 Much of the recent research has pointed, not just to massive fires, continental devastation, and burning, but to an impact into the Laurentide Ice Sheet (LIS) in the great lakes region that caused the disruption of the ice sheet. The resulting sudden influx of freshwater into the north Atlantic is thought by some to have caused a shutdown of the thermo-haline cycle that brings warmth to northern Europe. And this is proposed as the trigger for the Younger Dryas cooling. And a return to ice age conditions that lasted another thousand years or more. In fact, there were two impact zones. One is the Chihuahuan ignimbrites you’re already aware of extending from the Mexican volcanic ark, up into west Texas, and New Mexico. The other was in the Great lakes region, starting from northern Minnesota, and north up into Canada. If we account for the rotation of the earth, they are separated by about an hour. And there is also a north-south lateral displacement of a thousand miles, or more.
The Chihuahuan ignimbrites are the blast effected materials of the larger of the two zones. And it was the first I was able to positively identify.
I’ve been calling it the ‘primary’ impact zone simply because it was the first I found. And it’s the bigger of the two. But in fact the LIS did get hit first. And we can use the 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. The last time there was any volcanic activity in the Archaean bedrock of the Canadian shield was more than two, and a half billion years ago. That is more than half the age of the Earth. And it is almost to 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 melting event is a major red flag. And by ‘geologically recent’ I mean any age since melt that is measured in millions of years our less.
In a 2007 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, We read,
Nature of the event: Toon et al. suggest that an impact capable of continent-wide damage requires energy of 107 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.
Peter Shultz's hypervelocity ice sheet experiments indicated that we can expect the ice to explode on impact like the reactive armour on a battle tank. So we don't 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 inconcievable heat most certainly left its mark.
And in the next paragraph we also read,
Toon et al. also noted that if airbursts explode with energy of 107 megatons at optimum height, they will cause blast damage over an area the size of North America that is equivalent to a ground impact of 109 megatons Such airbursts effectively couple the impactor’s kinetic energy with the atmosphere or surface producing devastating blast waves well above hurricane force. In 1908, at Tunguska, Siberia, an object 150 meters in diameter, either a carbonaceous asteroid or a small, burned-out comet, produced a more than 15-megaton airburst with an intense fireball (107 °C) that scorched more than 200 km2 of trees and leveled more than 2,000 km2 of forest yet produced no crater or shock metamorphism. A debris shower from a heavily fragmented comet would have produced an airburst barrage that was similar to, although exponentially larger than Tunguska, while causing continent-wide biomass burning and ice-sheet disruption, but again possibly, without typical cratering.
Enigmatic depressions, and disturbances, in the Canadian Shield
(and the destruction of the Laurentide Ice Sheet)
If we find any evidence whatsoever of geologically recent surface melting anywhere in the Canadian shield, the heat, and pressure, to melt, and move, the material could not have come from within the Earth. And the only other source of of such violence is extraterrestrial.  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 lines of movement, and flow, in the lighter, almost white pyroclastic stone. And the marks of 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 patterns of movement, and flow in the surface melted stone are almost in perfect condition and as easy to read as following spilled paint back to the can.
The area is known as the "Patterned Peat Lands of Minnesota". The consensus view held by most geologists is that the ’patterns’ are the result of glacial erosion, and/or turbulence from the floodwaters of glacial lake Agassiz. But after literally thousands of hours studying the motions, and emplacement of the Chihuahuan ignimbrites, the signatures of violent, and sudden, fluid motions in rivers of melted stone were unmistakable. And when I looked up the rock types for the area the geology maps confirmed my suspicions.
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.
This is 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 described further 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."
And there we find our smoking gun. The light, pinkish, material is the "felsic volcanogenic, and volcaniclastic rock". But it is misidentified. The Geologists on the ground who mapped this area assumed the source of the heat and pressure for the rivers of melted stone was volcanism. But there is no source vent for geologically recent volcanism anywhere in the Canadian shield. And those flows of melted rock are in undamaged condition on top of the surface rock like splashes of paint.
Below is a false color radar image depicting elevation. It's graded from darkest-lowest to lightest-highest elevation. The whole region is almost as flat as a parking lot, and the deference in elevation for the area of the black splash from lowest to highest is only a couple of feet. But the ghostly image of the splash and it's associated rivers of melted stone show up clearly as raised features in the terrain.
 Because it is so level, drainage in the region is poor. And, for the most part, where you see green in these images you are looking at peat of varying depths. The color of the peat bogs in the area are a good proxy for the contours of the depressions. The deeper, and richer the color, the deeper the depression. And here the ice 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 colored felsic rock, of the rest of the melt formation. It has a very high carbon content. And is on the list of rock types as slate, and graphitic slate but the pattern of its emplacement is obvious. And it is very clearly a component of the rest of the melt formation. It didn't have its beginnings in a sedimentary deposit. It was tossed there on top of the ice while still in a melted state the consistency of hot tar  The surface rock of the blast burns 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" 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. And finally, to the completely melted "volcanogenic" rock whose chemistry seems to say it originated from somewhere else. But there is no volcanic vent that can be associated with any of them. There isn't even a geomagnetic anomaly that can be interpreted as an ancient, and hidden vent. And the fresh burns can be found scattered all the way up to the Arctic circle
In each of the blast burns we see the full range of conditions and temperatures from hydrothermal to "volcanogenic". Those materials, in context with each other they way they are, and the patterns of movement, and heat flow, in the melted, and semi melted, rock describe a giant, multiple, hydrothermal explosive event in the ice sheet that was different, more powerful, and violent, than anything ever studied before. And, without a volcano to blame, we have to acknowledge that the heat, and pressure, that made it all happen didn't come out of the ground. Most of the old literature focuses a lot of attention in the peat depressions and their possible formation. 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. 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 melt flows at all. The solidified melt shows 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 are as pristine as the day they first cooled.  The lines of movement in the melted, flowing stone in the area are clear, and well preserved. So their movements during emplacement are easy to read. They, and the nature of the rocks in the areas around them, are consistent with being the burn marks of tremendous hydrothermal explosions in the ice sheet.
The blast burns are the grayish to pinkish, sometimes blurry looking areas with flowing lines of once fluid and moving pyroclasts 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. The flowing lines were formed when the stone was flash melted in the heat of the impact. The ice took the impacts much the same way reactive armor works on a battle tank. So there are no shock effects. But there were ground effects never the less.
All of the energy of the impacts was converted to heat. So, instead of a crater, or craters, we see the signature of the violence in fast flowing rivers of flash melted stone. And materials born in hydrothermal violence like the migmatides. That melted stone flowed among the shattered remains of the ice sheet. And the "Patterns" are in fact, the patterns of movement, and material flow in the "volcaniclastic", and "volcanogenic", rock that have remained virtually undisturbed since the time of their formation, and emplacement.
 Just like Mexico. There are only two possible directions to look for enough heat and pressure to melt a few cubic miles of the Earth's surface. With out a volcanic vent to blame we can rule out down.
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 It may not be so obvious to someone on the ground but from high altitude it's clear that he patterns are fact the un-eroded patterns of material movement in clastic flows, and partially melted surface rock. Imagine the surface with all vegetation striped away. We see that, at the time of its emplacement, the melt flowed around, and among obstacles that are no longer there. The fragments of the shattered ice sheet were icebergs. And those icebergs were the missing obstacles the blast melt was flowing around, and through. And over the millenia, the shallow depressions that are footprints of those icebergs have become filled with peat.
 Those pristine surface melt formations can not possibly date back 2.5 billion years. The flows of melt are undamaged by any glacial activity, so the the ice sheet was blown away by the event that formed them and has never returned since.
Like most other clastic materials, they were moving rapidly. And they solidified suddenly almost in mid flow. Those lines of movement are a snapshot in time. And they are an accurate record of the motions of the flows during their last moments in a fluid state. And their mode of emplacement. So it goes to fluid mechanics, and becomes a detailed study in the fluid motions of pyroclastic materials. You couldn't ask for a more complete, and honest data set. And every last detail of it's its story is permanently, and faithfully etched in the lines of movement in the rivers of melted, and flowing, stone. The hydrothermal blast burns, and their associated metamorphic facies, extend well up into Canada. And, taken together, they account for more than enough violence to destroy the eastern end of the Laurentide ice sheet into the north Atlantic in just a few minutes.It was a very sudden event. And in those few short minutes most of the eastern end of the LIS was blasted, melted, broken up, and sent downstream. Tens of thousands of cubic miles of icebergs, and cold, fresh, water was moved off the land, and into the ocean. The sudden influx of fresh water into the north Atlantic caused a shut down the thermal halene cycle like turning a switch. And it raised sea levels world wide. The thermal halene cycle drives the ocean currents that bring tropical warmth to northern Europe And when it stopped flowing. it quickly plunged Europe, and the whole of the northern hemisphere back into ice age conditions.
We need look no further for a trigger for the Younger Dyas cooling. The two clusters of comet fragments produced the single most violent natural disaster in 65 million years. The northeast cluster destroyed the LIS. In doing so it plunged most of the world back into ice age conditions that held on for centuries. And it raised sea levels, and set off mega-floods, and disaters, of biblical proportions worldwide. The southwest cluster produced an impact firestorm with temperatures hotter than the surface of the sun that sterilized half the continent. For the survivors in the southeast, and the rest of the world as well, the food chain of the entire northern hemisphere would have been severely comprimised. The remaining giant animals that went extinct soon after the event most likely starved. The species that survived were the adaptable ones. And the smaller species that didn't need so much to eat.
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