other products of incomplete combustion. (No: teasing out a few microscopic soot or charcoal particles does not make a horizon a “char” or fire-layer.)
    Otoh, the impact-proposal has for years been couched in terms of a “black mat” layer. These features are by definition not charred. They’re black, but they weren’t produced by heat.
    Conflagrations do not generally leave behind a widespread ‘char-layer’. Especially not composed of fine fuels (mat-materials), because these are the first fuels to be consumed in the combustion-process. And thus, if the layers are “black mats”, there was no general conflagration.
    The nature of these black features that investigators are obtaining samples from, certainly does matter, and vagueness only accentuates questions about them. The context, setting & conditions of any physical sampling procedure, always matters a great deal.

    • Ted Clayton feels, judging from the two posts above, that unless he can imagine how an impact formed the three continent sized black mat/layer it couldn’t have occurred.
      This is quite unscientific.
      The scientific approach is to examine the layer in question and see if has markers unique to an impact, and to rule out other explanations for such markers, if they were found.
      If such impact markers are found, then it is appropriate to speculate concerning the details of the formation of the layer.
      Whether a correct understanding of those details is reached or not, it doesn’t matter to the more important question if the layer formed at the time of a major impact, which is answered not by vague imagining of how such a thing could have happened, but by careful examination of physical evidence.

      • Published peer-review science has already established that commonly-observed wetland “black mat” horizons normally contain the particles said to be impact-markers. Samples from black mats both older and younger than the Younger Dryas Boundary show similar collections of particles and spherules. (Yes, black mats – other than at the YDB – are common features in the ground.)
        The particles could originate from routine, ongoing cosmic impacts … substantial tonnages of meteors & such burn up in the atmosphere every year (without disturbing the environment). Some scientists anticipate that terrestrial processes, perhaps several kinds, are the source.
        Most black mat layers of various ages contain the marker-particles, but do not correlate with any known climate or ecosystem changes.

  41. Kudos to commenter Ted Clayton for actually discussing the core question of the physical evidence, as opposed to how “reasonable” various imagined scenarios seem to him.
    Unfortunately, he claims it is “established” that the impact markers found in the dark layer in question are found in all dark layers.
    It appears he forms a viewpoint and then reads only scientific papers that support the preconceived view.
    Quite unscientific. Yawn.

  42. mr lorax –
    You quote Ted Clayton thus:
    “Ted Clayton feels, judging from the two posts above, that unless he can imagine how an impact formed the three continent sized black mat/layer it couldn’t have occurred.”
    Actually, Ted Clayton got it wrong. It isn’t on three continents. It is on four. N America, Europe, Asia (Syria), and the northern end of the Andes (I can’t recall at the moment if it is Venezuela or Columbia), which is, of course, S America.

  43. There is also the problem that impact-proponents used samples from selected black mat horizons that turned out to have a range of different dates; only a few actually being the right age for the Younger Dryas Boundary. Again, peer reviewed and published.
    Steadily upping the ante on the scale of the proposed impact serves to ratchet up expectations; suggests we should see supporting evidence of an escalating profile. While not necessarily a ‘deal-breaker’ among scientists, ‘bigger and BIGGER’ is especially risky with the media and the public.
    Even the Chicxulub impact at the K-T boundary, dubbed the ‘dinosaur killer’ and the validating feature for Luis Alvarez’ famous interpretation of a widespread “enriched iridium layer”, is not immune to scientific second-guessing.
    Questions always existed, and continue with refinements by both leading and yeoman scientists, whether this putative impactor was an asteroid, since various aspects of the evidence make it look more like a smaller but faster comet.
    The problem in Chicxulub as a comet-impact being that comets are mainly water, and such an object would be unlikely to provide the iridium in Alvarez’ layer. Similar complications can pertain to simultaneous assertions that a YDB impactor was cometary in nature, and that abundant metallic particles are evidence of that cosmic impact … again, comets being watery.

    • Obviously the dates of the dark layers are important, identical dates would support but not prove an impact hypothesis, while a variety of dates suggest another mechanism.
      However, your comment “again, peer reviewed and published” as if the reported range of dates cannot be in any way erroneous indicates a naive and cartoonish understanding of the scientific process.
      Real science is always in a state of change and self-questioning. Certainly past theories and measurements have been found to be in error as will future “peer reviewed and published” results.
      These dark layers in question are interesting in part due to their broad extant, and it is interesting to consider the mechanism producing such layers, either at the same time or around the same time. Some claim that layers covering such a large geographic area are quite unusual in the geologic record, suggesting very unusual circumstances that prompted their formation.
      The carbon dating these layers in question to dates +-20% of the start of the Younger Dryas date would suggest carbon dating process is not be as precise as assumed, if in fact most of these layers were coincident in time, assuming the nano diamond results hold up and the nano diamonds are unique to these particular layers and not common to all dark layers as some claim.

      • The carbon dating these layers in question to dates +-20% of the start of the Younger Dryas date would suggest carbon dating process is not be as precise as assumed, if in fact most of these layers were coincident in time…

        The old joke in Medicine goes: “The surgery was a complete success; unfortunately, the patient died”.
        Radiocarbon dating itself can have useful precision, but ‘complications’ inherent in samples & sites can and often do introduce or necessitate large error-factors.
        We have numerous ‘classic’ examples of single artifacts and sites, the reported or claimed dating of which has ‘see-saw’ greatly, as new studies have been done or even the same study has been repeated, over a span of decades and even generations. It’s a matter of vagaries with the ‘patient’, rather than issues with the ‘surgery’ per se.
        When the dating-target is not just a single artifact or well-characterized site, then the complications & contaminates can readily spiral into the unmanageable. “A beautiful surgery (hypothesis), tragically impugned by an uncooperative patient (fact)”.
        Or, in common lingo, “They shoulda thought of that, before”.
        It’s a problem, ‘bracketing’ dates for even a single item or place. Try to do the same for many different items & places, and we are easily confronted by classical combinatorial runaway. Uncertainties, free-breeding in the dark like mutant rabbits.
        Given dating-uncertainties of +-20%, lab results for a sample believed to be in fact 12,800 yo can swing 2,560 years up or down. Conversely, samples that are in fact 2,560 years too old or too young, can report as on-the-money.
        Given this kind of difficulty, how did YDIH proponents expect to convincingly show that an impact took place ‘one day’ 12,800 ya?
        Actually, not all samples or sites are subject to this 40% error-spread. The maturity of radiocarbon dating-practice allows for the identification of factors & conditions that erode or solidify the confidence that can be ascribed to results, on a case-by-case basis. “Patients unlikely to survive can be identified, and should not be allowed to impugn the doctor or the procedure”.
        Apart from the problems identifying good Younger Dryas onset layers, there is also the discovery of particles said to be impact-markers in horizons dating far older and far younger than the YD. These marker-particles are proving to be common, back into the Late Pleistocene, and throughout the Holocene. They’re ‘everywhere’.
        Personally, I interpret black-layers and black-mats as features mainly derived from the enormous dust-storms of the era. The sudden climate change at the onset of the Younger Dryas is linked to a severe drought, which greatly facilitated the dust storms. The windblown sediment buries living vegetation, and especially in wetland contexts, ‘pickles’ it.
        The Younger Dryas Impact Hypothesis is linked to the Carolina Bays Impact Hypothesis. The later enjoyed a day in the scientific sun, back in the 1940s-50s. It had been boosted & legitmized by the very real Tunguska event of 1908. The Carolina Bays idea, however, failed to meet basic fact-tests as impact-features, though some folks have continued to carry its torch. There appears to be some ‘active’ overlap of the old CBIH and the new YDIH … and this is not auspicious, scientifically.

        • There is actually quite a bit in what you just said that I agree with.
          Still, when you go and say this, I have an easy comeback: “Given this kind of difficulty, how did YDIH proponents expect to convincingly show that an impact took place ‘one day’ 12,800 ya? ”
          Pinter/Holliday, in their last paper (that I know of) complain that a few hundered years are sinking the YDIH boat, and here you are saying that all those dates are such wide ranges that who can tell exactly what day? You are arguing the exact opposite of what they argue. And it comes down to,
          “If the dates are so uncertain, how can the YDIH OPPONENTS say that the dates DO NOT align?”
          As to sampling, I have specifically pointed out Pinters and Holliday’s and Scott’s sampling was taking to wide of samples, when Firestone clearly pointed out the necessity of taking micro-samples – VERY narrow slices of the layers. Why? Because the spike is found in a VERY narrow slice, and if you take a wider slice, the spike gets lost. This is independent of the dates that come back. This is just to properly find the materials and put them into a narrow enough window of time. If the spike is in a 0.5cm-5cm slice (2.3cm average) and the replicators take up to 5cm-28cm slices (11cm average), they are not going to see the spike – because in transport, etc., the important 2.3cm gets mixed up in the other 8.7cm and the signal gets watered down. Since Firestone CLEARLY spelled this protocol out, it was incumbent on those trying to replicate to do it the same way. Otherwise it’s not replication at all – the attempted replications is bad from the start. They didn’t take those micro-samples properly.
          As Israde replied about the sampling of Surovell 2009:

          Deficiency #1: YDB Samples Too Thick Stratigraphically. A) Quote from Firestone et al. (2007a) regarding the YDB interval: “we found a thin, sedimentary layer (usually <5 cm).” B) Source, Table S1 in Surovell et al. (2009) shows that the candidate YDB interval at 7 sites was sampled at a resolution ranging from 5-28 cm, averaging 11 cm. Problem: Firestone et al. collected sediment samples at 7 sites at which they discovered high abundances of YDB markers in a thin layer with vertical thicknesses ranging from 0.5 to 5 cm and averaging 2.3 cm, as illustrated in their Fig. 1 in Firestone et al. Surovell et al. collected some samples that were sufficiently thin, but also collected much thicker samples, ranging up to 28 cm thick (averaging 11 cm), much wider than the average YDB layer averaging 2.3 cm where the MSp are concentrated. The thickest sample (28 cm) collected by Surovell et al. diluted the markers by an average of ~5× and up to ~60×, masking. Although we do not consider this to be a fatal deficiency, it does make spherule detection more difficult.

          Notice that she is not addressing the dating issue, but it applies here as well.
          (Personally, I think even the 5cm sampling was too wide, given the sharpness of the peaks as given. It seems that 2.5cm samples might have even given a higher amplitude spike. perhaps 2.5cm is not really possible, physically – I don’t know.)
          Taking microsamples DOES allow for the raw C14 dates to be much more specific. But, I agree with you, the raw C14 dates may come back spread out over time a little bit, even if the +/- is tightened up. I am not sure about the +/-20% that mr. lorax asserts. I’ve never seen any C14 dates that had a +/-20% or even close to that. At the same time, I am suspicious myself of some of the small +/-s that I have seen in papers of all sorts over the years. A +/- of perhaps 5-10% I might not dispute too loudly. But then, in that, you and mr. lorax and I essentially agree on this – if not in exact degree.
          Van Hoesel got her knickers in a twist over 100 years, when the ranges were +/-200 years, and she confused IntCal09 and IntCal13. Anyone who thinks the dates are exactly precise is living in an imaginary world. To me, within 100 years is certainly as close as one can get.*** The YDIH proponents never have thought that the dates were right on the money. That is an issue brought up by the opponents, and it is a straw man argument. The proponents realize that the date precision depends VERY MUCH on microsampling – to keep the sample as tight as possible. WHAT MORE CAN THEY DO?
          Once the samples come back from the C14 labs, the dates are what the dates are, along with the +/-s. As I understand it, then, the max and min are converted over (calibrated) with IntCal13 (usually using one of the softwares available), and the calibrated max and min are what they are.
          The labs can only work with what is given them, and if the sample covers 3″, then that represents hundreds or perhaps a thousand years sometimes. And then within that sample, they grab what they think will represent the sample properly – but how can they know that they aren’t grabbing the highest particle layer or lowest layer within the sample? That is why the tighter (narrower) the sample is, the better – so that there is not much difference between the highers and lowest dirt particles in the sample.
          The YDIH proponents realized this – which is why they did microsampling in the first place. And continue to. The shaprper the spike and the narrower the sample, the stronger they think their arguments are. And then Survell comes along and butchers his sampling and gets different results, and then he claims the high ground? Not even.
          ***I say this is in spite of the very arduous and always continuing efforts of Reimer and the IntCal group to get the calibration curve nailed down. I also see the problem being in the sampling. Once the C14 B.P. dates come down, the calibrated dates are actually very tightly constrained. I recommend that anyone go look up what the calibrating group does.

      • Steve Garcia said @September 22, 2014 at 12:00 pm

        As to sampling, I have specifically pointed out Pinters and Holliday’s and Scott’s sampling was taking to wide of samples, when Firestone clearly pointed out the necessity of taking micro-samples – VERY narrow slices of the layers. Why? Because the spike is found in a VERY narrow slice, and if you take a wider slice, the spike gets lost.

        The width of the sample isn’t ‘that big a deal’. The lab methods & processing recover virtually every particle from the sample-material. If we think a given 10 cm-thick sample included a physical layer actually only 1 cm thick that contained the particles, we just divide the recovered particle-count into 1, instead 10. Presto – a spike 10 times higher/sharper … the same spike we would get, taking a 1 cm-thick sample containing only the layer.
        Sloppy, maybe; scientifically problematic, not so much.
        A bigger problem, is that interesting detritus indeed isn’t confined to narrow layers; the stuff is widespread, both in time & space.
        Although I take the Younger Dryas climate-change as yet-another whip-lash in the greater Pleistocene climate-careen, and think the cosmic impact mechanism will find no better home here than in the Carolina Bays (which truth be known may be Firestone’s core interest), the particles themselves and the technology for gathering & analyzing them is captivating. I look forward to new studies of these tiny artifacts, at the YDB and elsewhere.

        • Ted –
          If I hear you correctly, you just stated something that simply isn’t even close to correct:
          The width of the sample isn’t ‘that big a deal’. The lab methods & processing recover virtually every particle from the sample-material.
          From a website dedicated to C14 dating:

          “The crucial advantage of the AMS method is that milligram sized samples are required for dating.” http://www.c14dating.com/int.html

          And from an actual lab:
          Carbon-14 Measurement Techniques
          Three methods are currently offered by RCD for carbon-14 measurement, benzene synthesis, direct absorption and accelerator mass spectrometry (AMS). AMS is the preferred method for samples with low carbon content, i.e. below 0.5g carbon. Full processing is carried out at RCD in the first two methods whereas the smaller samples, which require the third method, are processed to CO2 then sent to the AMS laboratory for measurement.
          The main features of the techniques are:
          Benzene synthesis . . . to achieve an overall precision of ± 1% (ie ± 2.5 Bq/kg carbon). Sample size required 1g to 4g elemental carbon.
          Direct absorption . . . Precision of the measurement is between 5% and 10% (ie ± 12.5 to ± 25 Bq/kg carbon). Sample size required 0.5g to 1g carbon.
          Accelerator mass spectrometry . . . Precision of the method is better than ± 1% (± 2.5 Bq/kg carbon) and the sample size required is 5mg to 10mg carbon.
          The main difference between the methods is the size of sample required for measurement, but the second technique, direct absorption, offers considerably lower precision than the other two and is, therefore, generally only of use in situations where the question is simply whether a sample is ancient (0% ‘modern’) or modern (> 100% ‘modern’) but not where finer detail is necessary to help unravel mixtures of sources or provide an actual age.” http://www.rcd-lockinge.co.uk/carbon14.htm
          So, the lab only tests up to 4 grams of the material provided not “every particle in the sample.” The lab methods & processing recover virtually every particle from the sample-material.” is absolutely pulled out of your imagination.
          ***
          The width of the sample IS a big deal, dude. The larger the sample (which in the field is normally put into a bag and mixed up within that bag), the more diluted the spike will be. That is simple math.
          But if you have a wider sample, then it literally becomes hit-or-miss as to what sample is actually sent to the lab. It might be blended, or it might miss the spike altogether. With the Surovell samples being 5X to 60X as much material as needed, the watering down of the samples by those ratios is simply unacceptable.

  44. Steve,

    … dude.

    Sorry for the confusion, but I was describing the linkage of the particles to what is thought to be the definitive parts of the Younger Dryas Boundary feature-structure. Not the radiocarbon dating.
    If the particles can be convincingly tied to the YDB layers, then the exact age of the event & artifacts is secondary. That would even over-rule dating mismatches. We can establish a linkage of this kind more-accurately through physical association, than by C14 dating different components of the ensemble.
    And, my read of Firestone is that he is making the same assertion; a physical relationship between particles & layers is his ‘smoking gun’, and C14 dates are corroboration.
    Although, yes, we can usual manage a lot better than +-20% (or there wouldn’t be much point), even very nice samples will leave a lot of leeway for temporal mismatch.
    If Firestone et al can figuratively show that he has a worked mastodon bone point (with genetics A) embedded in the intact skeleton of a mastodon with genetics B, with bone partially grown back around the point, then those physical structural associations ‘make his case’ better than getting into a ‘dueling C14 contest’ ever could. In fact, the Manis mastodon components are simultaneously one of the classic ‘physical association’ smoking guns, and a notorious long-running ‘dueling dates’ soap-opera.
    But the Manis dating-issue is small-potatoes, and would be with the YDIH project too, if the (cosmic impact) particles can be ‘pinned’ to the (climate change) event-signature. I think that’s what Firestone is aiming for. Others can argue the dating.

    • Ted –
      Thank you for this rational discussion, BTW.
      IAt this point I’d simply like to ask you to go read some of the later papers. Surovell and Holliday are fixated on the first Firestone paper, as if that was the end all and be all of this research. (Which it is not; far from it.) Except when the YDIH proponents vary at all from that “first proposal of principal” paper Holliday accuses them of not having their story straight. Otherwise he hammers on that first paper like the others had not been written. Papers by Wittke, and LeCompte, and Israde, and Kennett and Kinsie and West and Mahaney and still others.
      And ALL of those “tie the particles to the YDB layer.” Otherwise they wouldn’t even be discussing them.
      As to the dating thing, as one guy just posted elsewhere, about van Hoesel and her nitpicking comments about dates that were only several DECADES apart (or so she thought):

      http://www.jstor.org/stable/10.1086/677046
      Later, van Hoesel et al. (2012, p. 7652) suggested that NDs in the Netherlands at the Aalsterhut site are “two centuries younger than the diamonds reported by Kennett et al.” (2009b) and therefore are from an unrelated event. They concluded this on the basis of an apparent age discrepancy between the mean age of the ND-rich layer at their site and mean age of the Arlington Canyon site in California. However, they overlooked the fact that the date for the Aalsterhut site fully overlaps those for many other YDB sites, including Murray Springs. To test their hypothesis, we performed Bayesian analysis (Bronk Ramsey 2009) and χ2 testing (Ward and Wilson 1978) on the Arlington Canyon radiocarbon dates. Both methods indicate that the Arlington Canyon radiocarbon dates have nonnormal distribution and thus are unsuitable for averaging (fig. B1). Bayesian analysis is particularly useful in detecting outlier dates (nonnormal distribution), including those that result from the old-wood effect, in which the date for charcoal or wood from a long-lived tree can lead to the erroneous conclusion that the stratum in which the charcoal was found is much older. Bayesian analysis rejected 14 of 16 Arlington Canyon dates as being outliers, consistent with the observation that local tree species have life spans of up to 1300 yr (see “Arlington Canyon, California” in app. B). After adjusting for the old-wood effect, OxCal modeled the YDB age for Arlington Canyon as 12,748 ± 46 cal BP (OxCal, ver. 4.2.3, IntCal-13; Bronk Ramsey 2009). This is statistically identical to the modeled YDB date for Aalsterhut of 12,746 ± 12 cal BP (10,870 ± 15 RCYBP; van Hoesel et al. 2012). These results contradict the hypothesis that the ND-rich layer at Aalsterhut is 200 yr younger than the ND-rich YDB layer at Arlington Canyon.
      Arlington canyon is the Channel islands site.

      First off, the YDB layer is at the very underside of the black layer – EVERYWHERE, on all the sites (that I know of, and I think I know them all) – and more.*** And when I say “YDB layer”, I mean the very thin layer with the suite of impact markers. It is THE layer that has the spikes, in carbon spherules, in nanodiamonds (including lonsdaelite), in magnetic spherules, in Iridium, in ammonia, in HE3, in shocked quartz. All of the markers are not found at all sites, but all sites have multiple marker spikes. And all of the spikes are at THAT age AND NO OTHER – within narrow limits, in spite of Holliday’s arguments to the contrary. Holliday’s and Sorovell’s arguments and work has been fully rebutted in the past (like the passage above about van Hoesel), and I fully expect that they’ve screwed up something again with their latest paper.
      – – – – –
      As an aside, the Channel Islands are where the dwarf/pygmy mammoths survived for quite a long time. These are to be distinguished from the Wrangle Island undersized mammoths, which were actually a bit larger than the ones on the Channel Islands. These two families derive from different parentage – different species of full-sized mammoths. One odd thing is that the mammoths on the Channel Islands are thought to have swum across from the mainland – but then they never swam back at any point.
      But the black layer and YDB layer both exist there, in Arlington Canyon, but somehow the small mammoths there survived whatever the YDB and black layer were caused by, when the full-sized ones on the continent didn’t.
      Like I’ve said before, speculating on these is interesting, but that is all we can do at this point, because not enough is known yet. Fundamental stuff needs to be laid out factually first. Hopefully with more info better questions can be asked. We are all standing on a foggy shore and trying to describe the land on the other side of the ocean, based on the patterns in the fog. The YDB proponents are trying to get things as solid as they possibly can, before trying to ask, “What does it all MEAN?”
      *** There is at least one area I know of with a black layer – ONE black layer – that is not yet included in the YDIH proponents work. It is in central and western Nebraska, where the layer is referred to as “Brady Soil”. http://www.nature.com/ngeo/journal/v7/n6/full/ngeo2169.html and http://www.biblioteca.org.ar/libros/91207.pdf
      This layer is not currently dated to the YDB, but it is not so very far off, and the independent researchers have been sampling for reasons other than to find spikes in magnetic spherules or nanodiamonds in a narrow band. Their sampling seems to be (my guess) not very layer specific, for the most part. So at this time I am speculating that this layer is also part of the YDB layer. But it is my personal hunch, and only a hunch. The above layers of Loess date after the YDB (9,000 ya), and the layers below date to pre-YDB (~13,500-15,000 ya). Where exactly is the bottom of the black layer? One of the papers mentions a date for the humus at the TOP the layer as being 9,000 ya C14 B.P, which is 10,200 calibrated B.P. – about 1,000 years too late to be the end of the YD cold period. But the Brady soil in photos has a very indistinct top to it. The layer is a meter or more thick, and the top is mixed with the loess above in a somewhat gradual transition, at least as shown by coloration. The thickness of the transition at the top is perhaps half a meter or more, so the transition may span 1,000 or more years, easily.

      • Steve,

        Thank you for this rational discussion, BTW.

        You’re welcome; and good on you as well!

        Surovell and Holliday are fixated on the first Firestone paper…

        Yes, Firestone 2007 saddles the author & hypothesis with baggage & weaknesses that should have been cut & corrected, before being submitted for Review, much less going to press and being committed to the official record. Carolina Bays? Uh-oh.
        The intellectual marketplace is highly competitive. Opponents will use Firestone’s indiscretion & haste against him, and all they have to do is keep mentioning the paper. Those who “hammer” 2007 today, will pass the baton to someone else, tomorrow.

        And ALL of those “tie the particles to the YDB layer.”

        They all want to, sure. Like the Carolina Bays, these black mats and black layers of interest appear to be the ‘calling-card’ of a complex constellation of phenomena, which arose & ran their coarse in the later 10-20K or so of the waning Glacial.
        Particles turn up in time-horizons well removed from the YD. That’s why impact-proponents are now ‘zeroing in’ on nanodiamonds – because other classes of particles are too easy to find in settings that are obviously not YD. But there are problems with the crystalline or cryptocrystalline carbon, too. ‘Stay tuned’.

        First off, the YDB layer is at the very underside of the black layer – EVERYWHERE, on all the sites (that I know of, and I think I know them all)

        It ‘should’ be impossible that a person would claim to know all the sites.
        Volcanic eruptions in large numbers are traceable at very large numbers of locales, lots of them crossing the YDB. Ash-falls that would be trifles compared to the proposed YD impact event are readily ID’d to a particular eruption of a particular mountain. At HUGE numbers of sites where many ashfalls are well-inventoried, the fallout of the YD impact should be the biggest & most-glaring of them all.
        But it isn’t there. That proponents & students of the YDIH point to a few dozen locales, while thousands of known ash-bearing strata are silent … uh-oh.

        • No offense, Ted, but you come up with stuff that doesn’t seem to have any basis in fact – stuff out of your interpretation of things, maybe, but not connected to the evidence very well.
          But let me first correct a perhaps misstatement of mine. When I said I know of all the sites, I meant the known ones – which is exactly why I suggested that the Brady soil might be added at some point.
          Volcanic eruptions: It is amazing and insulting – and especially ill-informed IMHO for opponents to assume that the proponents have not looked at the possibility of volcanic provenance for various materials that they ended up concluding was impact-related. Ted, you are listening to the accusations of Holliday (mostly), who is the biggest dickwad in the opponents’ camp. And you obviously – and I DO mean obviously – not informed of what the proponents actually say, except for the 2007 paper.
          And you talk about the 2007 paper as if Firestone himself wrote it all and did all the science on it. Actually, no one in the world is an expert on all of those areas of evidence, and Firestone had LOTS of help. And every one of them was and IS a solid scientist who doesn’t go around signing onto every idea that comes along. They all needed to see the likelihood of this idea being valid. ESPECIALLY since they knew it flies in the fact of all the Gradualism that is out there. They had to have balls to sign onto this idea. And they knew it.
          Ash falls? You are grasping at straws. That was one of the first things they looked at. And then the first thing they rejected. That appears to be a speculation of yours, but it is one that doesn’t hold water. No ashfall in history comes anywhere close to the 50 million square km area. Not even Krakatoa or Stromboli. Perhaps the Yelllowstone supervolcano, but I guarantee that if a supervolcano had gone off anywhere near 13,000 ya, we would have heard about that long ago and have other evidence, on the ground at ground zero. And ashfalls are almost always clearly assignable to particular volcanoes, as you say.
          Ash is also SO clearly not impact related materials. Ash layers are clearly identifiable. You are talking apples, when this is all oranges. Sorry. That doesn’t fly. The only – ONLY – other layer that comes close to the black layer visually is the K-T Boundary of 65 million years ago. But that one has been covered by much more sediment layers and has been compacted, usually down to an inch or three. The black layer in some places is a foot thick or so, though most are in the 2 inch to 8 inch range.
          The Carolina bays? You are beating a dead horse. Bring your knowledge up to at least 2010. See? You, like Holliday and Surovell act as if no evidence has been worked on since 2007. If you want to live in the past, go ahead. This issue has gone way past 2007. It’s like you are rooting for the 1908 Chicago Cubs.
          The “baggage & weaknesses that should have been cut & corrected” – That is pretty much a joke, right? Since Hooliday mocks them ignorantly about changing their story. And you here say that they HAVEN’T changed their story. At least get on board with your leader. Like the Carolina bays I just addressed. Holliday thinks he can have it both ways – accusing them of not dumping the baggage and then “hammering them” (your phrase) when they did.
          You see, Holliday and Surovell believe this is a debate of words. As mr lomax said, that is the way the science is done with anthropologists, but THIS is a hypothesis with physical evidence, and physical evidence outweighs words.

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