In June 1908, an explosion rocked a remote, swampy area in central Siberia, in Russia; it came to be known as the "Tunguska event." A later expedition to the site found that 20 miles of trees had been knocked down and set alight by the blast. And today, it is understood that Tunguska's devastation was caused by a 100-foot asteroid that had entered Earth's atmosphere, causing an airburst.
Some 13,000 years earlier, just after the end of the last ice age, the Earth's climate had begun to warm up to temperatures like we enjoy today, when an occurrence thought by some researchers to be an extraterrestrial impact set off an "impact winter". And caused a return to ice age conditions that lasted another thousand years, or so. The "Younger Dryas event," as it is known, coincided with the end of the prehistoric Clovis culture. And the mass extinction of almost all of the giant animals that lived on North America at the time.
Before the Younger Dryas event, much of north America had an ecology similar to what we see today in the lush African savanna. And after the YD event more then 35 genera had vanished. The giant sloth, short faced bear, dire wolves, saber toothed cats, a species of camel, horses, and two species of elephant were wiped out by the YD event. And that's just the short list. All of that astonishing biodiversity was blown away.
Perhaps the single most important paper on the subject of the Younger Dryas, is the 2007 paper by R.B. Firestone et al, and titled: Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling.
In that paper, a team of twenty six scientists, studying sedimentary deposits presented a whole suite of compelling evidence for a massive impact event of a comet that appears to have broken up, and scattered, fragments all across North America. The multiple, air bursts are thought to have triggered wide spread bio mass burning on a continental scale. As well as causing a return to ice age conditions, and the extinction of many species. Including the mega fauna like mastodons, wooly mammoths, and giant sloths.
That paper caused a pretty good stir in the academic community. And it has become the 'Flagship', so to speak, of the Younger Dryas impact hypothesis. But while they had good evidence from the ground that a very large impact had occurred in the recent past, it was clear that the event was vastly different from anything that had been studied before. And without an astronomical model that could confidently describe the nature of the impactor/s, they were were at an impasse. "Where's the crater?" became a rallying cry of opponents to the hypothesis.
But in fact, impact research is an infant science. Who is to say what a full suit of impact markers should be? And what of airburst blast effects? Who says the event had to produce a crater?
Tunguska of 1908 was the largest impact event in recorded history. And yet, the blast affected materials at ground zero do not qualify it as an impact structure. Indeed, if there hadn't been any eye witnesses, our impact scientists would be in complete denial of an ET origin for all the violence there that day. There is no reason to think Tunguska was an isolated event. Or even a big one, on the grand scale of such things.
At Sandia Labs, Mark Boslough used their 'Red Storm' supercomputer to simulate the airburst and impact of a 120-meter diameter stony asteroid. The colors in the simulation we see below are graded by temperature. White = 5800K; Red = 2000K. Dr Boslough tells us that, in it, we see the ablated meteoritic vapor mixes with the atmosphere to form an opaque fireball with a temperature of thousands of degrees. As it hits the ground, the hot vapor cloud expands to a diameter of 10 km within seconds, remaining in contact with the surface, with velocities of several 100m/s. And at temperatures exceeding the melting temperature of quartz for more than 20 seconds. Moreover, the air speed behind the blast wave exceeds several hundred meters per second during this time.
For comparison, an ordinary oxy-acetylene cutting torch in a steel shop uses a thin stream of hot gases at only about 900 degrees C. and 40PSI to cut steel. The speed of that stream of hot gasses is only a little bit more than a stiff breeze. But that's all it takes to turn solid iron into a melted, aerosol, spray. And to blow it away in runnels of melt into heaps of slag.
Dr Boslough tells us that: "Simulations suggest strong coupling of thermal radiation to the ground, and efficient ablation of the resulting melt by the high-velocity shear flow."
We have its existence predicted in peer reviewed literature. But so far I haven't heard anyone attempt to describe the form that such geo-ablative melt might take as it is emplaced. While in motion, any ablated materials from a large, geo-ablative, airburst like that would be in atmospheric suspension, in a density current similar to a pyroclastic flow. And when everything comes to rest, the resulting rock form might be visually indistinguishable from ordinary volcanic tuff, or ignimbrite. If so, we face a conundrum in the Earth sciences. Because it has always been assumed without question that only terrestrial volcanism can melt the rocks of the Earth, or produce 'Tuff'.
If very large airbursts can produce formations of geo-ablative melt, instead of craters, then almost every last pebble of airburst melt on this fair world of ours has been mis-defined as volcanogenic.
Astronomers Victor Clube, and William Napier, had been talking about the giant comet they described as the progenitor of the Taurid Complex since 1982, in their book The Cosmic Serpent. But no one had connected the dots, and put the Younger Dryas comet, and the Taurid Progenitor together. Except in private, speculative, emails, and letters. And to the best of my knowledge there was nothing in refereed literature.
Then, In early 2010 Professor Napier published a paper in the Journal Monthly Notices of the Royal Astronomical Society titled, Paleolithic extinctions and the Taurid Complex in it we read:
"The proposition that an exceptionally large comet has been undergoing disintegration in the inner planetary system goes back over 40 years (Whipple 1967), and the evidence for the hypothesis has accumulated to the point where it seems compelling. Radio and visual meteor data show that the zodiacal cloud is dominated by a broad stream of largely cometary material which incorporates an ancient, dispersed system of related meteor streams. Embedded within this system are significant numbers of large NEOs, including Comet Encke. Replenishment of the zodiacal cloud is sporadic, with the current cloud being substantially overmassive in relation to current sources. The system is most easily understood as due to the injection and continuing disintegration of a comet 50-100 km in diameter. The fragmentation of comets is now recognized as a major route of their disintegration, and this is consistent with the numerous sub-streams and co-moving observed in the Taurid complex. The probable epoch of injection of this large comet, ~20-30 kyr ago, comfortably straddles the 12.9 kyr date of the Younger Dryas Boundary.It was indeed an astronomical catastrophe. And the nature of the event bears no resemblance whatsoever to anything in any NEO hazard assessments, or anything in current impact theory.
The hypothesis that terrestrial catastrophes may happen on timescales ~0.1 Myr, due to the Earth running through swarms of debris from disintegrating large comets, is likewise not new (Clube & Napier, 1984). However the accumulation of observations has allowed us to build an astronomical model, closely based on the contemporary environment, which can plausibly yield the postulated YDB catastrophe. The interception of ~1015 gm of material during the course of disintegration is shown here to have been a reasonably probable event, capable of yielding destruction on a continental scale.
The object of this paper is not to claim that such an encounter took place at 12,900 BP - that is a matter for Earth scientists - but to show that a convincing astronomical scenario can be constructed which seems to give a satisfactory match to the major geophysical features of the Younger Dryas Boundary data.
If indeed the YDB event was an astronomical catastrophe, its occurrence bears little relation to current impact hazard assessments derived from NEO surveys."
With Professor Napier's work specifically proposing in refereed literature that the Taurid Progenitor was the Younger Dryas comet, he changed the game completely. Because he didn't just give us a convincing astronomical model of the event. We also have a pretty good picture of the physical properties of the thing that did the disastrous deed. And if you can describe a beast, you can predict its footprints.
It is important to note here that the astronomical model of the Taurids implies that most catastrophic impact events are probably the result of a very large cluster of smaller fragments, and cometary debris. And not a single, large bolide.
Mark Boslough's simulations predict the temps, pressures, flow directions, and rotation speeds, of a single impact down-blast vortex. And since we are working from postulate that the events of the YDB were caused by the impact storms, of the debris streams, of the fragmented Taurid progenitor. The YD impact hypothesis as it stands, describes tens of thousands of such airbursts in a little over an hour. And accompanied by clouds of particles down to the size dust grains falling into the atmosphere at something like 30 km/per second, as the Earth crossed through the orbital path of the giant fragmented comet's debris stream.
Firestone, and friends proposed destructive forces equivalent to as much as 109 megatons of TNT. And at temps hotter than the surface of the sun. (a half pound of TNT will blow a hole in the ground you could lose a small car in)
Professor Napier states "The interception of ~1015 gm of material during the course of disintegration is shown here to have been a reasonably probable event, capable of yielding destruction on a continental scale." Using a gram scale to weigh a giant comet is like giving the distance to moon in inches. The total mass of the fragments that hit the Earth that day works out to well over 1.1 billion tons. 109 mega tons TNT of destruction doesn't seem like such a stretch, when you work out how big the parent comet was.
Deep Impact mission to comet TEMPEL 1 showed the head of that comet to have the consistency of a dirty snow bank. It also showed that the object is a geologically active body. Comet HOLMES is unstable, and prone to violent outbursts. Comet LINEAR, and Comet Scwassmann-Wachmann 3, shown here make it abundantly clear that total, explosive, fragmentation of a comet can occur spontaneously at any time. And it can happen before it even gets close to a planet. It doesn't need the atmosphere to do that.
If you can describe a beast, you can predict its footprints. Since the YD impact hypothesis has become a fully fledged theory that gives a specific description of the exact nature of the impactors, then it follows that we should also be able to predict the nature, and severity, of the blast effected materials. Only the first fragments to fall would have fallen into cold atmosphere. The rest would have fallen into already superheated atmosphere, and just cranked up the heat, and pressure. So we're not necessarily looking for craters where solid bolides hit the ground. We are looking for the signatures, whatever they might be, of a 'Perfect Storm' of ablative airbursts, with winds gusting to supersonic, and downdrafts hotter than the surface of the sun. In the impact zones, the surface of the Earth didn't get smashed and broken by the event. It was flash melted, and blown away.
Extraordinary hypotheses require extraordinary proofs. If the Younger Dryas Impacts were, in fact, the multiple airburst impact storms of the Taurid Progenitor, then there should be hundreds of thousands of cubic miles of flash melted rock, and blast effected materials, on this continent, as pristine as the day they first cooled. And with no giant volcanic system to account for them. And in fact, such continental scale, orphaned materials do indeed exist. And they can be found in two large geologically recent, multiple airburst, impact zones. One is The Northeast Impact Zone, extending from the Great Lakes to the Arctic circle. And the other major impact zone can be found in central Mexico, and extends up into west Texas, and New Mexico.
The Chihuahuan Ignimbrites of central Mexico have always been a mystery as to their source. Generations of geologists have assumed they must be volcanogenic. And one typically hears the excuse that it could take decades to find the vents, and magma chambers it all came from. But of more than 350,000 cubic miles of pristine pyroclastic materials in the Chihuahuan Desert, and the Sierra Madre Occidental mountains, less than 15% can be attributed to a volcanic system. And when we use modern high resolution satellite imagery to view the typical Airburst Impact structure at 29.702168, -105.686617 we can see why. That structure, and the geo-ablative curtain of airburst melt surrounding it, is typical of more than 50,000 square miles. And terrestrial volcanism had nothing to do with it.
The high resolution satellite imagery that's become available in the past decade has revealed a new perspective that hasn't been available to geologists of the past. Answering the question of where those pyroclastic materials came from is easy when you can read the patterns of movement, and flow, that were frozen in time from the moment of their emplacement. And as easily as following splashes of spilled paint back to a can.
The most startling revelation will come from studying those perfectly legible patterns of flow. And when you realize that gravity pulling them down a slope, and away from a vent, was not the motive force while they were in motion. And that you are looking at wind-driven patterns of movement, and flow, during the emplacement event, like the froth, and foam on a storm tossed beach. And when you begin to see that those pyroclastic flows describe a completely different kind of non-volcanic catastrophe from anything ever imagined before.
What kind of naturally occurring, non-volcanic, event can flash melt, and ablate, the surface of the Earth, and turn more than 50,000 miles into a single random colliding, inter-flowing, wind-driven, sheet of pyroclastic flows, and ablated landforms? Or suddenly blast away a large section of an ice sheet as big as the continental United States?
Imagine along with me for a moment. What say we take a great big comet, say 50 to 100 km wide, out of the Oort Cloud, or the Kuiper belt, and inject it into the inner solar system. And we park it an elliptical, Earth crossing orbit, and break it up into not so little pieces. Let's give it enough time for tidal forces to break it up completely, and stretch it out into a very long debris stream of particles, and fragments. Our average fragment size was about the size of the Tunguska object. But they ranged from more than a half mile wide, all the way down to clouds of dust.
As the Earth's orbit brings it across orbital path of the giant, fragmented comet's debris streams, the fragments begin to fall into the atmosphere from the south at a low angle. And more than 30 km/sec. The first fragments to hit will produce atmospheric temps well over 100,000 degrees C. And they are just cheerleaders, twirling batons in front of a parade. The rest fall into already superheated impact plasma, and just crank up the heat, and pressure. In this way, almost 100% of the kinetic energy of the fragments gets translated to heat, and pressure in the atmosphere. And that heat, and pressure, hits the ground as an almost continuous, supersonic, stream of airbursts, hotter than the surface sun.
With just a few short minutes of that, I'll bet we could sterilize the whole lush, African Savanna, and make it look just like central Mexico, and the American Southwest. And in fact, according to the fossil record, every mega-faunal ecological niche we see in the African Savanna, and more, is represented in the fossils below the Younger Dryas Boundary layer. But not above it. All that astonishing biodiversity was burned, and blown away in seconds.
Sound Crazy? Not so fast. The 2007 Firestone paper cited Toon et al when they proposed temps as high as 107degrees C. There's that exponential thing again. That's 10 million degrees Celsius. But Professor Napier pointed out for me that even if a bolide hits the atmosphere at 30 kilometers per second, and all of its kinetic energy is translated to heat in the atmosphere, it is difficult to get more than 100,000o C. But that's ok. Because either way, even with the more conservative figure, we are still describing temperatures that are more than enough to vaporize any known substance on the surface of the Earth. And to blow it away like wax under a high pressure blowtorch.
A compelling, almost conclusive, case can be made for the argument that the Younger Dryas cooling, the mega faunal extinctions of the early Holocene, and the demise of the Clovis people were all caused by the same event. It was the multiple, thermal airburst, impact showers of the fragments of the Taurid Progenitor soon after its complete breakup. And the thermal explosive catastrophe its debris stream brought, was more violent than anything ever imagined.
In the simulation we see above, Dr Boslough simulated a single bolide. The blast effected materials of the event describe a giant stream of fragments such as that, accompanied by clouds of particles down to the size of dust grains.
No one has ever found a crater that can be dated to the event. But that much heat, and pressure, only goes away peacefully in children's bedtime stories. And no craters, does not mean there are no planetary scars.
Because it was already broken up before the Earth encountered its debris stream. The atmosphere translated nearly all of the kinetic energy into heat. But it didn't dissipate it. It transferred the heat directly to the ground in an almost continuous rain of devastating supersonic, geo-ablative, down-blasts.
The eastern end of the Laurentide Ice sheet got hit in an area from Northern Minnesota, and the Great Lakes to the Arctic Circle. When the first down-blasts of thermal impact plasma hit the Laurentide Ice sheet they caused titanic, hot and powerful, hydrothermal explosions (steam) that lofted huge icebergs hundreds of miles in all directions.
A few short minutes later, those flying chunks of ice were the impactites that formed the thousands of oval depressions all over the eastern side of the continent called the "Carolina Bays". And the signs of massive flooding that have been attributed by generations of geologists to the bursting of ice damns holding back Glacial lake Agassiz are, in fact, the flood effects of the flash melting of major portions of the eastern end of the Laurentide ice sheet. In a matter of minutes, much of the eastern end of the LIS was obliterated. Much of which probably went into the atmosphere as steam. The immense hydrothermal explosions also lofted the iceberg sized chunks of ice that produced the Carolina Bays when they fell back to Earth.
The other much larger cluster of fragments hit in central Mexico, and the American southwest. The Earth was probably in the path of the devastating streams of high velocity, air bursting comet fragments for about an hour. And out of tens of thousands of large, air-bursting, fragments there is not one single impact structure that bears any resemblance to what standard impact theory might expect. Or a "full suite of impact hallmarks" all of the planetary scarring of the event has been mis-defined as volcanogenic. And most of the ages of those blast effected materials have been over estimated by orders of magnitude.
The most devastating geo-ablative effects were in central Mexico, and the American Southwest. In seconds all of central Mexico was pulverized into a surreal, and blasted, landscape of heavily ablated, and melted terrains, like a Salvador Dali painting. It generated a post impact mega tsunami of thermal impact plasma taller than the atmosphere, hundreds of miles wide, and hundreds of miles from front to back, that rushed downrange to the northwest at supersonic speeds. And it sterilized the western half of the continent on a swath from Mexico to the Arctic, along a storm front extending from California to the great plains.
The Mexican cluster of fragments was approximately 500 miles wide. As the first of the fragments hit they detonated high in the atmosphere. But the explosions retained their momentum. And they hit the ground as devastating supersonic down blasts hotter than the surface of the sun. And as I said, only the very first fell into cold atmosphere. The rest of the fragments just piled on in, and added to the heat, and pressure. The overpressures from the blast waves were so powerful they blasted whole mountain ranges aside like clumps of flour on a bakers table. And still, they continued to pile in. And the heat, and overpressures, continued to build.
The blast wind would've incinerated everything it passed over. In the hottest part of the impact zone, vast quantities of stone were vaporized, and whipped up into the storm, where the atmosphere worked like a refining tower. And in a fiery rain the materials precipitated out of the plasma storm down wind according to their condensation temperature, and specific gravity. This was like nothing ever imagined in our most frightening nightmares of disaster, or catastrophe. During the impacts, and for a few minutes after, most of North America from Mexico to the Arctic, and from California, to the plains of the Midwest, was engulfed in what might best be described as a full blown magneto-hydro-dynamic plasma storm. Like something we should only expect to find on the surface of the sun. And there is not one square inch of the surface terrains of western North America in its path that doesn't bear the scars of that blast of heat.
In fact look closely in modern satellite images. You see that all of the high ridges of the mountain ranges of California, Colorado, Utah, Wyoming, and Montana that had glaciers at the time bear clear and obvious signs of the heat. And a profound feature that is easy to spot is melted glacial ridges, blown over to the north and northwest like runnels of melted wax on the side of a candle. And we typically see high glacial valleys below those melted ridges that have all of the material that was once suspended in the Glacier lying exactly below where it was in the glacier. Indicating that the ice evaporated so fast there was no flow of water down slope to move any of the glacial till. So we see that the glacial till dropped out so fast it's as if the ice just vanished in a quick puff of steam.
Almost at the same time Mexico was getting hit, the eastern end of the ice sheet was getting pounded just as hard. But the ice added another factor to consider in understanding the blast effects. Under the thermal airburst down-blasts, the ice reacted explosively, like reactive armor on a battle tank. The impacts into the ice sheet triggered titanic hydrothermal explosions that lofted huge berg sized chunks of ice for hundreds of miles forming the 'Carolina Bays'.
The ice sheet impacts evaporated millions of acre feet of water directly into the atmosphere. There was probably much more of the ice sheet that went up as steam, only to rain down in the days, and weeks, that followed than was melted to flow into the sea. As North America burned, the storms around the world raged. It rained everywhere for weeks.
Sea levels rose as the blasted, and melted ice sheet flowed in mega floods to the sea. And just as today, most of the larger populations would have been in low lying areas. The seas rose too fast or anyone, and anything, living in coastal areas anywhere in the world, to escape. Every coastline all over the world was effected. And everywhere it would have been much like a giant tsunami. But this time, the flood waters rose and never receded.
Much of an ice sheet bigger than the Continental United States was destroyed. The whole world was shaken to the core. And, like taking weight from a floating barge, the sudden shift of the weight of so much ice caused a massive uplift of the middle of the continent. Coupled with the powerful detonations of so many exploding comet fragments, it caused earthquakes, and volcanic eruptions all over the world. And global seismic activity was the worst in many millions of years.
While the mega floods from the blasted ice sheet were still flowing into the sea. Most of the biomass of western North America was burned away and much of the resultant smoke, and soot was blown high above the atmosphere where it blocked sunlight for years. There was an immediate sharp drop in temperatures world wide. It was the worst kind of 'Perfect Storm'. Made all the worse because at the same time the destruction of the LIS caused a sudden rise in sea levels world wide. It it may have caused a shutdown of the thermal haline cycle which brings tropical warmth to the North Atlantic. Be that as it may, Northern Europe quickly cooled to arctic temperatures. And the cold remained for centuries.
The Clovis people, and whole species, and ecosystems, were annihilated in seconds. Most of the western half of the continent was incinerated, and sterilized. The other half was devastated. The food chain of the entire northern hemisphere was severely compromised. And except for rare, and random, patches here, and there, that remained somehow unscathed like the one surviving undamaged house in a neighborhood hit by a tornado. The lush savannah the giant animals of North America depended on for food was gone down to the last blade of grass. Those giant animals that survived in the southeast corner of the continent faced a drastically altered, and reduced food supply. And they simply starved. The specialist predators that depended on those animals for food perished as well. The species that survived extinction were the most adaptable, the smaller ones that didn't eat much, and those that were just plain lucky.
If there were any human survivors of that day, anywhere in the western hemisphere, they were hiding in a deep cave somewhere well south of the impact zone. And they were cringing in terror as their world was erased and made new again. Any who peeked out of the cave without getting themselves killed, may have told stories of fire breathing dragons remaking the world with breath so hot it could melt mountains.
The progression of the event was a result of the Earth's movement along its orbital path, as it crossed through the orbital path of the giant comet's debris stream. Not a product of the Earth's rotation. So that, in a daytime event, the fragments are outbound from perihelion. The airburst storms would begin in the west, and progress to the east. As the Earth Crosses the debris stream. In a night time event, the debris stream would be inbound towards their perihelion, and the opposite would be true.
Using modern satellite imagery, a very compelling case can be made that the scenario described above is very close to the exact truth. The remaining debris of the Taurid Complex is still out there. And there are still fragments of significant size in Earth crossing orbits. It is almost a certainty that the next major impact event will be an airburst. And it is a certainty that we haven't seen the last catastrophic impact of the Taurid Complex.
Something wicked this way comes.