Support: comet impact may have triggered the Younger Dryas period

From the University of South Carolina – PNAS: Topper site in middle of comet controversy

By Peggy Binette, USC

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

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

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

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

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

Younger-Dryas is what scientists refer to as the period of extreme cooling that began around 12,900 years ago and lasted 1,300 years. While that brief ice age has been well-documented – occurring during a period of progressive solar warming after the last ice age – the reasons for it have long remained unclear. The extreme rapid cooling that took place can be likened to the 2004 sci-fi blockbuster movie “The Day After Tomorrow.”

Firestone’s team presented a provocative theory: that a major impact event – perhaps a comet – was the catalyst. His copious sampling and detailed analysis of sediments at a layer in the earth dated to 12,900 years ago, also called the Younger-Dryas Boundary (YDB), provided evidence of micro-particles, such as iron, silica, iridium and nano-diamonds. The particles are believed to be consistent with a massive impact that could have killed off the Clovis people and the large North American animals of the day. Thirty-six species, including the mastodon, mammoth and saber-toothed tiger, went extinct.

The scientific community is rarely quick to accept new theories. Firestone’s theory and support for it dominated the annual meeting of the American Geophysical Union and other gatherings of Paleoindian archaeologists in 2007 and 2008.

However, a 2009 study led by University of Wyoming researcher Todd Surovell failed to replicate Firestone’s findings at seven Clovis sites, slowing interest and research progress to a glacial pace. This new PNAS study refutes Surovell’s findings with its lack of reported evidence.

“Surovell’s work was in vain because he didn’t replicate the protocol. We missed it too at first. It seems easy, but unless you follow the protocol rigorously, you will fail to detect these spherules. There are so many factors that can disrupt the process. Where Surovell found no spherules, we found hundreds to thousands,” said Malcolm LeCompte, a research associate professor at Elizabeth City State University and lead author of the newly released PNAS article.

LeCompte began his independent study in 2008 using and further refining Firestone’s sampling and sorting methods at two sites common to the three studies: Blackwater Draw in New Mexico and Topper. He also took samples at Paw Paw Cove in Maryland, a site common to Surovell’s study.

At each site he found the same microscopic spherules, which are the diameter of a human hair and distinct in appearance. He describes their look as tiny black ball bearings with a marred surface pattern that resulted from being crystalized in a molten state and then rapidly cooled. His investigation also confirmed that the spherules were not of cosmic origin but were formed from earth materials due to an extreme impact.

LeCompte said it was Topper and Goodyear’s collaboration, however, that yielded the most exciting results.

“What we had at Topper and nowhere else were pieces of manufacturing debris from stone tool making by the Clovis people. Topper was an active and ancient quarry at the time,” LeCompte said. “Al Goodyear was instrumental in our approach to getting samples at Topper.”

Goodyear showed LeCompte where the Clovis level was in order to accurately guide his sampling of sediments for the Younger Dryas Boundary layer. He advised him to sample around Clovis artifacts and then to carefully lift them to test the sediment directly underneath.

“If debris was raining down from the atmosphere, the artifacts should have acted as a shield preventing spherules from accumulating in the layer underneath. It turns out it really worked!” Goodyear said. “There were up to 30 times more spherules at and just above the Clovis surface than beneath the artifacts.”

LeCompte said the finding is “critical and what makes the paper and study so exciting. The other sites didn’t have artifacts because they weren’t tool-making quarries like Topper.”

While the comet hypothesis and its possible impact on Clovis people isn’t resolved, Goodyear said this independent study clarifies why the Surovell team couldn’t replicate the Firestone findings and lends greater credibility to the claim that a major impact event happened at the Younger Dryas Boundary 12,900 years ago.

“The so-called extra-terrestrial impact hypothesis adds to the mystery of what happened at the YDB with its sudden and unexplained reversion to an ice age climate, the rapid and seemingly simultaneous loss of many Pleistocene animals, such as mammoths and mastodons, as well as the demise of what archaeologists call the Clovis culture,” Goodyear said. “There’s always more to learn about the past, and Topper continues to function as a portal to these fascinating mysteries.”

Goodyear joined USC’s College of Arts and Sciences and its South Carolina Institute for Archaeology and Anthropology in 1974 to pursue prehistoric archaeology.

The Topper story

Albert Goodyear, who conducts research through the University of South Carolina’s S.C. Institute of Anthropology and Archaeology, began excavating Clovis artifacts along the Savannah River in Allendale County in 1984. It quickly became one of the most documented and well-known Clovis sites in the United States. In 1998, with the hope of finding evidence of a pre-Clovis culture earlier than the accepted 13,100 years, Goodyear began focused excavations on a site called Topper, located on the property of the Clariant Corp.

His efforts paid off. Goodyear unearthed small tools such as scrapers and blades made of the local chert that he believed to be tools of an ice age culture back some 16,000 years or more. His findings, as well as similar ones yielded at other pre-Clovis sites in North America, sparked great change and debate in the scientific community.

Goodyear reasoned that if Clovis and later peoples used the chert quarry along the Savannah River, the quarry could have been used by even earlier cultures.

Acting on a hunch in 2004, Goodyear dug even deeper into the Pleistocene terrace and found more artifacts of a pre-Clovis type buried in a layer of sediment stained with charcoal deposits. Radiocarbon dates of the burnt plant remains yielded ages of 50,000 years, which suggested man was in South Carolina long before the last ice age.

Goodyear’s findings not only captured international media attention, but it has put the archaeology field in flux, opening scientific minds to the possibility of an even earlier pre-Clovis occupation of the Americas.

Since 2004, Goodyear has continued his Clovis and pre-Clovis excavations at Topper. With support of Clariant Corp. and SCANA, plus numerous individual donors, an expansive shelter and viewing deck now sit above the dig site to allow Goodyear and his team of graduate students and public volunteers to dig free from the heat and rain and to protect what may be the most significant early-man dig in America.

The Topper timeline

1998 Goodyear and his team dig to a meter below the Clovis level and encounter unusual stone tools up to 2 meters below the surface.

1999 Team of outside geologists visit Topper site and propose a thorough geological study of the location.

2000 Geological study done is by consultants; ice age sediment is confirmed for pre-Clovis artifacts.

2001 Geologists revisit Topper and obtain ancient plant remains deep in the Pleistocene terrace. Optically stimulated luminescence (OSL) dates sediment above ice-age strata show pre-Clovis is at least older than 14,000 years.

2002 Geologists find new profile showing ancient sediment lying between Clovis and pre-Clovis, confirming the age of ice age sediment layer between 16,000 – 20,000 years.

2003 Archaeologists continue to excavate pre-Clovis artifacts above the Pleistocene terrace. New and significant Clovis artifacts are found.

2004 Goodyear discovers major Clovis occupation on the hillside. Additionally, radiocarbon dates for sediment associated with pre-Clovis artifacts come back at 50,000 years.

2005 “Clovis in the Southeast” conference held in Columbia, S.C., with tours of Topper and Big Pine Tree sites.

2006 The 3,500-square-foot roofed structure is built over pre-Clovis excavations.

2007 Firestone study about a possible Clovis comet is published in the Proceedings of the National Academy of Sciences, including evidence from Clovis age sediments from Topper.

2008 PBS “Time Team America” spends a week at Topper filming for an hour-long television special devoted to Topper.

2008 SCETV broadcast of “Finding Clovis,” a public television presentation of Topper Clovis. 2009 PBS “Time Team America” program airs.

2011 Topper and Big Pine Tree included in a study of post-Clovis Paleoindian decline/reorganization that is published in the journal “Quaternary International.”

2011 The first permanent exhibit of Topper artifacts installed at the University of South Carolina Salkehatchie.

2012 Independent study of micro-spherules related to an extra-terrestrial impact hypothesis is published in the Proceedings of the National Academy of Sciences using Clovis-age sediments from Topper that confirm the original 2007 Firestone study.

2013 The pre-Clovis occupation of Topper will be presented in October at the international conference on the peopling of the Americas, titled “Paleoamerican Odyssey,” in Santa Fe, N.M. http://www.paleoamericanodyssey.com/

=====================================

h/t to Dennis Wingo

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Phil Wilson

Great article. The whole pre-Clovis ‘heresy’ debate fractured American science deeply through the end of the 21st century. Glad to see a paper that addressed why the initial findings weren’t easily replicated. Good science articles like this make WUWT a greg must read site.

Nerd

Interesting. Everybody should read The First American by Hardaker. http://www.amazon.com/The-First-American-Suppressed-Discovered/dp/1564149420 It caused a big controversy back in the old days due to dating (250,000 years!). I wonder if they’re going to start looking into that now. Even 50,000 years old was very tough for people to accept back then too. It took 30,40 years to get to 50,000 years old. Talk about slow progress!

oldseadog

Maybe OT, but “The scientific community is rarely quick to accept new theories”.
Didn’t take the warmists long, though.

Jeff D.

oldseadog says:
Didn’t take the warmists long, though.
Acceptance is way easier when your check depends on it.

Crispin in Waterloo

The presence of the black spherules of terrestrial origin means a major ground impact. OK. I presume that based on a search for Iridium concentrations in various N American sites of the right age, it may be possible to locate the impact site. I understand that is how the Yucatan impact site 65m years ago was located.
Perhaps it was in Hudson Bay which is quite shallow. Being so recent it would otherwise have left a very rather obvious mark.
Is there any evidence for a simultaneous change in the sea level around the 40-50 degrees latitude mark? That would indicate that the Earth wobbled and settled on a slightly altered axis. If this is the case then it would change the ‘expectable’ future of climate, in effect putting us forward or back on the Milankovich Cycle. High latitude, high speed impacts are quite capable of altering the length of the day and the tilt of the earth and the precession rate. It sounds as if this may have been one. Perhaps we have broken out of our 500k year pattern. Interesting.

Goodyear & Firestone , hmm .

Yet another reason to provide the most detailed account possible of one’s experiment.

Crispin in Waterloo

@Nerd
Excellent link.
“‘…the dates were so old that to take them seriously would impugn their own scientific credibility.”
So it is not for the first time that people discovering scientific truths turn silent in order to protect their positions from those contollling the dominant paradigm.
The difference with ‘climate science’ is that the evidence for a CO2 hypothesis never dominated anything – it was just a hypothesis. At least the Clivis First supporters had plenty of evidence, they just rejected other evidence.
Surely is it interesting to note that the Reis Map of Antarctica (the original was painted on animal skin) shows what the shoreline was about 250,000 years ago, a similar age? Here we go again…

No Name Guy

Hmmmm…I notice a complete lack of references to “peer review” and lots of work trying to independently replicate the earlier study / studies.
Who would have thought of that…..real science in this field, unlike certain others (cough…AGW / warmists…..cough). Could it be that these folks actually understand the scientific method while our warmist friends don’t?

P. Solar

vukcevic says:
September 20, 2012 at 10:50 am
>> Goodyear & Firestone , hmm .
Yes, you have to wonder is someone is having a laugh sometimes. Why is no one mentioning Dr Dunlop’s noteworthy research on this period 😉
“The so-called extra-terrestrial impact hypothesis adds to the mystery of what happened at the YDB with its sudden and unexplained reversion to an ice age climate,… ” Goodyear said/
So is it now common practice to misuse the term “ice age” instead of glacial period ? Or are these guys archeologists who do not understand the terms they are using?

NZ Willy

I presume these “black spherules” have also been found at non-quarry sites, else they would only some kind of soot related to tool manufacture.

Crispin in Waterloo says:
September 20, 2012 at 10:49 am
Perhaps it was in Hudson Bay
Nastapoka (http://en.wikipedia.org/wiki/Nastapoka_arc) was most likely hit by a huge lamp of iron which is slowly sinking into the upper mantle, as both the Geoid depression and the strong magnetic field intensity indicate.
http://www.vukcevic.talktalk.net/Hudson.gif

MarkW

Crispin:
Would a comet have much iridium?

MarkW

NZ Willy:
Just how much soot does chipping chert produce?

Is there any evidence for a simultaneous change in the sea level around the 40-50 degrees latitude mark? That would indicate that the Earth wobbled and settled on a slightly altered axis. If this is the case then it would change the ‘expectable’ future of climate, in effect putting us forward or back on the Milankovich Cycle. High latitude, high speed impacts are quite capable of altering the length of the day and the tilt of the earth and the precession rate. It sounds as if this may have been one. Perhaps we have broken out of our 500k year pattern. Interesting.
Crispin, “altering” is difficult to argue with, but “measurably” or “significantly” altering requires some defense, does it not? The mass of the Earth is ballpark 6 \times 10^{24} kg. The mass of a kilometer radius comet is ballpark 5 \times 10{^13} kg. The ratio of the masses is thus ballpark of 10^{-11} (comet to planet). Even comet with a diameter of 4 kilometers would still have only one ten billionth the mass of the Earth, and would have a one part in a billion impact on any macroscopic aspect of the Earth’s orbit or rotation rate or inclination. I’m not seeing that having much impact on length of day or precession rate or any Milankovitch cycle behavior — I doubt that one could detect its influence compared to other natural sources of “noise” (nutation, tidal coupling, orbital resonance with the gas giants, movement of the continents, continental-scale uplift and downfall, melting of icepacks (which alters the moment of inertia tensor, not just its magnitude. A largish comet would have roughly the same sort of effect on tensor moments than the eruption/explosion of Tambora, which caused 16 cubic miles of mountain to basically blow away into the atmosphere, and there are literally dozens of Tambora-scale events likely to have occurred over the last 12,000 years.
Even if the comet was considerably larger — say, 5 km in radius (and hence 125 times more massive) it would barely perturb the Earth’s orbital properties. The Earth is small compared to stars and gas giants, but it is enormous compared to most observed comets or probable candidate asteroid sizes.
I may be making some sort of arithmetic or conceptual error here, so please feel free to correct me — this is back of the envelope stuff — but I’m having a hard time agreeing with you that alteration of axial tilt or length of day or eccentricity of orbit due to any likely comet impact at any latitude would have any serious effect on the climate beyond the obvious, and extreme, short-and-medium term effects of releasing a few gigaton-of-TNT-equivalents of energy, cubic miles of vaporized or pulverized matter, and a supersonic shock wave of pyroclastic flow sufficient to blow down and/or ignite or bury or flood any structure within a million square kilometers or so of land surface area. Which might well be enough, but which isn’t orbital.
Having meditated upon Tambora (and Krakatoa) and its (their) apparent LACK of clearly visible long term impact on the climate, I’m increasingly inclined towards the belief that the Earth’s negative feedback is more than sufficient to cope with even gigaton-scale explosions involving cubic miles of ejecta. There is a “suspected” impact site for a crater large enough to dwarf Krakatoa or Tambora in Hudson Bay, although AFAIK there is no hard evidence that proves it to be such a site or (obviously) a site that has the right age to have been associated with the YD.
I’ve read a number of articles suggesting a meteoric cause for the YD, and there is “some” evidence that supports it. So far, though, I don’t think there is smoking-gun-specific evidence that e.g. includes the probable impact site or any sort of hint about how large it was. It might not have had to be very large, of course, if the Earth was still in the critical regime in between warm and cold phase where small fluctuations would have been nonlinearly amplified by the critical instability, or if it (for example) broke an ice dam and caused the OTHER major suggested YD cause, sudden freshwater dilution of the North Atlantic that interrupted the thermohaline circulation for a thousand years or so.
rgb

MarkW

vukcevic says:
September 20, 2012 at 11:28 am
“was most likely hit by a huge lamp of iron ”
Was there a genie in the lamp?

MarkW

rgbatduke says:
September 20, 2012 at 11:55 am
Is it possible that since the Younger Dryas impact occured at a time of climate transition, that the climate could have been more sensitive to pertubations?
The other events that you mention all occurred when the climate was solidly within the inter-glacial.

Strange coincidence: BBC4 (UK) is at this moment transmitting ‘Horizon’ about the asteroids, there are apparently 900 of 1 km or larger diameter.

davidmhoffer

So how does this timeline work?
16,000 years ago there was an ice age culture in NA. It started to warm up. Until that ignorant ball of rock about 13,000 years ago, cooled things off a bunch. When the dust from that settled, it started to warm up. Something happened about 600 years ago, cooled things off a bunch, we call is the LIA. When the dust from that settled, it started to warm up. Again.
I conclude from the available evidence that the internal combustion engine was invented 16,000 years ago. There’s no way that the earth could have been warming for 16,000 years punctuated only by the YD and the LIA from just natural causes could it?
Oh wait. This was a North America thing, not a global thing. Probably only “regional”. Never Mind.

Crispin in Waterloo

@rgbatduke first
There is an important assumption you make in your reasonable back of the envelope analysis that must be dropped: that when it comes to changing the pole or rotation, the Earth is basically lke a solid ball, cricket ball if you will. It is not.
There are three poles for the Earth, the lithosphere, the core, and everything in between. They rotate slightly differently and the lithosphere can be perturbed independently of the other two. They are not, at present, aligned. They were disturbed 3200 years ago and probably again in about 1650 BC. The flooding of the Dogger Bank was probably a single-day event. Ditto the civilisation that farmed what is now the floor of the Irish Sea. There are stove walls around fields in Wales that go into the sea and continue across the seafloor. This is describe in detail in a book: Atlantis of the west: the case for Britain’s drowned megalithic civilization”, by Paul Dunbavin, 2003. The first three chapters are relevant to the axes and their relative motion. He postulates there was a 7 year long cylical wobble that was significant enough to be visible to humans. It has now damped down considerably but is still detectable (to about 10 inches I think).
Basically a high latitude impact or as described in http://cometstorm.wordpress.com/2011/04/27/a-different-kind-of-climate-catastrophe-2/ ( h/t Tallbloke) can make the lithosphere wobble without immediately affecting the major % of the mass of the Earth. It is one reason why the theory that enough ice piling up on the poles, asymetrically, can make the ‘earth flip’ (in fact, move the lithosphere relative to the mantle). My reference to the Milankovich Cycle was really made while thinking about the precession of the tilt. To be clearer, I was thinking of the change in insolation between summer and winter which goes through a cycle. I was not thinking about moving the Earth from its orbital path, just that the effect is the same.
@vic
That iron is consistent with most of the theory in the link above, but only if it is really recent.
@MarkW
Iridium is very rare on Earth and much more plentiful in asteroids and rocky comets. It is used as one of the proofs that some lump is extra-terrestrial. When blasted all over the show, a layer of iridium indicates an inmpact, the thicker the layer, the closer it is assumed to be. That is how the Yucatan impact site was located, first generally then confirmed from the air.
A definite impact site is the crater around Sudbury Ontario, but it is old. They are mining the nickel from the bolide and it used to provide 95% of the nickel in the world. Most of the world’s nickel is in the core out of reach. 🙂

JA

So, a comet’s impact set off an ice age that lasted a 1300 years; and all of this took place over 12K years ago.
So, what caused this ice age to end and warming to begin?
Let’s see, oh, it must have been elevated levels of CO2, because THE DEBATE IS OVER – CO2 CAUSES GLOBAL WARMING. THERE IS A SCIENTIFIC CONSENSUS ON THIS FACT.
What you say, CO2 levels were not elevated at the time the YD ice age ended and the climate warmed up.?
Well then , if you believe that you are fascist/commi pig s**t on the payroll of big oil.

george e smith

So why a comet ? Is the core of a comet not simply a meteorite ? Presumably the ice coating would leave not a trace; the old tired worn out who dunit ice dagger murder mystery.

Re Mark W: “Is it possible that since the Younger Dryas impact occured at a time of climate transition, that the climate could have been more sensitive to perturbations?”
Good question. Problem is that nobody knows (to my knowledge) what the sensitivity is and what drives the move to and from glaciation. The thing that makes the YD so interesting is that it marked a strong move back to glaciation for a millennium after the climate was coming out of the last ice age. After the YD, the warming trend resumed, so you have 4 different moves in the direction of climate within the period of a couple thousand of years – a strong move toward warming starting around 15k years ago, a sudden and sharp cooling trend around 12,900 years ago, steady state during the cold, followed by a resumption of the warming trend 10,500 years ago. How do you explain any or all of these? The suggestion of an impact event answers the middle two.
And the YD event is thought by some to be a series of multiple impacts / airbursts centered about two sites in North America – Michigan and central Mexico. Think of thousands of Tunguska sized airbursts over the course of an hour as the earth rotates underneath a thick part of a incoming debris stream. Think continental extinction event. And there may be another center of impact. It is all very new and the discussion is very loud. The significance of this paper is that one set of critics have been shown to be wrong. Cheers –
http://www.whoi.edu/science/GG/paleoseminar/pdf/broecker88.pdf

Legatus

One thing you need to know about such studies in areas like paleontology and such ancient studies of man, critters, and such is that the evidence is often fragmentary in the extreme, small fragments of bone and the like, similar to here. The evidence is so fragmentary that it is subject to a huge range of interpretations. Once someone digs up some such, they often spend decades arguing about what it actually means. This often runs into entrenched (to an extreme degree) interests which fight to keep their previously “established” theories intact to preserve their own prestige and standings in the academic community. An example was where some guy suggested that dinosaurs were warm blooded. He was attacked and basically saw his career take a big hit, and now, 20 years later, pretty much everyone agrees that dinosaurs were warm blooded. http://en.wikipedia.org/wiki/The_Dinosaur_Heresies .
I would not be surprised to see this new study, as well as any evidence for mankind in the Americas before about 13,000 years ago treated pretty much like a Watt on PBS interview.

Paul Marko

The YD ice comet theory may explain the origin of the Siberian and Alaskan “Muck” beds that cover approximately 14% of the earth’s land surface surrounding the Arctic Circle. The beds contain a jumbled assortment of whole and pieces of extinct fauna, most notably the mammoths, all frozen so rapidly that their food source remains undigested in their stomachs, and flower petals and grasses preserved in their mouths. Russian research revealed suffocation as the initial cause of death prior to burial and freezing.
The “Muck’ also contains abundant lenses and house-size deposits/inclusions of a saline, bubble included, granular ice that oxidizes orange upon exposure, thought to be extraterrestrial.
The petroleum industry in Alaska has also noted flora anomalies associated with the “Muck” deposits:
“Though the ground is frozen for 1,900 feet down
from the surface at Prudhoe Bay, everywhere the oil
companies drilled around this area they discovered
an ancient tropical forest. It was in frozen state, not
in petrified state. It is between 1,100 and 1,700 feet
down. There are palm trees, pine trees, and tropical
foliage in great profusion. In fact, they found them
lapped all over each other, just as though they had
fallen in that position.”
Lindsey Williams, The Energy Non-Crisis, 2nd edition
(Kasilof, Alaska: Worth Publishing Co., 1980), p. 54.
The fauna and flora deposits have all the earmarks of an explosion, sudden death and burial.
The quick freeze is another problem.

Disputin

My question with the Younger Dryas is: yes, I can see how a cometary impact might have caused a sudden plummeting of temperature, but what caused the equally rapid warming at the end of it?

Duster

Crispin in Waterloo says:
September 20, 2012 at 10:49 am
The presence of the black spherules of terrestrial origin means …

There are no proposed “black spehules of terrestrial origin.” The argument by Firestone is that the “impact” was actually an aerial blast. The spherules are presumed to be part of the object that blew up, if such a thing happened. Part of the argument us that there is no astrobleme because the detonation took place above an ice sheet, which would absorb the brunt of the energy released. This could possibly account for the purported Atlantic “freshening” suggested at the onset of the YD. Depending upon just where the epicenter of the blast might have been, neither the Clovis site, nor Topper would necessarily have experienced much more than dirty rain. Clovis is roughly 2,000 miles from the center of Hudson Bay and Topper is about 1,900 miles away from the same point.
Of far more interest when considering the period of the Younger Dryas is the huge C-14 anomaly which indicates a large increase in cosmic rays or some other form of event that exposed the earth to a serious increase in highly energetic radiation. At the Southeast Paleoindian Conference at the University of South Carolina Firestone initially suggested that the purported cometary impact could account for this, but when we questioned him about that, could not offer any convincing mechanism.

Crispin in Waterloo says:
September 20, 2012 at 12:45 pm
…………..
Some 25,000 years ago the Laurentide ice sheet had a thickness of several kilometers, the vast majority of the ice eventually melted at the end of the Ice Age. Impact did not leave any debris, so if it did happen it would be at the end of the last (or possibly an earlier) Ice Age, perhaps with the ice thickness up to several tens of meters.

Nerd

Disputin says:
September 20, 2012 at 1:49 pm
My question with the Younger Dryas is: yes, I can see how a cometary impact might have caused a sudden plummeting of temperature, but what caused the equally rapid warming at the end of it?
====
Plasma event? – http://www.robertschoch.com/plasma.html – I thought that was interesting.
It reminded me of that moving Knowing…

Brian Adams

Golly, real science based on physical evidence, not computer models, and a publicized protocol which can be replicated, not “proprietary” raw, and “corrected”, datasets which are off limits to skeptical scientists.

Chuck Forward

Rgbatduke,
You have not taken into account the energy component of velocity and explosive content of the comet storm, especially with an oblique hit. From the evidence so far, a fair portion of the North American glacial cap was shattered and flung south. That a lot a mass to be on the move and when the non-vaporized chunks came back down, their MV=MV would have far greater influence than the comet itself. Evidence also points to vast fresh water lakes below the glacial cap draining south, not northward which also changed the mass distribution on the earth’s surface. While the mass of the earth is great, it is rotating in a vacuum and only the gravitational influences of the Sun and planets keep it rotating around the sun. The polar point currently walks and wobbles just by tidal changes caused by such distance gravitational influences so just think what a quarter of the northern icecap being hurtled south could do.
Evidence for affecting the pole position can be seen by taking a look at the glacial distribution of the last ice age (Wikipedia map of ice age) and draw a circle around the glacial extent. The center is located in northern Greenland. The Bering Strait, eastern Siberia and Alaska would have been 800 miles further south thus able to support the mega-fauna at the height of the last glacial age where they couldn’t exist today at the height of the interglacial period. Now draw a map of the today’s snow extent and its center is at the current pole. One can also make the argument that the Bering Strait had not been punched through until that hit and the Arctic Ocean had no flow thru component of cold water from the pacific until the last 12,900 years. Had the giant tsunami that accompanied the impact not punch a path through, the Bering Strait might not exist today and the Arctic Ocean would be a closed body of water with a circulation pattern using only the warmer Atlantic waters. Those warmer waters would be causing greater snow accumulation and glacial buildup surrounding the arctic ocean. Glaciers build at altitude and flow downhill until they become self-supporting in height like Greenland. Could the last Glacial age actually be warmer than today? This brings up the question whether the polar weather patterns are now changed enough to prevent a glacial buildup like before with less oceanic moisture present at the pole.
What caused the long recovery time after the hit is open to speculation but my take is a portion of the atmosphere got ripped away by the impact as majority of the comet fragments would be airbursts. At the edges of the conflagration would have experience flash freezing and hurricane winds. The loss of atmospheric pressure produced adiabatic cooling across the globe. This coupled with a polar wobble would have extended the polar zones. This also reduced the insulating blanket of the atmosphere so it took another thousand years for the ocean to outgas enough to build it back up as the polar wobble settled down. What affect the lower pressure and cooler temperatures had on plants and animals can be questioned. The worldwide biosphere would have been stressed and the larger fauna taking the bigger hit. The animals which lived at higher elevations prior would have greater chance of surviving afterward.
The Clovis were totally destroyed and only a small band of Siberia mammoth hunters were on this side of the Bering strait before it got punched through. It is they that eventually repopulated the Americas (all American Indians DNA can be traced back to seven women IIRC).
Chuck Forward

Crispin in Waterloo

@Duster
“There are no proposed “black spehules of terrestrial origin.” The argument by Firestone is that the “impact” was actually an aerial blast. The spherules are presumed to be part of the object that blew up, if such a thing happened”
No, the spherules are said to terrestrial in origin. The melting of the surface and the blast of hot gases that made the ground flow which produced them is explained in detail at the reference I gave above, suggested by TallBloke. It is quite long. The object(s) that struck the earth are presumed to have evaporated, there being no classical impact site evident. There was plenty of melting on surface materials as the temperature of the heat blast was about 100,000 degrees C. The landing of a train of objects is thought to be needed to create a continent-wide catastrophe as a second object plunges into the fire trail of the first. He also suggests that the Laurentian Ice Sheet may have been catastrophically melted. There is in the central-northern US evidence of a series of glacial lake discharges of huge proportion that were from that sheet’s melting which does not exactly line up with the idea; also the explosive destruction of the Laurentian Ice Sheet followed by melting does not exactly fit with the idea of an impact followed by a huge cooling event. The impact, yes, the LIS melt, maybe not. I think the LIS breakup was long before.
There is a lot of mammoth evidence that their deaths were very rapid, chilling and species-complete. I also heard once that they are all facing in the same direction (i.e. away from something). Other of course blame mankind for killing them all, in spite of the evidence. The 3m tall deer in Ireland also disappeared at this time.

Would a tsunami have resulted? The sea-level being 120 or so meters lower would cover the effects, I suppose, but shelf coring projects could have covered the interval …
Hmmm. Somewhere in the 12,500 YBP area there were massive landslides and subsequent glacial dam collapses and a mega-flood from central Alberta down through Montana, Idaho and out through Washington State, leaving an erratic train of Cambrian blocks from the Tonquin Valley into Montana, dry waterfalls in Idaho and the scablands of Washington.
Okay, lots of things happen all the time. But a couple of catastrophic events seem to be lining up … somewhat.

Ben

Interesting…
Does reading research from Goodyear and Firestone make you Tired?
Is it a good thing or a bad thing if the Goodyear and Firestone data is Inflated?
Hopefully with this new research direction, Goodyear and Firestone will Tread carefully.

Steve Tabor

There was global warming at the time, fed by released methane. It’s well-known that methane gas forms spherules by induction.
Induction of what? Don’t ask.

Chris Schoneveld

” Radiocarbon dates of the burnt plant remains yielded ages of 50,000 years, which suggested man was in South Carolina long before the last ice age.”
Very strange! We are living at present in an iceage which started some 500,000 years ago. Even if the ice age term is confused with the term glacial period, this sentence makes no sense since the last glacial period lasted from 110,000 years ago to some 12,000 years ago. This glacial is called in Europe the Wurm, in North America the Wisconsin. So 50,000 years ago was right in the middle of a glacial period.

MarkW

Chuck,
By what mechanism would an air burst rip off a huge chunk of the atmosphere. And no, the shock wave would not be big enough to do it.
Secondly, if such a big chunk of the atmosphere did get ripped off, how did the Earth manage to get that atmosphere back over the last 20K years?

Astounding the resolution and chronology attainable by careful sedimentology methods. The ‘umbrella’ effect described here is everywhere in the sedimentary record, and it would appear to apply no matter the source of the sedimentary particles!

Hmmm…
Considering that the YD impact hypothesis as stated in the PNAS paper “Evidence from central Mexico supporting the Younger Dryas extraterrestrial impact hypothesis” by Isabel Israde-Alcántara et al, (the most recent iteration of the YDIH) now uses the astronomical model provided by W.M Napier in Palaeolithic extinctions and the Taurid Complex, and which describes comets from the Taurid complex impacting as large clusters of small fragments, then maybe it’s time to consider the very real probability that we are not talking about a single bolide impact at all. But rather, a concentrated impact storm consisting of something like 10,000 Tunguska class airbursts in a matter of seconds.
Professor Napier points out that the breakup of comets is now recognized as a common route to their destruction. And when we look at images of fragmented comets like Comet Linear, or SW-3, we can see that he is probably correct.
The thing is, all of the available impact simulations we see are based on the assumption of one-at-a-time single bolide impacts. In spite of the fact that such common objects exist in elliptical orbits that cross all of the orbits of the inner solar system, no one to date has done any real science to consider what the impact of such a cluster would do.
But if a dense cluster like Linear that’s a few hundred miles wide of small air bursting comet fragments arrives within a few seconds of each other, then we get to find out what happens in an impact storm when only the first fragments on the leading edge are falling into cold atmosphere, and the rest fall into the already superheated atmosphere created by the impact plumes of those that lead the way. And they just crank up the heat, and pressure.
In other words we are talking about an extinction level catastrophic impact mechanism that’s different from anything that’s ever been studied before, and which leaves no crater.

vigilantfish

I wish I had something to add to this stimulating and educational discussion, other than to comment how it’s frankly quite freaky how often scientists’ last names or initials relate to their field of expertise. E.g. in my own area of study, Charles Fish, the fisheries scientist, or C.O’D. Iselin, the second director of the Woods Hole Oceanographic Institution. Let’s see: Goodyear, Firestone, vulcanized rubber — Vulcan, god of fire, exploding bolides…I get the impression of much heat production being involved in this aerial explosion. It’s a stretch.

Yoshi Sheva

” comet impact may have triggered the Younger Dryas period” Nope. Definitely not. It was the humans what done it.

JimF

vukcevic says:
September 20, 2012 at 11:28 am
Did you read that Wikipedia report on Nakapooska? Good geologists examined the area in detail and found no evidence of it having an impact origin. Therefore, there is no “lump of iron” sinking into the mantle. It is an odd geomorphic feature, but why don’t we stick with the facts?

JimF

In my previous, make “Nakapooska” read “Nastapoka”.

MarkW says: September 20, 2012 at 11:55 am
………………
Hi Mark
Sorry missed your comment, however the answer has to be: most definitely not, although overheated large meteorite or even asteroid, coming trough the atmosphere could be classified as a source of illumination. Possibly yes, in a case of primitive extraterrestrial technology, but iron would be less suitable than titanium and ceramics, as I believe are currently employed by contemporary space vehicles. Using spellchecker in such cases is no good, need also to check alternative meaning too, so one has to have sense of humor or desist from posting.

JimF says:
September 20, 2012 at 11:44 pm
vukcevic…Did you read that Wikipedia report on Nakapooska? Good geologists examined the area in detail and found no evidence of it having an impact origin. Therefore, there is no “lump of iron” sinking into the mantle. It is an odd geomorphic feature, but why don’t we stick with the facts?
Yes I have, but you obviously did not read what I wrote:
vukcevic says:
September 20, 2012 at 3:14 pm
Some 25,000 years ago the Laurentide ice sheet had a thickness of several kilometers, the vast majority of the ice eventually melted at the end of the Ice Age. Impact did not leave any debris, so if it did happen it would be at the end of the last (or possibly an earlier) Ice Age, perhaps with the ice thickness up to several tens of meters.
As our friend Steven Mosher often says: ‘go figure’.

AllanM

Ben says:
September 20, 2012 at 5:18 pm
Interesting…
This research is clearly funded by Big Rubber!

JimF says:
September 20, 2012 at 11:44 pm
Good geologists examined the area in detail and found no evidence of it having an impact origin.
…… in the Hudson Bay basin, iron formation, 100 feet thick or more, is the topmost member of a sedimentary series of unknown age.
The formation is thin-bedded. Some of the layers contain much magnetite and specularite, some are jaspery, and some consist of clastic material with considerable carbonate. http://gsabulletin.gsapubs.org/content/56/6/589.full.pdf

Adam Gallon

MarkW says:
September 20, 2012 at 11:53 am
Crispin:
Would a comet have much iridium?
george e smith says:
September 20, 2012 at 12:48 pm
So why a comet ? Is the core of a comet not simply a meteorite ? Presumably the ice coating would leave not a trace; the old tired worn out who dunit ice dagger murder mystery.
Comets are essentially “Dirty Snowballs”. Their Iridium content would be miniscule, so no signature like the K-T Boundary layer.
Comets & meteorites are different creatures, the former being largely made of ices, that latter of rocks and/or metals. Cometary bodies are less likely to retain their form when they enter the Earth’s atmosphere, so the “Airburst” ensues, as happened with the Tunguska Event. Little cratering is one outcome of this.
Comets aren’t just a meteorite covered in a layer of ice, a cosmic M&M!

klem

There are alot of scientist who still assign blame for the demise of mastodon, mammoth and saber-toothed tiger on human predation. I think they believe that humans are born sinners and are is some way responsible for everything bad, all they need to do is find the evidence to support that belief. Comet or meteor impact does not support it.