Ignimbrite (from the Latin for ‘Fire Cloud rock’) is a deposit of rock formed by a pyroclastic density current, or pyroclastic flow. And in a hot suspension of particles and gases.
Sometimes impact melt is mistaken for ignimbrite. And the reason for that common mistake is that at the moment of formation, and emplacement, they are both deposited in a cloud of superheated fragments, and debris. And this results in a similar brecciated, or broken, internal structure. I don’t want to digress into a discussion about volcanoes. But it is important to understand how these kinds of materials move while in a fluid state.
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.
Under the present paradigm, it’s assumed that only terrestrial volcanism produces ignimbrites. And the word is commonly considered to be synonymous with volcanic tuff produced in an explosive eruption. Like the eruption of Mt Vesuvius in 79AD that destroyed the cities of Pompeii, and Herculaneum.
That eruption was described in great detail by Pliny the younger. And whose uncle, Pliny the elder, was killed by it while trying to rescue some ffriends. Hence, we get the term ‘Plinean Eruption’
In such an eruption, all of the rock erupts explosively from below the surface. And produces a huge ash column that rises sometimes miles high before collapsing. The rock, as well as the heat, and pressure, it brings with it, share the same subterranean source. The pressure begins to dissipate very quickly with any distance from the vent. And It does not provide a motive force once the volcanic materials are on the ground. Once an ash cloud has collapsed, and the material falls to Earth, the only motive forces left to provide material movement are gravity, and momentum.
Such a flow is also known as a pyroclastic density current. In order to be a fast moving density current, and not a slow and gooey flow of lava, the particles, and fragments of melted, and semi melted, stone need to be suspended, and carried along in the hot gasses of the fire cloud. Once they settle settle out, they quickly loose their momentum, and come to rest. So any given piece of ignimbrite. can be thought of as a signature of sudden, and explosive, fluid motion. And the length of time it’s in motion is never more than a few seconds.
For the purpose of understanding the patterns of movement that become frozen into the stone at the moment of its emplacement, gravity is the motive force. And it can be thought of as being in front of the material, pulling the density current down slope. Its motion can build up considerable momentum. But continuous atmospheric pressure behind the flow is not a driving force in the formation, and emplacement of a volcanogenic, gravity-driven, density current.
Under the present geological paradigm, terrestrial volcanism is thought to be the only possible source of an ignimbrite producing pyroclastic density current. And gravity is thought to be the only possible motive force to provide material movement.
But in fact, there is another far more violent way to produce a pyroclastic density current. One that is wind-driven, rather than gravity-driven. The source of the material is the ablated surface itself, not a subterranean magma chamber. And the heat, and pressure, to melt it, and get it all moving is not terrestrial volcanism either. This material is produced by a very large, geo-ablative example of the airburst that exploded in 1908 over a remote place in Siberia called Tunguska.
More than 1000 times as powerful as the the atomic bomb dropped on Hiroshima, the Tunguska blast was the largest impact event in recorded history. Yet it didn’t make a crater. In fact, it didn’t do anything the standard model of an impact event might predict. The so called “full suite” of impact markers is not to be found there. And if there had been no witnesses, the Earth sciences would be in complete denial that the violence that day came from above.
The explosion flattened an estimated 80 million trees covering 2,150 square kilometers. Yet it’s fireball never reached the ground. Only its detonation shockwave did. There is no reason to assume that the Tunguska airburst was unique. There is also no reason to think it was a very large example of an airburst event.
Mark Boslough, a scientist at Sandia National Labs, has this to say about airbursts.
“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.”
~Dr. Mark Boslough Sandia National Laboratory
Dr Boslough has produced a super computer generated simulation of the airburst of a 120 meter stony asteroid that is an example of the larger, ablative version of an airburst that is a must see.
In it, we see the exploding object detonating high in the atmosphere, and becoming a supersonic down draft of thermal impact plasma hotter than the surface of the sun. But watch the sequence closely. And pay particular attention to the post impact updraft at the center of the flow. And to the directions of flow of the airburst vortex at the surface, as the impact plume develops at the center of the vortex. You might want to replay it a few times.
The Tunguska fireball didn’t reach the ground. But Dr Boslough has given us a good idea of what happens if a bigger object produces a fireball that does.
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“Simulations suggest strong coupling of thermal radiation to the ground, and efficient ablation of the resulting melt by the high-velocity shear flow.”
–Mark Boslough, Sandia Labs.
One of the best kept secrets in science today is just how good the satellite imagery available through Google Earth of the American southwest, and central Mexico has gotten in the past decade. The biggest leaps in quality have happened in the past two years. The imagery has gotten good enough to assign a directional vector to almost every pixel. And to read the directions of the fluid emplacement motions of geo-ablative flows of airburst melt like reading a dance chart.
The area depicted in the slideshow below indicates that Dr Boslough is exactly right about the geo-ablative properties of a very large airburst event. It also shows that once you figure out what to look for instead of craters, the planetary scarring of such events aren’t hard to find at all. In fact. Ablative airburst geomorphology, in pristine condition seems to be rather common in North America.
Hmmm…. There seems to be a new kind monster in the closet.
It’s called a Geo-ablative Airburst. In that simple sentence, Dr Boslough has, in effect, postulated the existence of a different kind of pyroclastic density current. The target surface becomes the source of the pyroclastic materials, instead of a volcanic system. And the heat, and pressure to melt, and move, it comes from above in the form of a Geo-Ablative Airburst. As you can see from the slideshow above, the planetary scarring of such events is not hard to spot.
All material motion across the surface of the Earth requires a motive force.
During emplacement, a volcanogenic pyroclastic flow relies on gravity for it’s motive force, and the explosive force of a powerful eruption to get everything into a superheated atmospheric suspension. Gravity provides the motive force down-slope for a volcanic pyroclastic flow. So it’s patterns of movement, and flow, will be those of a fluid seeking the lowest points in the terrains.
But Geo-Ablative melt is the product of a different kind density current, driven by atmospheric pressure in a large thermal airburst impact event. The particles, and fragments, suspended in the flow didn’t erupt from the ground, they were ablated from the surface itself by the heat, and pressure, of an airburst. The fluid motions of a pyroclastic flow of geo-ablative melt can be characterized as wind-driven. Therefore they will be seen to have moved from areas of highest pressure, to areas of lower pressure. And their patterns of movement, and flow will be reminiscent of the debris laden froth, and foam on a storm tossed beach.
The structure of a fragment of Geo-Ablative melt might be visually indistinguishable from that of ordinary volcanic tuff. But there is a simple way to identify formations of airburst melt. And to scope out good candidate locations for field studies. The different motive forces involved during emplacement, one gravity-driven, the other wind-driven, result in distinct, and easily recognizable patterns of movement, and flow.
So the final test would be in field work, and in detailed chemical analysis of suspected airburst melt.
A very strong case can be made that a region including almost all of north central Mexico, and west Texas is in fact, a single, multiple geo-ablative airburst impact zone. Here after referred to as the ‘Mexican Impact Zone’ or MIZ
I have invested well over 4,000 hours studying satellite imagery the blast effected materials of that impact zone.
In the term ‘Blast Effected Materials’ I mean to say, any material that owes its chemistry, condition, or position, to an explosive event. No matter whether volcanic tuff, or airburst melt, all ignimbrites are blast effected materials. From a forensic perspective, if you want to understand an explosive event after the fact. You study the condition, position, and chemistry, of the blast effected materials. And from that forensic perspective, the blast effected materials of the Mexican impact zone describe the single most violent natural disaster on Earth since the impact event that is caused the demise of the dinosaurs 65 million years ago.
And at first, I couldn’t imagine how evidence of the violence of a geologically recent impact event that must have effected the entire continent. And probably the climate of the entire world, could have been missed.
And then I found a paper by R.B. Firestone et al titled Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling
A compelling case can be made that The Taurid Progenitor hit the Earth as a stream of tens of thousands of fragments like the Tunguska object. And accompanied by clouds of smaller fragments, and particles, down to the size of dust grains. It probably came out of a daytime sky. And it hit at a low angle of about thirty degrees, coming from the southeast. And at a velocity of about 30 kilometers per second. Only the very first fragments fell into cold atmosphere. The rest fell into already superheated atmosphere, and added to the heat and pressure. The down blasts were almost continuous until the Earth finally moved out of the orbital path of the fragmented comet’s debris stream. And the last of the fragments fell.
The process probably lasted a little more than an hour. And the resulting heat, and pressure, of the intense impact showers ablated vast areas of the surface terrains of North America like wax under a high pressure blowtorch.
The motive force for the resulting density currents of geo-ablative melt was atmospheric pressure driving the flow from behind, like the wind drives the debris laden foam, and froth, on a storm tossed beach. And that driving wind was a more than hurricane force, gusting to supersonic, hyper-thermal blast wind, of rapidly condensing thermal impact plasma. Similar, in a vastly scaled down way, to the aerosol spray of melted droplets of iron, and slag, produced by a cutting torch in a steel fabrication shop.
From a forensic blast analysis point of view, we can say that all ‘ignimbrites’, by their very nature, are a ‘Blast effected material’. It all goes to fluid mechanics, and studying how they moved, and flowed, at the time of their emplacement. Thanks to the completely different energies involved, the different modes of ignimbrite formation, and emplacement, each produces a different kind of density current. And they have distinct, and easily recognizable patterns of movement, and flow. Reading those patterns of movement, and flow is as easy as reading a dance chart. Or following spilled paint back to the can.
I would have thought that the geology of the north American continent was all very well studied. But when you start looking for any detailed research on emplacement of the pristine sheet ignimbrites in north, central Mexico, and west Texas, and the exact nature of the explosive events they were formed in. You’ll quickly find that, except for a few prospectors looking for money rocks, they are almost completely unstudied. There is much untested speculation as to their origin. But they are almost completely unmapped. And, no formal study of their fluid emplacement motions has ever been done.
Those hundreds of thousands of cubic miles of pristine ignimbrites are very clearly the blast effected materials of an explosive natural disaster far more violent than anything in many millions of years. And arguably one of the most violent events in the history of this continent. You could completely empty the Yellowstone super caldera in Wyoming, and you would have only a very small fraction of the volume of perfectly pristine ignimbrites in the Chihuahuan desert of north central Mexico. What little mention you read of them is pure speculation as to their origin. And there hasn’t been a single formal study of their emplacement.
They’re not even mapped!
After digging a little in the old literature to see what was known about them, as opposed to what was assumed, I came to the realization that, in fact, very little is known about them at all. Almost all of the geophysical research in the region is funded by mining companies prospecting for mineral resources. Basic geophysical research is something for universities to worry about I guess. But, as a result, except for about 100 kilometers, or so, along the Chihuahua City – El Paso highway, they are almost completely unmapped. And no one can provide a single map showing the location of one of those supposed rifts. That would’ve had to open, and close without a trace, like magic. Much less one that can be reconciled with the patterns of movement, and flow, at the time of emplacement, which are clearly, and legibly visible in high altitude aerial images.
There is a more than 50,000 square kilometer mega-flood of high speed,random-colliding, inter-flowing, rivers of melted stone in central Mexico, and up into west Texas that are as pristine as if they just cooled last year. When you find them described on a map, they are defined as volcanic tuff. But, of more than 350,000 cubic miles, less than 15% can be attributed to a volcano.
Waiting a lifetime for those Geologists on the ground was not an option. And, in frustration because I couldn’t get my hands on any decent research papers on the subject, I set out to work out the patterns of movement, and flow, for myself to get a better understanding of the explosive events they formed in.
That they were emplaced as a fluidized density current of blast melted stone is an empirical fact. The structure of a rock formed, and emplaced in a pyroclastic density current is not hard to recognize. But this is where the standard model for a density current gets into trouble.
According to that model, the only motive force for a density current is gravity. So, in the world according to uniformitarian model, a slope must exist for the material to flow down. That model also assumes that a volcanic vent must exist at the top of that slope. And terrestrial volcanism is thought to be the only source of melted stone, or the violently explosive heat, and pressure, required to get it into atmospheric suspension for a while. So theorists of the past had to come up with a plausible way to get so much blast melted stone up in the air into a pyroclastic density current at the same time.
Until the world was given a wake up call by watching the fragments of Shoemaker Levy 9 slam into Jupiter no 0ne could imagine that such destruction could come from above.
Their answer, and the model that most geologists have come to agree with, is a theoretical kind super giant volcanic eruption called an “Ignimbrite flair up”, when fault-grabens are thought to have transformed into vast rifts that opened up in the middle of the continent that spewed a few thousand cubic miles of ignimbrites and then closed again, without a trace. But the mantle physics required for the giant, trap door, rift vents they propose just don’t work in the real world.
And to date, there is not a single shred of tomagraphic, seismic, aeromagnetic, ground penetrating radar, or any other evidence that confirms the existence of such a rifting vent. There has never been a model for the mantle physics required for how a fault-graben suddenly turns into a rifting vent that opens, and closes without a trace . Nor has any data ever even hinted at the location of a magma chamber under Mexico big enough to account for a few hundred thousand cubic miles of eruptive material.
The sheet ignimbrites of the Chihuahuan desert, extending all the way up into west Texas, and New Mexico are on top of every thing else in perfect condition. They are the pristine capstone of the geologic column. And with the exception of the occasional sage brush here and there, they did not look much different when they were still hot, and smoking.
If you are looking for the sources of such mystery materials, and you can’t find a volcanic vent, being able to see how it was flowing, and which direction, just before it came to rest, can reveal the answer. But don’t expect the truth you read in those rocks to agree with the standard uniformitarian model. it doesn’t.
If you want to understand an explosive event after the fact, you study the condition, and patterns of movement, in the blast effected materials.
The sudden, unimaginably violent events of their formation can be understood to an amazing, and extraordinary, level of detail if one simply studies how they moved during emplacement. We need only to get enough altitude to see the actual patterns of movement, and flow, to determine the true points of origin, of a sheet of geo-ablative melt. So the science of Fluid Mechanics has the trump card.
It doesn’t get any easier than when the materials are , in pristine condition, and exposed, on the surface. And, in a hi-resolution satellite image, the motions of the ignimbrites in north central Mexico, and those in west Texas, are as easy to read as the patterns of movement, and flow, in splashes of mud, or spilled paint. You can look at a flow, and easily see which direction it was moving at any particular point.
The movements of an unconstrained fluid are defined by the forces moving it.
And for our purposes we’ll need to refine that profoundly simple observation a little more and say that there are two fundamental forces to consider; gravity, and pressure.
Take a droplet of paint, and put it on a level surface. Then blow it around with a straw. That’s a pressure driven fluid. It’s characteristic patterns of movement, and flow, are the result of the motive force being behind the flow, and pushing it. It piles up at the low pressure areas on the periphery where the pressure is no longer strong enough to move it.
Next, tip the surface a bit and let the paint flow downhill. That’ll be a gravity attracted fluid. Its patterns of movement, and flow, are consistent with the motive force being in front of the flow, and pulling it down hill. It doesn’t work on level ground.
The lines of flow in an unconstrained, and wind-driven, fluid will always be away from the driving force. Even if that fluid is melted stone being driven up hill. And when those lines of flow are frozen into a pyroclastic river of melted stone they become a permanent, reliable record of the nature of the forces that melted, and moved it.
Cover a surface with about an inch of wet, slightly sticky, grainy, mud the consistency of thin, wet, concrete. Hit it with short bursts of compressed air coming down from above to simulate the patterns of movement, and flow, in a pressure driven flow of geo-ablative melt.
A fun variation if you want you involve children is to use runny oatmeal spread out on a cookie sheet. If you have the kids surround the Cookie sheet, and blow the oatmeal around with short, random, puffs of air thru a straw. You get the same flow patterns.
The point of the second version of that experiment was two fold. I wanted to see some more examples of wind swept, pressure driven flows. And I wanted to establish that my approach to reading the material movements of wind driven fluids could be taught to others.
We are all descended from the most successful hunter-gatherers of all time. Those who couldn’t see which way their dinner went, didn’t eat. As a result, good pattern recognition skills are an innate human trait. All of the kids easily learned to recognize, and even to direct, and control, the flow patterns of a pressure driven fluid. I was quickly able to determine that it’s difficult to do focused, and objective, observation with oatmeal in your ear. And that, at the heart of this hypothesis, is the fact that this really is so simple that a child could learn to read the motions of the flowing, wind-swept, rivers of melt.
If it takes months, or years, to map a few miles along a highway from the ground it’s time to bring the work into the twenty first century and use the satellites our tax money paid for, and do it from space, or it’ll never be finished. Thanks to NASA, Land Sat, and Google, Anyone can produce their own image map of any given area on the continent. And in full spectrum color with resolution down to about 1 meter per pixel if need be. And computer memory is the only constraint to size.
I have a couple I’ve had printed professionally that cover a whole wall. If you look at a specific location anywhere in those flows, it is very easy to see which way it was flowing at any given point. And backtrack it to its source location. A sheet of clear plastic, and a handful of markers, and you have a large area, hi-resolution flow map. Complete with little directional arrows. Fluid motions that would have taken a lifetime to determine, and map, by traditional ground based surveying techniques can now be read at a glance by almost anyone with a good PC, and a copy of Google Earth.
Either that material is the geologically recent result of the largest super eruption since primates first came down out of the trees. And most of central Mexico is one giant, explosive, caldera that no one ever noticed as such. And all of the missing vents will be found… someday. (And never mind that all of the emplacement motions of the simultaneous, inter-flowing, density currents of melted stone describe a sudden, virtually instantaneous, event.) Or all of the melt is the result of the most violent ET encounter in 65 million years. And it, and its ground effects, are different from anything ever studied before.
Both are pretty extraordinary possibilities. The visual evidence is more supportive of the latter though. Because, when viewed from high altitude, it is profoundly obvious the heat and pressure to melt, and move, all that material came from above. But, no matter what the source of the heat, and pressure was, the more than 40,000 sq km simultaneously random-colliding, and interflowing, mega-flood of blast-generated ignimbrites, at the very pinnacle of the stratigraphic column describes a geologically recent explosive event that was arguably the single most violent natural disaster in all of human existence. Yet, with the exception of a few prospectors looking for money rocks, it’s almost completely unstudied.
The blast effected materials of North Central Mexico describe a highly fragmented, and loosely grouped, cluster, about 500 km wide, like a giant, flying gravel pile. The thing would have looked like a sister to the images of the fragments of comet Linear seen here. It came in at very high velocity, and low angle of approach from the southeast. And almost all of the fragments exploded above ground like Tunguska. Except that, in Mexico, only the very first of the fragments on the leading edge fell into cold atmosphere. The rest fell into already super heated impact plasma, and just added to the heat.
The primary impact zone is a 500 by 1300 km oval that covers most of north central Mexico. And extends well up into west Texas, and New Mexico. The other impact zone is a little smaller in the great lakes region. And it extends from northern Minnesota, well up into Canada.
The patterns of movement, and flow, are dramatically obvious in high resolution, high altitude, aerial photos. And a careful study of the fluid motions of the sheet ignimbrites of north central Mexico, and west Texas quickly reveals, in exquisite detail, a thermal explosive process of simultaneous ablation, and emplacement, which is completely inconceivable from the strictly ground based observations, standard theory viewpoint of the past: The melt was pressure driven from behind like frothing whitewater waves on a stormy beach by atmospheric forces alone. And it did not come out of it’s source locations in an eruptive event. It was flash melted, and blown off of it’s source locations in. And ‘Fire cloud rock’ is a bit of an understatement. But it’s still an excellent descriptive.
Much of the literature assumes multiple eruptive events for the ignimbrites of the Chihuahuan Desert. But again high altitude imagery shouts the truth. No matter what the source of heat, and pressure that melted, and moved them; whether volcanogenic, or the result of a thermal ablative airburst event, all ignimbrites are a fluid in motion at the time of their emplacement. And they solidify very quickly upon coming to rest. We can know that any given fragment of ignimbrite was only in a fluid state for a few violent seconds at most. So if two flows of melted stone are representative of two separate events, even a separation of only a few seconds, then one of them will be seen to be over-topping the other, already solidified one. But if they were both melted, and flowing at the same time, the interaction between the two will be a fluid convergence. i.e. They will inter-finger. Or they will come together like two rivers flowing into one.
Everywhere, in all of the tens of thousands of square kilometers of random, colliding, flows of pristine surface ignimbrites you’ll note that, without exception, the patterns of movement in all of the material is consistent with very fast, and sudden, motion like ejecta.
Every interaction between colliding flows can be described as a fluid convergence, such as two rivers flowing into one.There is not one, single, over-topping flow. The inescapable conclusion is that contrary to the old literature, all of the pristine, wind-driven, ignimbrites in the Chihuahuan Desert were in rapid, fluid, motion at the very same time.
All of that blast melted stone describes an intricate, almost infinite, dance of violent fluid motions. And all of those turbulent, inter-flowing, motions describe the very same moment.
A gravity attracted fluid will always flow to the lowest elevation. The motive force is in front of it, pulling it down slope. But an unconfined fluid which is driven across a fairly level surface by a wind blowing over it from behind will behave differently. It moves from the area of highest pressure to the lowest. With distance from its pressure source, its motion slows, and it piles up at the areas of lowest pressure. In the case of ignimbrites born of a thermal ablative airburst event. Identifying the source locations for the materials is easy. You simply backtrack the flows to the bare places behind them where there are no ignimbrites.
At the source locations, the orogenies, and other blasted landforms, of the region have been assumed to be very ancient. Because they appear to be heavily eroded. The trouble with that standard assumption is a serious lack of alluvium covering the ignimbrites, which are in almost perfect condition, except for the occasional sagebrush, or cactus, growing in the cracks. But no one could have imagined that these landforms are in fact heavily ablated by a thermal ablative process that produced, and emplaced the ignimbrites in seconds. The landforms of north central Mexico, and West Texas aren’t heavily eroded. They are heavily ablated.
And there’s the other problem with the standard model. The estimated age of the terrains of central Mexico, and much of the American Southwest is based on assumptions of slow, and gradual erosion. After all, it should take millions of years to wear those landforms down to a nubbin like that… Or should it?
By the standard model’s thinking, the Ignimbrite “Fair Up” happened somewhere around 25 million years ago, or in the Mid Tertiary. And the landforms arising from them have been eroding, and weathering, since that time. But that scenario requires the ignimbrites to be under the alluvium that washed down over the eons, as the forces of weather eroded those landforms so much.
And after so much time, where exposed on the surface, the ignimbrites themselves should be every bit as weathered as the landforms rising among them. Instead, they are on the surface, in pristine condition. And the alluvium they should be buried under does not exist. If we want to say the ignimbrites were emplaced 25 million years ago. And that the landforms in this image have been eroding slowly for all the time since, then we are going to need to account for the missing alluvium. And we are going to have to give a plausible explanation of how the ignimbrites have survived unchanged for so long on the surface
Every square inch of the area within the oval is a blast effected material of an explosive event.
Below is a small part of the Mexican impact zone. A close study of the motions of the ignimbrites gives one an understanding of why I have called them a ‘Rosetta Stone’. The mountains, and orogenies among them have been described as heavily eroded. And the perceived amount of erosion is the basis for their estimated ancient age. The problem with that estimate is the almost complete lack of alluvial by products of hydrologic decomposition.
These next three images are all found in the image above. The Lat, and Lon, are in the info bar. I hope you take a closer look for yourself with Google Earth. The image quality is as good as it gets. And you can zoom in and study even the tiniest details.
All the way around the mountain above, the sheets of melt were blown away from it like the froth on a storm-tossed beach. And with all the speed of an ejecta curtain. But look closely along the left side about a quarter of the way in, and you can see where two of the comet’s fragments have detonated at ground level into the still moving melt.