Study casts doubt on mammoth-killing cosmic impact

From UC-Davis:

asteroid-impact

This artist illustration shows an asteroid hitting the Earth. Credit: Don 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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joelobryan

“… the cool period, which fell between two major glaciations,…”
Wasn’t the end of the Y-D is considered the start of the Holocene.?

Good point. It should read something like “the cool period, which interrupted the gradual warming taking place at the end of the last Ice Age”, or something like that.

Francisco

I wonder if they will, eventually, disprove the asteroid theory and show somehow that CO2 raised over 400ppm and that is what killed the dinosaurs

milodonharlani

Francisco:
The Team has already tried to blame CO2 for past mass extinctions, including the Triassic-Jurassic event, which actually benefited dinosaurs at the expense of competing groups, & the previous Great Dying at the Permian-Triassic boundary, which enabled their early evolution. And the Carbonari Mafia also tend to prefer more late Mesozoic volcanic CO2 to or in addition to the Cretaceous-Tertiary mass extinction event impact hypothesis.
So your joke is sadly real.

the absence of evidence is not the evidence of absence

Ted Clayton

Actually recognizing the absence of evidence can reduce the likelihood of choosing an explanation for which there is actually no recognizable evidence.

RogueElement451

I cite , Sherlock Holmes , the dog that did not bark.

Ted Clayton

Indeed; Fitzroy Simpson was not the culprit.

Rick K

How does one sustain “intense fire and melting” in a mud-brick structure?
Look, I just ask the questions…

I guess you could set the roof on fire.

mebbe

Don’t forget the straw in the bricks!

Geoff Withnell

Mud brick is largely straw.

Thats not what I learned by reading “The Three Little Pigs”

The wolf’s oxygen input by huffing and puffing made the straw in the mud brick burn hot enough to melt silica? A wolf driven kiln? There’s a dirty panting joke in there somewhere I just can’t tease out.

Phlogiston

Sounds like a straw man argument.

Jeff Alberts

Just ask The Talking Heads.

ConTrari:
Something learned in engineering school in the late 60’s. Timber frame buildings will last longer in a fire than steel. The steel will deform and collapse. Big wood timbers char on the outside and prevent the interior wood from burning. Of course, you can’t build as big as steel and concrete, but one reason old wood buildings would survive. Not sure about today’s wood buildings with metal connectors though.

mikewaite

The Crystal Palace in London , built for the Great Exhibition of 1851 was constructed of glass and cast iron. It burned down , completely , 80 years later . Always wondered about that.

ConTrari

Must have been something combustible inside…iron will be disfigured at high temperatures, actuelly more so than solid wood structures.

looked that up – it had old, dried out timber flooring, plus it had been loaded up with flammable items. And of course, there was no such thing as a sprinkle system in those days.

Remember that our civilization is built on paper. It burns.

D.J. Hawkins

@wws
Perforated pipe sprinkler systems were being installed in the US by a predecessor to Grinnell in 1850; the concept originated in England in 1812. In 1812, the Theatre Royal was covered by such a system. In 1860 a patent was issued for the first fusible link device recognizable as a sprinkler.
So, had they chosen, the builders of The Crystal Palace could easily have installed or retrofitted a sprinkler system to provide fire protection.

george e. smith

Cast iron burns real gud if you have some oxygen around. IANAW but I have seen them cut big holes in iron with a “cutting torch”. Ordinary sparklers for Guy Fawkes Day, are just iron wire.
I once set fire to the iron alloy leads of a TO5 power transistor, by “overdissipating” it, till it got hot enough to torch the leads. It was an RCA transistor, and after it cooled down, the transistor chip inside the can was still perfectly good. That was circa 1963.
I had replaced a crummy Germanium transistor in a high Voltage power supply for a Tektronix transistorized oscilloscope (model 321 portable), with the RCA silicon one.
Unfortunately the RCA was also a good high frequency transistor, as well as high power compared to the Ge one.
So the transistor ignored the low frequency inductive coupling through the transformer ferrite core, and just used the air core coupling between the transformer windings, sans the core (the core was still there just being ignored at the high oscillator frequency it preferred.) Thing got so darn hot, the transistor leads caught fire, which also shut off the circuit. Shouldn’t meddle with things you don’t yet understand !!
Did get it working eventually, just by learning some things. I separated the feedback winding of the transformer, and stuck it on a separate leg of the ferrite core, so the only way it could oscillate was by using the magnetic coupling through the core, which forced it to run at the proper frequency.
g

george,
Interesting story, as usual. Thanks.

Aluminum burns really well – big fear for those aluminum frigates. When aluminum is more widely used in automobiles, we’ll see some really big sparkers. As for steel, it will burn as well in the right conditions.
http://www.airproducts.com/~/media/Files/PDF/industries/metals-discussion-steel-burning-oxygen-steelmaking-metallurgist-perspective.pdf
http://www.bbc.co.uk/bang/handson/steel_wool.shtml

milodonharlani

Wayn,
Already long a problem for aluminum helicopters, fixed wing aircraft, armored personnel carriers like M113 & infantry fighting vehicles lie Bradley.

Stephen Ricahrds

Wooden floors

beng1

Well, yeah, most any pure metal will burn, but it’s an issue of surface-area presented (toss steel-wool into a fire & watch). An aluminum strut will burn w/difficulty, but powder it & you’ve got solid-rocket fuel.

Rick K

My thanks to all here (and downthread) for related comments on this. Comments were funny, interesting and enlightening.
I’d write more but my back yard is on fire…
The grass roots are acting like straw!

Ernest Bush

Tar was used to line the vessels used to store liquids and food stuff. It may have been used in other ways. Also, some of the vessels would have been used to store cooking and lighting oil? Also, what others said to your question.

jorgekafkazar

Brick ovens of this type:
http://www.essenceoftheages.com/incienso/horno2.jpg
Fuel is continuously added. Eventually, the oven brick decomposes and the structure has to be replaced. An ordinary campfire might produce much the same effect if banked with soil.

Many of the houses had open areas. That region of the world was advanced in metallurgy.

rah

In many places in the world there are the remains of where they smelted Iron and then made steel most often identifiable by the slag from the process which was waste of no value. Charcoal was used to reach the temperatures necessary and to provide the carbon needed to create steel from iron. Some of these places are still recognizable in deserts and savannahs where man used up the trees for wood and changed the ecology. The fact is that back when Iron and then steel were made in those mud/brick ovens the operations to move to places where the wood fuel necessary for the process was available.

Alan the Brit

Interesting article that shows how things aren’t always melodramatic in life! I hate to be picky, but that artist’s impression, whilst very pretty, assumes a 90° impact to the Earth’s surface, an unlikely situation in practice, me thinks! Similarly, in whichever of those disaster movies (the one with Maximillian Schell is the one that springs to mind) in which a comet/asteroid collided with the Earth, the movie even showed the comet/asteroid passing at an angle in the atmosphere, yet when it impacted, the graphics special effects guys showed a similar impact explosion, whereas it should have shown the blast directed across the Atlantic toward Europe, with a likely smaller wave heading back toward America!

Geoff Withnell

Actually, simultions indicate that, except for extreme low angle impacts, the ecplosion is relatively symmetrical.

Ernest Bush

Meteor Crater in Arizona is probably an example of that.

Simulations? Models.
The final impact is probably modeled quite well, but not the passage through the atmosphere. Remember the Chelyabinsk meteorite, or the Columbia space shuttle.

Exactly right. Those simulations are backed up by actual crater counting on the Moon and other solar system celestial objects. Thus there is experimental evidence to back up these models. If you are interested in learning more google the name “Jay Melosh” who is one of the world experts in this field.

There’s Tunguska, which is supposed to be an airburst / glancing angle atmospheric event. NASA’s gas guns and Sandia Nat’l Labs also do quite a bit of high velocity impact testing and that data was used to build their models. You’ve got to know how that MIRV is going to act on re-entry or particle impacts on spacecraft.

tonyc

Alan, why are almost all of the craters on the moon round?

george e. smith

Because the moon’s surface is a diffuse reflecting surface, not a billiard table bumper.
The “hole in the ground” is not the hole that the projectile made on impact, it is the hole made by the resulting explosive cataclysm, and that is quite axi-symmetrical. Does anybody really know at what angle the pebble that created Meteor crater in Arizona, struck the surface. The hole is at least 100 times the diameter of the pebble that made it.
G
The light scattered off fresh snow, is total independent of the incident sun angle, at least up to the Brewster angle.

Alan the Brit

Good point! has big rethink on statement! 😉

The study area of Syria was associated with early agricultural settlements along the Euphrates River.
==============
why study an area that has been disturbed by settlements? If micro-diamonds and other impact objects were present in the area, they would be present in the undisturbed soils. by picking an area that was contaminated by settlements, the researchers cannot place any confidence in their results.

Ted Clayton

In this particular case & study, the researchers are confirming a hypothesis about spherule or scoria formation, from the burning of settlements (and perhaps other human-combustion processes in the same area). Besides, they probably already doubted that spherule-drift & deposition occurred over vast areas. Thirdly, there is real value in establishing the presence & pattern of such special settlements-deposits, since at the end of the Bronze Age an apocolyptic settlement-burning event terminated that cultural era and set the stage for the subsequent emergence of Classical Civilation, in Europe. Over 90% of settlements were burned aggressively in this single great social convulsion, about which most questions await answers.
But more generally, yes, absolutely, the way to check out the idea of an early Holocene asteroid/comet strike is to look for spherules etc in geological horizons away from known archaeological sites. Such as in bog & lake sediments, and in settings were wind-blown dusts are known to have been lain down & preserved (which discribes vast areas of Midwest USA). Yet, proponents of the YD impact themselves have consistently restricted their inspections to Clovis cultural sites … leaving themselves open to this counter-suggestion – and evidence – that actually the spherules could have resulted from human-activity.
Good point … but more a problem for supporters, than for critics.

Dang those pesky tectites.

Alan the Brit

@Rick K
January 7, 2015 at 5:57 am
How does one sustain “intense fire and melting” in a mud-brick structure?
Look, I just ask the questions…
Could it have been from the remnants of an early furnace for metal working? I would be surprised if an open domestic fire could produce sufficient heat to create the scoria!

How does one sustain “intense fire and melting” in a mud-brick structure?
=====================
Silicon dioxide
Melting point 1,600 to 1,725 °C (2,912 to 3,137 °F; 1,873 to 1,998 K)
http://en.wikipedia.org/wiki/Silicon_dioxide
The average house fire burns at a temperature of about 1,100 degrees Fahrenheit, which isn’t hot enough to destroy most metals and earthly-made substances. And if an item is well-placed and small in size, its chances of survival increase drastically.
http://www.live-safe.org/tag/fire-loss/

Ted Clayton

While silicon dioxide is a very common mineral, there are many others. Mud brick, adobe do contain SO2, but it serves mainly as a bulking-agent or filler, and is not the component that gives these structural materials their key properties.
Clays are essential to such bricks, and as exhibited in pottery and other fired materials, they sag and melt at much lower temperatures. A hot cooking oven will suffice for some pottery.
Fluxing agents and catalysts are critical in many pottery and metallurgical technologies. These serve to lower the melting temperature of minerals and metals. Ash from fires is a strong flux; burnt lime (bones & shells, and whitewashes for painting mud-daub walls) is used as a bulk fluxing agent. Fluxes (like lime itself) are often relatively soluble, and subsequently leach from materials they helped to form.
Salts are also strong fluxes, but they usually ‘damage’ a material intended to have structural properties. In Nature, though, any place that accumulates salts, such as arid lands or landlocked watersheds, will tend to exhibited the effects of salt-fluxing, under any kind of fire-regime. Salt-minerals also readily leach.

jorgekafkazar

SO₂ is a gas. You mean SiO₂.

Ted Clayton

I did mean SiO₂, thank you! And SO₂ is an actor in these processes, in its own right.

M Courtney

How does one distinguish house fires from lightening strikes?
They are both small and localised.
The debris from an astronomical impact should be far easier to distinguish without using settlement history.

Jeff Alberts

What’s a “lightening” strike? Please illuminate me. 😉

M Courtney

It’s like a lightning strike but misspelt.
Sigh, I’ll have to hand back my cheque from Big Oil now.

asybot

@M Courtney: is that check smaller then the postal stamp? do not insure the mail it’ll save some money!

jorgekafkazar

I like it. Lightning has explosive force that would distribute any molten materials over a much wider area than house fires.

Steve Lohr

Not so much. Actually lightning forms silica tubes in plain sand. I have also been told it causes erosion of rock which may eject material but I doubt very far. Struck trees may have portions of the wood explode outward apparently from the sudden generation of steam, but again not driven so far. A friend’s house was struck and he reported that everything that had a transformer in it exploded or burnt. I doubt that a mud hut would generate any sort of explosion. Earth with organic material,when struck, gets really hot as I have observed it directly, which could theoretically generate some molten material. It certainly has no problem starting fires.

Libyan desert glass (LDG), or great sand sea glass is a substance found in areas in the Libyan Desert. Fragments of desert glass can be found over large areas, up to tens of kilometers.
The origin of the glass is a controversial issue for the scientific community, with many evolving theories.
http://en.wikipedia.org/wiki/Libyan_desert_glass
add house fires to the list.

… but they’re never going to get as many theories as Trenberth’s missing heat has.

Ted Clayton

Very interesting deposits, these glasses in the Sahara! And some of them seem like rather pure silicon dioxide, which takes very high temps.
A problem is that ‘typically’, natural glasses are not especially durable, across geological spans (10s of millions years, as some say of Libyan etc desert-glass). But to the extend these are made from pure quartz sand, maybe that’s a different thing.
I favor unknown or unrecognized or sporadic/episodic lightning phenomena, as the source of these glasses (rather than a big ET strike) … but when the hostilities cool off, maybe we can get some effective investigation going on in this region.

jorgekafkazar

I like the theory that LDG is castings from giant sandworms…

Ted Clayton

Horsetail has this same metabolic faculty. Too bad we can’t get Frank on the Mars advisory board.

Interesting take and to expand on it. what happens to airborne silica sand during a lightning strike? Those plasma temps are certainly hot enough and that would also explain the distribution over a wide area. Might be an interesting avenue of research for a Master’s thesis (assuming no one’s done it.) I’d need to see the experimental data that says this can happen in “normal” fires with plant material as fuel… I don’t really buy that one.

The debris from an astronomical impact should be far easier to distinguish without using settlement history.
================
exactly. why use an area contaminated by human settlement? You might be seeing melted silica from pottery kilns and/or copper smelting. house fires are not hot enough to melt silica. to then jump to the conclusion that since these objects are the result of human activity, similar objects in areas where there are no settlements must also be a result of human activity is false logic.

Ted Clayton

Forget silica, it’s a white herring. 😉

Peter_S

Bronze smelting really only began around 2000BC, although in roughly the right area. Before that, even copper smelting started about 6000 years ago, with lead smelting (not hot enough anyway) possibly slightly before that, but not 12,900 years ago. Roof fires are a possibility, but probably not hot enough before they burn out. Simple fire pits are the most likely explanation, kept burning for long periods of time, possibly years, because fire was not easy to generate. The contents would be spread over the millennia.

pocketsponsor

@ Peter_S January 7, 2015 at 6:20 am
Bronze smelting really only began around 2000BC, although in roughly the right area. Before that, even copper smelting started about 6000 years ago, with lead smelting (not hot enough anyway) possibly slightly before that, but not 12,900 years ago.
Times are really changing Peter. History is being revised with all the new data… it is quite likely that smeling and metal work began over 12000 years agao. In the next 5 years you will hear more and more and the dates for the beginning of civilization will be pushed many thousands of years. It’s an exciting age we live in.
http://www.philipcoppens.com/gobekli.html

Archaeologically categorised as a site of the Pre-Pottery Neolithic A period (c. 9600–7300 BC), the world’s oldest temple sits in the early part of that era and so far has been carbon-dated to 9500 BC. It is the time-frame when Plato’s Atlantis civilisation is said to have disappeared. And it was built an incredible 5,000 years before the rise of what many consider to be the “oldest civilisation”, Sumer, not too far south of Göbekli Tepe as one goes down the River Euphrates and leaves the highlands of the Taurus Mountains in Turkey

The site of Çayönü also revealed the use of metals and the earliest evidence of the smelting of copper, though some nevertheless argue that the copper was originally cold-hammered rather than smelted. The use of copper should not come as a total surprise, as the site is within range of copper ore deposits (as well as obsidian) at Ergani in nearby Diyarbakir Province. And all of this in a site dated to 7500–6600 BC.

The past five decades have so radically reshaped our understanding of the period 10,000–4000 BC, specifically the level of “civilisation” our ancestors had achieved in those days, that this shouldn’t at all come as a surprise. And it seems that it’s a given that somewhere, even older towns are waiting to be uncovered.

http://www.dartmouth.edu/~toxmetal/toxic-metals/more-metals/copper-history.html

There is disagreement among archaeologists about the exact date and location of the first utilization of copper by humans. Archaeological evidence suggests that copper was first used between 8,000 and 5,000 B.C., most likely in the regions known now as Turkey, Iran, Iraq and — toward the end of that period — the Indian subcontinent. Archeologists have also found evidence of mining and annealing of the abundant native copper in the Upper Peninsula of Michigan in the United States dating back to 5,000 B.C.

pocketsponsor –
Do you happen to notice that all of those dates are at least 3,000 years AFTER the start of the Younger Dryas (which is also the start of the Holocene)?
No one here has picked up on the fact that none of this development – INCLUDING HOUSES – is at least 1,000 years after the Younger Dryas start?
You can’t burn houses 13,000 years ago if houses don’t exist yet.

one can imagine future archaeologists, digging up the remains of a modern city destroyed by nuclear war or comet impact. and finding large quantities of melted glass, they would conclude this was a result of intense heat of the buildings burning. from this they would then conclude that the melted glass in the Libyan desert must also be a result of human activity.

I have seen that conclusion in speculative history books. I did not know there was a mundane explanation. Now that I have seen one, house fires, etc. seem a more believable explanation than a prehistoric nuclear war.

Ted Clayton

Early nuclear bomb tests in Nevada etc, detonated on towers not very far off the ground, created layers of this often greenish glass on the ground surrounding the burst. People shortly made the connection with Saharan glasses … and the ancient or alien nuke war meme got started.
Depending on what the bomb was, and what the glassified soil was, it’s fairly easy to analyze the material and make – or break – a nuke fireball connection.
“Trinitite”, bomb-glass from New Mexico, acquired commercial value, for collectors. Some then made ‘fake’ Trinitite, but simple tests soon showed the difference, even when hoaxers included fairly elaborate ‘recipes’ of radioactive minerals, to make the stuff sound good under a Geiger counter.

Finn

How mud houses burn:
The hamlet in question, is a mixed hunter and farmers. By beeing farmers over generations, they have discovered that mixing the stalks from grain, reduces the need for mud in the bricks, it reduces both weight and drying time. Letting them build both faster and bigger structures.
Along the sides of the houses, straw or wood roofing would be built, to shade the ones slaughtering last nights kills. This has been done in the same place for generations, also blood from animals has been used to waterproof the straw/clay bricks also for generations. Adding fat and other organics to the brick mix.
Then a few years of unusual dry weather, the buildings dry up, in places the straw is all that holds the powdered clay/mud together.
Then the heard of some hunted animal return, there is a good hunt and a following feast. The wind blows some ambers onto the exposed straw. And the now, what was once a hamlet, but through generations have grown to a small village. Explosively erupts in flame, leaving only half told tales of angry animal gods and melted droplets of clay.
Repeat, repeat, repeat…

Jeff Alberts

Spelling isn’t your strong suit, is it.

u.k.(us)

Maybe English ain’t their first language ?
How does your Chinese, Arabic or Japanese translate ?
You do keep us on our toes though.

kenw

please contribute something of substance. this isn’t a spelling forum.

Ernest Bush

Grammar is Finn’s problem here and it is mostly because there are periods where commas belong and commas in strange places. There are no spelling problems at all. The problem could even be translation software. It doesn’t slow down the reading and we get a new perspective on the article. Save the wise cracks for Trolls.

you feel proud of that statement?

Hugh

When you educate yourself in a foreign language and take the pain of learning vocabulary, obscure grammatics and even more obscure spelling at age of ten or later (try yourself inflecting umtwana in plural, explain ablaut and umlaut, then maybe try classifying sibilants in modern Chinese), the last thing you want to hear is you are using translation software. Really.
English has certain difficult features. One is use of articles – but easy for most European language users. One is prepositions. It is easy to miss one or use a wrong one. Spelling is hard, but learnable. Pronunciation is harder than spelling – many learning English as a foreign language learn by writing and never quite learn how the words are said.
The easy part in English is its lack of inflection. Words like nonbespectacledly are not ruining life. It lacks complicated gender rules, like German (am Main, but an der Oder). It has only little posh exceptions like datum – data. The tonal structure is bearable and writing requires only little more letters than Romans used.

Lonie

The language police strike again .

jorgekafkazar

Close enough for climate work.

TedM

If the commenter is Finnish, as his screen name may suggest. then I think his English is remarkably good. No need for comments such as yours.

Phlogiston

Why would you need to “slaughter” a “kill”? It’s already dead. Just asking…

Ted Clayton

Yes … yes, even today, we have awful explosions in grain-elevators, big storage bins for harvested grains. The ‘fuel’ for these explosions is nothing but bits of organic chaff and grass-plant parts … but finely-divided, mixed with air, and ka-BOOOMMM.
“Conditions” for & of fires do count. Old-time mud-brick settlements had their liabilities … and at times their misfortunes would be truly spectacular. We have these unusual fires to thank, for a lot of unusual preservation contexts that thrill archaeologists, and students.

Jimbo

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,…..
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.

One study says that mammoths survived until 7,600 years ago.
http://www.livescience.com/9771-mammoths-alive-thought.html

Alan the Brit

My memory cells have rattled slightly. Was there not a BBC Horizon programme years back looking at the disappearing Mammoth issue, which concluded that they may have remained around until relatively recently, certainly in Siberia? Anyway, that was back in the day when the Horizon prog was a real science show! Sadly it has gone the way much of the BBC stuff has gone!

milodonharlani

Dwarf woollies survived on Wrangel Island off eastern Siberia until about 3600 years ago.
There is no evidence supporting an impact event as cause for the YD. Indeed there is no reason to look for an unusual cause in the first place, ie to reject null hypothesis, The YD was no different from the prior two Dryas events or the similar excursion c. 8200 years ago. The same patterns occur during other transitions from glacial to interglacial phases. The Dryases are also akin to Heinrich Events during glacial phases.

mogamboguru

The Ivory Tower at it’s best: Syria sits squarely on top of the list of regions in the world which were earliest in developing pottery and metallurgy and, afterwards, entertained both for thousands of years to come – therefore, it’s the LEAST suited area to base a model on studying naturally occurring siliceous scoria droplets on, because the samples taken thereare tainted with droplets of uncertain origin up to the brim. Just a little more knowledge in human history would have saved the University of California’s day with a snap. But nooooo…

Simple fire pits are the most likely explanation
============
the problem is generating a high enough temperature, which required the invention of something like the chimney or bellows to force air through the coals. a pit fire likely limits combustion by using up the available air. technology is required to feed air into the bottom of the pit. something like a mud brick tunnel built up the slope of a hill.

Just an engineer
Ted Clayton

… a pit fire likely limits combustion by using up the available air.

To make charcoal, place wood nicely in the pit (or just in a mound on the ground), and then cover it with a layer of soil and sod, and even a daubed layer of clay-mud. Now the heat cannot escape easily, and temperatures will rise very high, with only a small air-supply and a modest rate of combustion. ‘Bank’ the heat in … that’s the origin of the word ‘bank’ … build the mound against a bank, and cover it to hold in the heat.
The making of charcoal leads to occasional ‘accidents’, the result of which is often extreme temperatures … and fascinating new materials and substances to find in the cooled ash-heap.

mpainter

Cosmic impact, extinctions, etc. are strawmen erected for this inconsequential study to blow down. Not worth the attention of a gnat.

Taphonomic

The actual article is paywalled, but here is a link to the abstract:
http://www.sciencedirect.com/science/article/pii/S0305440314004403
Main thrust appears to be that the scoria droplets can form at modest temperatures below 1200 C.

ferd berple

Were the authors able to create scoria droplets from a brick straw fire?

ferd berple

sco·ri·a
/ˈskôrēə/
noun
noun: scoria; plural noun: scoriae
a cindery, vesicular basaltic lava, typically having a frothy texture.
slag separated from molten metal during smelting.

ferd berple

Scoria Substitutes
Where scoria is not available a lightweight aggregate can be produced by heating shale in a rotating kiln under controlled conditions. With the proper type of shale the material will have the properties, appearance and vesicles of scoria. It is sold under the name “expanded aggregate”, “expanded clay” or “grow rocks” and used for the same purposes as crushed scoria.
http://geology.com/rocks/scoria.shtml

Hell_Is_Like_Newark

Re-posting this link as it is relevant to the discussion:
https://cometstorm.wordpress.com/2011/04/27/a-different-kind-of-climate-catastrophe-2/
The author did a yeoman’s job of fleshing out his version of the impact hypothesis. I have issues with his ideas about impacts forming the Carolina Bays, but the rest I think he is on the right track with everything else.

Ted Clayton

I have issues with his ideas about impacts forming the Carolina Bays

Pragmatically, the Younger Dryas Impact Hypothesis IS the Carolina Bays Impact Hypothesis.
Look up ‘carolina bays’. Hundreds of thousands of oriented elliptical depressions & lakes, spread over a large quadrant of the eastern USA. This is a truly amazing phenomenon. Hair-raising, even. ‘What on earth are these things … are they even Earthly at all!?”
Carolina Bays fascination amped-up sensationally, with the advent of the airplane … whereupon the full scale & scope of the marvel leaped from academic armchairs to popular – and lurid – radio broadcast infotainment, etc.
And the very real Tunguska event … then the long-delayed expedition to the area, and the jaw-dropping National Geographic photographs. Carolina Bays speculation went ballistic.
For a time, in the 1930s and 40s, hardcore science got caught up in it, published positive & supportive articles. By WWII, though, academia had sussed it out sufficiently to know, “Whatever caused these things, it wasn’t a cosmic shotgun blast across the face of America. It wasn’t our mega-Tunguska, and icy comet fragmeting, gouging and then melting without a trace”.
Not everybody got the memo. Some angrily wadding it up and flung it back. Younsters at the time, became seasoned oldsters, in the 1970s and 1980s. They remembered very fondly, and they’d never really let it go.
Yes, Virginia, the Carolina Bays excitement does live on. It happen 12,900 years ago.

Hell_Is_Like_Newark

The author that I linked to theory is that the bays were formed by impacts of large blocks of ice. That ice was ejected when comet fragments exploded over the Laurentide ice sheet. I suspect the ice blocks would pretty much disintegrate from the various forced places on them as they hurtled through the atmosphere. I could be wrong though.

Ted Clayton

I suspect the ice blocks would pretty much disintegrate from the various forced places on them as they hurtled through the atmosphere. I could be wrong though.

Oh I think you’re right, and then some.
Yes, I did scan slowly down through Dennis Cox’ big climate page. I saved it; he put a lot of work into it, and it contains various good or interesting things.
Ice-chunk scenarios have a big problem, because ice for sure does lack the mechanical strength for this kind of ‘handling’; it can’t withstand high energy-loading, really of any form or kind. It ‘flows’, just under its own weight, even at 1 measly gee. Any shock-front sufficient to fling chunks 100s of miles, would utterly pulverize them; the powder will then melt, evaporate, and flash to an incandescent ball of glowing steam, all in one bat of the eye. Then the fireball quickly radiates most of the energy into space. Oops.
It would just look an appropriately sized thermonuclear burst, out in the middle of the Laurentide. A disintegrating incoming comet likewise just becomes major fire in the sky. A comet has to be big, in order to get down through the atmosphere, shedding plasma as it descends, but the bulk of it ‘punching through’. Big.
The recent revelation or underscore that even decently-strong solid rock cannot usually withstand atmospheric entry forces for long, puts ice-ideas in an even worse position than they already were. It just goes Boom.
====
There have long been suggestions that Chicxulub can be better-interpreted as a comet; smaller than the energy-equivalent asteroid, but moving very fast (as comets normally do). And it landed in 1,000′ deep continental shelf ocean. If so, then we’re talking about the Muthu of all steam-explosions, followed quickly by the Downpour of All Downpours… a million Niagara Falls ripping out the bedrock over a radius of 100s of miles (mostly just back into oceans) … setting up the Great Grandaddy of All Hurricanes … sucking IN its own ‘dust’-cloud, and water-stripping solids & chemicals back to the surface.
An ice-mediated Carolina Bays or Younger Dryas event suffers the same, much smaller, steam-explosion, radiative-cooling, condensation-catastrophe, self-cleansing dynamic. With significant amounts of ‘over-driven’ ice, we end up with a Beyond Biblical Flood. Forty Days And Forty Nights of torrential downpour, compressed into a matter of hours. And it’s cyclonic, pulling in rather than dispersing the debris-cloud.
The dust & spherules are washed out and carried down watershed flood-ways.
Things do go Bang, but if it starts with ice, it ends up as rain – big rain, fast & hard.

Dodgy Geezer

@Rick K
January 7, 2015 at 5:57 am
How does one sustain “intense fire and melting” in a mud-brick structure?
Look, I just ask the questions…
The king of Kadesh led a major revolt in Syria around 1500 BC. I suggest you ask some of the troops of Thutmose III….

ConTrari

They had a nice brew-up. A nice cuppa. That’s what soldiers do.

jorgekafkazar

Face the opening windward.

ConTrari

Another scientific theory gone bust. Happens all the time…in real science. But not in climate science, ’cause that just ain’t science.
Are there any outraged persons calling this new theory “asteroid denialism”? Well, there should be. Melted mud bricks, what kind of disaster is that? But no. People think, reflect, evaluate the evidence. What a stange, quiet world compared to the whirligig of climate debate.

GuarionexSandoval

There is a lot more evidence of something huge happening back then than scoria droplets. And though it does not support a comet impact, it does support the idea of something celestial and worldwide, given the millions of pictorial representations from all parts of the globe from that era, representations that demonstrate by foreshortening the latitude from which they were observed.

Pat

“and coincided with the extinction of mammoths and other great beasts”
Considering that about 50% of species over 70lbs and 100% of species over 2000lbs vanished, I’d say that was an understatement…

milodonharlani

Except that that isn´t what happened. Even modern scaled-down bison can weigh a lot more than a ton. And species which disappeared from the North American mainland survived the YD on other continents or islands. Human predation is a better hypothesis to explain the extinctions which did occur around that time.

Phil's Dad

So does this mean The Younger Dryas was man made?
/sarc

http://www.sciencedirect.com/science/article/pii/003358947790031X
I think the Gothenburg Magnetic Excursion in conjunction with very weak solar conditions could explain the Younger Dryas.

ferd berple

the Gothenburg Magnetic Excursion could also be evidence of an impact, affecting the relative rotation between the earth and the core, and thus the magnetic field.

Ernest Bush

Our grandchildren, if not ourselves, may very well get to document all the chaos a magnetic polar flip causes in detail. Perhaps things will be as drastic as they were at the beginning of the Younger Dryas. Already earth quakes and volcano eruptions seem to be on the increase, along with the acceleration of the movement of the poles.

ShrNfr

There is veritable impact on science in this report.

Duster

This article is interesting and all, but, they total failed to replicate the original studies. The “scoriae” they investigate is not the same materials cited as evidence of an impact event by Firestone and crew. As I personally have reservations about an impact triggering the Y-D, I find the “critical” studies like this one very irritating. They fail to investigate the actual kinds of evidence that were cited by either the original “impact” paper or the follow ups. That is, the presence of nanodiamonds, the presence of carbon microspherules, iron droplets and other materials that would indicate an actual impact. Instead, they are looking at debris from cultural layers, where they know they will find soot and other by-products of household fires, and then report that they did not find evidence of an impact. Worse they look at material that they know spans several millennia where evidence of the “event” would be constrained physically to a very specific stratum. Bad science is not constrained to climate science.

Bad science is not constrained to climate science.
and neither are bad skeptical tactics.

Duster –
Amen.
It goes deeper than that. The supposed building fires at 13,000 years ago are a full 1,000 years before the beginning of agriculture and 14000 years before the first settlements (according to Nat Geo). So the authors did not even check to see if houses or buildings even EXISTED. (They did not.)
Good catch on the switcheroo of the materials. Surovell in 2009 pulled the same switcheroo by sampling very thick stratum and sampling in different spots on the site. Then he concluded that he, also, could find no evidence of spikes in the materials. He couldn’t follow sampling protocols, and he blamed the YD impact people for being wrong – when in fact he would have failed junior high chemistry for such failures to follow lab methodology.

Alan Robertson

We have no idea of what caused this or that epic climate event in the planet’s history.
“…I’ll never worry
Why should I?
Its all gonna fade…
Still crazy clueless after all these years”
(apologies to Paul Simon)

Although this article is of interest, it is only focussing on one small part of the planet. There are so many other indicators from other parts of the world of what was very likely a huge cosmic encounter. This signalled the beginning of the Younger Dryas approximately 13,000 BP. See also the book “Sudden Cold an Examination of the Younger Dryas Cold Reversal.

milodonharlani

There are no valid indicators of a cosmic impact at that time.

You are welcome to your opinion.
Copernicus’ skeptics said there were no valid indicators that the Sun moved around the Earth.
Wegener’s skeptics said there were no valid indicators that continents move.
Until about 1810, scientists swore up and down that there were no valid indicators that rocks fall from the sky.

Alan the Brit

Harping back to my earlier post about the BBC’s Horizon science programme, they also did one around 15-20 years ago, (when it was a real science show) about cosmic impacts from asteroids & the like. The show suggested that there are 100s of potential collision bodies around the Earth. Once scientists had detected the remnants of an old crater, they seemed to have discovered many impact craters all around the Earth, & those were just the land based ones!

The count of potential collision bodies is up to over 1400. And their scan of the skies is only about 10% done.

ironicman

The guys over at The Cosmic Tusk will not be amused.

Oh, dude, I was so amused I didn’t know where to start ripping this apart. See below…
But first, see Duster’s comment above at January 7, 2015 at 11:12 am. He is not a CosmicTusk guy. And he has reservations, as he says, about such an impact. But he nails this paper to the wall.
Samplinging the wrong materials from the wrong microlocations means that all further discussion about those materials is a moot point. The YDIH skeptics have pulled this one before.
As Steve McIntyre often says, “You have to keep your eye on the pea.”
MY main thing is that I know how old agriculture and civilization are. They are not as old as 12,800 years ago. So discussions of “building earth” are absolutely ludicrous and ill-informed. Buildings didn’t exist 12,800 years ago, so building fires could not have occurred. You can’t burn what doesn’t exist yet.
The oldest buildings on Earth are at Gobekli Tepe, which is 12,000 years old. And what was Gobekli Tepe’s temple built of? Stone. BIG 1-piece stone columns (not totally unlike at Stonehenge) and stone in-filled walls.
Try burning a stone building sometime. It is KIND OF hard to get the fire going.
Try burning down Stonehenge.

Bruce Sanson

A possible mechanism for rapid warming out of the last ice-age then small rebound to cooler temperatures goes as follows. Arctic and Antarctic glaciers slowly grow out over open ocean. This crimps annual sea-ice build inhibiting deep water upwelling closer to the equator leading to less low cloud formation resulting in quite rapid warming. Eventually one or more major overhanging glaciers suffers catastrophic fracture opening a much greater area for annual ice build leading to a small period of cooling. What drives the initial warming is likely orbital parameters plus the fact that the earths received solar wind increases as the earths orbital inclination increases

Doug

Just wondering… If there was a major comet/asteroid impact that hit a glacial ice mass a mile or two thick how deep into the underlying earth might the penetration be and how much evidence as mentioned in the article would there actually be? Also, it seems like the heat energy from such an event would release a tremendous amount of moisture likely supersaturating the atmosphere of the whole planet. After this it rains, a LOT. Flood legends, 40 days and 40 nights of rain, quick frozen mammoth carcasses with green grass in their digestive tracts (far north snow instead of rain, LOTS of snow) all indicate something very big and unusual happened. Ancient myths and legends likely have some (if not a lot) of basis in actual events that have been distorted but not totally lost as the generations passed. Humans from 15,000 +/- years ago were just as capable as humans born today.

mysteryseeker

hi Milodonharlani: With due respect, there are many indicators of what many believe was a cosmic encounter with a comet (pieces of) 13,000 BP. They include carbon 14, beryllium 10, nitrates, ammonium, and the much touted nanodiamonds; still from a number of locations around the world. And many intriguing other features such as: extremely rapid onset of severe (almost glacial cold) in most of the world, (perhaps aside from Antarctica). And all of this fits well with what a number of astronomers including: Dr. William Napier, Dr. Victor Clube and Dr. Duncan Steel have postulated for years. Rod Chilton.

milodonharlani

None of those alleged indicators is valid. The long awaited nanodiamond isotopic analysis late last year showed no difference, although work continues. Also last year it was discovered that ET lonsdaleite is just a disordered form of ordinary diamond. At every turn the skeptics have been shown correct. But it seems that nothing stops the true believers & careerists, who just reformulate their hypothesis anew or attack the bearers of bad scientific news.
Both studies may be found here, although you,ll need to search for them:
http://cosmic.lifeform.org/

The nanodiamonds were not formed from ET material but from terrestrial material subjected to very high temperature and pressure induced by the impact, so the isotopic analysis is aimed at a strawman.

“None of those alleged indicators is valid.”
And yours is the only opinion that counts. You must have 97% consensus on that, I assume.
Thanks for informing us.

So what finished off the mammoths, then? Or are they still around somewhere?

milodonharlani

RoHa:
The mammoths weren´t killed off by the YD. They survived until 3600 years ago. What wiped out the last isolated survivors is subject to debate.
Mysteryseeker:
There are no valid indicators. All have been thoroughly debunked in detail, but the YDIH adherents just keep moving the goalposts.
Last year two more nails in the coffin were added, but the zombie hypothesis still staggers on. Lonsdaleite was found to be a disordered form of ordinary diamond. The eagerly awaited nanodiamond isotopic analysis preliminarily showed no difference in terrestrial & ET ratios, although work continues.
There is no reason to suppose that an impact caused the YD. It´s no different from other such climatic swings & the extinctions supposedly owing to it weren´t.

“the zombie hypothesis still staggers on.”
Zombie mammoths? We’re doomed!

u.k.(us)

Holy crap, all I want to do is de-fund the windmills.
Now you try to bury me in muck, mire and science.
It almost seems like you think our elected officials will listen 🙂

“Dense concentrations of mammoth bones, tusks, and teeth are also
found on remote Arctic islands. Obviously, today’s water barriers
were not always there.”
Or mammoths were excellent swimmers.

Phlogiston

Mods – the length limit of posts needs to be much shorter. We’re drowning in mammoth crap.
Folks reading with mobile phones especially iPhones could start sue-ing WordPress for RSI of the thumb.

Ted Clayton

Should that be Alan Dershowitz or Paul Cassell?
Or maybe Amanda’s implant?!

The thing that is being over looked is is the Younger Dryas is not a one time event. There were many abrupt dramatic swings 20000 to 10000 years ago probably due to the fact that the initial state of the climate was very close to glacial versus inter- glacial thresholds during that time .
The Oldest and Older Dryas were also periods of rapid climate change and there is no way all these climate changes were cosmic in origin.

A valid argument. One that is often given. The big swings actually goes back to nearly 50,000 years ago. So the YD advocates must explain those, also, in order for their lab results to be valid, right? With the silly skeptics papers like this one out there, no progress will be made toward looking past the forensics until those forensics are widely accepted. No work at all can be done yet to rectify the seeming discrepancy you point out. They can only jump one hurdle at a time. To address that one is to put the cart before the horse.
I myself can see ways around it. Are my ways valid? No, but they are reasonable/plausible, if even only to me right now.
Seriously, be aware of this:
If the YDIH is ever accepted widely – making a new paradigm in essence – many things will have to be re-interpreted – data, papers, evidence, ice cores, Bond events, Dansgaard-Oeschger events, climate change, extinctions of animals, and even uniformitarianism itself may be modified. That is not a full list.
As to those very rapid climate changes, let’s throw this at you:
[Wiki – Dansgaard-Oeschger events] “The processes behind the timing and amplitude of these events (as recorded in ice cores) are still unclear. The pattern in the Southern Hemisphere is different, with slow warming and much smaller temperature fluctuations. Indeed, the Vostok ice core was drilled before the Greenland cores, and the existence of Dansgaard–Oeschger events was not widely recognised until the Greenland (GRIP/GISP2) cores were done; after which there was some reexamination of the Vostok core to see if these events had somehow been “missed”.[verification needed]
A closeup near 40 kyr BP, showing reproducibility between cores.
The events appear to reflect changes in the North Atlantic ocean circulation, perhaps triggered by an influx of fresh water.”

…”The ice core’s signals now recognised as Dansgaard–Oeschger events are, in retrospect, visible in the original GISP core, as well as the Camp Century Greenland core.[15] But at the time the ice cores were made, their significance was noted but not widely appreciated. Dansgaard et al. (AGU geophysical monograph 33, 1985) note their existence in the GRIP core as “violent oscillations” in the δ18O signal, and that they appear to correlate to events in the previous Camp Century core 1 400 km away, thus providing evidence for their corresponding to widespread climatic anomalies (with only the Camp Century core, they could have been local fluctuations). Dansgaard et al. speculate that these may be related to quasi-stationary modes of the atmosphere-ocean system.
The YD is the only one of those “violent oscillations” that has been seen to actually make consequential changes to the climate. The “Dryas” part applies to the change in climate in Sweden that was illustrated by the dryas plant, a tundra plant. It wasn’t there and then it was. Twice – in the older Drays and then again in the Younger Dras.
Our evidence IS mostly the ice cores, for the violent nature of the swings – but how big were they, really? All of them?
And are multiple meteor strikes within that 50,000 years out of the question? Not according to some astronomers. Ever heard of the 8.2Kya event? It’s in Wiki. Was it an impact of a lesser nature? How about the 536 AD event? Were there more? Ever heard of the Taurids? (Tungska seesm to perhaps have been one.) Encke’s comet?
Why are Bond events so regular? As were D-O events? And the same length of spacing – one in the Pleistocene and one in the Holocene. Nothing on Earth has been identified as having a 1470-year cycle. Could it be meteors?
Whatever your answer, are you SURE?
I am not. I don’t know the answers. But at least I am looking and encouraging others to look.

Nice picture though!

Steve O

There’s only one theory that I know of that explains the mammoth findings — the one put forward by Immanuel Velikovsky. Remember, there have been findings of mammoth with “fresh” meat, and individuals preserved well enough to determine that they fed on tropical flowers.
For this to happen, the climate needs to change from being temperate to being frozen quickly enough that the stomach contents of these large animals do not complete their digestion. And then they need to remain frozen into the present day.

mysteryseeker

I wish to stress that the onset of the Younger Dryas was likely as rapid as one year or two (there are references ) and the severity of the Younger Dryas though interrupted at times throughout the 1300 year long interval, was extremely cold, up to 15 degrees Celsius in Greenland and almost as much in Western Europe. This was much more extreme than either the Older or Oldest Dryas. I am not certain that Dr. Richard Firestone would be a quick to give up the nanodiamond proxy.

milodonharlani

That would require him to give up on a long career or crusade.
The YD was also more pronounced than the following 8.2K event but not than many of the similar cold snaps in the previous geologic record. There is no need for special pleading in its case. To the extent that it was more pronounced, ice melt conditions adequately explain its observed character.

“That would require him to give up on a long career or crusade.”
You are amazingly ill-informed. Firestone has almost completely dropped off them map on the YDIH. There is no indication that he has done a paper on it since about 2009.
Not much of a crusade – 2 papers and a book…

There were events greater then the Younger Dryas according to the data I just sent.

Actually, dude, if you are talking about that WUWT post link, if you look at the GISP temperature graph (Figure 2), you are mistaken.
The start of the YD shows a 9°C drop in temps – the largest drop on the graph, as well as the most sudden. If you are talking about the entire YD stadial, that is not what the YD impact Hypothesis is addressing. It only addresses the onset. The end of the Younger Dryas or the end of the Older Dryas are other issues altogether.
Confusing the two as one issue is like confusing a gas pedal and a brake, and arguing that what one does is tied to the other, and that the explanation of one is necessarily tied to the explanation of the other.

mysteryseeker

Hi again Mildonharlani and also Salvatore Del Parte: It just so happens that the 8,200 BP interval though mostly less severe than the YD, did have an even more severe drought in Africa for instance. Also, I would ask of Salvatore, what other intervals had more a more severe climate in the last 15,000 years or so? I do not believe there were any.. Finally, what would you both suggest was the cause of the Younger Dryas and the 8200 BP intervals? Surely not the outmoded slowing of the North Atlantic Ocean Circulation. Rod Chilton.

milodonharlani

Rod,
The entire, thousands of years long Last Glacial Maximum was colder than the YD, as were Heinrich Events, which have similar traits & probably causes to the rapid cooling events during transitions from glacial to interglacial phases.
I don´t know what you suppose is outdated about the well supported explanation for the YD & similar events, but the effect of fresh meltwater on thermohaline circulation is still the leading hypothesis, with abundant good reason:
http://www.ncdc.noaa.gov/paleo/abrupt/data4.html

So what if there were warmere or colder periods than the YD stadial? The issue isn’t max or min. The issue is the suddenness and the degree of drop – and what possibly could have caused such a sudden and severe change.
Look, dude, Firestone didn’t invent the Younger Dryas. The biologists did. And he wasn’t looking to solve it. He is an isotopes guy at Lawrence Berkeley. Lots of other people got involved, and now Firestone is hardly a blip on the map anymore.
If you think the climate was the cause, why do you think there are other people out there suggesting other solutions? Because the climate thing by itself doesn’t do it. They are all smart dudes, the climate guys and the impact guys. But none of them has won the day yet. So it is still an open question.
Why does only the impact idea get slammed in the popular science press? Ask that one some time.

Exactly, on the 8.2 kya event. Good get.

mysteryseeker

Hi Milodonharlani: I agree that the LGM was colder as were similar Glacial periods prior to the last one, and yes there were considerably longer as well. However, the Heinrich event were not as cold nor as widespread as the YD. Oh and I think the subject of the North Atlantic should be well and truly dead. If you wish to see what an expert, oceanographer, Dr. Carl Wunsch states about this check his website out. Rod Chilton..

milodonharlani

Heinrich events were colder. as they occurred during the glacial phase, including at both ends of the LGM. Most of the roughly 100K years of the last glaciation were colder than the YD, as of course too were prior glaciations. The YD was nothing special at all & needs no special explanation. It´s just another ordinary fluctuation in climatic cycles.
http://en.wikipedia.org/wiki/Heinrich_event#mediaviewer/File:Heinrich-events.png
Dunno what part of Wunsch{s work you have in mind. Maybe his thoughts on D-O cycles or his modeling of deep ocean circulation? Both predate my NOAA link. Please be more specific. Thanks.

“The YD was nothing special at all & needs no special explanation.”
Once again, it wasn’t any impact people who started the buzz about the Younger Dryas. It was the biologists. Then the climatologists. THOSE are the people who say this statement is wrong. They know something weird and big and unexplained happened.
“It´s just another ordinary fluctuation in climatic cycles.”
If you base that on solely the Greenland ice cores, don’t. The southern record shows much smaller ups and down. What was the overall Younger Dryas effect? We can’t go by 3 ice roes in Greenland and extrapolate the whole globe off them, not without some other sources that agree on both the timing and the magnitude. And those don’t exist at present, so you can’t say what you said and expect it to be true.

Bill Illis

One issue which is not discussed that much is that, when the glaciers started melting, the water outflow expanded lakes by 100s of kms and made every major river flowing south/west/east to the sea, about 100 times bigger.
Any species that did not have a boat (all of them that is except us and maybe the polar bears) could NOT (and NOT is 100% true in this case) ford the Mississippi River started about 13,000 years ago and ending about 7,000 years ago. If a Mammoth herd decided to try to cross the Mississippi at 11,900 years ago, they were all doomed.
All the large animals that migrated to some extent, faced this dillemma from 13,000 years ago to 7,000 years ago. Do we go back or do we attempt to swim for it. The Lake is still rising and we are stuck on this island. Do we make a swim for it. Our herd has always crossed this river in June but now it looks twice as fast. Do we swim for it. These decisions were faced at least every week. Entire herds of every large migrating animal were wiped out on a regular basis by just trying to swim for it.
The reproductive capacity of large animals is not high enough to compensate for these “doomed swim for it” deaths.
In addition, most of the large animals were, in fact, large herbivores living on grass. As the ice ages ended, the extent of grassland reduced by something like 2000%. The large animals needed to migrate more to find what they were looking for. Some of them, like the Mastodon, were small brush leaf eaters but they needed an extensive expanse of small bushy plants to sustain themselves and as larger trees recovered during the ice age melting, they disappeared.
Now throw in human hunters with atlatls and cliff jumps, whereby whole herds could be killed off so that hunter gatherers could obtain 1/10th of the herd’s meat to keep them well-stocked for a few months (note that a hunter-gatherer society is consistently experiencing periods when they are going to sleep without eating ANYTHING in the day and they would not really care if they killed off 10 times more animals than they needed to in order to eliminate that night-time hunger for a few weeks – I dare you to not eat anything tomorrow), well, that helped lead to extinction of all the large animals.
Glaciers melting, water everywhere, human cliff jumps, hunter-gatherers deciding that over-kill is better than hungry nights, that is all that is needed to wipe out several dozen species of large animals.

milodonharlani

The human hunters are what made the Holocene different from prior interglacial transitions.

Ted Clayton

Early Holocene humans were spread very thin across the North American landscape. The picture of their somehow prodigious food-consumption driving an extinction crisis is hard to bring into focus.
Mammoth and mastodon hunt-remains are disproportionally in bogs, which are a great danger for very large beasts. Local humans ‘improved’ their local wetlands, and ‘managed’ trails around them. When a beast was found in their area, they would drive it along ‘fenced’ trails, and onto the soft ground that was camouflaged. Their weight then doomed them; just wait a few days.
To ‘track down’, chase & spear or shoot an elephant with arrows is a very dicey proposition … and I propose that it was uncommon and abnormal, until eg after domestication of the horse. Dogs are not effective against elephants. Sharp sticks are too puny … elephants are quite fast, and display awe-inspiring fury. They’ll kill human tormentors very dead, out on open ground.
How come elephants are not extinct in Africa or Asian?
What could one do with an elephant-carcass, a long ways from their living site? Very, very little. Even a modern deer-hunter knows to resist that good-looking buck … way down the hill in a deep draw, or at the end of long, brushy hike from her vehicle.
No … mammoths and other large, mobile beasts are unlikely to have been unduly pressured by early Holocene humans. Something else undercut them.

milodonharlani

Paleo-Americans didn´t use arrows but atlatl darts tipped with Clovis points.
Human predation was sufficient to wipe out large species over time when they were already subject to the sorts of pressuress described so well by Bill. It doesn´t take much, as witnessed by extinctions elsewhere when humans invade continents or islands with naive prey populations.
Humans and elephants evolved together in Africa. Mammoths (and mastodons, which aren´t technically elephants) in North America were not used to human predation so fell as easy prey.

Ted Clayton

Humans and elephants evolved together in Africa. Mammoths (and mastodons, which aren´t technically elephants) in North America were not used to human predation so fell as easy prey.

Species subject to predation do not have to evolve with particular predator-species to recognize predation-behavior by them, and exhibit the typical stimulus-response (prey avoids, flees from anything that acts predatory).
North American game-species did not recognize humans as predators when they first showed up, but they recognized predation-behavior by them, instantly, and adjusted their perceptions of humans, promptly.
North American deer did not evolve with firearms, but today they recognize ‘hunting season’ with the first fall rifle-shots in the woods. They then become very much more difficult to locate. Many game-populations are ‘introduced’ to firearms, unawares & naive … but every populations of every species ‘figures out’ what guns mean and how to respond to them, promptly.
No, the first Americans got exactly one free shot at the naive big-game, and then they wised up in a hurry. ALL of these animals were heavily predated, continuously, and they all reacted to the behavior, not the species.

milodonharlani

Adult mammoths were not subject to predation. Saber tooth cats &npossibly lions & short faced bears may have preyed upon babies, but only at great risk.
Mammoths were not used to the hunting practices of people, such as stampeding them into bogs or off cliffs. Humans killed off the cows & calves, then moved on to new areas with still naive populations.
Deer, elk & even pheasants, whose lives are short, soon learn to gang up & find relative safety from hunters with fire arms, but deer were not wiped out by the Clovis people- Less adaptable bigger game with longer gestation periods. for whom hiding cover is harder or impossible to find´& more specific feeding needs however were.
The evidence of oceanic islands, Australia & New Zealand show what human predation can do, ie cause extinction of large prey species.

Ted Clayton

Adult mammoths were not subject to predation. Saber tooth cats &npossibly lions & short faced bears may have preyed upon babies, but only at great risk. [emph. added]
It would be no less risky for humans to mess with mammoths, than it was for carnivores. They will wheel & turn on a threat, from any species. “Panic & run into the bog, my hind foot! I’ll trample you to a grease-spot, instead!” Paraphrasing.
Predators as a rule do try to pick on the young, weak and old. That this would also be the case with mammoths, wouldn’t materially qualify their status as prey.
‘Traditionally’, saber-tooths were presumed to live high on the megafaunal hog, including (if not ‘especially’) mammoths. Lately, another interpretation aims to make the case that hyper-canines are (perhaps counter-intuitively) not about hyper-big prey. Instead, this adaptation expresses & supports a fundamentally divergent hunting-technique (kill-method), which was applied to normal-sized prey. This newer take on the saber-functionality would (if true) free megafauna from a ‘dedicated’ predator (and promote the ‘not subject to predation‘ position).
Exaggerated canines have been repeatedly revisited, across evolution. Eocene-Pleistocene sabers are sported by a large variety of animals, presumably occupying a comparable variety of niches.
However, if saber-tooths were able to get along fine on common prey, their own subsequent extinction then becomes harder to explain. Average-size prey-species are the ones that made it through the extinction-event. Normally, saber tooth tigers are said to have died out, because the megafauna they were specialized for & dependent upon, die out.
Ultimately, extinction, like climate change, is a pervasive fact of Nature … and nailing down either general or specific causes looks like a work in progress.

Damn, Ted, I can’t believe it, but for once I agree with you. Those have been my arguments since the first time I heard the Overkill theory. How DUMB s it to kill an elephant or mammoth when you can’t eat it all nor take it all back with you. Better to hunt stuff you CAN take back.
Also, if you look at the distribution of Clovis sites around N AMerica, you quickly see what they don’t tell you with the Beringia idea, (whether right or wrong about that). What do you see? The vast majority of Clovis sites are in the US Southeast, south of the Ohio River and east of the Mississippi.
There are also only 11 Clovis sites that are also demonstrated mammoth or mastodon kill sites. NONE of those are in the US Southeast.
What does it mean? Nothing conclusive, except that the Overkill Theory may need some considerable reworking.

Ted Clayton

Yeah, though the original concept had that piquancy and free-thinking irreverence we like so well (wut? Indians not eco-geniuses? oh no!), once it gets suited-up and enters the octagon of real hypothesis-competition, it comes up a rookie.
It’s an eye-roller, every time someone trots out the ‘buffalo jump’ as instrumental in continent-wide extinctions. Such jumps are notable & memorable, owing in large part to their scarcity. And what will an isolated 11-person hunter-gatherer group do with 100 tons of rotting buffalo? How does such a spectacle increase their fitness?
Bogs; same kinds of limitations-issues, particularly in the temperate zone. Many parts of the country lacked bogs. In some big regions that had them, the terrain & vegetation-cover worked against using the soft ground as a trap. Bog-traps need favorable & cooperative surroundings; by no means will just any ol’ muck-hole do.
Getting a decently-situated bog to actually work, virtually always takes a lot of work, improvements. There is recurring, twice-a-year upkeep, and there is material preparation to be done. Fire (smoke) would be the most efficient & effective driver, and this requires cached fuel, known & prepared fire-sets, and intimate knowledge of the routes between all the action-points & support-resources.
Yes … in fact it does not take much of a pit-fall to gravely injure an elephant. Just a couple yards tumble, and we’re talking a megafauna critter in big trouble. The ‘pit’ does not have to ‘contain’ the (mega-)animal – ‘the damage is done’, just by the fall. Even an unexpected drop of only 2 or 3 feet can easily mean a lame or crippled beast. Horse riders live in fear of mere gopher-holes.
And local bogs, once ‘tuned up’, give evidence of having been recurring game-getters.
===
Whenever & wherever there is a persistent “mystery”, there is the chronic temptation to step into the vacuum and offer a resolution … and (er, because) there is always an audience for such efforts. Extinction is a huge mystery … and a huge fact of Life.
There is an archaeological trend, toward greater status for, more widespread use of, and earlier occurrence of the ‘landscape game-fence’. Usually, these are not impervious barriers, but are erected as ‘suggestions’ to ‘prompt’ path-selection by (usually) migratory animals. Such fences sometimes ran for impressive distances, and incorporated very clever landscape-integration devices. While these fences would reduce the outlay involved in harvesting animals, they also plainly point to major investment & commitment which then tied groups & cultures to their particular locale.
In order to have exterminated many species of megafauna, aboriginals would have had to journey deep into the refugia of such types of wildlife, making it their priority to seek scarce sorts of game, even while ignoring easier solutions to their grocery-needs. Growing signs of increasingly important fences, at earlier dates, suggests that the Paleoindians of America settled more quickly & comfortably into homebody-mode than formerly assumed, and were thus not the type to press deep into unfamiliar habitat, ‘on some wild-elephant-chase’.

Phlogiston

(Reposted from an earlier nano diamond thread):
phlogiston on August 30, 2014 at 5:32 am
The Bolling-Allerod (Northern hemisphere warming at 14,600 yrs ago) and Younger Dryas (subsequent 1000 yr cold interval) were parts of the last deglaciation which were driven by oceanographic processes. There is no need for an atmospheric deus ex machina. Over the deglaciation starting as early as 22yrs ago the general picture is steady changes in Antarctica contrasting with unstable fluctuations in the NH driven by the Atlantic Meridional Overturning Circulation (AMOC). The root cause of this is an instability in the AMOC arising from a positive feedback which it possesses.
Cold water formation and downwelling in the Norwegian sea drives the gulf stream – reactive flow of Carribean warm and – critically – saline water across the Atlantic to north west Europe. This gulf stream water has high salinity, and this makes the cold water formed in the Norwegian sea even more dense than would result from its temperature alone. So this cold and saline water sinks all the way to the Atlantic floor and is one of the principal drivers of the global thermo haline circulation (THC). Now more of this “deep water formation” at the Norwegian sea actually speeds up the gulf stream – something has to replace all that sinking cold super-salty water so this is supplied by the gulf stream. Thus the positive feedback – more gulf stream leads to more cold supersaline Norwegian sea downwelling leading to more gulf stream etc.. Where you have a positive feedback in the system you have the conditions for nonlinear oscillation. This is directly analogous to the ENSO in the Pacific, the positive feedback of the Bjerknes mechanism (cold upwelling strengthens trade winds strengthening cole upwelling etc.) giving rise to the ENSO nonlinear oscillator, although the AMOC operates over much longer – century and millenial – timescales than ENSO (decadal).
So a basic oceanographic feature comparing the NH with the SH in the palaeo record is more fluctuation and instability in the NH and more stable, gradual changes in the SH. The nonlinear instability of the AMOC is the root of this. Also, there is a clear signature of interhemispheric bipolar seesawing, whereby when the NH moves in one direction, the SH moves in another. This is not universal however – sometimes at the moments of biggest transition, NH and SH move together.
About 22 kYa (thousand years ago) Antarctica started warming. The NH at the same time slightly cooled. However at about 14 kYa the “Bolling-Allerod” (BA) happened, i.e. the NH abruptly warmed, as evidenced by Greenland cores. This caused a reciprocal pause and slight reversal in the (already long established) gradual Antarctic warming – the bipolar seesaw again. At the time of the BA there was a sharp rise in global sea level – 20 meters in 500 years. Weaver et al 2003 (link below) show that this was caused by a collapse of the gradually warming Antarctic ice sheet. The pulse of fresh meltwater from Antarctica had the effect of speeding up the AMOC and the gulf stream in the NH, bringing rapid warming to the NH and the BA.
The bipolar seesaw continued – as the NH became sharply warmer, there followed in the SH the “Antrctic reversal” where temperatures went slightly into decline. However down in the deep ocean, interactions between cold bottom water formed in the Antarctic and Arctic caused – about a thousand years later – an abrupt stoppage of the AMOC and the gulf stream. In fact the cuplrit was Antarctic Intermediate water (AAIW) – see again Weaver et al. With the interruption of the gulf stream the NH went cold again – the Younger Dryas. In response – by now you get the picture – the Antarctic turned to gradual warming. After about 1000 years of NH cold with no gulf stream, the effect of the Antarctic collapse subsided allowing the AMOC and the gulf stream to resume. Now followed an exception to the bipolar seesaw – both NH and SH warmed together, around 12 kYa. This marked the final end of the last glacial and the Beginning of the Holocene.
http://rockbox.rutgers.edu/~jdwright/GlobalChange/Weaveretal_Science_2007.pdf
http://epic.awi.de/15280/1/Lam2004a.pdf

DesertYote

I have been wondering for awhile what the affects of the changing sea level had on the thermal haline?

Not surprising
Like Global Warming, the Asteroid Dino hypothesis gained popularity not through evidence (there’s very little) but due to politics. Basically it’s message was “Nuclear Winter Killed the Dinos so Just Think What Will Happen to Your Children So We Must Stop Reagan!!”
After the cold war ended it stayed around because of it’s Hollywood coolness factor, the Dinos are near & dear to our hearts and going out in a bang seems like a fitting end.
Now they go for comets wiping out the Ice age mammals because it fits with the Liberal Noble Savage Myth. It hurts the Liberals sensibilities that “Noble and pure” ancient man drove all those animals extinct. So they invented Comets & Asteroids to do the trick instead.
Some Hypothesizes have 5 or 6 different comets hitting to explain all the extinctions, which is just the same as more & more epicycles
An Asteroid killed the Dinosaurs and later one killed the Mammoth Scientists are almost as bad as the alarmist.
Here’s as extreme example
This study found that Iridium is missing from the Chicxulub crater itself!!!!!
http://www.lpi.usra.edu/meetings/lpsc2003/pdf/1811.pdf
So the question is how can an Asteroid or whatever that caused the Chicxulub crater produce a iridium spike around the world when it didn’t contain iridium?
The findings in that report clearly show that whatever happened at Chicxulub has nothing to do with the K-T yet the scientist(s) refuses to even consider the possibility, They even say so in the paper, Quote from the conclusion “If we exclude the extremely implausible assumption that the K/T boundary is not related to the Chicxulub impact event”. That is just poor science and sounds like the alarmist, You can’t just exclude evidence you don’t like.

milodonharlani

The nuclear winter scientivist scam came after the K-T impact hypothesis, not before it.
The authors of the study you cite plainly do not agree with your conclusion. Evidence in favor of the impact hypothesis for that mass extinction event is overwhelming. OTOH, there is no valid evidence in support of a YD impact, not even a crater.

Ken L.

Nanodiamonds and the Younger Dryas extinction, Aug. 28,2014:
http://www.news.ucsb.edu/2014/014368/nanodiamonds-are-forever

Stephen Ricahrds

It’s worth reading some of the russian discoveries of mamoths. Some have been found with food still in their stomachs and more recently, recoverable blood.
Then think how cold it would have to be to stop internal decomposition almost instantly.

Ted Clayton

It doesn’t have to happen instantly. Normal subarctic cold will do the trick fine.
The wetlands and boglands and swamplands of the high north are vast, and they are also by far the richest grazing and browsing habitat. But mammoths cannot venture onto such soft & ‘bottomless’ conditions, until winter has frozen them rather deep.
There was always pressure to return to the winter feeding-grounds, as early as possible, and this itself claimed many, many hairy elephants. Some bogs & pools are warmed by decomposition, and will be froze-over only thinly, compared to surrounding sites. Deeper snowfalls, which are not the norm in these arid regions, would make it very treacherous for the big animals, being then unable to properly assess ground-conditions by sight, before stepping on it.
Even moose, caribou, buffalo and elk have these problems. In the USA, we’ve had a herd of 21 elk drown after breaking through the ice, in Colorado, just in the last couple weeks.
That’s how mammoths are ‘frozen in their tracks’, with undigested food in them.

Rhoda R

Thank you. That is the best explanation for the frozen-food-in-stomach aspect of the Mammoths that I’ve heard.

Ted Clayton

Thanks for the nice words! Yeah, there’s a bunch of oddities grown up around ‘instantly-frozen’ mammoths. They are found standing, even running, ‘frozen in place’, because they were trapped, struggling in ‘quicksand’. Even a small mammal, even dipped in liquid air, would collapse and thrash some, before it froze completely stiff … won’t appear ‘life-like’, but will ‘look dead’.
Air itself will rain & snow out before it can get cold enough do what they showed in Day After Tomorrow (people frozen rigid in mid-movement) … and still couldn’t do it that fast.
Cold doesn’t ‘go in’, heat has to ‘come out’; move, flow. Fourier made his mark with The Analytic Theory of Heat neigh 200 years ago, and we name the Fourier Series and Fourier Transform in recognition of his breakthroughs on the movement of heat.
Salad will last quite a few days in an ordinary fridge, still presentable. There’s no problem with food in a mammoth’s mouth or stomach not rotting away in the subarctic chill. We can even accurately identify Ice Man’s last meal, in the Temperate Alps.
Yer local home-construction contractor (who has to meet insulation standards & regs) has more heat-transfer acumen under her little fingernail, than these guys using mammoth ice-statues to argue eg for preternatural pole-flipping effects, etc. 😉

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.

Phlogiston point 4 does not support your theory which you presented above.
What can we learn from all of this?
(1) The ice core isotope data were hugely significant because they showed that the Younger Dryas, as well as the other late Pleistocene warming and cooling events, could not possibly be caused by human emissions of CO2 because they occurred thousands of years before such emissions had any effect on atmospheric CO2.
(2) The magnitude and intensity of multiple climatic fluctuations has been up to 20 times larger than warming during the past century.
(3) Single events, i.e., volcanic activity or cosmic impacts, cannot have caused the abrupt Dansgaard/Oerscher warming and cooling events because of the multiplicity of warm/cold events over periods of thousands of years.
(4) The absence of a time lag between the N and S Hemisphere glacial fluctuations precludes an oceanic cause and is not consistent with the North Atlantic Deep Ocean Water hypothesis for the cause of the Younger Dryas.
(5) The abruptness of the climate changes and their multiplicity could not have been caused by slow, Croll-Milankovitch orbital forcing