#A Catastrophe of Comets » Feed A Catastrophe of Comets » Comments Feed A Catastrophe of Comets » A Different Kind of Climate catastrophe Comments Feed Large Aerial Bursts and the Impact Threat alternate alternate A Catastrophe of Comets WordPress.com A Catastrophe of Comets The geophysical world according to me, and a few folks I happen to agree with A Different Kind of Climate catastrophe Younger_Dryas-Trigger A couple of years ago, as a hobby, and pass-time, I set out to see if I could work out a better way of identifying potential sites to go meteorite hunting. I had learned to do battle damage assessment from aerial reconnaissance photos a long time ago in the Army. And the blast damage, and ground effects from an explosive event, are pretty much the same, no matter what the source of the explosion might be. It's only a question of scale, and explosive force. Visually, there is very little difference in the appearance of a bomb crater, and an impact crater of the same size. So a forensic technique of reading the patterns of movement in the emplacement of blast effected materials on the ground applies well in the search for potential impact related geology. The quality of the image data now commonly available to anyone with a good PC, an internet connection, and a copy of Google Earth, is excellent. In the past five years, the publically available image data has really come into its own. And today's 21st century satellite imagery allows us to study the surface of the Earth at a level of detail our fathers could never have imagined. Back in the 1920's, using aerial photography, a geologist named J. Harlan Bretz noticed evidence for the mega-floods that sculpted the Grande Coulee, and the `Channeled Scablands' of eastern Washington. Bretz was the first to use Aerial photographs to detect, and map, catastrophic mass movement of the Earth's surface materials when he described the scarring of a catastrophic glacial flood event at the end of the last ice age, in an event he called The Spokane Flood. Aerial photography allowed him a perspective from which patterns of fluid flow, and catastrophic mass movement of terrain materials, could be perceived on a scale that had been unimaginable until he described them. What he had found, were the patterns of fluid flow, like the ripples you see in the sedimentary deposits of a stream bed, but these `ripples' are hundreds of feet high. Bretz saw them as empirical evidence of a major catastrophic flood event, on a scale that the standard theorists of his day thought was inconceivable. Today we know that all of the water came from a glacial lake now referred to as Lake Missoula. The huge lake formed in western Montana during the ice age, when a lobe of the Cordilleran Ice Sheet extended far enough south that it blocked the Clark Fork River in Northern Idaho. More 600 cubic miles of water was released when that ice dam failed. And the volume of the resulting flood torrent has been calculated at 8 to 10 cubic miles per hour. Or flow a rate that amounts to 10 times the combined flows of all the rivers on the planet Earth. It turned out J.Harlan Bretz was exactly right. Although most of the academic community of his time thought he had a screw loose, or two. Almost a hundred years before him, most geologists had already decided to agree without question that sudden, catastrophic, geologic changes just didn't happen anymore. And that all geomorphology on the surface of the Earth is the result of slow processes we see going on around us today, and requiring millions of years. They were naively mistaken. One of the biggest mysteries I've ever confronted lies in the question of how theoretical geology could be so far removed from the empirical reality now clearly visible, and legible, in modern 21st century satellite images. It didn't take much digging in the history books to figure out where the Earth sciences went wrong. The root problem with the thinking in the Earth sciences goes all the way back to Gottfried Leibniz, in the early 18th century, and his slogan of `Natura Non Facit Saltus', (Nature does not jump). Leibniz may have been a mathematical genius. But he wouldn't even pass a 5th grade geology test of today. Yet he had the full backing of governments, big business, and the big churches. Because he believed, and taught, that the Great God of the Universe had created planet Earth, with all its flora, and fauna, just for us, and to do with as we pleased. The old clichés like `buying a pig in poke', `don't let the cat out of the bag', and `empty sack of lies' all have their roots in the same old con. It went something like this: At an old country fair, a con artist would approach a likely looking mark to sell him a piglet in a `poke' bag. But it's not really a pig in the bag; it's a cat. The cat wiggles, and squirms, just like a little pig when you poke him through the bag. And as long as the bag stays closed, the con works just fine. But as soon as the bag is opened, the cat escapes. And the victim is left holding nothing but an empty sack of lies. Carl Linnaeus, and Charles Darwin, loved Leibniz. And they both quoted him verbatim. He managed to almost completely eliminate any academic consideration of episodic worldwide catastrophes from western thinking. And by the time James Hutton, and Charles Lyell, came along, most geologists were well-conditioned followers of his way of thinking. Hutten gets the credit for the origin of Uniformitarianism. Charles Lyell just popularized his ideas in 1830, when he published his book `Principles of Geology'. But Hutten, and Lyell, just picked up on Leibniz's thinking, and ran with it. They weren't brilliant geological thinkers either. But their unquestioned uniformitarian/gradualist assumptions, based on the idea that the earth was shaped only by slow-moving forces still going on around us today, and expressed in the slogan of "The present is the key to understanding the past", has become the foundation postulate of the Earth Sciences ever since. Governments, and big institutions, loved it. And they bought it like a pig in a poke with generous funding packages that came with rules that shut the door to any consideration, or publication, of theories of sudden catastrophic events, as a possible driving force in the geo-morphology of this world for more than 150 years. That's a cruelly long time time to leave the poor kitty in a bag. But the questions of just what the hell happened around 13,000 years ago that caused the extinctions of the mega fauna in North America, the disappearance of the Clovis culture, and a return to Ice age conditions that lasted more than a thousand years, has caused us to take a closer look, and I'm afraid we've let the cat out of the bag. The trouble we face today, Just as Mr. Bretz did back in the 1920s, is that through the same 19th century process of mutual-inter-assumptive reasoning, and confabulation, instead of sound, experiment-driven, science, the Earth sciences are still founded on that unquestioned `Gradualist' assumption. But gradualism only works until something sudden happens. And Harlan Bretz showed us that if you want to understand, or predict, the nature of the planetary scarring of a geologically recent catastrophic event, especially one that's different from anything that's ever been studied before, Sir Charles Lyell's 19th century, gradualist-assumptive, reasoning just won't get you there. Apparently, being able to see the truth is no guarantee that anyone's going to bother to look where you're pointing anytime soon. It wasn't until 1965 that a report from an independent geologist's tour concluded that Harlan Bretz was right. And finally, in 1976, at the age of 96, he was awarded the Penrose Medal of the Geological Society of America. Which is just about the most prestigious award a person can get in the field of geology. Upon receiving the award, Mr. Bretz is said to have complained to his son that he couldn't gloat properly, because all of his enemies were dead. The satellites of today have raised the ante. Using aerial photography from blimps, and airplanes, Bretz could see evidence of catastrophic material movement on a statewide scale. With the imagery now available through Google Earth, we can detect, and read, patterns of catastrophic mass movement of terrains on a continental scale. The event Bretz perceived was only implausible from a standard theory viewpoint because of its size. And yet, by comparison, and in the final analysis, someday it may be seen that his glacial mega flood in the Pacific Northwest was only a minor little footnote in the events of the early Holocene. And some of those events were far more terrible then a glacial flood. _________________________________________________________________ TunguskaBlast In June 1908, an explosion rocked a remote, swampy area in central Siberia, in Russia; it came to be known as the "Tunguska event." And a later expedition to the site found that 20 miles of trees had been knocked down and set alight by the blast. Today, it's understood that Tunguska's devastation was caused by a 100-foot asteroid that had entered Earth's atmosphere, causing an airburst. mamoth 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 much like what we enjoy today, when an occurrence thought by many researchers to be some kind extraterrestrial impact set off an "impact winter", and a return to ice age conditions that lasted another 1,300 years, or so. And the event 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. Perhaps the single most important paper on the subject of the Younger Dryas Cooling, 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 The 2007 Firestone 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. In it, a team of twenty six scientists studying sedimentary deposits from sites all over North America 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. In all, I think something like 35 genera went extinct. Its exact cause is by no means, a settled science though. And the biggest weakness in the YD impact hypothesis, as written, is that it's impossible to construct a model with a four mile wide bolide that has enough time in the atmosphere to break up completely, and scatter fragments, and devastation over a continent sized area, without making a good sized crater somewhere. And "where's the crater?" became a rallying cry of opponents to the hypothesis. The debate continues to go around, and around. Firestone, and friends, had found compelling evidence in the stratigraphic record that implied some kind of very large impact related catastrophe had occurred to trigger the Younger Dryas Cooling, and the megafaunal extinctions. But it was clear that the event was vastly different from anything that had been studied before. So they could only speculate on just exactly what the nature of the event was, or what had hit us, or where the actual impact zones were. Without an astronomical model that could confidently describe the the nature of the impactor/s, they were were at an impasse. _________________________________________________________________ Meanwhile, astronomers Victor Clube, and William Napier, in their book The Cosmic Serpent, had been talking about the giant comet they described as the progenitor of the Taurid Complex since 1982. Their data is as solid as anything you can dig up with a trowel. But except for them, and a few others like Bob Kobres, no one had connected the 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. 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 ~10^15 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 it's footprints. _________________________________________________________________ Linear_composite2c From Comets, Catastrophes, and Earth's History by W. M. Napier we read , "The evidence that an exceptionally large (50-100 km) comet entered a short-period, Earth- crossing orbit during the upper Paleolithic, and underwent a series of disintegrations, now seems compelling. The idea is not new, but it has been strengthened by an accumulation of evidence from radar studies of the interplanetary environment, from the LDEF experiment, from numerical simulations of the Taurid complex meteoroids and `asteroids', and from the latter's highly significant orbital clustering around Comet Encke. RAS-comet2 The disintegration of this massive Taurid Complex progenitor over some tens of thousands of years would yield meteoroid swarms which could easily lead to brief, catastrophic episodes of multiple bombardment by sub-kilometer bolides, and it is tempting to see the event at ?1 12,900 BP as an instance of this. Whether it actually happened is a matter for Earth scientists, but from the astronomical point of view a meteoroid swarm is a much more probable event than a 4 km comet collision. The exact mechanism that causes the breakup of comets remains a matter for additional study, and debate. Perhaps they simply loose cohesion as the volatile ices that hold them together sublimate away. Be that as it may, the images of Comet LINEAR , and Comet Scwassmann-Wachmann 3, make it abundantly clear that total, explosive, fragmentation of a comet can occur at any time. And it can happen before it even gets close to a planet. It doesn't need the atmosphere to do that. Those two comets also make it clear that professor Napier is probably right. Both of those objects are typical daughters of the Taurid complex. So they are also typical of the kinds of objects we see in Earth crossing orbits. And while they themselves don't represent an immediate threat, There is the potential for many more undiscovered Near Earth Objects out there just like them that do. With the Taurid Complex as the astronomical model for the YD impact hypothesis, we don't need to account for how the YD comet broke up. Because we know it was already a cluster of smaller fragments before it got anywhere near this fair world of ours. I asked NASA's David Morison what he thought of the possibility of a cluster impact event. And he expressed his doubts. Saying that he thought it was `highly unlikely'. But the fragmented nature of the objects above would seem to say that the opposite is true And the realization that most catastrophic impact events are probably the result of a large cluster, or stream, of smaller fragments, instead of a single, large, bolide as has been assumed in the past, represents a significant paradigm shift in NEO threat assessment, and impact science. To give you an idea how for reaching the paradigm shit is, consider that for decades NASA has been doing intensive studies to estimate the age of surfaces on Mars, and the Moon, based on the number of craters they can count in a given area. They've been working from the assumption that all impacts happen one fragment at a time, and at a fairly constant rate, or flux. But all it would take is the impact of one cluster of comet fragments like we see in the two comets listed above, to result in many thousands of individual impacts in a matter of seconds. That fragmented objects like that are fairly common, and are typically found in short period elliptical orbits that cross all the orbits of the inner planets is a demonstrable fact. The fact that they can occasionally collide with them is an unavoidable consequence of that fact. The fact that they can, means that they have indeed done so in the past. In other words, the idea that you can accurately estimate the age of a planetary surface in the inner solar system by counting the number of craters is as naïve as a children's bedtime story. And the assumed ages of many of the surfaces of Mars, and the Moon must be overestimated by orders of magnitude. All that being said, it will come as no surprise to me if mainstream planetary scientists at NASA hold on to those old `one bolide at a time' impact estimates with grimm determination for decades to come no matter how good the data is to the contrary. After all, no one is going to be in a rush to put decades of work counting craters on the same dusty library shelf with flat Earth theory, and geo-centrism. Impact research is an infant science. And thanks to poor funding for Near Earth Object research, and for impact science in general, we don't have a very good handle yet on the variety or quantity, of objects out there that might threaten our world, much less a comfortable understanding of the different kinds of devastation that might be released in a catastrophic impact besides what we see in a generic, single bolide, crater forming, ballistic-kinetic impact event. So who is to say what a full suite of impact markers should be? And what of airburst blast effects? Tunguska of 1908 was the largest impact event in recorded history. And yet, the blast effected 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. And, in a poster by Dr Boslough titled, The Nature of Airbursts and their Contribution to the Impact Threat. we read: "Ongoing simulations of low-altitude airbursts from hypervelocity asteroid impacts have led to a re-evaluation of the impact hazard that accounts for the enhanced damage potential relative to the standard point-source approximations. Computational models demonstrate that the altitude of maximum energy deposition is not a good estimate of the equivalent height of a point explosion, because the center of mass of an exploding projectile maintains a significant fraction of its initial momentum and is transported downward in the form of a high-temperature jet of expanding gas. This "fireball" descends to a depth well beneath the burst altitude before its velocity becomes subsonic. The time scale of this descent is similar to the time scale of the explosion itself, so the jet simultaneously couples both its translational and its radial kinetic energy to the atmosphere. Because of this downward flow, larger blast waves and stronger thermal radiation pulses are experienced at the surface than would be predicted for a nuclear explosion of the same yield at the same burst height. For impacts with a kinetic energy below some threshold value, the hot jet of vaporized projectile loses its momentum before it can make contact with the Earth's surface. The 1908 Tunguska explosion is the largest observed example of this first type of airburst. For impacts above the threshold, the fireball descends all the way to the ground, where it expands radially, driving supersonic winds and radiating thermal energy at temperatures that can melt silicate surface materials. The Libyan Desert Glass event, 29 million years ago, may be an example of this second, larger, and more destructive type of airburst. The kinetic energy threshold that demarcates these two airburst types depends on asteroid velocity, density, strength, and impact angle." At Sandia Labs, Dr Boslough used their `Red Storm' supercomputer to simulate the airburst, and impact, of a 120-meter diameter stony asteroid. And it represents an example of that second, geo-ablative kind of air burst. IFRAME: http://www.youtube.com/embed/mCCKW_STVqE?version=3&rel=1&fs=1&showsear ch=0&showinfo=1&iv_load_policy=1&hd=1&wmode=transparent The colors are graded by temperature. Whit =5800K; Red = 2000 K. 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 40 PSI. 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 ablate solid iron, and to blow it away, into runnels of melt, and 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." I think his simple statement may represent the cusp of another major paradigm shift in the Earth sciences. Especially when you think it through. And when you consider what form the blast effected materials of a geo-ablative airburst like that should be expected to take. During the event, any ablated materials would be in an atmospheric suspension, in a `fluidized' flow. Similar to a pyroclastic flow. But wind-driven, like the froth, and foam, on a storm tossed beach, not gravity-attracted, like a pyroclastic flow down the flanks of a volcano. So we face a conundrum. Standard uniformitarian/gradualist geologic theory has always assumed without question that only terrestrial volcanism can produce pyroclastic rock. And deposits of sheet ignimbrites have always been seen as conclusive evidence of explosive volcanism. Even when no volcanic vent, or magma chamber can be identified. The word `ignimbrite' comes from the Latin for `Fire Cloud Rock'. So, since geo-ablative airburst melt would be formed and emplaced in a cloud of fire, it's still a good word to describe airburst melt. Volcanic Tuff, and Airburst Melt, are both `Fire cloud rocks'. An important thing to keep in mind is that, no matter whether a piece of `ignimbrite' is truly volcanogenic, or if after detailed chemical tests, we can conclude an ET origin, either way, such materials are always the product of a violent explosive event. And as the blast effected materials of an explosive event, the patterns of movement, and flow, that get frozen into them during emplacement can reveal much of the true nature of the explosive event that put them there. I don't want to digress into a discussion about volcanoes. But it's important at this point to understand the internal structure of these kinds of materials, and how they move during formation, and emplacement. And why it might be easy to get them confused. It's time to put on your fluid mechanics hat. _________________________________________________________________ FLOW FLUIDIZATION From How Volcanoes Work The extraordinary velocity of a pyroclastic flow is partly attributed to its fluidization. A moving pyroclastic flow has properties more like those of a liquid than a mass of solid fragments. It's mobility comes from the disappearance of inter-particle friction. A fluidized flow is best described as a dispersion of large fragments in a medium of fluidized fine fragments. A constant stream of hot, expanding gases keeps the smallest of the fragments (ash and lapilli size particles) in constant suspension. This solid-gas mixture can then support larger fragments that float in the matrix. In Fluid Mechanics Such a flow is also known as a density current. So, a rock of geo-ablative airburst melt should be expected to be similar in structure to `ignimbrite'. And it might be visually indistinguishable from volcanic tuff. The final test for ET origin would be to look at the isotopes. Horton Newsom at NMU tells me that we should expect to see significant siderophile, or platinum group element, enrichment as supportive evidence of ET origin. But there might be a easier way to identify geo-ablative airburst formations, simply by reading the patterns of flow that were frozen into them when they were formed, and emplaced. Because of the difference in motive forces involved, one wind-driven, the other gravity-attracted, there would be fundamental differences in the way geo-ablative melt, and it's volcanogenic cousin moves, and flows, during formation, and emplacement. And in satellite images, in `orphan' ignimbrite deposits, we're looking for wind-driven patterns of movement, and flow. And by `orphan', I mean to say that no volcanic system has been positively identified to account for them. And since the debris of the Taurid progenitor is thought to have hit sometime in the geologically recent past, we should expect those geo-ablative formations to be in very good condition, undisturbed, and on the surface. For more than 150 years, standard gradualist geology theory has assumed without question that only terrestrial volcanism can produce the explosive forces needed to make a pyroclastic density current of flash melted stone. And for generations they've used sheet ignimbrite deposits as conclusive evidence of explosive volcanism, in spite of often not being able to locate a vent, or magma chamber, it came from; not even with our best 21st century technology. But Since geo-ablative airburst melt would be in the form of a wind-driven pyroclastic flow while it's in motion, that's exactly what structural form any geo-ablative material would take as it comes to rest, and cools. And except for its wind-driven patterns of flow which become frozen in at the moment of emplacement, it would be visually indistinguishable from ignimbrite, or volcanic tuff. _________________________________________________________________ The Ignimbrites of the Chihuahuan Desert of North Central Mexico are one such orphan deposit. There, and in the Sierra Madre Occidental mountains to the west, there are more than 350,000 cubic miles of random colliding, inter-flowing, sheet ignimbrites, undisturbed, on the surface, in pristine condition, with wind-driven patterns of flow. And less than 15% can be positively attributed to a volcano. The problem with studying them in the past, has been that they cover such a vast, and remote, desert area, that using antiquated surveying techniques of the past, it has been difficult, and time consuming. As a result, except for a 100 km stretch along the roadside between Chihuahua City, Mexico, and El Paso Texas, they are almost completely unmapped. And in refereed literature, all we find of their origin is speculation. The theorists of the past had to come up with a plausible model of an explosive event powerful enough that it could get hundreds of thousands of cubic miles of rock up in the air into atmospheric suspension, in a pyroclastic density current, at the same time. And if `the present is the key to the past', as they say, there is nothing in recorded history that gives us an example of how something like that could happen. They could not imagine such energies coming down from above. So they invented a theoretical kind of super-giant eruption called an Ignimbrite "Flare Up" event. It's thought the event dates to the mid tertiary, when extensional forces in the middle of the continent are thought to have caused fault-grabens in the middle of the continent, hundreds of miles long, to suddenly open up, transforming into vast fissures that belched all those ignimbrites in an unimaginably violent explosive event, and then closed up again. But there are major problems with that theory. First of all, after decades of geological surveys to catalogue Mexico's mineral wealth, no seismic, tomographic, ground penetrating radar, or any other data, has ever revealed a single one of those fault-graben-turned-fissures. Much less a magma chamber big enough that almost all of central Mexico must be a supergiant caldera that makes the Yellowstone caldera look like a mouse breaking wind by comparison. And no one can explain the crazy mantel physics required for those giant, magic trap-door vents that are assumed to have opened, and closed, without a trace. The old gradualist-assumptive model falls apart quickly when questioned closely. But whether volcanogenic, or exogenic, pyroclastic rock is always the signature of a violent explosive event. And if you want to understand an explosive event after the fact, you begin by studying the emplacement motions of the blast effected materials. Doing so may have been difficult, and time consuming, on the ground. And with an old fashioned surveyor's transit the task would've taken decades. But the satellite technology of the 21st century has made it possible to map the emplacement, and directionality, of those flows to an amazing level of detail. And from the comfort of one's own desk. Using Google Earth's `save image' feature, I made a very large, hi-resolution image map of overlapping saved images seamlessly stitched together with Photoshop. I then had the image map printed out professionally in a hi resolution format that covers a whole wall. A sheet of clear plastic for an overlay, some markers to draw little arrows to indicate the direction of flow wherever they were discernable, and I had a high resolution flow map of the Chihuahuan Ignimbrites that would've taken decades of difficult surveying, in the middle of some of the most inhospitable terrains on Earth, to produce the old way. The problem with the assumed ancient age is that they are all in perfectly pristine condition. And they are the undisturbed capstone of the terrains they're blanketing. Whatever else they are, geologically old, they're not. And after a few thousand hours of studying their patterns of emplacement, I can tell you that those are are wind-driven patterns of motion frozen into those pristine pyroclastic rivers of flash melted stone. The heat, and pressure to ablate the surface, and to produce and emplace, the Chihuahuan ignimbrites came from above. The ignimbrites themselves consist of materials from the original surface. But flash melted, and blown around a bit. Just like the froth, and foam, on a storm tossed beach. The age estimate of the terrains of central Mexico is based on assumed slow erosion rates of ordinary wind, and rain. The landforms in the region seem to be worn down to the nubbin. And no one could ever have imagined that ablation from above might be a factor. But an ablative airburst event can be expected to move more material in seconds than ordinary weather can in many millions of years. If we are working from the standard postulate that the Chihuahuan ignimbrites were laid down before the landforms rising among them began eroding, then the ignimbrite sheets should be as heavily weathered, and eroded, as everything else. And they should be under the alluvium that erosion would've produced. But the millions of years worth of alluvium we should expect to see covering the Chihuahuan ignimbrites is missing from the satellite images. And as anyone who looks closely can see, the ignimbrites themselves are almost perfectly pristine, and unweathered. Good field work, and detailed chemical analysis of field specimens will have the final word. But a very compelling case can be made from satellite image data for the statement that the mountains, and landforms of North Central Mexico weren't heavily eroded to their present state over millions of years. They were heavily ablated in a large, multiple airburst, impact storm. And over a period of just a few seconds. The vast, interflowing, ignimbrite sheets are the product of that ablation. And their almost completely unweathered condition, as the capstone of the terrains, disproves the assumption of ancient age. The ablative event must have been only a few thousand years ago. _________________________________________________________________ The real test of any supercomputer simulation, or model, like Mark Boslough's, is whether or not it is predictive of something we can find in real life on the ground, and in this case, we can. Take a good look at that simulation again. Remember, you are looking at a cross-section. Imagine it in 3D. Take a good, close look at the bottom of the down blast vortex. Watch it full screen, and pay special attention to the patterns of flow at the point of contact with the ground. In the image below, I've chosen an ordinary-typical example from the Chihuahuan Desert to give you an idea of what something like can do. And what I've been talking about. The mountain you see in the image below is at 29.702168, -105.686617 about 150 miles south, southeast of El Paso, Texas. And it is not unique. There are many others nearby. Since they tend to exhibit many of the same features we would expect to see in an impact structure, such as shatter cones, breccias, and shock metamorphic effects, there is no question but that they must be related to some kind of violent explosive event. But without a circular crater rim, the exact nature of the explosion that produce them has been a mystery. So Geologists of the past have called them "Crypto-Explosion Structures". The terrain you see in this image is ordinary-typical of more than 50,000 square miles. Note the radial, outwards flowing curtain of melt. The wind-driven patterns of flow frozen into that curtain at the moment of its emplacement are a perfect match for the patterns of flow at the bottom of the large airburst vortex in Dr Boslough's simulation. The white line in the bottom of the image is 5 miles long. bp1 Click on the image to view a 3D Photosynth of this mountain As you can see, the radial, outwards flowing curtain of breccias, and pyroclastic rock is almost perfectly pristine. There is no question but that the mountain is the source location of the materials in the curtain. But the mountain itself is a cuesta that consists of uplifted meta sedimentary strata. It's not a volcanic vent, or rift, at all. These are the patterns of movement you see when a fluid is driven across a surface by high velocity atmospheric pressure. Like I said, just like the foam, and froth, on a storm tossed beach. Gravity wasn't the motive force for the material movement we see evidence of here. The indication of the speed of the materials in the emplacement of the curtain of melt is the outwards pointing chevrons clearly visible in the patterns of flow. The shocker here, is that the mountain probably didn't exist in any form at all at until the moment of the impact. I suspect that it was uplifted as the surface rebounded upwards after the impact shockwave hit. In other words, in a sense, it `bounced' up after the impact of the shockwave like the surface of a trampoline. But we need to look closely at the ablative patterns of flow in its outer surface. In the simulation, note the supersonic upwards flow in the center of post impact vortex. The mountain was born almost in an instant as the surface bounced back from pressure of the shockwave, and it rebounded up into the impact vortex. So, at the same time the ablated material in the radial curtain was being ablated, and blown outwards, the rebounding surface at the center was ablated, and the materials that were removed, were drawn up into the impact plume by the upwards flow at the center of the vortex. At this point, it's hard to say where they might have fallen back to Earth. bp9 And the signature of that supersonic, and ablative, upwards flow in the middle of the vortex is in the deep V shaped excavations that wider at the top, and center of the flow. What has been interpreted as the work of millions of years of erosion is in fact, the work of just few seconds of an ablative airburst. And probably not so long ago at that. Dr Boslough only simulated the airburst of a single fragment. But the blast effected materials in the giant impact zone this airburst structure is setting in the middle of, describe a cluster consisting of thousands of air bursting fragments that big. And if Comets Linear and SW-3 are any model of the density of the debris cluster, those larger fragments were probably accompanied by clouds of stuff down to the size of dust grains. And all of it falling into the atmosphere at something like 30 kilometers per second, like a giant shotgun blast. There are well over 50,000 square miles of geo-ablative terrains like that in North Central Mexico alone. The zone extends up into west Texas. And the region is unique on the surface of the Earth. The Arid climate has preserved the blast effected materials in context, and in perfect condition. And except for the occasional sage brush, or cactus, most of it is in almost the same condition as it was the first year after the impact storm. I don't see anything in the satellite images that would allow one to pin down the exact age of these formations with any degree of confidence. But I struggle to understand how anything on the western half of the continent could've survived the fires. The entire food chain over a vast area would've been compromised. Most of it burned away down to the last blade of grass. Since these formations are in such good condition, I like their emplacement event for a suspect in the early Holocene megafaunal extinctions. A very compelling case can be made that a similar large cluster of comet fragments also hit the Laurentide ice sheet in a region from northern Minnesota to the Arctic ocean. And I have a hard time imagining the climate consequences of destroying an ice mass almost as big as the continental US, and suddenly evaporating a couple of hundred thousand cubic miles of ice directly into the atmosphere. All the while burning the biomass away from the other half of the continent. I'll describe the blast effected materials of the Northeast impact zone a little later on. But for now, there is more to show you in the west, and southwest. _________________________________________________________________ The other day I was watching an episode of the `Meteorite Men'. It was the one in which they went to try their luck at the Odessa crater, in Texas. It was a good show. But the guys had a tough time of it. Untold numbers of meteorite hunters, and collectors, have worked that site over the years. And they've turned the ground over so much looking for meteorite fragments, it's barely recognizable as an impact structure anymore. Geoff, and Steve, worked that site every which way but loose. And they still came up empty handed..., almost. It wasn't until they gave up looking, packed up their gear, and started driving away disappointed, that the Meteorite Men found anything. On their way out of the area, in the gravel of the road, they spotted meteorite fragments lying right there in plain sight. So they stopped, took out their metal detectors, and started digging fragments. After giving up on a day of frustration, they made a pretty good haul, right there in the gravel of the road. And they left the area with some really nice Odessa Irons. And then, as happy as can be, they just drove away, richer by a few nice meteorite fragments, (As a matter of fact, a few thousand dollars worth!) and a good episode for their TV show. But in missing the significance of where they found those iron meteorite fragments, they also drove away from what may be the most single most important clue of their careers. Here's a Google image of the Odessa Crater, and the Museum at 31.765137, -102.479064. As you can see, it's been so dug up, and turned over by meteorite hunters over the years it's barely recognizable as an impact structure anymore. You see, when those dirt roads in that oil field were graded, they hauled in aggregate to elevate the road surface a few inches above grade for better drainage. That aggregate did not come from inside the crater. It came from a quarry location about 20 miles away. The mystery there was; since the dump truck that brought in that thin layer of aggregate got its load from a quarry miles away, and not the Odessa Crater, how did all those Odessa Irons get into that load of aggregate for the road bed? The answer, is that that Odessa crater is not alone. It is only one of many thousands in a vast cluster event. Turn on Google Earth, and scan the area carefully from an eye height of about 5 km. Scattered among the oil fields there are too many craters like the Odessa structure to count. I have heard that `most geologists agree' that the Odessa event was about 60,000 years ago. I don't believe that for a minute. I want to see proof. I've also heard estimates as young as 20,000 years. Until I see some radiometric data, I am working from the postulate that they are much younger than that. Less than 13,000 years old as a matter of fact. And they are all the same age. Give, or take a few seconds. There are also thousands of fairly normal craters in New Mexico, and west Texas averaging about 100 meters wide that have never been seriously considered as potential impact structures. And for no other reason than there are too many of them, all the same apparent age. And it has always been assumed that a multiple fragment impact storm, or cluster impact event would be "Highly unlikely". So, with the exception of the Odessa crater, all of its sister craters that we can clearly see in the satellite images of the Oil fields near Odessa, and Midland Texas have been ignored. This one is near Odessa, at 31.617601, -102.271674. It's a little over a hundred meters wide. And it is typical of thousands. This next one's at 31.788219, -102.153964, and is 189 meters across. And there are a few more Odessa craters in this Gallery View Odessa Craters View Full Album _________________________________________________________________ There is another type impact structure I've been told is highly Unlikely. And that's oval craters caused by oblique impacts. But in the early Holocene sediments of a dry lake bed in northern Nevada at 39.739717, -115.388916 we can find a place where a cluster of oblique impacts hit the submerged sediments of what would've been a shallow lake at the time. Here's the north end of the lake from an altitude of about 45 km. Nevada Unlike the airburst formations in central Mexico, there are good visual cues here to establish an age, give, or take a few centuries. I did a few crude impact experiments with a low powered rifle, and a mud puddle. Not exactly laboratory conditions. But good enough to determine that the weird, feather shaped ejecta plumes downrange to the northeast from the points of impact are consistent with a low angle impact of about 30 degrees into a submerged surface, and are probably the result of the ejecta's interaction with the water of the lake. And to determine that the strangely distorted beach lines that correspond to that lake level are the result of some of the lake sediments being splashed out of it banks. On the north end of the lake, and the cluster of oblique craters, we see where, as the lake returned to its banks after the impact event, the beach lines criss-crossed some of the ejecta plumes. Beach lines in a dry lake are like bathtub rings. And they give us an age. That set of beach lines represents the lake's last, and lowest, shore line before it dried up completely. Which puts it sometime in the early Holocene, maybe less than ten thousand years ago. I don't know if an impact scientist has been on the ground there yet, probably not. But I do know that a 600 gram, carbonaceous chondrite, meteorite fragment was found in a neighboring dry lake bed. But it gets better. The direction of those plumes points to about 24 degrees north by northeast. If we go looking downrange from there, we can find another field of oblique craters with the same direction, and trajectory, in the early Holocene sediments of the Red Rock River Valley in southwest Montana. RedRockRiver We also have good visual cues to date this fall. Look in the upper left of the image map above. The ejecta splash from the oval crater at 44.642265, -112.077185 was blown over the top of, and is blanketing, one of the ancient meanders of the river. And at 44.644033, -112.076880, the ejecta that's covering that late Pleistocene/Early Holocene meander provides an excellent stratigraphic horizon for dating the event. The two crater fields were probably formed in the same fall of fragments. Remember Harlan Bretz's catastrophic flood event in Eastern Washington? The timing of the two oblique crater fields in Nevada, and Montana, and the fact that Lake Missoula was downrange from the Montana impacts implies that the last time that ice dam failed, the impact storm these two fields of oval craters describe may have been the trigger, was it? _________________________________________________________________ The Northeast Impact Zone, and the destruction of the Laurentide Ice Sheet The distribution of the blast effected materials found in the Younger Dryas Boundary layer imply that the Laurentide Ice Sheet took a major hit. Firestone and friends thought that the most likely target zone was in the Great Lakes region. From Evidence for an extraterestrial impact 12,900 years ago that led to the megafaunal extinctions and the Younger Dryas cooling. by R.B. Firestone et al, 2007 we read: "Toon et al. suggest that an impact capable of continent-wide damage requires energy of 10^7 megatons, equivalent to an impact by a 4-km-wide comet . Although an impactor that size typically leaves an obvious large crater, no such late Pleistocene crater has been identified. The lack of a crater may be due to prior fragmentation of a large impactor, thereby producing multiple airbursts or craters. Hypervelocity oblique impact experiments (Peter. H. Shultz , unpublished data) indicate that a low-impedance surface layer, such as an ice sheet, can markedly reduce modification of the underlying substrate if the layer is equal to the projectile's diameter. These results suggest that if multiple 2-km objects struck the 2-km-thick Laurentide Ice Sheet at 30°, they may have left negligible traces after deglaciation. Thus, lasting evidence may have been limited to enigmatic depressions or disturbances in the Canadian Shield (e.g., under the Great Lakes or Hudson Bay), while producing marginal or no shock effects and dispersing fine debris composed of the impactor, ice-sheet detritus, and the underlying crust." [Update 3/25/2012: At time of Firestone et al's publication in 2007, the work of Toon et al was well respected in the impact research community as the state of the science with regards to scaling of impact events. So the estimate that it would take a 4 mile wide bolide to account for a continent wide impact layer is based on their work. And in spite of the fact that Clube & Napier had been talking since 1982 about the very real probability that a comet might hit as a large cluster of small fragments, in 2007 few scientists on the American side of the Atlantic were paying much attention to their work on the Taurid Complex. They are now. In March 2012 Isabel Israde-Alcántara et all published a new paper in PNAS titled `Evidence from central Mexico supporting the Younger Dryas extraterrestrial impact hypothesis'. This new paper effectively ties the Younger Dryas Impact Hypothesis to to Clube & Napier's "Coherent Catastrophism" astronomical model of the Taurid Complex. And yet, still at this time, the thinking in the impact research community remains firmly stuck on looking for a crater from a large single bolide, ballistic-kinetic impact event. Peter Shultz's hypervelocity ice sheet impact experiments indicated that we can expect the ice to explode on impact like the reactive armor on a battle tank. So we don't necessarily expect to find any shocked minerals. Because all of the kinetic energy gets translated to heat. In fact, we aren't looking for any of the normal features we would expect to find in an impact structure. The ice sheet impacts didn't produce a single crater. But the violence of those impact induced hydro-thermal explosions, and all that inconceivable heat in the presence of a lot of water most certainly left its mark. We can use the predicted location in the Archaean bedrock of the Canadian Shield to our advantage for a positive identification of the impact sites. The region is some of the most stable continental crust on Earth. And with the exception of some Dyke formations that date to about 1 million years ago, the last time there was any volcanic activity in the Canadian Shield was more than two, and a half billion years ago. That's really deep time! It's more than half the age of the Earth. And it is almost too ancient to grasp. But during that time, super continents like Gondwanaland, and Pangaea, have come together, drifted apart, come together again, and drifted apart yet again to become the world we know today. Giant mountain ranges like the Himalayas have been raised up to dizzying heights, crumbled to dust, washed out to sea, and then raised up again too many times to count. Entire ecosystems, the dinosaurs, and countless other species have evolved, flourished successfully for eons, and gone with barely a fossil to remember them by. More than half the age of the Earth is an awfully long time. So any evidence whatsoever of a geologically recent surface melting event is a major red flag. And by `geologically recent' I mean an age since melt that is measured thousands of years. We don't have to look very far to find our surface melt formations. Just northeast of Upper, and Lower Red Lakes, Minnesota we see clearly legible patterns of movement, and flow, in surface melted stone. And the flows are almost in perfect condition. It's the lighter pink colored, almost white stone. And it's the marks of titanic hydrothermal explosions in the ice sheet. The heat source was hot enough to burn all the way down through the ice and partially melt the surface of the stone below. And the story told in the rivers of flowing stone is as easy to read as following spilled paint back to the can. The whole region is as level as a parking lot. Drainage is poor. And, for the most part, where you see green in these images you are looking at peat of varying depths. And here the ice seems to have provided enough of a heat sink to quench, and preserve, some of the extra terrestrial material that brought all the heat. You see it in the black arrowhead splash of molten material blown off to the side, and framed so nicely by the lighter native rock. Below is a false color radar image depicting elevation. It's graded from darkest-lowest to lightest-highest elevation. The deference in elevation for the area of the black splash from lowest to highest is only a couple of feet. The region is as flat as a parking lot. But the ghostly image of the splash and it's associated rivers of melted stone show up clearly as raised features in the terrain. RadarMapForWeb The area is sometimes referred to as "The Patterned Peat Lands of Northern Minnesota". Drainage is poor. And peat bogs are everywhere. But contrary to some of the old literature. The Laurentide ice sheet didn't form the patterns. And the peat didn't either. It only conforms to them, and fills in the low spots with green color; the deeper the peat, the darker the green. So in these image maps the depth of color of the peat bogs in the area is a good proxy for the contours of the depressions. The darker the green, the deeper the depression. The rectangular grid pattern you see is formed by a grid of drainage ditches. The rectangles are 1 x 2 miles wide. So we also have a good scale in the images. The rock composition for the general area of the black splash is labeled on the USGS's geologic maps as: "Para gneiss and schist-rich migmatite -grades into undivided meta sedimentary rocks." Migmatite is a rock of both metamorphic, and igneous, origin that exhibits characteristics of both rock types. Migmatites form under extreme temperature conditions during metamorphism through the heating (but not quite melting) of rocks in the presence of a lot of water. And where partial melting occurs in pre-existing rocks. They aren't crystallized from a totally molten material, and are not generally the result of solid-state reactions. Migmatites are composed of a new material crystallized from incipient melting, and an old material that resisted melting. Exactly the kind of rock we would expect in the burn scars of comet induced, hydrothermal explosions in the ice sheet. And the meta sedimentary rocks are further described as: `Meta sedimentary rocks-undivided-greywacke, slate, local units of conglomerate, arentite, graphic slate, fine-grained felsic volcanogenic, and volcaniclastic rocks, lean oxide iron-formation and its metamorphic equivalent. Includes the Knife Lake Group and the Lake Vermilion Formation in northeastern Minnesota.' So the full range of temperatures, and conditions we should expect of an impact in the ice sheet, from hydrothermal to pyroclastic, is represented by the rock of the blast burns in the area. Min18 The only examples we've had in recorded history of the emplacement of a pyroclastic density current is in an explosive, `Plinian' eruption. So the standard model assumes volcanic activity as the source of all clastic rock. And just as in Mexico, some unrecoverable flaws in that assumption are revealed here. First of all, the problem with the words "volcanogenic", and "volcaniclastic", is that there is no volcano there. We are looking at an area of the Canadian shield. The bedrock is Archaean. There hasn't been any volcanic activity there in 2.5 billion years. And without a volcanic system you can't make a case for volcanism as the heat source for the pyroclasts, and metamorphic facies, unless you can show that the materials themselves are that old. As we've noted before, a pyroclastic density current does not move slowly like lava. While in motion, the particles, and fragments, of super heated rock are in atmospheric suspension. And the material is in a cloud of fire that's typically moving at hundreds of miles per hour. That's where we get the word `ignimbrite', which comes from the Latin for `Fire Cloud Rock'. The motive force for a standard model, volcanogenic, pyroclastic flow is provided by gravity as an ash column collapses, and the materials are pulled downslope away from a volcanic vent. Min38 So the most glaring discrepancy is the lack of any volcano whatsoever to account for these flows of pyroclastic rock; no vent, no magma chamber. The pristine flows of "volcaniclastic" rock could not have come out of the ground. The other problem with using the standard model here is the lack of slopes to flow down. All mass movement on the surface of the Earth requires a motive force to get things moving. On such flat, and level, ground, and with no gradient whatsoever, we cannot assume gravity as the motive force for these pyroclastic flows. The heat, and pressure to melt, and move,those pyroclastic materials could only have come from above. The lines of movement in the melted, flowing stone in the area are clear, and well preserved. Also, they, and the nature of the rocks in the area, are consistent with being the burn marks of tremendous hydrothermal explosions in the ice sheet. They are the grayish to pinkish, sometimes blurry looking areas with flowing lines of once fluid, and moving,' stone in them. And the number, and spacing of the hydrothermal burns is exactly what we would expect from many pieces of a large, fragmented, comet exploding in the Ice sheet. Note the the inclusions of black material in the flows of fine grained clastic rock like the inclusions of till in a flowing glacier of ice. It is the fine grained, high carbon, material defined on the list as slate, and graphic slate. But that stuff was flowing with the melt at the time it was emplaced. And that doesn't jibe with the well observed explanation for the sedimentary formation of a normal slate deposit. Whatever the inclusions of black, high carbon, material are made of, it isn't slate. Min25 Most of the old literature on the region focuses a lot of attention in the peat depressions and their possible formation. The area is also known as "The Patterned Peat Lands of Northern Minnesota". There is speculation that Multiple glaciations caused the patterns. Or Lake Agassiz, and related glacial mega floods may have had something to do with it. But the profoundly simple fact is that ice sheets, and glacial lakes don't make pyroclasts, or blast melt, or any other igneous rock form for that matter. They can only erode away some of the surface detail. And if you look closely you will see that there is no missing surface detail in those flows. The solidified flows show show almost no exfoliation, or decomposition. There is no glacial scaring on them at all. And Except for some peat growing here and there in the cracks, and depressions, the melted flows of felsic "volcaniclastic" rock are almost as pristine as the day they first cooled. And yet we know there hasn't been any volcanic activity there in more than half the age of the Earth. Min34 By its very nature, the fine grained felsic "volcaniclastic" and "volcanogenic" rock on the list was a fluid, in rapid motion at the moment of its emplacement. And here, as in Mexico, those motions are as easy to read as flowing paint. The ice did play a major role here in the formation of these patterns. But not in the manor that has been assumed. The depressions are the footprints of obstacles the melt was flowing around, and through, when it was emplaced. Those obstacles are no longer there because they were icebergs that were the comet blasted remnants of a shattered Laurentide ice sheet. To sum up, the surface rock of the blast burns in the northeast impact zone grades from migmatites, which were formed from ordinary sedimentary deposits that were heated almost to the melting point under terrific heat, and pressure. And in the presence of a lot of water. To "volcaniclastic", and "volcanogenic" rock which was probably the same stuff. But heated all the way to a fast flowing state, and fluffed up a bit with hot gasses. So in the recipes, and conditions, needed for the formation of the rocks of each of the blast burns we see the signatures of the full range of conditions and temperatures from hydrothermal to "volcanogenic", we should expect in the planetary scaring of an ice sheet impact. Those hydrothermal burn scars can be found in large numbers all the way to the Arctic. And when viewed forensically as the blast effected materials of an explosive event, they describe the almost complete destruction of the Laurentide Ice Sheet is a mater of minutes. [Note: there has been speculation that the Carolina Bays along the eastern seaboard were caused by impactites of ice that were produced when the LIS was hit. But dating seems to indicate they are too old to be related to the YD event.] _________________________________________________________________ A Comet Storm 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 a bit. Our average fragment Should be 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're just cheerleaders, twirling batons in front of a parade. The rest fall into already superheated atmosphere, 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, hit's 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 10^7 o 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 it's kinetic energy is translated to heat in the atmosphere, it is difficult to get more than 100,000^ o 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 storms caused by the fragments of the Taurid Progenitor soon after its complete breakup. And the thermal explosive catastrophe its debris streams brought, was more violent than anything ever imagined. There are still a lot of different theories as to the trigger event for the Younger Dryas cooling. And the cause of the megafaunal extinctions. As for me, I am firmly in the camp that's convinced it was an impact event. But I perceive a vastly different kind of impact event from anything that's ever been described, or studied, before. And if you'll imagine along with me a little more, I'll try to summarize, and describe, the event as I think it probably happened. _________________________________________________________________ Some time between 20,000, and 30,000 years ago a great comet 50 km to 100 km wide was thrown into the inner solar system. And it immediately began to break up. That disintegrating comet was the progenitor of the Taurid Complex. A family of objects in related, short period, Earth crossing orbits. And 12,900 years ago, just after the end of the last ice age, two large clusters of fragments from that monster, both with the fragment size, density, and distribution like we see in comets Linear, or SW-3. Had a celestial train wreck with this fair world of ours. The individual fragments of each cluster were so close, that in the heart of their respective impact zones, only the first fragments to fall, fell into cold atmosphere. The rest fell into the already superheated impact plumes of those that had gone before. And they just cranked up the heat And pressure. Something like 1.1 billion tons of material fell in those two clusters. And the event lasted a little over an hour. The progression of the event was a result of the Earth's movement along it's 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, if it was a daytime event, the fragments would've been outbound from perihelion. And as the Earth Crossed the debris stream, the airburst storms would've began in the west, and progressed to the east. In a night time event, the debris stream would be inbound towards their perihelion, and the opposite would be true. You get a better idea of the progression of the event if you consider how fast the Earth itself is traveling. Assuming that the Earth's orbit is roughly circular, we can work out it's orbital speed with some fairly simple algebra. Since the average distance from the Earth to the Sun is 149,597,890 km., the Earth travels a distance of 2*Pi*(149,597,890), or 949,951,264.43 km per year. But I can't wrap my brain around that number when you write it that way. I need it broken down a little more. There are 365 days in a year, and 24 hours per day. So we get a velocity of 107,300 km/h, or if you prefer, 67,062 miles per hour. So what? How do we put that into a scale that makes some sense? We need to put that number into some kind of subjective context to make sense of it. Consider this: Earth's Diameter at the Equator is something like 7,926.28 miles, or 12,756.1 km. Which means we're riding the Earth through space along her own orbital path at a little more than 8.41 times her own width every hour. So, as the Earth crossed the orbit of the Taurid progenitor's still concentrated debris streams, she would have only been in the path of that stuff for about an hour. And the two large clusters of fragments would have fell within a few short minutes of each other. 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 down-blasts of thermal impact plasma hit the Laurentide Ice sheet, they caused titanic hydrothermal explosions (steam) that lofted huge icebergs hundreds of miles in all directions. 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 ice sheet impacts evaporated millions of acre feet of ice directly into the atmosphere as steam. 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. There were probably torrential rains everywhere in the northern hemisphere for weeks afterward. How long exactly? Who knows? We can only estimate. But for a good ball park figure to start from, the biblical 40 days, and 40 nights, sounds about right to me. 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 very probably the flood effects of the flash melting of major portions of the eastern end of the Laurentide ice sheet. And the outflows from the resulting floods would've been to the north into the Arctic ocean, and the North Atlantic. There would also have been armadas of icebergs after the event in both areas. And I expect that the glacial till in those bergs must have been deposited on the ocean floor below as they melted. So I'd expect to see some evidence of that armada of icebergs in ocean cores. 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 would've risen 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. Out of tens of thousands of large, air-bursting, fragments there is not one single impact structure the northeast impact zone that bares any resemblance to what standard impact theory might expect. There are a few hundred normal craters averaging about 100 meters width, in the southwest, on the outskirts of the primary impact zone there. And that have been pretty much ignored by the academic community. But for the most part, all of the planetary scarring of the event has been mis-defined as ancient volcanogenic. And most of the ages of those blast effected materials have been over estimated by orders of magnitude. The other much larger cluster of fragments hit in central Mexico, and the American southwest. And it produced the most devastating geo-ablative effects of the two. The Mexican cluster was approximately 500 miles wide. As the first of the fragments hit, they detonated high in the atmosphere. But the explosions retained their downwards 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. Mexico didn't have an ice sheet to protect the surface by exploding on impact like reactive armor on a battle tank. And there, the overpressures from the blast waves were so powerful they blasted whole mountain ranges aside like clumps of flour on a bakers table. As the comet's debris continued to pile in, the heat, and overpressures, continued to build. In seconds all of North 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 storm front, hundreds of miles wide, and hundreds of miles from front to back. And it rushed downrange to the northwest at supersonic speeds, sterilizing 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 blast wind 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 impact 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 a firestorm 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 bare the scars of that blast of heat. In fact, look closely in modern satellite images. You'll see that all of the high ridges of the mountain ranges of California, Colorado, Utah, Wyoming, and Montana that had glaciers at the time bare clear and obvious signs of the heat. And a profound feature that is easy to spot in satellite images 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 deformed, and melted, glacial 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 glacial till dropped out so fast it's as if the ice just vanished in a quick puff of steam. While the mega floods from the blasted ice sheet were still flowing into the sea. Much 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. And 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 something like 1,300 years. The Clovis people, and whole species, and ecosystems, were annihilated in seconds. Much 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, and east, of the impact zones. 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. All that might sound like the product of an overactive imagination. But using modern satellite imagery, a very compelling case can be made that the scenario described above is very close to the exact truth. One could make a good case that similar comet impact storms from the Taurid Complex caused the Bronze Age collapse 5,200 years ago. In fact there is a very real probability that devastating impact storms from the Taurid complex were a bi-annual event of varying intensity that happened twice a year for many millennia both before and after the postulated YD trigger event. And the YD event 12,900 years ago was just the worst of many. Our ancestors lived under a far different, and dangerous sky than what mankind enjoys today. 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 event of the Taurid Complex. Something wicked this way comes. It's been here a few times before. It's caused extinctions before. It's even killed humans in large numbers before. And it can be implicated in the collapse of many bronze age civilizations. Next time it comes back, it would be good to see it coming in time to get people out of the way. And to prepare for human survival in a drastically altered globate climate. Yet congress would rather whiz away 70 million dollars trying to convince us a trace gas that's important for life to flourish on this planet should be thought of as a pollutant. All the while giving funding for impact research, and the search for Near Earth Objects, little more than lip service. Share this: * StumbleUpon * Facebook * Digg * Email * Published on May 18, 2011 at 4:28 pm Comments (6) The URI to TrackBack this entry is: http://craterhunter.wordpress.com/a-different-kind-of-climate-catastro phe/trackback/ RSS feed for comments on this post. 6 CommentsLeave a comment 1. On October 29, 2011 at 11:45 am Largest Asteroid in 2 decades to buzz Earth - SLUniverse Forums said: [...] [...] Reply 2. On February 23, 2012 at 9:31 pm Alexei Rudoy said: Superpaper, thank you very much. YA opublikuyu stat'yu na svoiom sajte s Vashego pozvoleniya....S uvazheniem! Reply + On February 23, 2012 at 10:13 pm Dennis Cox said: Thanks for the compliment. YA chest'yu, chto vy zainteresovany v moej rabote. I ya rad dat' vam razreshenie na podelit'sya im v vashej stat'e. Reply 3. On March 6, 2012 at 4:41 pm Bundy said: Absolutely brilliant....extremely riveting,great work.This should be picked up by scientists to further your studies on the subject matter. Reply 4. On March 15, 2012 at 10:59 am E.P. Grondine said: Dennis, you never mentioned this gentleman's work before. (Making a guess at it, I'd say it was E**** J****. On the other hand, the other impact craters around the main Odessa crater are known in the meteorite collecting community.) Google up the Assiniboine memories of the drainage of either Lake Missoula, or another glacial lake. The "Great Fire" was seen by other peoples besides the Sioux (I can not share who with you now, nor their accounts), but you have to remember that the Sioux proper were farther north, most likely along the open Cordellera. While we may have some "Boslough" features here, as you point out, the key is dating. Others have made the mistake before of associating impact features with only one impact, when they belong to different ones. While I agree that the Carolina Bays were formed by secondary impact ejecta, as the Carolina Bays were being exploited by Clovis man, they preceded the Holocene Start Impacts. Caused by yet another different impact. For that matter, we don't know with any certitude whether these impacts were caused by Comet Encke, or a different comet, perhaps the progenitor of the Draconids. Though deposits of the Great Fire are found globally, there are no burn indicators in Eastern North America. There were other "Ice Ages", and none of them can be linked with impact events. As near as is currently known now, the Glacial Sheet had already begun to melt. The YD cooling (in Europe) was caused by the drainage of the that ongoing glacial melt. In sum, what we have here is a typical Ice Age cycle, but during this one a major impact event occurred. good hunting and see you on the meteorite list, E.P. Reply 5. On March 15, 2012 at 11:02 am Dennis Cox said: Ed Grondine said: "Dennis, you never mentioned this gentleman's work before." "(Making a guess at it, I'd say it was E**** J****. On the other hand, the other impact craters around the main Odessa crater are known in the meteorite collecting community.)" Actually, this work is mine. And I've been talking about it for coming up on three years now; ever since I started writing this blog in 2009. I've just never mentioned it over on George Howard's blog The Cosmic Tusk. Although in light of the data presented in the new paper regarding the Younger Dryas Impact hypothesis, Evidence from central Mexico supporting the Younger Dryas extraterrestrial impact hypothesis, I am torn between updating this one to reflect the new data, or leave this version as-is as a historical document, and write another one from scratch. As for the additional craters around Odessa and West Texas, I remain to be convinced of the dating of those events. Or the dependability of any of the field of geochronology for that matter. And I'm extremely skeptical that the reliability of radiometric data doesn't get blown all to hell by the energies of a major impact event. I've discussed the additional craters around Odessa and the rest of West Texas with both Ted Bunch at NAU, and Pete Schultz at Brown U. They were both reluctant to accept that so many craters could exist in a single crater field. And after telling me I had a very "good eye" they both assured me that they must be "Something Else". But without being able to say just exactly what other geologic processes besides impact might exist that can produce geomorphology that's indistinguishable from impact craters in hi-resolution satellite imagery. And without being able to cite sources to show that any real research had actually been done to determine what that "something else" might be. The radical part that the impact community is having a hard time considering is the idea that thousands of small impacts can happen in a single cluster impact event. As you probably know, the consensus view held by NASA planetary scientists is that impacts happen at a slow, and predictable rate, one at a time. And that you can therefore estimate the age of a planetary surface by counting the number of craters in any given surface. But the simple unassailable fact is that large clusters of small cometary fragments do indeed exist in short period Earth-crossing orbits that also cross the orbits of all the planets of the inner solar system. In fact they're fairly common; as these images of comets Linear, and SW-3 can attest. The problem for mainstream planetary scientists is that if they acknowledge that such large clusters of small fragments really do hit the planets of the inner solar system from time to time. Then decades of work estimating the age of surfaces on the Moon, Mars, and every other rocky body in the inner solar system go right out the window. Google up the Assiniboine memories of the drainage of either Lake Missoula, or another glacial lake. A Google search didn't turn up anything about Assiniboine "memories". But I do happen to know a fair amount about the Glacial Lakes of the Pacific Northwest. There were only two by the end of the last ice age. The other one to the west of Lake Missoula was Lake Columbia. I lived in Spokane Washington for 16 years and I am well familiar with the `Channeled Scablands', and the Grand Coulee, of Eastern Washington. I used to spend my weekends flying an ultra light aircraft, and chasing coyotes down in those coulees, pretending I was Luke Skywalker chasing Womprats. It's an old playground of mine. And the geology of the region was a passionate interest for many years. So I am well aware how those catastrophic terrains formed. I am also familiar with the mechanism that caused the sudden drainage of lake Missoula. During the ice age, Glacial Lake Missoula was impounded behind an "Ice Dam" when a tongue of the Cordilleran Ice Sheet called the Purcell lobe extended down south far enough that it formed and ice dam that blocked the south fork of the Clark Fork River in Northern Idaho. Lake Missoula filled and drained many times during the ice age in a repeating cycle. The Glacier would advance, blocking the river and backing up the waters of Lake Missoula. When the lake level would get high enough that the ice dam couldn't hold back the pressure of all that water, the dam would fail, releasing a catastrophic flood downstream. The glacier would advance again, blocking the river again, and the cycle would repeat. Judging by the number of strand lines from Lake Missoula's ancient beaches, the cycle may have repeated as many as 40 times during the last ice age. Another blockage occurred to the west of Lake Missoula where the Okanogan Lobe of the CIS plugged the Columbia River's course impounding the waters of Glacial Lake Columbia; a body of water with a 500 square mile surface area at maximum fill. The same process happened there many times during the ice age as well. The last time glacial Lake Missoula drained has been dated to about 10,000 years ago. Since the Younger Dryas Boundary layer has been dated to about 12,900 years ago, we are looking at nearly 3,000 years between the postulated impact event that's thought by many to have triggered the Younger Dryas cooling, and the last ice dams of the Cordilleran Ice Sheet on the Columbia, and Clark Fork rivers. During that time Lake Missoula may have filled, and drained again, as many as a dozen times. And the only mega flood of the late Pleistocene that wasn't produced by the sudden failure of an ice dam was the one produced by Lake Bonneville. Wikipedia: Lake Bonneville was a prehistoric pluvial lake that covered much of North America's Great Basin region. Most of the territory it covered was in present-day Utah, though parts of the lake extended into present-day Idaho and Nevada. Formed about 32,000 years ago, it existed until about 14,500 years ago, when a large portion of the lake was released through the Red Rock Pass in Idaho. Following the Bonneville Flood, as the release is now known, the lake receded to a level called the Provo Level. Many of the unique geological characteristics of the Great Basin are due to the effects of the lake. The Bonneville flood released nearly 1,000 cubic miles of water, making the total volume of water released twice as large as the biggest Missoula Flood. However, unlike the repeated Missoula Floods which each happened over a period of just days, the Bonneville Flood occurred over a period of several weeks. Other sources date the Bonneville Flood to as much as 17,400 years ago. But either way, Lake Bonneville can be ruled out as being associated with the Younger Dryas event because it dates to too long ago. The geology of the region has been intensely studied. And the mechanism of the repeated formation, and subsequent ice dam failures of the Glacial Lakes at the foot of the Cordilleran Ice Sheet is well understood. Although the story of how geologists came to understand it all is a very exiting read in itself, there has been nothing found in the geological record so far to indicate any of the often repeated great floods of the Channeled Scablands of Eastern Washington, or the Grand Coulee were triggered by an impact event. The "Great Fire" was seen by other peoples besides the Sioux (I can not share who with you now, nor their accounts), but you have to remember that the Sioux proper were farther north, most likely along the open Cordillera. While other people besides the Sioux may indeed have seen the "Great Fire" as you call it. They were most certainly not "farther north" than the southern edge of the Cordilleran Ice Sheet when it happened. Your assumptions that the Sioux were living north of there while lake Missoula had water in it don't hold up. No one ever lived north of a late Pleistocene glacial lake in the Pacific Northwest while it had water in it. There were no human settlements north of either of the glacial lakes at the time. Because the Cordilleran Ice sheet that blanketed the western half of the northern tier of the continent was every bit as thick and extensive as the Laurentide Ice Sheet that blanketed the Northeastern side of the continent. It was up to two miles thick in places. And it blanketed almost all of western Canada all the way to the Pacific. The CIS extended as far south as the northern shores of both glacial Lakes Missoula, and Lake Columbia. An ice dam was required for a glacial lake to fill up. And that only happens during an ice age. So at any time in the past when there was water in Lake Missoula or Lake Columbia there was also an extensive ice sheet that made anywhere north of either of them unfit for human habitation. Simply put: No ice sheet=no ice dam. No ice dam=no glacial lake. Or: Glacial lake=ice dam=ice sheet north of lake=unfit for human habitation. It's not clear which "Open Cordillera" you are referring to. All of the Mountain ranges of the western half of the continent extending from Southern Mexico to Alaska, from the Rockies of Wyoming, Colorado, Utah and Montana to the Sierra Nevada, Cascade, and Olympic Ranges of the Western Coastal states can be described by the broad term "Open Cordillera". So it's not clear which Mountains you are referring to with your broad use of that term. But the Bitterroot Range formed southwestern shores of Lake Missoula. And every thing north of the lake was under the Cordilleran Ice Sheet. The Canadian Rockies are sometimes called the Canadian Cordillera. But they were also under the CIS during the ice age until about 10,000 years ago. And the mountains west of the Channeled scablands and south of the CIS were the Cascades I am extremely skeptical that accurate accounts from any culture, written, oral, or otherwise, exist that are 13,000 years old. And unfortunately, even if those oral traditions really are accounts of an impact event that's associated with the draining of one of the Glacial Lakes, the catastrophic damage done to the terrains of the Pacific Northwest by the repeated great flood events, of the Channeled Scablands, and the Grand Coulee, was so extensive, and so extreme, that it probably removed all traces of anything but the floods themselves. While we may have some "Boslough" features here, as you point out, the key is dating. Others have made the mistake before of associating impact features with only one impact, when they belong to different ones. I've never said I think there was only one impact event. Note that from the beginning when I first started writing about this in 2009, the astronomical model I have always been working from has been founded on Clube and Napier's work on the Taurid complex. That model puts the entry of the Taurid progenitor object into the inner solar system and into a short period orbit of only 3,3 years 20,000 and 30,000 YA. and it's progressive breakup would've begun immediately. So the devastating impact storms from the Taurids which were the impacting debris from that deteriorating monster would've been a bi-annual event of varying intensity every June, and November for thousands of years both before, and after, the YD event, or Holocene Start Impacts as you refer to them. The event that's evidenced in the materials of the Younger Dryas Boundary layer was probably just the largest, and most violent of them. While I agree that the Carolina Bays were formed by secondary impact ejecta, as the Carolina Bays were being exploited by Clovis man, they preceded the Holocene Start Impacts. Caused by yet another different impact. I agree with this too. In fact' they have been removed in the new paper on the YD hypothesis as being unrelated to the Younger Dryas Impacts. In light of the new paper from Mexico I'm not sure whether I should edit them out of this piece, or put a footnote to that effect. For that matter, we don't know with any certitude whether these impacts were caused by Comet Encke, or a different comet, perhaps the progenitor of the Draconids. That is a fair statement because we really don't know anything with certainty at this time. Comet Encke is related to the Taurid family of objects as the largest known remaining fragment of the Taurid progenitor object. The astronomical model of the Taurid Complex provided by Clube, and Napier remains the best fit to what we do know at this time. That's why it's the preferred astronomical model given in the latest expression of the Younger Dryas Impact Hypothesis as stated in Mach 2012 paper in PNAS titled Evidence from central Mexico supporting the Younger Dryas extraterrestrial impact hypothesis by Isabel Israde-Alcántara et al. However if you can show reason to believe that the Draconids are a better astronomical model for the YD event than what was given in that paper you should do so. Though deposits of the Great Fire are found globally, there are no burn indicators in Eastern North America. There are also no evidences of what I interpret as geo-ablative topography there. I think that's what accounts for the species that did survive. It was the `safe zone'. There were other "Ice Ages", and none of them can be linked with impact events. As near as is currently known now, the Glacial Sheet had already begun to melt. The YD cooling (in Europe) was caused by the drainage of that ongoing glacial melt. In sum, what we have here is a typical Ice Age cycle, but during this one a major impact event occurred. You are probably correct. Reply Leave a Reply Cancel reply Enter your comment here... ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ Fill in your details below or click an icon to log in: * * * * Gravatar Email (required) (Address never made public) ____________________ Name (required) ____________________ Website ____________________ WordPress.com Logo You are commenting using your WordPress.com account. ( Log Out / Change ) Twitter picture You are commenting using your Twitter account. 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Post Comment * CAPTION: March 2012 M T W T F S S « Feb 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 * ________ Search * Contents + Home + A Different Kind of Climate catastrophe + A thermal airburst impact structure + Southwest Montana + The Meteorite Men and the Odessa Craters + Fire Cloud Rocks + The Mexican Impact zone + The Benavides Impact Structure o An impactite in the melt o An oblique impact crater + California Melt + The Northeast impact Zone and the destruction of the Laurentide Ice Sheet + New Insights Into Extraterrestrial Impacts, Younger Dryas Cooling, Mass Extinction, and the Clovis People I + Comets and The Bronze Age Collapse + Large Aerial Bursts and the Impact Threat + Reference Links * Categories + Alternate impact theory + Authors notes * Links, Books, and Other Blogs + A Catastrophist's Manifesto by Han B. Kloosterman + A Neolithic Comet by William Napier. + An Overview + Analysis of the Younger Dryas Boundary Layer + Anthropology.net + Bill Napier's Essay: Giant Comets -- Messengers of Life and Death + Bill Napier's recent paper, 'Palaeolithic extinctions and the Taurid Complex' + Bob Kobres, A Nickle Pickle + Catastrophic Impact Events in the Late Pleistocene + Centauri Dreams + Center for the Study of the First Americans + Climate Depot + Comets, Catastrophes, and Earth's History + Cosmopier! + Disaster Archeology + Fireballs and Meteorites - SOTT.Net + George Howard's 'The Cosmic Tusk' + Highly Allochthonous + Meteorites, Asteroids, and Comets: Damages, Disasters, Injuries, Deaths, and Very Close Calls + NASA's Astrophysics Data System + Perigee Zero + Richard Firestone's 'The Cycle of Cosmic Catastrophes: How a Stone-Age Comet Changed the Course of World Culture' + Rodney Chilton's 'Sudden Cold' + The Fragmentation of small asteroids in the atmosphere + The Meaning of The Vedas + The Meteorite Men + The structure and evolution of the Taurid complex + Time's Nemesis * * Contact me * Blog at WordPress.com. 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