From UC-Davis:
Rock soil droplets formed by heating most likely came from Stone Age house fires and not from a disastrous cosmic impact 12,900 years ago, according to new research from the University of California, Davis. The study, of soil from Syria, is the latest to discredit the controversial theory that a cosmic impact triggered the Younger Dryas cold period.
The Younger Dryas lasted a thousand years and coincided with the extinction of mammoths and other great beasts and the disappearance of the Paleo-Indian Clovis people. In the 1980s, some researchers put forward the idea that the cool period, which fell between two major glaciations, began when a comet or meteorite struck North America.
In the new study, published online in the Journal of Archaeological Science, scientists analyzed siliceous scoria droplets — porous granules associated with melting — from four sites in northern Syria dating back 10,000 to 13,000 years ago. They compared them to similar scoria droplets previously suggested to be the result of a cosmic impact at the onset of the Younger Dryas.
“For the Syria side, the impact theory is out,” said lead author Peter Thy, a project scientist in the UC Davis Department of Earth and Planetary Sciences. “There’s no way that can be done.”
The findings supporting that conclusion include:
- The composition of the scoria droplets was related to the local soil, not to soil from other continents, as one would expect from an intercontinental impact.
- The texture of the droplets, thermodynamic modeling and other analyses showed the droplets were formed by short-lived heating events of modest temperatures, and not by the intense, high temperatures expected from a large impact event.
- And in a key finding, the samples collected from archaeological sites spanned 3,000 years. “If there was one cosmic impact,” Thy said, “they should be connected by one date and not a period of 3,000 years.”
So if not resulting from a cosmic impact, where did the scoria droplets come from? House fires. The study area of Syria was associated with early agricultural settlements along the Euphrates River. Most of the locations include mud-brick structures, some of which show signs of intense fire and melting. The study concludes that the scoria formed when fires ripped through buildings made of a mix of local soil and straw.
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http://cio.eldoc.ub.rug.nl/FILES/root/2000/QuatIntRenssen/2000QuatIntRenssen.pdf
I subscribe more to this theory as a cause for the Younger Dryas.
Sometimes I have the impression that the solar brigade (it can only be the sun) and the CAGW advocates (it can only be CO2) are together on the same side of this debate. Both furiously trying to ignore the ocean. Its a road to nowhere.
Salvatore
Look at this post by Bill Illis from a previous thread on a similar topic:
http://wattsupwiththat.com/2014/08/29/younger-dryas-climate-event-solved-via-nanodiamonds-it-was-a-planetary-impact-event/#comment-1722327
“Count the YD’s”. The point is that the YD – or more precisely the BA that came just before it and is a more real phenomenon than the YD – is just one of at least 20 high amplitude oscillations of climate temperature in the NH. By contrast the SH is much more stable. That is exactly the point I was trying to make in the above post. The AMOC makes the NH bi-stable, so it switches manically between high and low while the SH moves much more slowly and sedately. Were each one of these “micro-interglacials” in the NH caused by some discreet solar fluctuation? To me it looks much more like an unstable oscillator containing a positive feedback switching between attractors.
there is more ocean in the SH
The data I just presented shows this not to be the cause because there is strong evidence that both the N.H. and S.H. cooled at the same time. It also does not explain the extreme variability of the climate within the YD 1300 year period of time.
Nevertheless I can see how the AMOC can play a role when the initial state of the climate is close to inter-glacial/glacial thresholds as it was in YD times but the climate in the past has done this when in a strong Inter- Glacial condition (Eemian Inter-Glacial for example) only to descend into a glacial state while in addition the climate has done this in the past with different land/ocean arrangements.
I keep going back to this statement below
The problem facing climate science is ,
Climate sensitivity to various forcings is exponentially dependent on the mean state of the climate and earth dynamics (state of the earth ) which results in so many climatic outcomes and correlations breaking down over periods of time.
I hope this event passes without to much drama Scores of GIANT asteroids on course to hurtle past Earth within the month, NASA reveals .http://www.express.co.uk/news/nature/549722/Giant-asteroids-close-Earth-month-February-Nasa
Lots of things to think about from the large number of posts here. To begin with, the Younger Dryas as it appears now had an extremely rapid onset. The latest information has it that it was only one or two years before much of the world was plunged into the icy realms. The atmosphere and a cause therein is surely the reason. Also, almost all of the world (except perhaps Antarctica’s interior and some say New Zealand) were involved in the sudden severe cooling. There was some very intriguing short term milder intervals within the 1300 year long Younger Dryas, also. This fits with the idea of cosmic showers from a not too distant comet break-up. How this could be so involves comet showers that were likely periodic, and thus there was times when skies clear and the sun were able to work its magic once again. Once again however, towards the end of the Younger Dryas, some more cosmic showers took place and returned much of the planet to the cold. Finally for now, I wish to point out that there remains considerable uncertainty regarding the timing, and extent both geographically and severity of Heinrich events. They appear not always to coincide with either meltwater entry into the North Atlantic, so their cause remains debatable. Finally, finally, for now the proxy that supposedly supports the AMOC (THC) premise was found not to be reliable. Thank-you, Rod Chilton.
There is nothing the least bit unusual about the onset of the YD. It´s just like the onset of cold snaps for millions of years before and at least the 8.2 K event after it and probably other Bond Cycles as well, less dramatic because of less ice.
Thus there is no reason to look to the asteroid belt for an explanation, especially since there is no valid evidence of an impact.
Hi Milodonharlani: Nothing unusual about the onset of the Younger Dryas occurring in a few years to perhaps even a few months? And secondly, how could the cold extending over large areas of the Earth also take place in that same very short time frame? Perhaps the other intervals (and yes the 8200 BP time period was also driven by the same forcing I speak of), you refer to may also have a cosmic origin. However, the problem with more ancient periods is that the resolution becomes too poor to make any conclusions in that regard. Thank-you, Rod Chilton.
The resolution of prior cold snaps is good enough for comparison with the YD, at least for hundreds of thousands of years. Farther back the absolute dating gets harder, but the rapidity of onset is still observable.
Both ice core & sea sediment records show the same patterns. The YD & 8.2 Ka events are no different. Rapid warming events are also plainly visible in the records.
The literature on the topic of sudden climate shifts is enormous.
A big bang can give us life as well as destroy it . https://www.youtube.com/watch?v=REw5-_rpFDE
Comment as posted at CosmicTusk (mostly):
Sorry if it is long…
REBUTTAL TIME / SHREDDING TIME
…Make no mistake about it. If/When the YD impact hypothesis is accepted (perhaps as long from now as a generation, after some of the old defenders of the faith die off) the paradigm known as Uniformitarianism will never rule the roost like it has done for about 150 years. It is a true paradigm shift. The seeds of it are all present already. It only needs to have enough people exposed to it. They can’t side with it if they haven’t been made aware of it. Younger minds are more titillated by new ideas; that is the random part of it, to some extent – the earlier they hear about the YDIH the more likely they are to give it a hearing.
But there is and will be resistance to the idea from several quarters. There is no getting away from that.
But it is amazing how bizarrely strained the logic of the defenders of the faith can get. HOUSE FIRES? (Even if they had the trees to build with and enough people…ROFLMAO)
Let’s first mention a few items:
13,000 – Syria/Dwellings – Civilization – Population – Scoria – Pack hunting on herds
13,000 —
13,000 years ago who was living in Syria? Gobekli Tepe (37.223056, 38.9225) is in southeastern Turkey, not far from the Syrian border and 97 miles from Abu Hureyra. It is an archaeological site that has been deemed the oldest human settlement in the world, at 12,000 years ago. So these people are talking about a full millennium earlier than Gobekli Tepe – which in itself is 2,000 years older than Jericho.*** That is a bit rich, to say the least. The Clovis Barrier people resisted pre-Clovis of just a few hundred years, and they resisted for decades. Gobekli Tepe has STONE structures, quite architecturally developed, actually, so in my OWN mind, there had to be a considerable amount of time for that to develop. It is actually more developed than Stonehenge by quite a bit, having raised carvings of animals on its columns. The site is quite extensive, but so far as I know there are no wooden structures. I could be wrong on that, but I am doubtful at this time.
*** [Wiki] “However, the spring at what would become Jericho was a popular camping ground for Natufian hunter-gatherer groups, who left a scattering of crescent microlith tools behind them. Around 9600 BCE the droughts and cold of the Younger Dryas Stadial had come to an end, making it possible for Natufian groups to extend the duration of their stay, eventually leading to year round habitation and permanent settlement.”
Syria/Dwellings —
Take in that bit on Jericho, and then think about 11,000 years BCE – 1,400 years BEFORE it was possible for the Natufians to settle in Jericho. 1400 years is between us today and the Visigoths. And what was there 1400 years before the Natufian settlements? Only 4 HUNDRED years earlier they didn’t have settlements with buildings, because they were hunter-gatherers, so what kind of dwellings were burning 1,000 years earlier than THAT? It boggles the mind how un-informed researchers can be outside their own little disciplines.
Abu Hureyra, Syria (included in the study in question, as well as in YDIH team studies) as I said is very conveniently only about 97 miles from Gobekli Tepe. Take a look on Google Earth at the kinds of houses they build in this part of Syria and Turkey (use Google Earth and its Panoramio photos – and try to find wooden structures.) That is pretty much due to the kinds of building materials that are available – sand and dirt to make bricks from. They don’t build much out of wood there, because wood is a high-value commodity. I am betting that wood has been a high-value commodity there since the last ice age ended. There is not much assumption by me on that, but there is a little – I DID go look, just to make sure. I’ve been in Syria and I didn’t see any wooden buildings that I can recall; everything was brick.)
A good look at Gobekli Tepe shows that the construction ws NOT mud and straw. It was STONE. Stone columns and stone in-filled walls. The stone walls even had artwork in bas-relief. At 12,000 years ago.
So maybe the climate was different then? Well, let’s remember that the last main ice age ended about 18,000 years ago and the global temps (according to the ice cores) were pretty much the same at the YD onset as it is now. That means 5,000 years of warming temps and global climate much like today. All of which adds up to the likelihood that they did not build houses out of wood, not if the climate was like now. The site was along the banks of the Euphrates, so they might have had wood. But with the climate like now, one would think they might be a bit dumb to use their wood when there is enough earthen material all around. They certainly don’t now, even though there are occasional trees. Building houses out of wood implies FORESTS, not occasional trees. And even in the farming areas now, what do they build dwellings out of? NOT WOOD.
So, basically, they are supposed to have burned non-existent dwellings (1,400 years before such things existed), built of materials that people in that region have no history of building with, and in such vast quantities that a black mat was created.
Right… NOT
Civilization —
Just how many houses do they think those people think HAD 13,000 years ago? What was the world population then? It can be very distorting, looking out from a world of 7 billion, to think that people were living in densely populated settlements – but it would also be wrong. As the Genographic Project of the Nat Geo says,
Taking root around 12,000 years ago, agriculture triggered such a change in society and the way in which people lived that its development has been dubbed the “Neolithic Revolution.” Traditional hunter-gatherer lifestyles, followed by humans since their evolution, were swept aside in favor of permanent settlements and a reliable food supply. Out of agriculture, cities and civilizations grew, and because crops and animals could now be farmed to meet demand, the global population rocketed—from some five million people 10,000 years ago, to more than seven billion today.
https://genographic.nationalgeographic.com/development-of-agriculture/
The population of modern Syria, for example is 22.85 million people – 4.5 times the ENTIRE WORLD population at 10,000 years ago, much less 13,000 ya. Note also that according to this source the agricultural revolution – which made the settlements POSSIBLE – did not start until THREE thousand years later. So, according to the anthropologists, settlements didn’t exist for the hunter-gatherers of 13,000 years ago. You can’t have settlements without agriculture.
Scoria —
Now let’s go to scoria. Look up scoria and what you find is that scoria is PUMICE. As in from VOLCANOES. Now, the paper (Thy et al, 2014) doesn’t call it scoria, even though the ARTICLE calls it that. The abstract calls it “siliceous scoria” – which is not correct. Sloppy research, sloppy article to an even higher degree (the journalist didn’t even bother eucating himself enough to use the correct terms). It is NOT scoria, whether siliceous or not. There is no such thing as siliceous scoria.
[Wiki] “Siliceous rocks are sedimentary rocks that have silica (SiO2) as the principal constituent.”
[Wiki] “Scoria is a highly vesicular, dark colored volcanic rock that may or may not contain crystals (phenocrysts). It is typically dark in color (generally dark brown, black or purplish red), and basaltic or andesitic in composition. Scoria is relatively low in mass as a result of its numerous macroscopic ellipsoidal vesicles, but in contrast to pumice, all scoria has a specific gravity greater than 1, and sinks in water.”
Ted Bunch is the one from the YDIH side of the discussion who brought Siliceous scoria-like materials to the discussion, in his 2012 paper. Ted Bunch could tell the difference between actual scoria and siliceous rocks. Thy and his co-researchers evidently didn’t bother looking it up. Bunch wrote, about his SLOs:
In addition, three sites (Abu Hureyra, Syria; Melrose, Pennsylvania; and Blackville, South Carolina) display vesicular, high-temperature, siliceous scoria-like objects, or SLOs, that match the spherules geochemically. We compared YDB objects with melt products from a known cosmic impact (Meteor Crater, Arizona) and from the 1945 Trinity nuclear airburst in Socorro, New Mexico, and found that all of these high-energy events produced material that is geochemically and morphologically comparable, including: (i) high-temperature, rapidly quenched microspherules and SLOs; (ii) corundum, mullite, and suessite (Fe3Si), a rare meteoritic mineral that forms under high temperatures; (iii) melted SiO2 glass, or lechatelierite, with flow textures (or schlieren) that form at > 2,200 °C; and (iv) particles with features indicative of high-energy interparticle collisions. These results are inconsistent with anthropogenic, volcanic, authigenic, and cosmic materials, yet consistent with cosmic ejecta, supporting the hypothesis of extraterrestrial airbursts/impacts 12,900 years ago. The wide geographic distribution of SLOs is consistent with multiple impactors.
Pack hunting of herd animals —
It shows how weak theskeptics’ entire stance is when they pick what they think is the weakest animal out of the herd of evidence that the YDIH researchers put up. The skeptics target a young animal and try to weed it out of the herd by pack tactics – leaving all the strong animals/arguments/evidence in place and hope that they can convince others by picking holes in the weakest aspects of the research.
THEN they go to an amenable science journalist (read: someone who can’t actually do science himself) and trumpet their attack as a complete and utter proof that the YDIH in its entirety is bogus. As if yelling louder makes something more correct. (Does any of this sound familiar to WUWT readers?)
If they want to attack something, they really need to attack the central evidence, the strongest evidence.
On a scale of 1 to 5, I give this a ZERO. A really LAME idea – really stretching credulity. BURNING BRICK OR STONE HOUSES. I live in one, and I guarantee that it is fireproof – except for the paint and furnishings. AND IF SUCH HOUSES BURNED, THE CHARRED STONES OR BRICKS WOULD STILL BE VERY APPARENT. You can’t undo overcooking of bricks. Where are the bricks – especially well over 1,000 years before the earliest human settlements in the world?
So the vitrification of “building earth” mentioned in the paper is simply really bad research. You can’t have building earth melting sand to glass if you don’t have buildings.
The YDIH is of interest to some for pragmatic reasons (dating, sampling, high-physics … many can ‘participate’ in a useful focus, without be ‘vested’ in the outcome), but the real driver behind it looks to me like old dogs chasing their boyhood excitement over the CBIH … the Carolina Bays Impact Hypothesis. In the 1930s and 40s, it had a brief run of academic acceptance. The Bays are a FAR stronger imagination-stimulus, than anything the YD can (visibly) offer, and CBIH popular enthusiasm (hysteria?) held until well after WWII.
Maybe, ‘like it did 150 years ago‘. Modern geology led the way out of Uniformatarianism platitudes, early in the modern (scientific) era, looking at massive deposits from glaciers in the Alps … and swung so far from Gradualism they ended up having to slap down Catastrophism, as well. No, we buy ‘Attack of the Change Gods’, no problem.
I wouldn’t put too much stock on the fact that the study in this Post is of materials & settings from a much later date than the YD, that it traffics in house-fire debris, or that it samples basically a garbage heap. It’s about the (small-particle) technique shared with YD impact researchers, not about the YD or a putative astro-strike.
Revisiting James Michener’s The Source is always a few minutes well-spent (imo), but that won’t distract doubters from the over-interpretations and fragile evidence (and occluded Carolina Bays memory-lane stroll) of the Younger Dryas Impact Hypothesis.
Bringing in the Carolina bays into this discussion is a red herring, and others who visit this threat should ignore it.
There are no YDIH scientists doing any Carolina bay research. That connection was floated by Firestone originally, but it fell apart, based on the dating of the bays. And none of them has touched it since then. For over 5 years now, if not longer.
Some of the lay people following the YDIH talk about the CBs once in a while, but it is just talk. But don’t put any of that onto the YDIH scientists.
Steve G,
You are being far to nice to the paper authors. This is “Dumb and Dumber” level science.
The straw _inside_ adobe mud-brick burning as hot as a blast furnace?
Before the Bronze age? (Let alone the Iron age?)
If fact, before sedentary agriculture?!?
The YDB papers are talking about physical processes that involve materials — nano-diamonds — formed at temperatures in excess of 2200 degrees Celsius.
The highest temperature mentioned in the “house burning before houses” part of the paper is _1,000_ degrees Celsius.
If the paper’s authors found evidence of forces air type blast furnace technology all over Syria associated with the Gobleki Tepe _THAT_ should have been the focus of the paper, as that would be a huge break through in our archeological understanding of that time and place.
Who are these Yo-Yo trying to kid? My six-year old could do better science.
I don’t know who is more stupid here. The guys who wrote it, the people who published it, or the readers who might believe such cow pie tales.
Any 1970′s California primary school student, with the history they taught then about the building of the Spanish missions, can spot the utter lunacy of that paper.
As always Steve, (Garcia great posts)! I am of course on the same page with you re: almost all of what you have written. And you are correct, just like the present climate change, if you are in the minority as I am, it is hugely frustrating. I have written countless letters to the media in that regard, and just like the Younger Dryas I met with huge reluctance. Thank-you, Rod Chilton.
Trent –
I wasn’t trying to be nice to the paper’s authors. I just point out where they are understanding stuff wrong and where they are really ignorant about human history.
For once some skeptics actually did their own actual science – field samples and lab tests – but they didn’t understand the Bunch and Wittke papers, so Thy et al., were testing the wrong things. Thy also didn’t understand what scoria are, versus “scoria-like” materials. THAT I pointed out – not for the paper’s authors, but for the audience here at WUWT.
As far as I can tell, the Younger Dryas Impact Hypothesis is the opposite of the discussion on global warming. In global warming it is the mainstream scientists who are off base and doing a lot of hand waving – and who need skeptics to set them straight with well-researched data and. On the YDIH it is the proponents of the hypothesis who have done the field and lab work necessary, while the mainstream uniformitarians are the YDIH skeptics and are doing a lot of hand waving EVERY TIME they publish a paper on the subject. The YDIH skeptics are doing science by press release, while in global warming it is the proponents who do it.
So I find myself on the skeptical side of global warming (trying to support what I see as solid science), and I find myself on the NON-skeptics side of the YDIH issue (trying also to support what I see as solid science). In both cases I see the science editors on the side of the hand wavers – which has made me lose almost ALL respect for science editors.
This paper, like the other YDIH skeptic papers, is flawed. Period.
Anybody whose main conclusion is that 1,400 years before houses were even INVENTED and which are made of stone or mud-and-straw could burn and cause some silicon in the ground to melt isn’t up to par from what I see.
Think about that time span for a minute: That is like arguing that the Visigoths’ cell phones didn’t pick up Wi-Fi in 600 AD.
Thy et al focuses on the temps while ignoring the fact that neither houses nor other buildings exist 12,800 years ago, and that mud bricks don’t burn, not even the straw inside the bricks. Add to that that Thy et al. did not even look into ANY of the other impact materials, and it becomes clear that the paper is an obvious attempt to pick off the weakest evidence (or at least what they think is) and pretend that the vast amount of other evidence doesn’t exist.
In climate science ignoring unfavorable evidence is called cherry picking. I think it is fair to conclude the same about Thy et al.
Me: “Think about that time span for a minute: That is like arguing that the Visigoths’ cell phones didn’t pick up Wi-Fi in 600 AD.”
That wasn’t quite the analogy I wanted. Let’s try again…
Think about that time span for a minute: That is like arguing that the Visigoths’ cell phones picked up Wi-Fi in 600 AD.
Houses or any other buildings 12,800 years ago are anachronisms. They didn’t exist. Thy et al doesn’t know this fact.
Houses and shelters and constructions had reach impressive levels of sophistication, well back into the Upper Paleolithic. Lascaux and Altamira point to people more than capable of well-designed homes.
Of course buildings existed, 20-40,000 years ago, and were the rage throughout the Würm, at the least. Good signs of familiar construction-methods, even 200-400,000 years ago. Circles of stones on the living floors of Olduvai Gorge, appear to be the remains of low walls or anchor-mass for eg pole-roofing, in excess of 1,000,000 years old.
Mud-straw brick in the Ice Age? No. Houses? Absolutely. Villages, as we know them? No. Sophisticated residential, light-industrial and storage facilities? Which sometimes suffered “house fires”, which (among other sources & causes) may well have created & deposited similar enduring & recoverable particles?
We can look forward to more studies building on the insights – and methods – of this one.
Correct. No mud bricks, even as late as the Natufian [early Natufian 12.8kya-10.8kya]. The earliest human settlements in the Near East were the Natufians. “The idea that the Natufians were the earliest farmers is as old as the orginal discovery of their cultural remainsby Garrod (1932)…. is now considered the right interpretation (Moore 1982, Unger-Hamilton)….
“B. Bird describes the scanty Natufian excavated under the Pre-Pottery Neolithic B village of Beidha [Jordan], dated to 12,500 B.P. (Byrd 1989). He stressed that, contrary to earlier reorts, there is no evidence for the use of mud bricks by the NAtufian occupants.” All from http://dash.harvard.edu/bitstream/handle/1/12210882/2743274%202.pdf?sequence=2
Regardless of what was going on whenever in the Würm up in Europe with wood, no such constructions were going on in the Au Hureyra region even as late as the Natufians. With mud brick and wood eliminated, only stone is left. And stone is what was used at Gobekli Tepe 12.0kya.
None of this shows any evidence of construction in the Abu Hureyra or Middle East region at 12.8kya , 800 years earlier than Gobekli Tepe..
Humans most certainly did make houses 12,800 years ago & indeed much earlier.
Some two million years ago, Homo habilis appears to have constructed the first structures in East Africa: simple arrangements of stones holding into position tree branches. A similar circular stone assemblage thought to be around 380,000 years old has been found at Terra Amata, near Nice, France (although there are dating questions).
Several man-madde habitats dating back to the Old Stone Age have been discovered around the globe. These include a tent-like structure inside a cave near the Grotte du Lazaret, Nice, France; a dwelling with a roof supported by timber, discovered in Dolni Vestonice, Czech Republic, dating to around 23,000 BC, the walls of which were made of packed clay blocks and stones; many huts made of mammoth bones found in Eastern Europe & Siberia, notably along the Dniepr River valley of Ukraine, near Chernihiv, in Moravia, Czech Republic & in southern Poland, and an animal hide tent dated to 15,000 to 10,000 BC, in the Magdalenian cultural period, discovered at Plateau Parain, France.
Even Neanderthals built mammoth bone shelters:
http://www.telegraph.co.uk/news/science/science-news/8963177/Neanderthals-built-homes-with-mammoth-bones.html
Dolni Vestonice clay building site:
http://donsmaps.com/tripleburial.html
“Dolni Vestonice is also the site of the earliest known potter’s kiln. For acres around, the fertile clay soil is seeded with carved and molded images of animals, women, strange engravings, personal ornaments, and decorated graves. In the main hut, where the people ate and slept, two items were found: a goddess figurine made of fired clay and a small and cautiously carved portrait made from mammoth ivory of a woman whose face was drooped on one side.
“The goddess figurine is the oldest known baked clay figurine. On top of its head are holes which may have held grasses or herbs. The potter scratched two slits that stretched from the eyes to the chest which were thought to be the life-giving tears of the mother goddess.
“Above the encampment in a small, dry-hut, whose door faced towards the east, was the kiln. Scattered around the oven were many fragments of fired clay. Remains of clay animals, some stabbed as if hunted, and other pieces of blackened pottery still bear the fingerprints of the potter.”
Mezhyrich mammoth bone structure reconstruction:
http://donsmaps.com/images23/mammothhousekiev.jpg
Just a quick point on Island extinctions, including the very big Island of Australia,There remains considerable controversy just as n North America, about the role (or non role) of human beings in the extinction of the great animals on the down under continent. Rod Chilton
Rod,
Please cite studies challenging the human hypothesis for Australian & Tasmanian extinctions. Thanks.
IMO it´s nearly as well supported as, for instance, the cases of New Zealand, Hawaii, Mauritius, Reunion, Madagascar, etc.
Here are some recent studies supporting the human hypothesis (including well known author Jared Diamond & celebrated wannabe Antarctic explorer Chris Turney in his actual area of expertise);
Miller, G. H. (2005). “Ecosystem Collapse in Pleistocene Australia and a Human Role in Megafaunal Extinction”. Science 309: 287–290. doi:10.1126/science.1111288. PMID 16002615.
Prideaux, G. J.; Long, J. A.; Ayliffe, L. K.; Hellstrom, J. C.; Pillans, B.; Boles, W. E.; Hutchinson, M. N.; Roberts, R. G.; Cupper, M. L.; Arnold, L. J.; Devine, P. D.; Warburton, N. M. (2007-01-25). “An arid-adapted middle Pleistocene vertebrate fauna from south-central Australia”. Nature 445 (7126): 422–425. doi:10.1038/nature05471. PMID 17251978.
Diamond, Jared (2008-08-13). “Palaeontology: The last giant kangaroo”. Nature 454 (7206): 835–836. doi:10.1038/454835a. PMID 18704074.
Turney, C. S. M.; Flannery, T. F.; Roberts, R. G.; et al. (2008-08-21). “Late-surviving megafauna in Tasmania, Australia, implicate human involvement in their extinction”. Proceedings of the National Academy of Sciences of the United States of America (NAS) 105 (34): 12150–12153. doi:10.1073/pnas.0801360105. PMC 2527880. PMID 18719103.
Roberts, R.; Jacobs, Z. (October 2008). “The Lost Giants of Tasmania”. Australasian Science 29 (9): 14–17.
Biello, D. (2012-03-22). “Big Kill, Not Big Chill, Finished Off Giant Kangaroos”. Scientific American news.
McGlone, M. (2012-03-23). “The Hunters Did It”. Science 335 (6075): 1452–1453. doi:10.1126/science.1220176.
Rule, S.; Brook, B. W.; Haberle, S. G.; Turney, C. S. M.; Kershaw, A. P. (2012-03-23). “The Aftermath of Megafaunal Extinction: Ecosystem Transformation in Pleistocene Australia”. Science 335 (6075): 1483–1486. doi:10.1126/science.1214261.
Earlier in this response column it was noted about telling direction of impacts by craters here is an explanation why that usually doesn’t happen. Only very low angle impacts which plunge into deep water may be slowed down. When a large mass of a hard material like silicate rock or iron hits the Earth the tremendous kinetic energy is converted into thermal energy at the end of its trajectory. This releases a vast amount of heat in a very small time, melting the rocks and vaporising the solid mass into a series of hot gasses such as CO2, water and silicate vapour. The process involves a rapid and enormous increase in volume, perhaps analogous to an underground nuclear detonation.
You can see clear evidence of this impact explosion mechanism for yourself if you look at the moon through a small telescope. The many thousands of asteroids and comets that have hit the moon over the last 4 billion years came in at every possible angle. If you imagine throwing stones into mud, the ones that hit at a grazing angle leave long elliptical indentations and it’s actually quite difficult to create a circular carter. However when you look at the moon, all the craters and basins are essentially perfect circles.
The explanation of this is that when an asteroid hits a planetary sized body, the initial crater (which may be elongated) is wiped out a few milliseconds later by the explosive release of kinetic energy. This explosion creates an essentially spherical impact feature. So all the craters on the moon are perfectly round despite the variety of impact angles. Same thing applies on earth.
Hi JIM: Very interesting, this seems a very plausible explanation and of course with earth having so many erosive processes it is all the more difficult to find all but the largest craters. Also, if striking ice as some of the Younger Dryas pieces may have done, even a greater problem to track. Rod Chilton.
A large impact from such a recent date would not have eroded away. Look at the relatively tiny, 50,000 year-old Meteor Crater, Arizona.
mysteryseeker January 12, 2015 at 3:34 pm
Yes, and oceanic impacts would be well nigh onto impossible to track, I’d think, but because our sphere is predominantly water, we should expect that most impacts will be into the seas. That being the case, we should expect to find some traces of these events.
I know from my own seat-of-the-pants experiments with soft-pellets fired into water that even low angle shots create a vertical spike, splashes fore and aft, and entirely circular concentric waves, or ripples.
I was wondering if Steve Garcia was going to turn up.
Judging by his rhetoric, I guess any day now we could be treated to the spectacle of a disbeliever in the Younger Dryas (YD) impact theory being beheaded live on YouTube. (Better keep my head down I guess..)
But talebanic aggressiveness about ones pet theory does not save it from being wrong, it if it wrong.
There is a problem with the YD. It doesn’t really exist in the strict sense. What is the YD? Take a look at the Greenland ice core temperature record of the last glacial cycle going back ~130 kyrs, courtesy of Bill Illis:
http://s18.postimg.org/4awjdwew9/New_Neem_Temps_vs_NGRIP_Antarctica.png
The YD is defined as the interval between the sharp warming episode called the Bolling-Allerod (BA), and the start of the Holocene about 1000 years later. But looking at the above ice core figure, it is clear that there is nothing at all unusual about the BA. The BA is simply one out of about 20 very short-lived sharp warming episodes that occurred during the previous glaciation. You could call these sharp spikes “micro-interglacials”. They have been quite well studied. It is remarkable that during full glaciation, global temperatures increased by up to 8C for periods as short as a few centuries. Then all the way back down to glacial.
This is classic behavior of a nonlinear unstable system that flips between two attractors. And the reason whyt this should be so is also well known. It is the AMOC (Atlantic Meridional Overturning Circulation) which contains an instability-inducing positive feedback based on salinity. Basically, the gulf stream carries saline water to the northeast Atlantic, and when this more saline water eventually cools around the Norwegian sea it becomes super-dense on account of its elevated salinity, and descends to form the North Atlantic bottom water, and the sinking of this is the driver of the AMOC. More gulf stream saline transport = more cold saline sinking water = more gulf stream etc. Now in the real world (in contrast to IPCC climate models) positive feedbacks don’t go on forever and destroy the universe – instead they sputter, starting and stopping intermittently. This is what is happening in the Greenland ice core record of North Hemisphere temperatures – they are sputtering up and down due to the bistable turning on and off of the AMOC. By contrast the southern hemisphere, lacking any equivalent of the AMOC, moves slowly and serenely between higher and lower temperatures. The contrast between the two hemispheres is striking.
So what is left to call the “YD”. It is just the interval between the last (of about 20) “micro-interglacials”, and the final interglacial which – due to changes in insolation – was able to hold on at the interglacial warm temperature plateau. The “YD” is just one of about 20 intervals between AMOC-driven nonlinear-unstable fluctuations in NH climate. Did every one of the 20 or so micro-interglacials terminate with its own impact event? No – probably none of them did. Impact theories are utterly redundant and unnecessary here. If you drop an apple it falls. We have gravity to explain this. No need to postulate that at the moment we drop the apple, by chance the earth is struck by a bolide making the apple seem to fall to the surface. No. Its just gravity. No other theory is needed.
The BA and “YD” are just business as usual for a glacial cycle with AMOC-driven bi-stability in the NH.