From the University of California – Santa Barbara some paleoclimatology without the need to see hockey sticks.
Comprehensive analysis of impact spherules supports theory of cosmic impact 12,800 years ago
(Santa Barbara, California) –– About 12,800 years ago when the Earth was warming and emerging from the last ice age, a dramatic and anomalous event occurred that abruptly reversed climatic conditions back to near-glacial state. According to James Kennett, UC Santa Barbara emeritus professor in earth sciences, this climate switch fundamentally –– and remarkably –– occurred in only one year, heralding the onset of the Younger Dryas cool episode.
The cause of this cooling has been much debated, especially because it closely coincided with the abrupt extinction of the majority of the large animals then inhabiting the Americas, as well as the disappearance of the prehistoric Clovis culture, known for its big game hunting.
“What then did cause the extinction of most of these big animals, including mammoths, mastodons, giant ground sloths, American camel and horse, and saber- toothed cats?” asked Kennett, pointing to Charles Darwin’s 1845 assessment of the significance of climate change. “Did these extinctions result from human overkill, climatic change or some catastrophic event?” The long debate that has followed, Kennett noted, has recently been stimulated by a growing body of evidence in support of a theory that a major cosmic impact event was involved, a theory proposed by the scientific team that includes Kennett himself.
Now, in one of the most comprehensive related investigations ever, the group has documented a wide distribution of microspherules widely distributed in a layer over 50 million square kilometers on four continents, including North America, including Arlington Canyon on Santa Rosa Island in the Channel Islands. This layer –– the Younger Dryas Boundary (YDB) layer –– also contains peak abundances of other exotic materials, including nanodiamonds and other unusual forms of carbon such as fullerenes, as well as melt-glass and iridium. This new evidence in support of the cosmic impact theory appeared recently in a paper in the Proceedings of the National Academy of the Sciences.
This cosmic impact, said Kennett, caused major environmental degradation over wide areas through numerous processes that include continent-wide wildfires and a major increase in atmospheric dust load that blocked the sun long enough to cause starvation of larger animals.
Investigating 18 sites across North America, Europe and the Middle East, Kennett and 28 colleagues from 24 institutions analyzed the spherules, tiny spheres formed by the high temperature melting of rocks and soils that then cooled or quenched rapidly in the atmosphere. The process results from enormous heat and pressures in blasts generated by the cosmic impact, somewhat similar to those produced during atomic explosions, Kennett explained.
But spherules do not form from cosmic collisions alone. Volcanic activity, lightning strikes, and coal seam fires all can create the tiny spheres. So to differentiate between impact spherules and those formed by other processes, the research team utilized scanning electron microscopy and energy dispersive spectrometry on nearly 700 spherule samples collected from the YDB layer. The YDB layer also corresponds with the end of the Clovis age, and is commonly associated with other features such as an overlying “black mat” –– a thin, dark carbon-rich sedimentary layer –– as well as the youngest known Clovis archeological material and megafaunal remains, and abundant charcoal that indicates massive biomass burning resulting from impact.
The results, according to Kennett, are compelling. Examinations of the YDB spherules revealed that while they are consistent with the type of sediment found on the surface of the earth in their areas at the time of impact, they are geochemically dissimilar from volcanic materials. Tests on their remanent magnetism –– the remaining magnetism after the removal of an electric or magnetic influence –– also demonstrated that the spherules could not have formed naturally during lightning strikes.
“Because requisite formation temperatures for the impact spherules are greater than 2,200 degrees Celsius, this finding precludes all but a high temperature cosmic impact event as a natural formation mechanism for melted silica and other minerals,” Kennett explained. Experiments by the group have for the first time demonstrated that silica-rich spherules can also form through high temperature incineration of plants, such as oaks, pines, and reeds, because these are known to contain biologically formed silica.
Additionally, according to the study, the surface textures of these spherules are consistent with high temperatures and high-velocity impacts, and they are often fused to other spherules. An estimated 10 million metric tons of impact spherules were deposited across nine countries in the four continents studied. However, the true breadth of the YDB strewnfield is unknown, indicating an impact of major proportions.
“Based on geochemical measurements and morphological observations, this paper offers compelling evidence to reject alternate hypotheses that YDB spherules formed by volcanic or human activity; from the ongoing natural accumulation of space dust; lightning strikes; or by slow geochemical accumulation in sediments,” said Kennett.
“This evidence continues to point to a major cosmic impact as the primary cause for the tragic loss of nearly all of the remarkable American large animals that had survived the stresses of many ice age periods only to be knocked out quite recently by this catastrophic event.”
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Clovis spearpoints are certainly stunning pieces of work and each one of us would like to be able to throw one of those big spears at something.
But they were abandoned when more efficient hunting techniques like the atlatl / dart system was brought in across the Bering land bridge.
No human would ever use a Clovis spear again after watching how easy an atlatl worked. It would have spread around the continent very rapidly as happened with all such large technological leaps. Humans have almost always had contact with neighboring groups.
My guess is this happened in North America right around the YD event naturally.
sunshinehours1 says:
May 21, 2013 at 6:06 pm
Comets cannot selectively kill large mammals (Mastodons, Sabre-Tooth Tigers) and leave small mammals (humans) alive.
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Actually they can, and do. By distrupting the environment.
Well, let’s accept that this was the cause of the Younger Dryas cooling. But then… what was the cause of the subsequent great and rather fast warming. SUVs and damned fosil fuels Clovis technology?
As regards a comet selectively killing the large mammals; a massive loss of flora for a single season due to an impact object would have that result. As regards the atlatl making the Clovis culture tools obsolete; the atlatl has been used since the ice ages began, a few 100K years ago. Long enough ago to have been used by the first humans to the Americas, however they arrived.
More excellent work from Los Gauchos.
The Wikipedia artcile debunking this theory linked to this paper claiming that the megafauna were already dying off well before the impact event:
“Megafaunal populations collapsed from 14,800 to 13,700 years ago, well before the final extinctions and during the Bølling-Allerød warm period. Human impacts remain plausible, but the decline predates Younger Dryas cooling and the extraterrestrial impact event proposed to have occurred 12,900 years ago.”
http://adsabs.harvard.edu/abs/2009Sci…326.1100G
If some argue that the Clovis people also died out, I would suggest they died out for the same reasons the megafauna died or because the megafauna died out ruining food supplies.
— Part 2 —
However, what caught my attention and set off my AR5 BS detector was this quote:
“”Whatever this was, it did not cause the extinctions,” Tankersley says. “Rather, this likely caused climate change. And climate change forced this scenario: You can move, downsize or you can go extinct.” http://phys.org/news/2013-05-mammoth-lament-cosmic-impact-devastating.html
Sorry, but this is just AR5 “Climate Change Kills” Bull****.
An explanation that rings truer.
“Northern mammoth populations grew after the Last Glacial Maximum, but then dipped again during the Younger Dryas period about 12,900 years ago. Although there is controversy as to what happened at that time, “there was certainly a very rapid and profound cooling of many regions then, followed by rapid warming,” MacDonald said. “Did this cause the extinction of the mammoth? Absolutely not. They were still present in far northern sites at the end of the Younger Dryas. Right now it’s not quite definitive how great an impact the Younger Dryas had.”
The last mammoths seen on the continents were concentrated in the north. They apparently disappeared about 10,000 years ago as the climate warmed and peatlands, wet tundra and coniferous forests developed, environments to which mammoths were poorly suited. The long-lasting proximity between mammoths and humans suggested that our species was perhaps a factor in the beasts’ decline, possibly killing off the final island populations of woolly mammoths that went extinct 3,700 years ago.
Overall, these findings suggest the mammoths experienced a long decline due to many factors.”
http://www.livescience.com/20894-woolly-mammoths-extinction.html
Jeff L says:
May 21, 2013 at 7:07 pm
“The pattern of the YDB field is interesting – I wonder if you could deduce a likely impact location based on the shape ??”
IIRC, there is a website devoted entirely to hundreds if not thousands of impact craters in West Texas and Northern Mexico from this time. I don’t have the time at the moment to give you more but I do think the YDB event was not a single impact. Rather it was a shotgun blast from a very large object that broke up at some distance from the surface. As for the 1300 years of the remaining YD I do not know the mechanisms involved.
http://en.wikipedia.org/wiki/Ahrensburgian How European tribes coped with the Younger Dryas
I’m also going to second the notion of following the Cosmic Tusk site.
FWIW, one of the major Nickle and Platinum Group Metals mines is in a place in Canada that is the ideal location for the major impact site into the ice field. The land around it evidences “burn through ice” effects. A large incoming bolide with break-up also accounts for the various smaller “burn mark” areas scattered around (and SL-9 into Jupiter showed break up happens outside the atmosphere from near misses of other objects…).
The ejecta from the Canadian impact landed in S. Carolina making a set of “bays” there with a particular shape and orientation that points back at the primary impact site.
As per the 1200 – 1300 year disruption: We had a MAJOR flood of water into the oceans from that impact vaporizing megatons of ice. That screws up the ocean cycles until things reorganize. It happened right as we were heading out of a ‘stable cold’ into a ‘stable warm’ pattern and truncated the “stable warm” until things got back on cycle.
Per Humans and Clovis not being extinct: Um, need I point out that the majority of the Clovis folks DID get extirpated? New folks came over from Asia and repopulated, and a small remnant of Cloves in New Mexico got absorbed into the new population. The (then) largely European type Clovis culture was effectively replaced with an Asian type.
It is also likely that the impact sent a wall of ice / slush over the pole into Siberia and accounts for the “sudden” burial of mammoths with food still being eaten / digested and the general chaos in the layer of permafrost of that era with all sorts of critters and not so tundra like plants in a jumbled mix. It was a tidal wave of slushy mud that hit them and then set up again.
(I would expect “interesting things” to be found in Arctic ocean bottom sediments, but doubt folks have looked much due to the ice cover…)
The impact likely also is the reason that the typical “peak and plunge” shape of other interglacials was, for us, truncated into a “not quite a peak and 10,000 years of flat”. Instead of a heating over shoot, we got ‘truncated’ with a cold spell and more or less stabilized. Now we’ve had our warm duration and the W/m^2 more than 60N degrees is on the edge of falling back into glacial stability mode (we are presently roughly in the ‘metastable’ zone as we leave ‘stable warm’ and the Little Ice Age was the first manifestation of that ‘metastable’… next cold plunge will be non-recoverable, but ought not to come for about 300 more years, IFF we are lucky…).
The notion of a “Stable pleasant time” like the Holocene is a fantasy. It was entirely an accident of that impact ‘peak clipping’ the usual “Peak and Plunge”. As soon as our 425 W or so drops below about 416 W/m^2 60 N we go cold and stay there. ANYTHING we can do to keep more heat up north gives us more time before the next freeze / glacial cycle. We want and NEED a hotter arctic. More so every century as the orbital mechanics move inevitably toward ever more “unstable to cold” pattern.
E.M.Smith says:
May 22, 2013 at 4:24 pm
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Well reasoned comments based upon discoveries & hypotheses of recent decades.
IMO it took quite a while before the “European-like” elements were replaced by the Asian. “Caucasoid” Kennewick Man, with an Archaic point in his hip, died c. 9300 BP or earlier, but in any case long after the Younger Dryas.
Vukcevic
I have often wondered about Hudson’s Bay general shape. It seems too circular to be a natural part of the normal earth, the magnetic anomaly really makes it interesting.
@milodonharlani:
The likely impact point is in East Canada, so from that POV, western N. America is far away and “over the top” of the pole for some bits. I would expect that the Clovis folks would have a remnant across the very south west, and potentially up into Washington. Extirpation was likely limited to the center / east arc, but the disruption to big game would have prevented effective repopulation for a long time. Then the added Asian types showed up and did the major repopulation.
If you look into Native American genetics, it’s a very interesting “mix”. More Asian on the west coast, more European on the east coast (even among those with “pure” ancestry – so not a recent admixture – and visible in the early paintings / photos prior to significant European invasion and colonization. You find specific alleles that only ‘make sense’ if there were an earlier European type population that “blended” with a later Asian type (likely in several waves) and with the locus of Asian arrivals being land bridge down the West Coast. (Oddly, too, there’s a batch of genetic and material goods that indicate a Japanese cluster in South America from folks escaping a volcanic event long long ago; so one of the “tribes” in, IIRC, Peru, is effectively Japanese from early historical times. There may also be a trace of Chinese genetics, but that’s hard to tease out of the general Asian base.) More speculative, there’s some evidence for an African / black genetic component in some of the Maya area / Olmec area; but poorly evidenced at present. What’s very very clear is that the North American genetic type among the various Native Americans is not a simple “out of Asia” type. (There’s even some Polynesian / Australian genetic bits, of unknown mode of arrival. Including some ‘pentagonal’ skull shapes in very small areas of California coastal Indians – a Polynesian marker – and an interesting tooth shape that’s fairly distinctive. )
It’s all incredibly interesting and a whole lot of fun, except for the hypersensitive folks who want to turn it all into some kind of political statement. It isn’t. It’s just a very interesting and very old long gone history. There’s even some evidence for even earlier occupations of the Americas up to 50,000 years being modestly attested while up to 200,000 years has some “plausible” sites being investigated.
http://chiefio.wordpress.com/2012/12/22/native-americans-and-european-roots/
http://chiefio.wordpress.com/2011/11/29/unsettled-age-for-american-early-habitation/
If folks would be less political about it and just find the stones and history interesting to explore, we would know much more and have a richer past. Oh Well…
The European genetic mush is even more of a mess. Anyone who thinks they are “pure” anything is just wrong. A “Spaniard” has as much chance of being a German as Phoenician as Celtic as Jewish as Berber genetic ancestry as all have traipsed through the area leaving genes behind. And don’t even get me started on the Roman Empire and the Egyptian history… We have records of Celtic mercenaries in Egypt…
http://chiefio.wordpress.com/2011/02/20/ramesses-the-red/
http://chiefio.wordpress.com/2012/09/22/im-hispanic-who-knew/
http://chiefio.wordpress.com/2011/03/08/galicia-or-galizia-polish-galicja-ukrainian-%d0%b3%d0%b0%d0%bb%d0%b8%d1%87%d0%b8%d0%bd%d0%b0-halychyna/
So someone from Northern Italy might be a Celt, German, Greek, Slav, or any of a dozen other “genetic types” or ethnicity… so just asking “What is a European type?” is a complicated question.
Anyway, lots of fun, but not very relevant to how a big rock from space made the Younger Dryas and how that then lead to an abnormally mild Holocene and the rise of modernity…
I was enthusiastic about this theory when I first read it but now I don’t know what to make of it. Two separate groups of “experts” come to different conclusions.
The black mat has been sometimes attributed to fire; however, it is also possible that it could be decayed vegetation arising from heavy flooding. If a comet vaporized a large section of ice, water could have been sent high into the atmosphere and created diluvial precipitation over North America and perhaps the Arctic and Siberia. In the northern areas, this could have fallen as ice and snow and significantly altered the albedo by expanding the area of snow or depositing so much that it might not melt during the summer. Along with a large amount of fresh water falling into the ocean, it seems to me, this could trigger a cooling.
I have always felt that there is “no case to answer” with the Younger Dryas (YD). Glacial periods – in contrast to interglacials such as (and especially) the Holocene, are characterised by rapid, even violent, climate temperature swings up and down, in the context of which the YD is completely unremarkable.
This view is reinforced even more by literature on the bipolar seesaw (reciprocal oscillation between north and south hemispheres) around the time of the YD and before, leading up to the Holocene. One of the most important such papers is Blunier et al 1997 who show that the YD was just the NH reacting to a warming southern ocean. It was proposed by Tzedakis et al 2012 that sharpened bipolar seesawing marked both the beginning and the end of interglacials. Thus in Blunier we see – in fig. 2 – first a warming in the southern ocean about 16 kYa, then the “Antarctic cold reversal”, a cooling oscillation in the SH, coinciding with sharp NH warming prior to the YD. Then a warming upswing in the SH ending the cold reversal coincides with the abrupt YD. It is noted by Barker et al 2009 that the seesaw is characterised by smooth sinusoidal oscillation in the SH but more abrupt changes in the NH, caused in the latter case by Atlantic meridional overturning circuation (AMOC) regime changes. Then at the Holocene inception both NH (abruptly) and the SH (smoothy) rise in temperature, but the SH again cools slightly in advance of the Holocene optimum.
One thing that is clear is how Jeremy Shakun, holder of the chair in climate fraud at Oregon SU, has shamelessly exploited the end-glacial bipolar seesaw to concoct a spurious proof of CO2 leading the temperature rise out of the last glacial. Southern ocean temperatures had been rising since 16 kYa and continued to rise during the YD, resulting in a small CO2 increase in anticipation of the Holocene, on the condition that you take the Holocene to begin after the YD. But CO2 was not driving the start of the Holocene, it was merely following the southern ocean established warming. (There is more ocean in the SH than NH.)
If we demand an atmospheric deus ex machina to explain every upward and downward wiggle of climate history we are falling into the ignorant trap and mental paralysis of AGW believers, who are unable to accept any cause of temperature change other than atmospheric input by humans and are in denial of the existence of the world’s oceans.
The timing is pretty clear.
It wasn’t a comet, it was super-predator humans. There’s a reason we keep animals in zoos now, you know.
It is doubtful that humans were present in N. America in sufficient numbers to account for the extirpation of the mega-fauna. Before they themselves were nearly extirpated, native tribes in N. America took as many buffalo and deer as they could kill at any one time, seemingly without making much of a dent in those populations. It took humans with firearms bent on mass destruction of the native people’s primary food source to very nearly exterminate the bison.
There remain far too many unknowns surrounding this event, but the black mat was not created by men, of that we can be fairly certain.
Comets, asteroids and volcanoes can’t impact the atmosphere for longer than a few years once the event has ended, so this rules out any of these for a 1300 year period, What was found in the fossil record was that the North Atlantic become much colder and the warm water moving North via the Gulf stream was channeled towards Southern Spain instead of between Scotland and Norway. The major change was ocean originated and this initial change would have cooled the northern hemisphere atmosphere considerably. Regions surrounding the North Atlantic would have had the biggest impact with areas other side of the planet hardly affected.
Temperature estimates from fossils further South towards the sub-tropics and tropics hardly changed. If a comet was responsible for the cooling it would have effected the sub-tropics and tropics too. The sun easily warms the colder ocean temperatures in just 6 months between winter and summer, so a overturning of cooler water with a comet impact in the North Atlantic ocean is ruled out too. A ocean circulation change was certain this caused the cooling over 1300 years with numerous up and downs in between. This event was not a planet atmospheric impact, but an ocean impact.
Volcanic eruptions from the early Holocene (say, 12,800 years ago) put down ash-layers which we readily find & identify at large numbers of locations. We commonly map the fallout-pattern from old eruptions at close grid-spacing, with high accuracy.
If the continent had been devastated by a huge blast at the beginning of the Younger Dryas, the tell-tale black layer would be commonplace in every corner of the land. It would be easily found at the 12,800 year horizon, wherever it has remained stable.
We would all be able to get in the car and take a short drive out to cuts & exposures, and have a look for ourselves at the black-layer signature of the stupendous cataclysm that befell early Native Americans, ravaged the environment & ecosystem from top to bottom, and radicalized the climate for more than a millennium.
But we don’t & can’t go out and look at this remarkable layer at the 12,800 year horizon, because it isn’t there. And the fact that there is no such widely-distributed layer, means there was no such widespread cataclysm. If there had been, we would know of thousands, or 10s of thousands of sites at which it had been documented.
Not if a flood followed an impact.
There are many known & identified layers & horizons within the soil & sediment record, from both before & after the 12,800 year horizon. These deposits have been stable & undisturbed, since before the Younger Dryas. The entire Holocene soil & sediment record is continuous.
There have been certain cataclysmic floods, such as those that passed through Washington state, as ice-dams holding back large melt-water lakes in the Rockies periodically gave way. From these examples, we know well what such mega-floods do to the landscape. The great majority of the continent shows no such effects. There has been no continent-scale flooding during the Holocene.
Had there been a continent-scale flood 12,800 years ago, it would have left its own very dramatic horizon-signature – exposures of which we would likewise drive out to in the car and gawk at, the hair rising up on our necks as the gargantuan spectacle whispers to us from across the ages.
But again, we don’t go out to observe and study this tremendous flood-mark left in the sediment-record, because it too does not exist.
I take it then that the remains of mammoths found in the semi-frozen muck of Siberia were not overwhelmed by flood, but by some other unknown force that killed them suddenly, and preserved them perfectly.
And I suppose that the New Siberian Islands of the Russian far north are not really comprised largely of the shattered bones of extinct megafauna, because there is no record of a flood that could have transported them there?
There is a lot of boggy terrain in the high north, which grows rich browse, but it doesn’t have enough solid ground for a mammoth to move around on it … when it’s thawed. This would be their winter-pasture, after if froze-over good ‘n firm.
Many tundra-ponds are active ‘compost-piles’, generating heat down-deep, well after the landscape looks like a deep-freeze. Mammoths pushing their luck for fresh feed, deceived by concealing snow-layers, or just drawing the short-straw with a warmer & thinner-frozen pond … broke through into these deep mucky bog-pits in large numbers, and died quickly, often drowning in the liquid goo as their own body-weight forced it up around them & over their head.
This terrain and these conditions are hazards to smaller animals too, and to smaller (and of course large) machines as well, still today.
It was winter and cold, when the mammoth stepped into its doom, and the struggling beast entombed itself in the excellent preservative of bog-mire, which then often froze solid.
Dating of bones & frozen tissue on the New Siberian Islands shows they have steadily accumulated over a span of 200,000 years, at least. During the Ice Ages, these are a nice piece of hill-country, out on a vast, flat plain … and this of course about 90% of the time.