UPDATE 3/12/12 – a new study presents very strong evidence for the comet theory, see here
Bishop Hill alerts us to this news item in Miller-McCune, a policy and research website. It seems the scientific claims can’t be replicated by others…but wait for the kicker.
OK, having read that primer, it looks like a slam dunk for falsification, right?
Yet, the scientists who described the alleged impact in a hallowed U.S. scientific journal refuse to consider the criticsā evidence ā insisting they are correct, even though no one can replicate their work: the hallmark of credibility in the scientific world.
…
āWe are under a lot of duress,ā said Kennett. āIt has been quite painful.ā So much so, that team members call their criticsā work ābiased,ā ānonsenseā and āscrewed up.ā
…
āIt is very peculiar,ā Holliday said. āThey propose an idea, a study contradicts it, then they criticize the scientists or the work.ā
Hmm, where have we seen this sort of behavior before? Man o’ mann,Ā I wish I could remember where contradictory peer reviewed scientific replication was dismissed as ābiased,ā ānonsenseā and āscrewed up.ā.
But it reminds me of what might go on in scientific circles above Monks restaurant:
The news item in Miller-McCune is highly recommended reading
Anthony you missed the real kicker which is in the comments section to the article:
Being a wordy fellow the good Dr. Stieg needed a second comment to complete his statement:
Just keep saying it- until we believe it….
You hope…
“Not a lie, if you believe it”.
This reminds me…
Now I’ll give you something to believe. I’m just one hundred and one, five months and a day.’
‘I can’t believe that!’ said Alice.
‘Can’t you?’ the Queen said in a pitying tone. ‘Try again: draw a long breath, and shut your eyes.’
Alice laughed. ‘There’s no use trying,’ she said ‘one can’t believe impossible things.’
‘I daresay you haven’t had much practice,’ said the Queen. ‘When I was your age, I always did it for half-an-hour a day. Why, sometimes I’ve believed as many as six impossible things before breakfast”.
(5. Wool and Water, Through the Looking Glass, by Lewis Carroll)
An open and Clovis case if you ask me.
The truly sad thing is, the incompetence in science is so widespread that you can’t trust the academics on either side of this debate. They all assume too much (that is in fact wrong), so points and counterpoints are just so much rank speculation.
I always like to to a Google time line for some of the subject you bring up even though one must “consider the source”. so I did a Google timeline for Cycle of Cosmic Catastrophes: and I attempt to post the link . .
http://www.google.com/search?q=Cycle+of+Cosmic+Catastrophes&hl=en&sa=X&tbs=tl:1,tl_num:80&prmd=ivns&ei=TMnSTaeVO8mgtgeazbiUCg&ved=0CGoQywEoBA&biw=1004&bih=594
I actually, would say (postulate) that if a big asteroid ever hit earth it . . . . would have gone “in” where the Dead Sea is and come out where the Yellow Stone is . . . like a giant gun shot wound . . . but, that would simply be a guess with no real evidence to prove it except my wondering mind about things like this . . . . hoping of course it would make a logical possiblity . . . .
Long, long, long ago . . . no one would ever have thought (or believed) a rock could burn . . . but we now know it is called coal . . .
The alarmists do have their heads on a swivel, don’t they:
I’d say everyone who likes to see good science should be appalled at this, not just CAGW skeptics. Of course, maybe the alarmists just see it as “business as usual.”
An interesting quote from the article: “Kennett seems fixated on the Younger Dryas, Broecker added, āHe wonāt listen to anyone. Itās almost like a religion to him.ā”
Like a religion…hmmmm.
Also interesting:
“āIt does feed distrust in science,ā says Wallace Broecker, a geochemist at Columbia University and an international dean of climate research. āThose who donāt believe in human-produced global warming grab onto it.ā”
Does that mean that only GW skeptics distrust dishonest science? Thanks for the compliment!
“Man oā mann, I wish I could remember where contradictory peer reviewed scientific replication was dismissed as ābiased,ā ānonsenseā and āscrewed up.ā.
But Anthony, your peer-reviewed scientific replication surfacestations work didn’t contradict the extant instrumental temperature records, it affirmed them!
I really don’t think you need to worry about it being the subject of accusations from the consensus such as ābiased,ā ānonsenseā and āscrewed up.ā If anything, many think its publication demonstrates remarkable integrity since this affirmative replication completely undermines what you have always contended it would show. Well played, sir, well played! Bravo.
> The news item in Miller-McCune is highly recommended reading
Indeed ! Did you see the comment by Eric Steig (or someone using that name):
I think I converted the HTML errors into something close to what Steig intended, they were badly messed up by human and silicon hands.
The story and substories are amazing – on many levels.
Queen:”I daresay you havenāt had much practice,ā said the Queen. āWhen I was your age, I always did it for half-an-hour a day. Why, sometimes Iāve believed as many as six impossible things before breakfastā.
Douglas Adams: “If you’ve done six impossible things today, why not round it out with breakfast at Milliways: The Restaurant at the End of the Universe”.
The curious(er and curiouser) thing comparing guys like Steig with H2G2 is that Adams took care to make his ludicrous ideas plausible – but these guys can’t seem to help making plausible ideas ludicrous.
Hey Laurie! Sorry to pick nits…
“Long, long, long ago . . . no one would ever have thought (or believed) a rock could burn . . . but we now know it is called coal . . .”
Coal is not a rock and it is not a mineral, it is organic. I know Wiki will call it a rock, but consider the source. In geologic terms, a rock is a aggregate of minerals.
I remember listening to Arthur Meyerhoff explain why continental drift was impossible. Immanuel Velikovsky was a crank, but he noticed important things that others ignored.
“Stones do not fall from the sky.”
Let science work its way without personalities getting involved.
In Greenland ice cores, 10-Be levels rise again during the Younger Dryas to almost the same concentrations as during the Ice Age and then fall to current low levels when the Younger Dryas ended. So how did cosmic rays know about the Younger Dryas? Just coincidence?
boballab says:
May 17, 2011 at 11:54 am
Anthony you missed the real kicker which is in the comments section to the article:
Eric Steig 2 days ago
Having been the victim of attacks on my character, as a consequence of publishing something that appears to go against the grain (though in my case it has turned out to be correct: OāDonnellgate),……..
===================================================
lol, oh my, reality is so hard for some people to deal with.
Hey Gator! “Sorry to pick nitsā¦”
āLong, long, long ago there were no such things as minerals, just earth, fire, air, and water . . . I think that how that goes. . . .
Didn’t the Clovis ‘disappear’ before ‘the comet’ which then began the Younger Dryas?
There is a concrete takeaway from this, and it is quite important. To come to a reasonable conclusion based on observations of a reasonable methodology, and then to be (apparently) refuted in a later study is NOT malfeasance. It’s science.
Everything on top of that, advocacy, personal attack, public dismemberment.. That’s malfeasance.
even though no one can replicate their work: the hallmark of credibility in the scientific world.’ expect it would seem climate science where saying trust me on this, seems to be enough.
Are you a liar?
How many planets are there?
If you say eight, you are hip to the new consensus.
If you say nine, you are either uninformed or love Disney characters more than scientific orthodoxy.
But what did you say 20 years ago? You probably said nine. Does that make you a liar?
Interesting topic. But one thing has always bothered me about this whole ‘Clovis disappearance’ concept.
They link the disappearance of the Clovis people with the disappearance of the “mammoths they fed on” as written here. That is the first problem. Mammoths were only ONE of their prey. (And mammoths survived on places like Wrangell Island
much later UNTIL human hunters got there.)
But ‘Clovis people’ are identified by their giant spearpoints. So whether those people actually disappeared or they just changed to different spearpoints (for increasingly smaller prey after the megafauna were mostly gone) is another whole question.
No doubt this was a period of great ecological change, driven by both climate and human activity. Much too complex for a simple ‘Lone Comet’ theory.
I started reading the article to try and find what the evidence was that hadn’t been replicated. The author didn’t get around to that tidbit until well over halfway through the article. I barely made it that far. I haven’t seen so much invective and so little science since the last time I read a post at Real Climate.
Mods : I did attempt to post this in Tips and Notes (honest) but it appears to be full.
Experimental evidence appears to support the mechanism for Svensmark’s GCR theory…..
http://science.au.dk/en/news-and-events/news-article/artikel/forskere-fra-au-og-dtu-viser-at-partikler-fra-rummet-skaber-skydaekke/
Hoser says:
May 17, 2011 at 1:39 pm
So how did cosmic rays know about the Younger Dryas? Just coincidence?
Isn’t it so that in colder times less snow is falling, increasing the relative amount of 10Be in the ice?
Interesting that Eric Steig pops up as a commenter, claiming to have also been a victim of character assassination for publishing something going “against the grain”, and offering support for the comet theory.
The parallels are just too obvious – the intransigence in the face of overwhelming refutation, the claim to victimhood, the re writing of history. But for Steig to claim he was publishing something “that appears to go against the grain” is just silly. The whole reason he got the attention he did, and so obviously craved, was that his work went very much WITH the grain, adding yet another continent to the global warming cause.
rustneversleeps said @ May 17, 2011 at 12:53 pm
“But Anthony, your peer-reviewed scientific replication surfacestations work didnāt contradict the extant instrumental temperature records, it affirmed them!”
So you are saying that instead of accepting what the data said, Anthony should have been a Real Climatologist and fudged the data? Wierd…
Apparently, Eric Steig thinks that another published paper questioning his work is a form of character assassination?
Is that even Eric? It’s hard to believe someone as smart as he is doesn’t know when to quit digging the hole he’s stuck in.
Don’t have time to read all the posts, gotta code review in a few, so just a quick comment that might be repeats of what others have written.
The disappearance of the Clovis Culture might just be an artifact of the data that has been preserved in the scant material that has survived. A lot of evidence sujest that the Clovis people just changed and moved on to bigger and better things..
As for the mega-fauna extinction, a highly advanced predators specifically designed to hunt mega-fauna appeared in North America. Everyone seems to forget this fact. I guess because it is contra-narrative. I am not talking about the Clovis people. The predator I am referring to is one of my old world cousins, ol’ C. lupus.
Buffoon says:
May 17, 2011 at 2:02 pm “There is a concrete takeaway from this, and it is quite important.”
The take away . . . was a massive worldwide regressive tax . . . an artificially high price of energy . . . . and artificially low supply of energy for the majority. . . and a massive money laundering program . . . through cap n trade . . . coupled with no apportionment and a very low profit tax rate . . . for the minority.
All based on bogus Science that resulted in claims that amounted to “there is just not enough to share without destroying us all!” (in my opinion)!
@Laurie, it depends on your tradition. In the indigenous Tibetan religion of Bon, those 4 “essentials” surround a 5th known as space.
Jeremy said: “Is that even Eric [Steig]? Itās hard to believe someone as smart as he is doesnāt know when to quit digging the hole heās stuck in.”
No, it sounds very much like him. That has been his attitude from the outset. Pretty pathetic.
Ferdinand Engelbeen says:
May 17, 2011 at 2:24 pm
Isnāt it so that in colder times less snow is falling, increasing the relative amount of 10Be in the ice?
______________________
Yes, except that it is so much more 10-Be that I doubt both the role of the sun and less snow. It makes me wonder about the GCR flux at the heliosphere. We do know that the GCRs are anisotropic and variable. I’m not sure we know just how variable GCRs can be and what controls that. Perhaps the galactic magnetic field.
DesertYote says:
May 17, 2011 at 2:47 pm
“As for the mega-fauna extinction, a highly advanced predators specifically designed to hunt mega-fauna appeared in North America. Everyone seems to forget this fact. I guess because it is contra-narrative. I am not talking about the Clovis people. The predator I am referring to is one of my old world cousins, olā C. lupus.”
Well, since the first people in North America, like all the hunter-gatherers in Eurasia, had tame wolves (dogs), imagine the combined effect. Then add fire. This combination seems to be almost always overlooked.
Gator says: “Coal is not a rock and it is not a mineral, it is organic. I know Wiki will call it a rock, but consider the source. In geologic terms, a rock is a aggregate of minerals.”
Wiki is not a synonym for Wankapedia, Gator.
Eric Anderson says: “No, it sounds very much like [Steig]. That has been his attitude from the outset. Pretty pathetic.”
From what I recall, Dr. Steig was fairly approachable early on, but became less so as he adopted an increasingly defensive attitude.
Peter Wilson says: “…But for Steig to claim he was publishing something āthat appears to go against the grainā is just silly. The whole reason he got the attention he did, and so obviously craved, was that his work went very much WITH the grain, adding yet another continent to the global warming cause.”
Not just another continent. According to climate models (and possibly correctly), in global warming, the polar areas would have the greatest warming. If Steig had successfully teased a significant warming signal out of Antarctic data, instead of merely smearing West Antarctica temperatures all around the pole, it would have been a major accomplishment. Unfortunately for him, “It is hard to make data where none exist.” (–K. Trenberth) Steig’s failure was just slightly less important than the collapse of Mann’s hockey stick. Note that iirc Steig never claimed huge amounts of warming in the Antarctic, just that there was a positive trend.
Yes, jorge. His pet theory got slaughtered and he lept to its defense with a flurry of of his own character assassinations.
Pathetic.
Mark
Ya know… every time this Younger Dryas impactor and the “lack of evidence” issue comes up, I think of the Cape York meteorite(s) and the Willamette Meteorite.
Interesting estimated dates.
http://en.wikipedia.org/wiki/Willamette_Meteorite
http://en.wikipedia.org/wiki/Cape_York_meteorite
But… a comet is not an asteroid, or meteor… unless you strip out all the volatiles.
“It seemed like such an elegant answer to an age-old mystery: the disappearance of what are arguably North Americaās first people. ”
It wasn’t elegant at all. It was completely ridiculous. A comet large enough to have killed animals over thousands of miles and changed the climate for centuries would have left a huge mark even if it did strike glaciers. In geological time, that 13,000 years is nothing. I have seen the guy claiming to have found iron filing all over North America and saying that was proof of a great impact. They normally look for shocked quartz or iridium and not iron filings so I thought the guy was nuts. I have even heard of them looking for microscopic diamonds. It sounds like it was probably West that I heard and I didn’t believe a word of it. It was a loony theory to be that recent without an impact site.
At some point, the Clovis culture developed the atlatl and the bow and arrow. These technological developments produced a much less risky hunting strategy than surrounding a large mega-animal and killing it with 6 foot long hand-held spears. The Colvis points naturally dissappeared as the technology spread across the US (and I would imagine this would have spread fairly rapidly once the benefits became apparent).
The Mega-Fauna went extinct when the climate changed and the large grassland/tundra environment dissappeared. The Mammoth ate grass. Because CO2 levels were so low during the ice ages, C4 grasses could out-compete all other types of vegetation and the non-glaciated parts of North America and Asia and Europe were a grass-herbivore paradise. When the ice melted and the CO2 outgassed from the Oceans and the rainfall increased, the trees and bushes grew back and the slow fertility/reproduction rate of the Mega-Fauna spelled their demise. There wasn’t enough people around at the time to kill off that many Mammoths and giant Buffalo and giant Elk. We took a few naturally but climate change did the majority of the work.
No impact events or climate scientists are required for this explanation.
Al Gored says:
May 17, 2011 at 4:03 pm
Well, since the first people in North America, like all the hunter-gatherers in Eurasia, had tame wolves (dogs), imagine the combined effect. Then add fire. This combination seems to be almost always overlooked.
###
It seems like everyone overlooks the North American Indian dogs, sad š
Was Michael Mann a co-author of the paper?
In reply to:
“Hoser says:
May 17, 2011 at 1:39 pm
In Greenland ice cores, 10-Be levels rise again during the Younger Dryas to almost the same concentrations as during the Ice Age and then fall to current low levels when the Younger Dryas ended. So how did cosmic rays know about the Younger Dryas? Just coincidence?”
There is a geomagnetic excursion that coincides with the Younger Dryas abrupt cooling. During a geomagnetic excursion the geomagnetic field intensity drops by a factor of roughly 3 to 5 and the non-diopole component of the field becomes stronger. It is a reduction of the geomagnetic field intensity and abrupt change in the geomagnetic field intensity that causes the increase in GCR to strike the earth. It is the increase in GCR that caused the Younger Dryas abrupt cooling. 80% of the cooling occurred within 10 years. The cooling period lasted for almost 1500 years.
The geomagnetic field excursions are cyclic. The sun is causing the geomagnetic field excursions when the solar cycle restarts after the geomagnetic cycle is restarted.
The burn marks throughout the Northern Hemisphere that all coincide is observational evidence of the mechanism. There are other burn marks on the earth’s surface that have been dated to later period. Those burn marks are elliptical in shape with orientation along a North west axis and with evidence of restrike. (One burn mark on top of another.)
Carolina Bays. The Carolina Bays are a group of Ā»500,000 highly elliptical and often overlapping depressions scattered throughout the Atlantic Coastal Plain from New Jersey to Alabama (see SI Fig. 7). They range from ā50 m to ā10 km in length (10) and are up to ā15 m deep with their parallel long axes oriented predominately to the northwest. The Bays have poorly stratified, sandy, elevated rims (up to 7 m) that often are higher to the southeast. All of the Bay rims examined were found to have, throughout their entire 1.5- to 5-m sandy rims, a typical assemblage of YDB markers (magnetic grains, magnetic microspherules, Ir, charcoal, soot, glass-like carbon, nanodiamonds, carbon spherules, and fullerenes with 3He). ā¦
http://www.pnas.org/content/104/41/16016/suppl/DC1#F7
http://adsabs.harvard.edu/abs/2004E%26PSL.219..377T
Geomagnetic moment variation and paleomagnetic excursions since 400 kyr BP: a stacked record from sedimentary sequences of the Portuguese margin
A paleomagnetic study was performed in clayey-carbonate sedimentary sequences deposited during the last 400 kyr on the Portuguese margin (Northeast Atlantic Ocean). Declination and inclination of the stable remanent magnetization present recurrent deviations from the mean geomagnetic field direction. The normalized intensity documents a series of relative paleointensity (RPI) lows recognized in other reference records. Three directional anomalies occurring during RPI lows chronologically correspond to the Laschamp excursion (42 kyr BP),the Blake event (115-122 kyr BP) and the Icelandic basin excursion (190 kyr BP). A fourth directional anomaly recorded at 290 kyr BP during another RPI low defines the āPortuguese margin excursionā. Four non-excursional RPI lows are recorded at the ages of the Jamaica/Pringle falls,Mamaku,Calabrian Ridge 1,and Levantine excursions. The RPI record is characterized by a periodicity of V100 kyr,paleointensity lows often coinciding with the end of interglacial stages. This record sets the basis of the construction of an authigenic 10Be/9Be record from the same sedimentary sequences [Carcaillet et al.,this issue].
The geomagnetic moment loss (30%) over the last two millennia deduced from archeomagnetic results (e.g. [38,39]) might foreshadow the next excursion for the end of our present interglacial, even though this loss started 2200 years ago from an exceptionally high geomagnetic moment value.
Spectral analyses of the RPI record reveal a dominant periodicity at 100 kyr,already reported by other studies (e.g. [41,59,60]). The RPI and Fig. 13. Power spectra computed with the Analyseries program [62] using the Blackman^Tukey (BT) (confidence intervalat 95% vP/P is comprised between 0.64 and 1.78) and the maximum entropy method (MEM). (a) N18O. (b) RPI. (c) Inclination. (d) Power spectra (thick line) and 95% confidence intervals obtained using the Multitaper method. (e) Cross-coherence and (f) phase diagram of N18O and RPI. The thick horizontal line is the 95% confidence limit for zero coherence; the circle indicates the lag (V68ā”=18 kyr) between RPI and N18O for the 100 kyr period. 18O records also present a phase shift of 18 kyr: RPI lows often coincide with the end of interglacial or interstadial stages.
Want some cheese with that whine, Eric? What a puke! As a geologist, I want to see his credentials revoked.
To whomever was going on about 8 or 9 planets – that’s just a matter of definition, not some horrendous lie or terrible error. I’m perfectly happy for Pluto to be a planet, but if you don’t think it is, well, I’m ok with that, too. It’s arguable (preferably over cigars and a couple bottles of good bordeaux).
This is a link to a paper that discusses the Younger Dryas black mats that are located at 97 locations throughout the Northern Hemisphere in Europe, Asia, Canada, and the US.
The Younger Dryas is a cyclic cooling event. The paleoclimatic record shows evidence of warming followed by abrupt cooling.
http://www.pnas.org/content/105/18/6520.short
Younger Dryas āāblack matsāā and the Rancholabrean termination in North America
Of the 97 geoarchaeological sites of this study that bridge the Pleistocene-Holocene transition (last deglaciation), approximately two thirds have a black organic-rich layer or āāblack matāā in the form of mollic paleosols, aquolls, diatomites, or algal mats with radiocarbon ages suggesting they are stratigraphic manifestations
of the Younger Dryas cooling episode 10,900 B.P. to 9,800 B.P. (radiocarbon years). This layer or mat covers the Clovis-age landscape or surface on which the last remnants of the terminal Pleistocene megafauna are recorded. Stratigraphically and chronologically the extinction appears to have been catastrophic, seemingly too sudden and extensive for either human predation or climate change to have been the primary cause. This sudden Rancholabrean termination at 10,900 _ 50 B.P. appears to have coincided with the sudden climatic switch from AllerĆød warming to Younger Dryas cooling.
Nothing in the Quaternary stratigraphic record is more impressive than the abruptness of megafaunal extinction near the end of the Pleistocene. If all remaining elements of Rancholabrean megafauna, other than bison, terminated at the end of the AllerĆød chronozone, as indicated stratigraphically by the Z2 contact, the exact time of the catastrophic event is not resolvable within 100 years by radiocarbon dating, although this will improve significantly with tree-ring calibration (4). Grayson and Meltzer (43, 44) argue that Pleistocene extinction was gradual with some elements dying out long before others. This may indeed be true for a number of taxa but for many forms there are still inadequate geochronological data to accurately determine the exact age of their extinction. The fact remains that the existence of mammoths, mastodons, horses, camels, dire wolves, American lions, short-faced bears, sloths, and tapirs terminated abruptly at the AllerĆød-Younger Dryas boundary.
Of the 97 geoarchaeological sites of this study that bridge the Pleistocene-Holocene transition (last deglaciation), approximately two thirds have a black organic-rich layer or āāblack matāā in the form of mollic paleosols, aquolls, diatomites, or algal mats with radiocarbon ages suggesting they are stratigraphic manifestations
of the Younger Dryas cooling episode 10,900 B.P. to 9,800 B.P. (radiocarbon years). This layer or mat covers the Clovis-age landscape or surface on which the last remnants of the terminal Pleistocene megafauna are recorded. Stratigraphically and chronologically the extinction appears to have been catastrophic, seemingly too sudden and extensive for either human predation or climate change to have been the primary cause. This sudden Rancholabrean termination at 10,900 _ 50 B.P. appears to have coincided with the sudden climatic switch from AllerĆød warming to Younger Dryas cooling.
http://cio.eldoc.ub.rug.nl/FILES/root/2000/QuatIntRenssen/2000QuatIntRenssen.pdf
Younger Dryas Abrupt Cooling Event
ā¦we argue that this is indeed supported by three observations: (1) the abrupt and strong increase in residual 14C at the start of the Younger Dryas that seems to be too sharp to be caused by ocean circulation changes alone, (2) the Younger Dryas being part of an approx. 2500 year quasi-cycle also found in the 14C record that is supposedly of solar origin, (3) the registration of the Younger Dryas in geological records in the tropics and the mid-latitudes of the Southern Hemisphere.
The Younger Dryas (YD, 12.9}11.6 ka cal BP, Alley et al., 1993) was a cold event that interrupted the general warming trend during the last deglaciation. The YD was not unique, as it represents the last of a number of events during the Late Pleistocene, all characterised by rapid and intensive cooling in the North Atlantic region (e.g., Bond et al., 1993; Anderson, 1997).
Moreover, the YD seems to be part of a millennial-scale cycle of cool climatic events that extends into the Holocene (Denton and KarleHn, 1973; Harvey, 1980; Magny and Ru!aldi, 1995; O’Brien et al., 1995; Bond et al., 1997). Based on analysis of the 14C record from tree rings, Stuiver and Braziunas (1993) suggested that solar variability could be an important factor affecting climate variations during the Holocene (see also Magny, 1993, 1995a),
Some hard coals contain more than 95% carbon and would be classified as mineral like diamond and graphite
The dire wolf coexisted with the megafauna for a million years, as did the ice ages. But within very few millennia of the arrival of humans most of the big species disappeared, one after another. With such easy prey human populations would have expanded rapidly, to the point that prey quickly went extinct. All it takes is a hunting strategy which is less lethal than the birthrate. Even if it were more lethal, the hunters would to turn to other game, and come back later, even centuries later, for the more dangerous ones.
The giant, giraffe like camels probably ate what other camelids ate–everything. Camelids thrived wherever they went, South America, Asia, Africa, and finally Australia (they evolved in North America). Everywhere but the American South West, where they were reintroduced in numbers too few to aggregate. Climate was not their nemesis, except for the bridges climate made for two legged predators.
And how likely was it that the bow and agriculture evolved independently in the New World? We know the Da Ne people were later arrivals. All these coincidences are about as likely as a comet or asteroid wiping out the Clovis hunters. Pacific islanders that made it to Hawaii and Easter Island must have arrived in America far earlier, with all their technology–not early enough to introduce the bow, but possibly agriculture.
And everywhere humans went the native species disappeared in mass. Dodos, elephant birds, marsupial sabretoothes, thylacines (eventually). The native American species were as doomed as were the Native Americans themselves when Columbus arrived. Any Polynesians making it across the Pacific would have had to contend with the native syphilis.
Enough of that, but if you want to talk about a real unscientific but universally held fallacy, talk about the dawk hawk stoop. –AGF
Bill Illis says:
May 17, 2011 at 6:53 pm
“At some point, the Clovis culture developed the atlatl and the bow and arrow. These technological developments produced a much less risky hunting strategy than surrounding a large mega-animal and killing it with 6 foot long hand-held spears.”
Bow and arrow is a very recent ivention, unknown in North America until about 5-6000 years ago when it first appeared in the Arctic. Not in southern North American until much later. Much too late for this discussion. But atlatls maybe.
“surrounding a large mega-animal and killing it with 6 foot long hand-held spears.”
As George Frison has demonstrated with fascimile Clovis spearpoints and spears on African elephants ( and indigenous people there demonstrated for eons) that is not how they usually killed them. Instead you throw the spear into their gut and wait, and patiently follow, until they are incapacitated or die. Could take days or even weeks. The reward was worth the wait. That’s how tiny Bushmen could kill huge elephants with little arrows, safely.
There was no concern for a quick ‘sportsmanlike’ kill. That’s modern thought. And those artist’s renditions of people swarming around mammoths are just that, artist’s renditions done for effect.
We’ve done this before, for people who are interested. http://wattsupwiththat.com/2010/09/30/no-evidence-for-clovis-comet-catastrophe-archaeologists-say/
I donāt know why it has to be a (1) comet/asteroid, period. What about a shower of smaller fragments? Over a period of a year or two. That also contain high concentrations of 10-be.
A cometary impact wouldn’t necessarily leave an impact crater, it’d likely be an airburst, like the Tunguska Event. If it did occur over an icecap area, then the ground surface below the ice wouldn’t show any sign of it. So, that part of the theory can withstand scientific challenge.
This interesting link was posted here a while ago. Here is another post by the same reader.
$Billions wasted on harmless CO2, when the real threats are disregarded.
I increasingly feel that big chunks of science have gone bad. People claim all sorts of expertise – such as the ability to positively identify various nano-components in soil fragments – and in the end they can be just kidding themselves.
People claim they can take masses of data, corrupted in a variety of ill-defined ways, and process them to extract interesting information – climate change, and studying fluctuations in the background radiation, come to mind.
Cancer researchers are willing to turn a blind eye to the possibility that their cell cultures are corrupted, and they are not studying the right cells:
http://news.bbc.co.uk/1/hi/programmes/file_on_4/7098882.stm
(this program is 4 years ago, but it still seems to be an on-going problem)
Peter Woit’s book details the way in which string theory has taken over theoretical physics, even though it has produced nothing testable.
The problem is that once science becomes dishonest, it is damn near impossible to know where the rot ends. There are rumors of other big scandals in science. Once I would not have believed them for a moment, but after watching the climategate coverup, I can’t be sure any more.
Don’t know what’s going on here, but this work being criticised, or rather the authors, was to check on someone else’s previous theory of a comet impact which wiped out rather a lot of species in North America. None of the ‘rebuttals’ make any sense, such as saying the mammoths were hunted to extinction (how by such a small population and not seen with the buffaloes and the vast population of later N.Americans until they were deliberately exterminated with superior fire power, etc.), or by saying the Clovis morphed into something else as this doesn’t explain the disappearance of these many and varied species, and, are all involved in the study of ‘dubious’ backgrounds as if that in itself makes the findings invalid anyway. In other words, the arguments against are really weird.
Anyway, here for the “Younger Dryas Boundary Impact Abstracts” http://www.georgehoward.net/final/AGUabstracts.pdf
What we do know is that we were coming to a periodic sudden rise in temps after about 100,000 years of being stuck in our Ice Age, this came to an abrupt end when we suddenly reverted back into it and when this happened a huge variety of species that had occupied those northern freed of ice climes, which had begun settling into seasonal patterns, became extinct at the same time. Maybe it was Summer.
Not sure of the dating of the ‘comet’, from this analysis. Maybe there’s a confusion between the end of the Ice Age into our Interglacial and the ‘comet’? Some stuff they found seems to have been rebutted as coming from a later date, 1,000 years later, which seems about right possibly for a beginning interglacial interrupted and then resumed another 1,000 years later – taking us more to the beginning of Holocene proper around 2-3 thousand years ago?
P.S. – There would therefore have been two huge melts associated with that time period. There could have been a first’s impact on whatever had begun to re-colonise the northern hemisphere, as land got swallowed up in huge rises in sea levels, some 300 ft, at the same time land rebounding when the final ice wall holding back melt to its north broke (there are native stories about such a thing, but not datable to 1st or 2nd event), and a second without the massive build up of ice of the first’s.
Something dramatic happened during the second that was ‘unprecedented’ in that the species which had adapted to being around further North after the beginning of the interglacial, suddenly disappeared. And, s’far as I can gather, we only know of them from remains found before the second cycle.
Eventually enough evidence will be accumulated to answer this question, but it will take time. The paper at the top of this thread isn’t much evidence at all, either way. Some researchers want to keep pushing the “man caused it” meme at all costs.
The below site isn’t conclusive for an impact, either, but certainly interesting:
http://craterhunter.wordpress.com/notes-on-ignimbrite-emplacement/part-two/
I think I have misremembered the sequence. It may have been that the Younger Dryas stopped the full effect of the first melt, at the beginning of the interglacial, and it didn’t come into full force as melt and huge rises in sea levels, the 300′ plus, until the interglacial could catch up with itself after another thousand years of extended cold.
Around the islands of ‘Britain’, the first melt caused a separation between England and Ireland, by the formation of the Irish Sea, but not until the second did the ice wall holding back the melted ice in huge lakes finally give way, flooding South creating the North Sea and separating England from the Continent.
This also shows up in animal migrations between England and Ireland. As the interglacial arrived and the climate became better further north, animals from ‘the continent’ began arriving in Britain and moving over to Ireland, the first wave of this was stopped by the creation of the Irish Sea and some creatures never made it over, the snakes, moles.
Yeah, Smokey, I donāt pretend to know exactly what happened but throwing all the baby out with the bath water seems foolish at this point. So, there might not have been a huge fire but a rain of melting ice from exploding core stream Taurids complex.
Quote: The disintegration of this massive Taurid Complex progenitor over some tens of thousands of years would yield meteoroid swarms which could easily lead to brief, catastrophic episodes of multiple bombardment by sub-kilometer bolides, and it is tempting to see the event at ā¼ 12,900 BP as an instance of this. Whether it actually happened is a matter for Earth scientists, but from the astronomical point of view a meteoroid swarm is a much more probable event than a 4 km comet collision.
I suggest searching for Otto Mucks Secret of Atlantis at Google Books online and reading it.
Thanks. Some of you have provided some very interesting links & comments that makes the “certainty” that it wasn’t some type of extraterrestrial event, a definite uncertainty.
The origins issue of people in the Americas has a long history of politicking. The over-hunting of big game hypothesis is still the strongest, but it does not sit well with Native American activists and friendly environmentalists. It suggests, bluntly and ucomfortably, that the Amerindian was, like the rest of us, a mortal, greedy human after all, not the spiritually superior and environmentally super-aware “Avatar” caricature. The Clovis folk, like many human groups before them, chomped themselves into trouble because they couldn’t help themselves. The asteroid hypotheis, the weakest of all, hopes to aquit the Amerindian of sin, hence the emotional reaction to any challenge.
I tend to think that because all humans were and are, simply human, the Clovis culture adapted with ingenuity, brilliance and drive characteristic of all humans everywhere, ancient and modern, by rapidly adjusting their tool technology, thus seemingly “disappearing” from our perspective. Unfortunately, these qualities are not politically as admirable as the “being one with Nature” myth.
A G Foster says:
May 17, 2011 at 9:03 pm
###
The sudden appearance of the Grey Wolf in North America and a changing climate had as much to do with the mega fauna extinction as humans. The Dire wolf was an open planes hyper-carnivore. The Grey Wolf is a forest dwelling meso-carnivore, that also happened to have evolved specifically to hunt holarctic mega-fauna from wooded margins. Xiaoming Wang and Richard Tedford have written some papers on this. The anthropogenic mega-fauna extinction theory is very similar to the CAGW theory. Both are loved by greenies because the seem to show that man is evil, and they both rely on ignoring vast quantities of contrary evidence. Man most likely had a role, but that is defiantly not the whole story.
Desert Yote,
Evidently, the anthropogenic mega-fauna extinction theory serves the Greenies well in either arguing for humans as environmental huns, or as an example of a modern materialistic heresy which disses environmentally-friendly pristine peoples. However, it owes its origin in a good body of evidence and the emerging cultural materialism models of the 60s and 70s, which view humans as very focussed and extremely efficient in providing for themselves.
Oops, I think my brilliant riposte to Darren Parker’s Otto Muck recommendation was eaten by the site filters, never to be seen again on this plane of temporal existence, leaving humanity and posterity a little poorer for its disappearance. Sniff, sniff.
It would seem that with my listing a host of names of cockamanie pseudo-historical theories on origins of races and civilizations, many of them promoted by surviving acedemician relics of an evil, but unmentionable twentieth century regime, I inadvertantly overloaded the WUWT server.
@ Peter Kovachev
The Secret of Atlantis – Otto Muck
http://www.archive.org/details/TheSecretOfAtlantis-OttoMuck
I am assuming it’s legal if you get it at a library . . . .
no real scientist has his/her head on a swivel … they know what they have done is ture and replicatable … the truth shall set you free …
its only the con-men who need to watch out …
I don’t think this is all over yet, as there are more pieces out there to be put together.
And I am not upset with the process, as it appears to me that there is an echo of the scientific method taking place: Data gathered. Someone sees connections, runs experiments, gathers additional data and posits a theory. Loudness ensues (testing). Theory is either upheld, modified or discarded. I think we are still in the Loudness ensues stage of this one. Unlike the glowarmers, to the best of my knowledge, nobody has been hiding data with this one.
Re: William’s Carolina Bays. Thanks for the photo of the bays. From the air, they look a lot like the small lakes that dot the Alaskan North Slope, which are all aligned in the same direction. Expect the mechanism for creation differs a bit, but amazing similarity from the air. Cheers –
Laurie Bowen,
Not sure I know what you mean, although I think the book is available in electronic format for free downloads. Regarding any bans, I only guessed that the automated filter banned an earlier post of mine because it listed by name a whole bunch of unwanted cooky theories which were fleshed out in war-time Germany, with many of the involved academics going back to teaching after the war and influencing a new cadre of believers. The hobgoblins include the hollow earth, ancient astronauts, Atlantis, Shangri La and flying saucers. The extent of pseudoscientific “research” in the Third Reich was quite significant and its inevitable re-emergence explains the explosion of weird theories in the happier and wealthier post-war years.
On the other hand, maybe there are no magical filters on the blog and I blew away my own post accidentally when I tried html tags.
The Grey Wolf competed with the Dire Wolves for 100s of ky before the mega-fauna extinction.
I remember reading an article on the atlatl, a researcher in Africa had trained himself to use one for years and got the chance to use in on an ill elephant that was to be put down anyway. One cast, the spear went all the way in and killed the elephant immediately.
Interesting analysis trying to work out why the Irish Elk became extinct in the Younger Dryas – http://bill.srnr.arizona.edu/classes/182/Giraffe/IrishElkExtinction.pdf
Just before the Younger Dryas there was the warm Allerod period during which the Elk flourished, (beginning around 12,000 BP). It had a longer growing season than the following Younger Dryas, or today, and the strain from juggling between the lack of sufficient nutrients to grow the huge antlers required for successful mating and the need to reduce size overall to survive poorer foraging, it seems, did for them.
And they put the trigger to the Younger Dryas cold down to Milankovitch of reduced Sun (Berger, 1978, 1992).
Personally, I like this variant of the theory http://cometstorm.wordpress.com/
On one extreme we have the dodo, which was wiped out in historical times (16th century as I recall), and on the other, the above mentioned Irish elk, which disappeared in Ireland shortly before the arrival of humans, hence due to climate changes. (But the theory that large antlers did them in seems rather specious–it requires a climate change so rapid that there was no time for adaptation, and we know that large antlered British deer were wiped out in historical times by selective hunting=selective breeding for small antlers.) Slightly removed from the dodo, is the elephant bird, which seems to have disappeared soon after the arrival of the Maoris. All your ideologies of evil or beneficent humans couldn’t save the elephant bird, or dodo, or thylacine, from annihilation at the hands of hungry humans–this is all historical fact, and it is pointless to argue the extinction of Pleistocene megafauna on any such ideological basis. We know human hunters were the “real men” who would burn down a forest to make a breakfast fire and wipe out a species for lunch. And we know that humans hunted mammoths. We also know that humans arrived suddenly in North America, and that human populations are capable of very rapid growth. After all, the Caucasion population of North America required only 400 years to reach 300 million. We know that buffalo are faster than elephants, and probably were faster than mammoths. We know that a mammoth can feed more people than a buffalo. And it is likely that mammoths had no instictive fear of humans. We know that 20th century Australians, even when they knew the thylacines were in danger of extinction, wiped them out anyway. And we can be sure that ancient Americans had little idea what mammoth populations were doing on a continental scale, nor would have care when starving.
So one of the few questions is, were the newcomers more likely to have practiced birth control and established an easy equilibrium with their prey, or have babies as fast as they could feed their mothers on mammoth meat? In other words, what advantages might we postulate the mammoth held over the dodo and the elephant bird? The most important factor may well have been how fast the prey could run, and the mammoth was probably somewhere between the elephant bird and the buffalo.
It’s true of course that the dodo and elephant bird were island species, which had no natural predators to worry about. But in some respects North America is an island when compared to Eurasia, and the arrival of the human predator spelled the arrival of the most ferocious predator of all. The two legged predator is neither good nor evil when he hunts, and he certainly was not environmentally concious–that is a luxury of a well fed, industrialized agricultural society, sufficiently removed from “nature” that it begins to distinguish between nature and technology.
On top of the appeal for a human invader which controls its population in some other manner than war and disease (and disease was probably not a problem for the first Americans) and famine, the nonhuman extinction hypothesis requires that we abandon all probability and statistics. Dozens of species thrive for millions of years, and at the precise moment in geological history that humans arrive, they disappear. Funny thing, that natural climate, which goes through its ice ages for three million years, and as soon as humans arrive it kills off the megafauna.
If it required unprecedented climate to bring humans to America you might make a case, but we are fairly certain that the timing of human arrival was determined by their newly acquired technology rather than unprecedented ice ages. They made better clothes and weapons and boats and lived further north so that they were ready when the path opened up.
CAGW has absolutely nothing to do with who or what wiped out the megafauna. That’s like saying modern humans are not capable of harming the environment. I for one am a “naysayer” because I consider AGW to be a farce by any scientific measure, just like I consider the nearly universal claim of a duck hawk stoop of 200mph+ to be utterly absurd, no matter who makes it. Such artificial linking of theories and ideologies is as when liberals lump creationists and “deniers” together. Not at all a propos. –AGF
Anthony –
The anti-Y-D impact side has had access to the main stream news media, and the pro-side has not. Supporting papers now number about 20, though mention of them gets left out when Vance Holliday and a few scientists whose long-held paradigms are threatened go to press in the guise of “objective” science reporters.
I will list here links to some articles at CosmicTusk.com, some of which have direct links to papers which have found supporting evidence for there having been a major impact and ejecta and impactites, including Helium 3, nanodiamonds, carbon spherules, etc., including elevated Iridium levels – not to mention the “black mat”.
Some of the studies purporting to “prove” there was no Y-D impactor have, in themselves, been sloppy, including the previously posted about Daulton “proof” that the Firestone people did not know their butts from holes in the ground about nanodiamonds – claiming that Firestone’s pre-2004 compatriots who did the crystallography should have known that what they were looking at was graphene and graphane – which is amazing, since graphene wasn’t even in existence before 2004. Daulton’s findings have been controverted by other studies since then – but those papers didn’t make it past the science reporters.
Anthony, you have this backward – it is the ANTI-Younger-Dryas Impact people who are gaming the science news system, not the Firestone people, who are merely keeping their noses to the grindstone and finding out what they can. The Y-D people don’t pretend (like AGW warmists) that they know everything; they admit thaat this is a complicated scenario, and multi-discipline. They have had to shift gears, but the broad scope seems to still point toward something happening at the 12.9 kya point in time, something that DID include the black mat (extending into Belgium and Venezuela, as the evidence shows so far).
Also, it is not the pro-Y-D side that is calling names and ducking behind ivory towers.
The list of links I have:
“Black Mat: Third paper details Venezuelan occurrence” (April 28th, 2011) – with link to full papers
http://cosmictusk.com/black-mat-third-paper-details-venezuelan-occurrence
“Vindication: Critic finds Nanodiamonds in Younger Dryas Boundary Claeys [sic]” (December 21st, 2010) – with link to full paper
http://cosmictusk.com/vindication
“Geomorphology Of Possible Younger Dryas Boundary Impact Structure A Cosmic Impact and Distal Ejecta Manifold” (November 26th, 2010 ) – with link to full paper
http://cosmictusk.com/geomorphology-of-possible-younger-dryas-boundary-impact-structure-a-cosmic-impact-and-distal-ejecta-manifold
“Article: Chilled Diamonds Shine Light on Comet Collision” (Published on September 16, 2010) – with link to full paper
http://cosmictusk.com/permanent-link-to-chilled-diamonds-shine-light-on-comet-collision
“YDB press release: Scientists discover nanodiamonds in Greenland ice
Scientists discover nanodiamonds in Greenland ice” (September 8th, 2010 in Space & Earth / Earth Sciences)
http://cosmictusk.com/ydb-press-release-scientists-discover-nanodiamonds-in-greenland-ice
“Black Mat: Third paper details Venezuelan occurrence”
http://cosmictusk.com/black-mat-third-paper-details-venezuelan-occurrence
“Clovis Age Crater Found in Canada: That Makes Three”
http://cosmictusk.com/clovis-age-crater-found-in-canada-that-makes-three
“Video: Evidence of Clovis Black Mat located in Ontario”
http://cosmictusk.com/video-evidence-of-clovis-black-mat-located-in-ontario
Anthony – I am perplexed how you can be taking the side you are, on this controversial topic. You are being a stooge for the very kinds of scientists as Mann and Phil Jones and at RealClimate.
The real scientists are the ones who were at the Acapulco conference in 2007 that brought this to the attention of the world. None of them is saying we need to kill off industry and put the whole world under the boot heels of some Uber-alles-comet-defending bureaucracy. It is a complicated theory, and some evidence is coming out in favor, and some (biased) studies are coming out claiming to hammer the nails in the Y-D Impact’s coffin. The evidence is still coming in, and it will be years before anyone really knows what happened.
Anthony, by taking the side you are, you are wrong. This is science in progress, with both sides looking for evidence. But the entrernched side has the red phone to the science reporters and editors, and they are getting MSM attention, while the upstarts have nos such advantage in getting their story out. Assertions by the “real” scientists that the pro-Y-D people are ignoring evidence is all a bunch of spin doctoring.
Anthony –
My apologies. I think I misconstrued your POV on this. You weren’t taking the side of the Holliday people, but seeing a parallel to AGW. I don’t know how I read that wrong. Mea culpa.
There is a definite “scientific insider” semi-coordinated attack going on. A paradigm is threatened, and the attack dogs are out in full force – mainly by controlling the “public” dialogue through science editors they are in bed with. Notice how all the news items that make it to the public are submissive of the whole idea, as if the 17 or so scientists on the Firestone paper were . . . . drum roll, please. . . . skeptics.
REPLY: Yes a parallel – No worries – Anthony
@DesertYote May 17, 2011 at 2:47 pm:
I’ve been keeping close tabs on this for quite some time, but don’t consider myself to be an expert. But what I’ve read is that the black mat is a dividing line. Before that, there were megafauna and Clovis man in the Americas. After that, for about 1100 years there were humans, but at that point humans start showing up. The megafauna didn’t come back at all after (above) the black mat. The Y-D theorists argue that the black mat is due to heavy duty and nearly continent-wide fires.
The main thing we should be aware of first is that it is technically the Younger-Dryas Stadial – a cooling period in between warm periods (at the end of the Bolling-AllerĆød Interstadial). Its onset was extremely sudden; after the planet had been warming up for several thousand years, we went back into an ice age again – but one that was too short to bring on massive glaciation (though some did expand). For all intents and purposes it is nearly impossible to say that the Younger-Dryas was not the end of the Pleistocene or the beginning of the Holocene.
As with the dying off of the megafauna, no one has a clear idea what brought on the Y-D Stadial, but it happened in so short a time that 10 years is an accepted figure. This sudden drop in temps was 27F in Greenland. That makes the 0.8C since 1900 a real piker. But the 10 years is only a best guess.
That all these things coincided – the great dying off of the NA megafauna, the disappearance of Clovis man, the black mat, the double-digit temperature drop – leaves it all wide open to interpretation.
Note the the “Clovis man kill-off” was only an idea, not proven science. How a few thousand spear-throwing guys could wipe out extremely large animals on a continent of 8 million square miles – that one is far less plausible than that a comet or meteor came and did them all in. But the kill-off also doesn’t explain why the black mat just happened to be right where the die-off was, and it doesn’t explain why the animals who had lived through ice ages before all of a sudden were taken out. Clovis man was all circumstantial evidence. Consider that NA and Africa are somewhat the same size – but all the millions of hunters in Africa couldn’t take out all the animals there. So how did a few thousand do it in NA? It didn’t happen. It was a silly specious hypothesis, and only got traction because no one had a better one. Now there is competition, and the Overkill theorists are defending their turf.
Ah, you may say, but all of the evidence about the comet is also circumstantial. Yes. And so is the 65 Mya dinosaur killer. And so is all of the evidence about Australopithecus and homo erectus (you could put all the pre-sapiens fossils recovered in all of history into one small room), so a lot of extrapolating is going on, no matter what the theory is. And so was the “Clovis man did it” theory.
@Adam Gallon May 18, 2011 at 12:31 am:
Good points, Adam.
The thing is, a little over 100 years ago, rocks didn’t fall from the sky. 40 years ago, Barringer Crater was not accepted as a meteor crater. Gene Shoemaker changed that last bit. 10 years ago, there was no consensus on what the Tunguska event was. It seemed certain to the people 100 years ago that it must have been a meteor – after all, rocks DO come out of the sky; that is what science had by then accepted. But only rocks. Not comets. They just fly by. Right now, we are in the infancy of studying what has hit the Earth.
Right now, they accept that Tunguska was a comet, but since it exploded in the atmosphere, they only accept that – and no more:
Let’s face it, they don’t accept anything until it happens. That comes from Uniformitarianism and Gradualism:
And until it DOES happen in the present, they simply won’t accept it as real. In 1994, when Shoemaker-Levy/9 hit multiple times on Jupiter, the geologists and astronomers were proven wrong – comets DO hit planets. But they couldn’t bring themselves to admit comets DO hit Earth. Jupiter, that vacuum cleaner in the sky, sweeps all those pesky little comets right out of the sky, so Earth has a bodygaurd, according to them.
Don’t be fooled. Tunguska was only ONE comet. Every comet is going to be different. Loosely agglomerated, they won’t act uniformly like iron-nickel meteors do. What one does may never happen quite the same way again. But the astronomers don’t see it that way. What can happen is only what we have seen happen – at least on Earth.
Look around at some areas on Google Earth and you will see around the New Mexico/Texas/Mexico border some amazing sites. Look in South America at the Rio Cuarto long elliptical impacts. We have only just begun to find out what kind of things have impacted the Earth. The geologists claim that all those things happened in the remote past, millions of years ago. But impact sites are being dated to 12.9 kya almost as we speak. (see my list above) The geologists, on this subject, are wrong. Gene Shoemaker got us to get our heads out of the sand about meteors, but we haven’t even begun to accept that comets have hit the Earth a lot – and there is evidence that some of those happened in the human era. Some seem to have hit in the historical era, but with so little research having been done, who knows what we will find out when all is said and done? The only thing that is really true is that we will find many impacts. It is too early to tell anything certain – but with idiots like Holliday out there, stopping scientific progress, that certainty will be a long time into the future.
Are we at risk now? We should be looking into it. Are we? Not really. (I don’t want to be an alarmist. If we don’t know, we should find out, and I suggest we do it fairly aggressively. If we are at risk, we are the only generation in history with a possible capacity to deal with it. If we are truly not at risk, then we can breathe safely. But not looking into it would be monumentally stupid.)
****
Murray says:
May 18, 2011 at 3:45 pm
Personally, I like this variant of the theory http://cometstorm.wordpress.com/
****
Yes, that site is absolutely fascinating & a must read. It’s getting to the point where it’s quite convincing.
Thanks too, to Feet2theFire for your links & comments. This is an evolving story. I’d bet 20 yrs from now geologists will wonder how they didn’t make the connections to this evidence earlier, just like continental drift. The prospect of a firestorm of fragmented comet-strikes devastating a continent in minutes so recently in the past is rather sobering.
Funny thing, those asteroids, that only kill the big game animals and leave the little critters largely untouched. And another thing, the extinctions didn’t occur all at once: they disappeared mostly within a couple of thousand years after the arrival of humans, some early, some late. And another thing, everywhere humans went, big animals went extinct within centuries: in Madagascar, Australia, lots of Pacific islands, including big birds in Hawaii andNew Zealand–everywhere humans went they wiped out the biggest animals.
This meteoric explanation is a pathetically unscientific fairy tale. Of course I said that a few times about the K/T event too, but we know when humans arrived in Australia and Madagascar and Hawaii, and North America, and hundreds of islands, and as close as the archeologists can tell, their arrival spelled almost immediate doom for ecologically naive game. See:
http://en.wikipedia.org/wiki/New_World_Pleistocene_extinctions
…which tells how most of the surviving species in North America were those which had evolved together with humans in the Old World, and had only recently migrated to the New. They knew enough to keep their distance from the two legged hunters. And there do appear to have been regional extinctions and eventual domestication of bison.
This all reminds me of the “discovery” of the “Flood” boundary in Mesopotamia a century ago. Problem was, they later discovered older flood accounts on tablets beneath the flood layer. And likewise, New Wrold species that went extinct did so on both sides of the Younger Dryas. The asteroid theory is an explanation in search of a problem–the correlation between human arrival and game extinction is very high. I could believe in CAGW by way of an annual 3mm sea level rise more easily than in ET Pleistocene extinction.
–AGF
Peter Kovachev, What I was trying to communicate was that with the current spotlight on “intellectual property” protections . . .
http://news.google.com/nwshp?hl=en&tab=wn&q=%22intellectual%20property%22%20protection
That if I access this book via a library . . . I have complied with C.Y.A. protocals. /sarc
It appeared to me that there was a common law copyright on the link I provided . . .
http://creativecommons.org/publicdomain/zero/1.0/
That’s all!
lowercasefred said :
āStones do not fall from the sky.ā
Says who?
So many thousands of years and they still haven’t been able to kill all the kangaroos..
http://australianmuseum.net.au/Megafauna-extinction-theories-patterns-of-extinction
Climate change what done it. When the food source disappears. As later with the Younger Dryas and the Irish Elk.
The Australian story should be particularly noted by those who want to blame everything on human destruction – it wasn’t the Aboriginal natives burning all the trees which then changed the landscape etc., it was the end of a climate cycle which dried up the lakes in summer, or completely. This also affected the humans who had been living with these mega beasts for some 30,000 years.
This a typical blame the natives site – http://www.convictcreations.com/aborigines/megafauna.html
Perhaps it makes some whities feel better for stealing their land ..
Very simple. Kangaroos don’t need water. That means they can go where people can’t. Try another species. –AGF
This Australian Museum website supposes that the the last ice age was worse than the previous ones, which we know to be nonsense. Big ice ages wipe out much of the evidence of the smaller ones, and the last one was the smallest of the four main ones. Why didn’t the earlier ice ages wipe out the megafauna? Because there were no people there. –AGF
@AG Foster –
The overkill hypothesis is somebody’s wet dream. it is very difficult for people in this world of 6.5 billion people to comprehend how sparsely the population of, say, Crystal Lake, Illinois (around 20,000) would fill 8 million square miles of North America. With half of them being women and half of the males being under the age of 12, it leaves about 5,000 hunter-age adult males. If each one covered five square miles a week (very doubtful), it would take 32 years (probably 125% of a lifespan – and 175% of a hunting career) to cover the entirety of NA, if they didn’t go over the same ground twice. And all the megafauna would have to not wander into the already covered area, which would give them 32 years of protection (0n average) from bumping into one of the 5,000. And if the hunters missed any, by the time they returned to a habitat, the megafauna would have 32 years on average to reproduce.
The idea of them scouring every habitat of every large animal in that area is so silly, I can’t believe that academics could ever have fallen for that. Don’t they have any common sense at all? It is Einstein’s Random Walk, with a dead carcass at every juncture.
I won’t even go into WHY they would kill such large beasts in such numbers. They certainly couldn’t have eaten them all. I get the impression that modern scientists believe that Clovis man was as carnivorous as modern day capitalists. It is just one of those forms of “Man, the evil creature, the one that has no right to live on Bambi’s planet.”
Laurie Bowen says: “Peter Kovachev, What I was trying to communicate was that with the current spotlight on āintellectual propertyā protections . . .” (May 19, 2011 at 9:51 am)
Oh, I see, sorry, didnt get it. I did notice too that it’s a Commons license, and wondered why as the book would still be protected.
It took the whitey to wipe out the food source of the Native Americans..
Back to Oz: http://www.abc.net/au/science/ozfossil/megafauna/climate/climate.htm
This is ridiculous. There were hardly any people at all in any numbers in any one place – a population around 5 million globally at the beginning of the Holocene – and these mega animals were in vast areas for all practical contact, empty of humans. Humans no doubt hunted them on the edges, or followed herds as did the Native Americans, but to think that so few with primitive weapons, though effective, killing for their immediate food requirements, could wipe out all these mega animals globally, is just absurd.
And on foot!
If you don’t know anything about the Bushmen of the Kalahari, well worth getting to know. They still hunt, those that haven’t been forcibly moved off their land.., in traditional ways.
Here’s an Attenborough on their hunt: http://video.google.com/videoplay?docid=-490028831040819475#
And do keep to the end, because you’ll find a common theme among hunter gathers the world over, respect.
There is nobody on the planet who has any notion what the population was 10,000 years ago. You all parrot the most hopelessly specious guesswork. Try to put together some reasoning to back up your wild figures! You can’t, because neither you nor anyone else has any basis by which to estimate ancient populations. Let me let you in on a little bit of info. The population of North Africa was about as great as the population of Europe only 2000 years ago. How do we know this? Take one tiny example. History tells us that three philosophers in the Roman period believed the earth was flat. None of the three were from Europe. Two were from Africa and one from the Near East (not Africa). One, Lactantius, became tutor to Constantine’s son. Lots and lots of famous “Greeks” and “Romans” came from Africa, like Augustine, and Eristosthenes, who calculated the size of the earth. In fact if you were to do a census on the provenance of famous Hellenistic thinkers you would find that about half were not from Europe. Leptis Magna provided the wheat for the Roman dole, and one emperor, Septimius Severus. Thousands of years ealier much or most of the Sahara was savanna, as the ubiquitous rock art proves. You can even find in the deserts of Sudan pictographs of people lassoing a giraffe, about 7000 years ago.
You might want to take a look at the book “1491” to get some idea how densely populated the Americas were before 1492–tens of millions, probably close to a hundred million natives. Traditionally low numbers are based on a perfect absence of data, and an absence of any sophistication in population studies. This “noble green savage” nonsense is truly a kindergarten fairy tale. All humans in all ages have been multiplying at the expense of the animal competition. Hundreds of perfectly factual examples may be provided, where we know with certainty that climate had nothing to do with the extinctions. And I repeat, do you people really think the climate did something in the Holocene that it had never done before? What utterly preposterous nonsense. You are welcome to retain your belief but don’t flatter yourselves into thinking you’ve got a lick of science to back it up, ’cause you don’t. Every passing year piles up more evidence against it, and it’s only the most irrationally precommitted who insist on defending it.
Why don’t you sit down and make a list of animals you can admit were wiped out by humans, just to show you are able to approach the subject rationally, and we’ll go from there. –AGF
AGF,
I don’t know this for a fact, but I’d guess your first sentence is wrong.
@AG Foster –
I think you may have mis-typed. Did you mean “North Africa”? Or North America?
Yep, read “1491.” Great book. Terra preta may be the single best development in the history of agriculture – one that the ancient South Americans created, yet today’s scientist are having a great deal of trouble translating into something real for today. But when we do, watch out.
But A., the numbers in the book are not agreed to by many, though I tend to agree with them in principle, intuitively. (But where are all those skeletons, or graveyards?) You reading the end result of 11,000-12,000 years of population growth and saying that the population was in the millions at that time is unfounded in the extreme.
ALL of the population figures for past centuries – not to mention previous millennia – are mostly guesswork, even by those who think they are. You are correct about that.
But I would put a lot more money down as a bet on 20,000 (+/- 2 magnitudes) people using Clovis points than some substantial percentage of the “1491” numbers.
Look up populations for cities and countries from just 200 years ago. In 1800, no city had 1 million people. The world population was only 2.5 billion about the time I was born (around 60 years ago). It is up about 2.3 times that now. The numbers for farther back in the past did not grow nearly as fast as now, due to sanitary conditions and lack of medicines. Until the Industrial Revolution, population was a slow grower, but 10,000 years is a lot of years of slow growth. When centralized civilization happened, populations grew (subject to epidemics, though).
Without centralized civilization and its infrastructure, please explain to me how the population was more than a few score thousands, only 1,000 years after the Asian influx over Beringia? If the people were much more than nomads, please tell us what you base such logic on. They had to be somewhat nomadic, after all, if they were to have covered all the bases in order to kill all the megafauna in North America. They certainly didn’t do that while rocking on the porches of their mansions.
Those “1491” numbers were based on high and centralized civilizations, even if they were assembled in smaller communities than we have today. Please, show me where millions could inhabit the Americas without an infrastructure tied in with a centralized civilization.
I don’t look on peoples of the past as noble savages, not in the slightest. Being in a world without infrastructure, they were so much closer to the realities of the functioning world than we are now, and that to me speaks volumes about how tough-minded and hard-nosed they had to be, in VERY practical ways, all across the board. Hard-nosed is not noble. Living close to the land isn’t either. Ask any hippies who lived on communes in the 1970s. Given a comparable infrastructure, I feel confident the ancient indigenous peoples would have been able to keep up with what we do today. I laugh up a storm when arkies treat them like village idiots, fearful of the skies and supposedly referring to insignificant dots of light in the night sky as “gods.” That is a fiction of the arkies. And I think they were no more noble than we are, either – just less disconnected from the world around them.
If you assert that the climate did NOT do something at the beginning of the Holocene, you are as ill-informed as you suggest I am. The Younger-Dryas Stadial lasted for about 1,100-1,200 years, and the temps dropped by about 25-30F, in a matter of less than 20 years – and stayed that way for almost the entire duration of the stadial. That is not me talking, but the scientists. You’re blowing it out your nether orifice. I am not one of the scientists, but I’ve been informing myself about this period for quite some years. I don’t know everything, nor do I know any part of it in full – but I am a well-informed lay person. You claiming that nothing happened to the climate at the Pleistocene-Holocene threshold is totally non-informed (the formal definition of ignorant). There is much more than a lick of science backing up what I have discussed here. When I give an opinion, I try to spell that out. When I talk about the science, I source it when I can.
And, Smokey’s guess is correct: There ARE people who have a pretty fair guess about what the population was 12 kya. Do I think they got it within 50%? Probably. Do I think they are off by 3 or 4 magnitudes? No.
You talk about the Overkill Hypothesis like it is God, then because I say it was never as sound idea in the first place, you make ad hominem attacks on me. Nice science. There might be a place for you with Michael Mann.
****
A G Foster says:
May 18, 2011 at 8:26 pm
After all, the Caucasion population of North America required only 400 years to reach 300 million.
****
Either a bad joke, or a typo that’s too high by 2 orders of magnitude.
Well sorry, AG, I misread your line. But 3 million is about right for the native US & Canada population when Columbus arrived. Mexico & Central America might have had an additional 3-4 million with their relatively advanced agrarian cultures.
Re.: Feet2theFire says:
May 19, 2011 at 10:39 pm
@AG Foster –
I think you may have mis-typed. Did you mean āNorth Africaā? Or North America?
Nope, I meant North Africa. Just trying to show how little the climatologists know about the historical effects of climate on population. Try to find an anlysis which acknowledges that climate change was responsible for the decline of Islam and the rise of Christianity. The population of North Africa hit a minimum in about 1900, and began to rise again.
When you speak of a 30 degree temperature change, you can only be referring to the local effect of newly established but permanent snow cover–not a global rise; that would be more like 3 degrees. And true, ice does drive out most species, as in the trivial case of the Irish elk: ice melts, elk move in; ice returns, elk starve. But you seem to have no idea what you’re up against when you speak of climate change extinction.
I never denied the suddenness of the Younger Dryas, but if freezing is invoked as an extinction agent, how do you explain the fact that mammoths survived only in the northernmost islands, except by supposing that they were apparently out of human reach? Mammoths survived on Wrangel Island up till 4000 years ago, about the time Eskimo technology allowed humans to penetrate so far northward. Clearly mammoths survived the two Dryas events. And if you invoke climate change as the cause, how do you explain the relative lack of extinctions in Eurasia at the same time, where the big game animals evolved together with the bipedal hunters?
As for population growth, the rules are simple. Where the supply of food is in excess the population increases until the supply is no longer in excess. Any time land bridges are formed, like the Isthmus of Panama or Beringia, animal crossings lead to great ecological disruption and extinctions ensue. But successful colonization in either direction may occur. So horses and camels which evolved in North America colonized Asia, and camelids earlier crossed into South America. So did lots of species, which wiped out hundreds of indigenous marsupial and edontate species, through predation or competition. As we speak feral iguanas are wreaking havoc on native Puerto Rican birds.
Humans are no different. Presented an easy supply of “ecologically naive” game, which have no more fear of humans than did the dodo, they killed them, ate them, and multiplied. And kept multiplying until the mortality rate of the big game surpassed its birthrate, at which point they are lucky to survive on remote northern islands. When the big game are gone the hunters turn to smaller game, and when food becomes scarce they turn on each other, and the population plummets. Disease was not a problem in North America. At that point the carnivores starve and die off as well.
So…try to explain the survival of mammoths on Wrangel Island while insisting on their extinction further south due to glaciation or “grassification” or meteors. I’m curious. –AGF
Feet2theFire,
This thread is still going? Cool. I’ve been so busy with my new project that I have not had time to properly read your comment, process it, and formulate a response. I have just completed a review of the latest research in carnivore evolution which included some data relative to this discussion. I think I can make a pretty strong case for the Grey Wolf being partly responsible for the Mega-fauna extinction, which, BTW, is not all that unique. I just don’t have the time right now, but this afternoon I should.
Al Gored,
I think you might have misunderstood what I am trying to say. I am not claiming that Humans were not a factor, but rather that they had help from the conversion of grassland/prairie to forest/woodland and another predator, like themselves who not only can take game bigger then itself, but is not dependent on that game, and also likes to live in forests, but has no problem hunting in grassland.
Thereās an elephant in the room!
There was once an elephant in a room. The beast was the subject of lifetimes of careful study, and speculation, by skilled, and dedicated, specialists of precise, but very limited, vision. The man who studied a leg said the elephant is like a pillar. The one who studied the tail said the elephant is like a rope. The one who studied the trunk said the elephant is like a tree branch. The one who studied the ear said the elephant is like a hand fan. The one who studied the belly said the elephant is like a wall.
The nature of the beast was all very contentious, and controversial. And even the fleas on the elephants backside joined in the debate, with the assertion that āThis is our ever unchanging world, you fools!ā. Until one day, a person came along who could see the whole beast from a distance, and he explained to them:
āAll of you are right. The reason every one of you is telling it differently is because each one of you has perceived a different part of the elephant. So, actually the elephant has all the features you mentioned. But there is so very much more to the beast than any of you know. You just need to get enough distance to see it all in contextā
The blind scholars all dismissed the new viewpoint as heresy. They argued that it had never been established among them, that ordinary vision was a valid tool of science. So, since this new, and heretical, viewpoint flew in the face of all they had so carefully, and painstakingly, confabulated about the the beast, they quickly resolved to ignore the new viewpoint. And to get on with their lifeās work of studying, debating, and confabulating theories as to the true nature of the elephant in the room.
Gradualism, and Uniformitarianism, only work until something sudden, and chaotic happens.
One of the biggest mysteries Iāve ever confronted lies in the question of how theoretical geology could be so far removed from the empirical reality now clearly visible, and legible, in modern 21st century satellite images.
It didnāt take much digging in the history books to figure out where the Earth sciences went wrong.
The root problem with the thinking in the Earth sciences goes all the way back to Gottfried Leibniz, in the early 18th century, and his slogan of āNatura Non Facit Saltusā, (Nature does not jump). Leibniz may have been a mathematical genius. But he wouldnāt even pass a 5th grade geology test of today. Yet he had the full backing of governments, big business, and the big churches. Because he believed, and taught, that the Great God of the Universe had created planet Earth, with all its flora, and fauna, just for us, and to do with as we damn well pleased.
The old clichĆ©s like ābuying a pig in pokeā, ādonāt let the cat out of the bagā, and āempty sack of liesā all have their roots in the same old con. It went something like this: At an old country fair, a con artist would approach a likely looking mark to sell him a piglet in a āpokeā bag. But itās not really a pig in the bag; itās a cat. The cat wiggles, and squirms, just like a little pig when you poke him through the bag. And as long as the bag stays closed, the con works just fine. But as soon as the bag is opened, the cat escapes. And the victim is left holding nothing but an empty sack of lies.
Carl Linnaeus, and Charles Darwin, loved Leibniz. And they both quoted him verbatim. He managed to almost completely eliminate any academic consideration of episodic worldwide catastrophes from western thinking. And by the time James Hutton, and Charles Lyell, came along, most geologists were well-conditioned followers of his way of thinking. Hutten gets the credit for the origin of Uniformitarianism. Charles Lyell just popularized his ideas in 1830, when he published his book āPrinciples of Geologyā. But Hutten, and Lyell, just picked up on Leibnizās thinking, and ran with it.
They werenāt brilliant geological thinkers either. But their unquestioned uniformitarian/gradualist assumptions, based on the idea that the earth was shaped only by slow-moving forces still going on around us today, and expressed in the slogan of āThe present is the key to the pastā, has become the foundation postulate of the Earth Sciences ever since. Governments, and big institutions, loved it. And they bought it like a pig in a poke with generous funding packages that came with rules that shut the door to any consideration, or publication, of theories of sudden catastrophic events, as a possible driving force in the geo-morphology of this world for more than 150 years. Thatās a cruelly long time time to leave the poor kitty in a bag.
But the questions of just what the hell happened around 13,000 years ago that caused the extinctions of the mega fauna in North America, the disappearance of the Clovis culture, and a return to Ice age conditions that lasted more than a thousand years, has caused us to take a closer look, and Iām afraid weāve let the cat out of the bag.
The most glaring flaw in the Younger Dryas Impact theory as written is that it is impossible to construct an impact model with a 4 mile wide bolide that has enough time in the atmosphere to break up completely, and scatter fragments over a continent sized area without making a good sized crater somewhere. And āwhereās the crater?ā has become the rallying cry of opponents of the hypothesis. But from Comets, Catastrophes, and Earthās History by W. M. Napier we read ,
The astronomical data on the Taurid complex is as good as anything you can dig up with a pick, and a trowel. So, if heās correct, then we should expect to see the planetary scarring, somewhere on this continent, of a very large cluster impact event of smaller fragments. Weāre not looking for a single large crater, or impact structure.
What if we set Sir Charlesās unquestioned 19th century, gradualist, assumptive reasoning aside for a minute and see what we can find? Anyone ever hear of the Odessa crater, in west Texas? What about all the other craters in the area? Donāt take my word for it. Look for yourself. In the world according to Google Earth, the Odessa impact was only one in a vast cluster event that produced thousands of them in a wide area that includes most of eastern New Mexico, and west Texas. Set your eye height to about ten miles, and liberally scattered among the oil fields of west Texas, and eastern New Mexico, youāll find too many craters in very good condition, and averaging 100 meters wide, to count.
Anywhere else in the solar system no one would hesitate to call them impact craters. But here on Earth, the academic community will entertain almost any fantastical theory for their formation. As long as that geologic theory does not evolve a catastrophic event.
If those thousands of pristine craters in the south west arenāt impact craters, then how did they form in such a wide variety of terrains?
Gradualism was in large part an appeal against a biblical creation of seven days or seven thousand years, and against the Noachian Flood, and was a vast and indispensable stride forward. And the neo-catastrophists mostly took their cues from Vellikovsky. It took some time to get the K/T event any respect but it has it now. Likewise it took a little time to understand that more sediment is deposited during a hundred year flood than in the hundred years in between. But many still see in Pangea vindication for the post-deluvian Peleg, who was named after a dividing earth (read “land”) –that is, Pangea broke up only a few thousand years ago.
The circumpolar current is a shadow of what was before the Isthmus of Panama arose, which was in turn a shadow of what was before Africa crashed into Asia. Consider what a homogonizing effect on climate such a current would have had, and consider what a cooling effect on climate the rise of Panama had. A very slow geological process gradually switched of a nearly global system of circulation. Such events seem to be more common than global extinctions due to asteroids, once every hundred million years or so. We are fortunate to have Jupiter and Saturn out their sweeping up the comets, keeping our little earth safe, most of the time. Recent ET events are certainly possible, but inherently unlikely as explanations for recent events–they should remain at the bottom of the probability list as agents of change.
Humans should remain at the top. –AGF
AGF said:
Pure uniformitarian assumptive reasoning. What about the craters mentioned above? Who did some real science on them?
The moon shows how common craters must have been on this geologically active earth, but the fact remains that planetoids and smaller masses have aggregated in the course of the solar systems history, making annihilating impacts more rare all the time. Shoemaker-Levi showed LaPlace was right in the way Yuri Gaganov showed the earth was round. That comet had been orbiting Jupiter for several decades before it impacted. It takes the gravity of two bodies to capture a third, and Jupiter is the bad boy that helps the sun do it. Jupiter is also capable of propelling a comet clear out of the solar system, but if and when it captures one, its moons make sure it won’t stay in orbit for long.
So no, this is hardly idiosyncratic speculation–the class of “Jupiter comets” are taken by current theory to have become such through Jupiter’s tremendous gravity. We may have been very lucky to have lived in the time of a comet impact on Jupiter, but it is probably no coincidence that that is what we have seen rather than an impact with the sun. Jupiter is like its own little solar system, with moons as big as earth, waiting out there like a spider to trap the comets, and leave earth safe enough for life to evolve and flourish, most of the time. –AGF
Word salad sucks. Give us a break!
Leave off the condescending, and impertinent, uniformitarian preaching, and gradualist inter-assumptive confabulation. Believe it or not some of us went to school too. And we are well aware what āMost geologists agreeā about regarding the grand uniformitarian assumption. And the naĆÆve fantasy that catastrophic impact events donāt happen. And in spite of the fact that it was adopted without question as the foundation postulate of the Earth Sciences in the early 19th century, we remain to be convinced that all geomorphology is the work of slow, and steady processes we see going on around us today, or that āThe present is the key to the pastā. Or that impacts happen at a slow, and steady, rate. The astronomical data does not support those silly, and naive assumptions. Nor does the geological record. But thatās beside the point.
You’re completely dodging, and ignoring, the question. What about all the small craters in New Mexico, and West Texas? The empirical fact, obvious for all to see, is that they do exist, and in vast numbers, and they are in very good condition. Anywhere else in the solar system no one would hesitate to call them impact craters. Yet here on Earth, the academic community will entertain almost any fantastical theory for their formation. As long as that geologic theory does not involve a catastrophic impact event.
But if those thousands of pristine craters in the south west arenāt impact craters, then how did they all form at dang near the same time? (The surfaces they’re in all date to the late Pleistocene.) And in such a wide variety of terrains? Can anyone show me where someone has done some real science on them?
Or are we supposed to go along with the high priests of the church of the Grand Uniformitarian Confabulation, who’ve always taught that we should assume without question that such things do not happen at all? And ignore the simple empirical fact that the planetary scarring of a geologically recent super cluster impact event in the American Southwest is as obvious as spilled paint in a driveway?
Heck, theyāre not even the only ones. There is also a whole slew of oblique impact craters from a cluster of objects the hit the late Pleistocene/Early Holocene sediments of the Red Rock River valley in Southwest Montana. That cluster of fragments hit at a very low angle coming from the southwest. And they produced oval impact craters. And if someone should want to actually do some science there, the ejecta from the oval crater at 44.642265, -112.077185 was blown over the top of, and is blanketing, one of the ancient meanders of the river at 44.644033, -112.076880. The stratigraphic horizon at the interface between the material of that ejecta splash and the ancient riverbed should give us materials we can get a C14 date from.
There is much science that remains to be done. And much data to be collected. But rumors that the Younger Dryas Impact hypothesis has been disproven are premature, and greatly exaggerated.
The existence of a bunch of craters in the desert that haven’t been studied makes for a pretty poor theory for Pleistocene extinctions. Until they’ve been dated why should I be expected to think they have anything to do with the problem. You seem to be assuming they are the same age. I would assume they are there because of the slow rate of desert erosion, not because they constituted a single event.
If you are claiming that both Dryas events were caused by meteors that landed in the same South West desert, well that really stretches my credulity. Sorry, but a bunch of unstudied craters, whether they landed in rapid succession or centuries apart, doesn’t explain the disappearance of species which seem to have gone extinct one by one over a period of several thousand years. –AGF
beng says:
May 20, 2011 at 6:29 am
“Well sorry, AG, I misread your line. But 3 million is about right for the native US & Canada population when Columbus arrived. Mexico & Central America might have had an additional 3-4 million with their relatively advanced agrarian cultures.”
Huh? Where did you get your numbers?
The one for Mexico+ is not even close to the estimates I have seen.
And many Native North Americans, notably in the southwest and eastern US, also had advanced agrarian cultures.