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
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?
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.
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. 😉
Reread the post. It is irrelevant to the impact theory the details of the black mat formation.
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.
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.
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.
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 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:
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
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:
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.
Steve,
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):
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,
You’re welcome; and good on you as well!
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.
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’.
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.