Loading...I had the good fortune to meet Michael Davias, the author of the Perigee Zero website, at the AGU Fall meeting last December. Mike has taken the Bay phenomena on-line better than anyone — including me. He has also been fearless in his (well considered) speculation. I have long intended to get Perigee Zero properly linked and posted on the Tusk.
I am particularly interested in posting Mike’s careful documentary images of Carolina Bays in the the Midwest [do not miss his comprehensive page on CarolinaCornhusker bays here]. These features, entirely true to their southern neighbors in orientation and dimension, are also entirely absent from the long debate over the origin of Carolina Bays. In fact, the scholarship on the distribution and orientation of these features seems to have died long ago. Incredibly, it is not unusual to this day to see Dr Prouty of UNC’s old ink drawing from the 1950′s used to demonstrate their range (, or the also moldy Eyton and Parkhurst orientation map of 1974. SEE BELOW
By using LiDAR, Allen West, me and, most expertly, Mike Davias, have shown the old conception of a Carolina Bay to be far more narrow than nature actually presents. Any theory of their origin must account for thier extraordinary regularity across half a continent.
I will put some more Perigee Zero stuff up later. But, to get you started, below are grabs from a superb Google Earth KMZ file from Perigee Zero:
CLICK HERE TO EXAMINE THESE FEATURES
Old ink Prouty map from the 50′s
Eyton and Parkhurst moldy map from 1975
It seems to be these scientists from the earlier times (William Prouty), and others before him, were far more open minded than the majority of scientists in the present day. This is despite earlier researchers not having near the investigative tools that we have today.
Yes, in a funny kind of turn around, they went from willing to see the truth when they didn’t have the tools to dig it up, to having the tools, and being closed minded to the truth they revealed.
These Midwest bays are very interesting. I’m still struggling with the physics of the PZ presupposition of an orbiting comet eventually impacting at shallow angle (~5 degrees). Assuming its kinetic energy transfer is perfect, no more than 9% will be directed downward, which, to be sure would still be a significant amount. (Of course, if you posit a large enough impactor, then anything is possible, I suppose.)
I’m still trying to get my head around how water ice that has been blasted into steam mixes with underlying soil and rock, in a completely chaotic event, then the mixture forms flying blobs of wallboard-compound-like consistency that remain intact over a 900 km trajectory moving at 4000+/- km/h through the air to create quite uniform elliptical divots only in the unconsolidated sediments of the coastal plain (and now in similar sediments in the Midwest). This is truly incredible to me. I think I have a physicist on my faculty where I work who may want to jump in on this. Perhaps we can work up some credible experiments.
Does anyone know what the underlying rock strata are in Nebraska?
I’m not sure if anyone has looked into this, but if you place a NC geology map under the Carolina bay kmz compiled by Dave Kimbel, you will note a fault line running more-or-less parallel to the coast well inland at the south end of the pattern, near the SC border. Interestingly, there are no bays inland of this fault line, while they are quite dense just to the coastal side of the fault. Now, why would comet splatter display a preferential distribution in relation to a geological fault? Just curious. (See the map at http://tin.er.usgs.gov/geology/state/state.php?state=NC)
Terry
Good points, Terry.
Unless the divots can be shown to be of a different soil than their surroundings, then we have to come back to other fragments diverted tangentially by the force of larger impacts as a possible causative agents.
Hi Terry,
The Bays are probabably not caused by the direct impact of comet ‘splatter’, or fragments.
I think the bays make more sense if we think of them as the scars of massive chunks of the blasted Laurentide Ice sheet thrown outwards from impacts into the LIS. This gives a plausible explanation of why no bolide fragments have ever been found in one of the Bays. It also explains why their long axis always points back to places on the ice. Think impactites of ice.
And there is no need to look for a crater in the Canadian shield. Because even if the ICE impacts made craters in the LIS much bigger, and deeper, than Barringer crater in Arizona, The ice sheet was thick enough that those craters would have disappeared completely when the remaining ice melted. Leaving behind only inigmatic depressions in the ice free surface we see today.
This was a vastly different kind of catastrophe. I’m sure it will eventually be possible to work out exactly what form the planetary scarring took. But in the final analysis, I don’t think those scars will be found to be the craters most folks have come to assume we should expect.
The signatures of this event should be the marks of seemingly impossible heat, and pressure, in the presence of a lot of water. Not ballistic/kinetic shock effects. Some form of migmatite that can be shown to have formed right out on the surface would be a pretty good smoking gun.
Or perhaps ‘volcanogenic’, or ‘volcaniclastic’ rocks that aren’t old enough. There has been no volcanic activity in the Canadian shield in more than 2.5 billion years. That’s really deep time; more than half the age of the Earth. So any formation of melted rock, or ‘tuff’ that returns an age since melt that’s measured in millions of years, or less, is also a red flag.
Landforms similar to the Carolina Bays can also be seen in the north coastal planes of Alaska. These “bays” are also oriented in relation to the coastline which would inticate to me that the Bays origin is water related. The elongated forms of these elipsiods might inicate a greater water velocity than those in the Carolina coastal planes. Check these landforms in Google Earth @ 70-59-30 N, 156-53-48 W.
Dennis,
OK, just for the moment let’s assume the divots were made by one of the phases of water from the LIS, rather than rock. Which phase could account for the uniformly-shaped, very smooth-edged, sub-elliptical, shallow depressions? If impactors were chunks of intact ice, then these features would look more like impact craters, especially from the larger chunks. Assuming that they had enough energy to vaporize on impact, the “craters” would look more like the ray patterns on the moon, I would think. If they were ice chunks that transitioned to water during impact of the comet or at any time during their trajectories, then the high velocity of the atmospheric transit would have splattered the globs of water into a zillion droplets, rather than discrete water-balloon-like impactors. And of course, steam explosions just above the surface, for so many different sized chunks would have required some sort of proximity fuze to produce such uniformly-shaped divots.
The PZ demonstration of wallboard compound globs suggest the kind of impacts that might have produced CBs, but there isn’t any credible explanation how such materials could form, then survive a 8-900 km, high velocity atmospheric transit.
Just thinking out loud. You guys have obviously put a lot more time into this topic. Has anyone thought of a subterranean source, like mudpots or something? I realize this goes completely against an old-earth paradigm, but this is what scientific revolutions are all about. Data that doesn’t fit. Thomas Kuhn would love this.
Forget subterrainean sources. And the material that impacted to create the bays didn’t survive the trip. The steam explosions were only in the LIS.(The pristine hydrothermal burn marks at the points of origin are not hard to find) That’s what launced them. I don’t think the ballistic ice, and slush, fragments had as much velocity as you seem to attribute to them. They would not have been solid chunks of ice. By the time they hit, they would have been semi-melted blobs of water, and slush. So the CB impactors didn’t hit; they splashed.
As for that ‘Old Earth’ paradigm, try a subtle shift in emphasis. Think old Earth-paradigm. The Earth’s old all right. Very, very old. It’s just that some of the surface terrains of North America that we’ve always assumed to be ancient, are brand spankin’ new. All of the Earth sciences are founded on the unquestioned, 19th century assumptions of uniform,gradual change, and the principle idea that ‘The Present is the key to understanding the past’. And yet, the simple empirical fact, is that it isn’t. In fact, there has been nothing in the short period of time referred to as ‘written history’ that gives us any clue at all as to the level of catastrophic, mass extinction, violence which has happened in geologically recent, human times.
We find ourselves at the cusp of a major paradigm shift in the Earth sciences that will change them all down to their very foundations. And that paradigm shift will be every bit as far reaching as the realization that the world isn’t flat.
The CB’s cannot be explained by any phenomena in the standard, assumptive, uniformitarian landform theory toolkit. You have to look at them from the other side of the paradigm shift. Or they’ll drive you crazy.
Dennis, on another subject dear to your heart.
Take a look at this passage from the paper: The Genesis and Collapse of Third Millennium North Mesopotamian Civilization (link here: http://www.scribd.com/doc/31277875/Mesopotamian-Collapse:
The excellent preservation
of layers of windblown dust in these specific
locations can be explained by the reduced
effects of post-depositional disturbance on
archaeological sites in comparison to surface
soils on the flood plain. Some coarse
sand layers of aeolian origin consist of
silt-sized volcanic glass particles and*************potassium
feldspar phenocrysts, clearly volcanic
in origin,***************embedded in a pale yellow, isotropic,
fine-ground mass. The close morphological
resemblance of these particles
with the features marking Tell Leilan occupation
hiatus phase 1 and the overall characteristics
of the stratigraphic unit suggest
that they relate to the same arid event.
Are the “pottasium feldspar phenocrysts, clearly of volcanic origin” of interest or help to you in this context? Seems the ignigbrites have the same stuff in them. But of course the ignigbrites are not in a recent archeological context….
P.S. You should google Peter Schultz’s (Brown U.) hyper velocity, oblique angle, ice sheet impact experiments at NASA’s Vertical Gun Range before you say with certainty that there isn’t a plausible model for lofting iceberg sized chunks of ice into a subsonic, ballistic arching, trajectory.
George asked:
“Are the “pottasium feldspar phenocrysts, clearly of volcanic origin” of interest or help to you in this context? Seems the ignimbrites’ have the same stuff in them. But of course the ignimbrites’ are not in a recent archeological context….”
I couldn’t read that paper. Sometimes Scribed is a little fuzzy. But your question seems to indicate that I need to clarify how I’m using the word “ignimbrite”
Keep in mind that impact melt is often mistaken for ignimbrite, or volcanic tuff. And to clarify what I am describing I have only used ‘ignimbrite’ for wont of a better word. There is a huge, and dramatic, difference between the processes that form, and emplace the melt I am describing, and anything even remotely volcanogenic.
If we break ‘ignimbrite’ down we get Ig-Nim-Brite, and translated literally to English. We get ‘fire-cloud-rock’ In the purest sense of the word that definition holds up. But I’m stuck with using old terminology that confuses what I want to say. I’ll explain.
In an explosive volcanic eruptive event, ignimbrites are produced as the rock erupts explosively from below the surface. 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. Any welding of the ‘Tuff’ is by heat remaining in the rock.
‘Impact melt’ is another form of ‘fire cloud rock’. Which is why it is sometimes mistaken for volcanic tuff. But we see a dramatic difference in its process of formation. Because the source of the rock is the surface itself, mixed with what’s left of the bolide. The heat, and pressure is produced instantaneously at the surface, and at the moment of impact. After the initial impact explosion there is no continued production of the heat source. And almost all material movement is provided by momentum.
But the melt I am describing was formed, and emplaced in a third, and vastly different kind of process from anything described before. This is a different kind of impact event from anything that has been described before. In it, the comet is heavily fragmented before it even gets close to the Earth. It hits as clusters, and streams, of high velocity, explosive particles, and fragments, that explode very high in the atmosphere. They aren’t point explosions either. The momentum is retained; even though all of the kinetic energy is translated into heat. And it continues downwards in moveing explosions, as super heated, supersonic, down-blasts like Tunguska 1908. But the Tunguska object arrived alone. I am describing a fairly constant stream of thousands of fragments like that. Accompanied by clouds of particles down to the size of dust grains. It hit at a low angle of about thirty degrees. 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 impact plasma, and just cranked up the heat and pressure. The down blasts are almost continuous until the last of the fragments falls, or the Earth finally moves out of the orbital path of the comet. In the case of the Taurid progenitor, the process probably lasted a little more than an hour.
The resulting heat, and pressure, didn’t make craters. It ablated the surface. And accumulations of that geo-ablative blast melt are the stuff I have been describing as non-volcanic ignimbrite. In this form of ignimbrite formation, and emplacement, the heat, and pressure is almost continuous. So it continues to ablate the surface, creating more aerosol blast melt. And acting as a motive force to drive the the motions of the melt, like the waves of debris laden froth on a storm tossed beach, until the last of the impact down-blast explosions. The resulting accumulations of breccias, and geo-ablative, aerosol, blast melt, are a form of ‘Fire Cloud Rock’ in the purest sense of the word.
The trouble for forensic geologists who’re trying to unravel this mess, is that if you do that to a volcanically active region, and that means most of Mexico, and the American southwest, then any volcanic materials already on the ground, or erupted during the impacts, are going to ‘contaminate’ the melt, so to speak. So chemistry doesn’t get to have the final word here. I think that speaks to your question.
But if you want to understand an explosive event after the fact, you should first look to the motions of the blast effected materials.
So It all goes to fluid mechanics, and studying how they moved, and flowed, during emplacement. In the model I am proposing, there are three different modes of ignimbrite formation, and emplacement, not just two. And thanks to dramatically different modes of formation, motive force, and emplacement. each, have distinct, and easily recognizable patterns of movement, and flow. When I speak of ignimbrites, I am mean to say specifically: Welded accumulations of geo-ablative breccias, and aerosol blast melt, produced in a multiple airburst, thermal atmospheric, geo-ablative impact event.
Dennis, a quick note before I re-read your great post. Scribd works if used correctly. Take a moment and look down at the bottom of the pane and click “full screen,” it looks like a little window frame. Given your obvious skill with Google Earth I am surprised Scribd is a challenge:)You are not the first to note the difficulty, however. You may need to put it in HTML mode NOT flash.
I want to know what you think of that paper. and the stuff they find. Then I have some other questions.
Thanks so much for you and the other guys attention to this site.
Regards,
GAH
I still can’t get that page to load properly. There is something wrong with the script on that page. Because 3 different computers and 2 different ISP’s lock up on it.
But I do have a comment based on that one line “pottasium feldspar phenocrysts, clearly of volcanic origin”
They say ‘clearly of volcanic origin’ when they see materials like that because they know that such materials are the signature of great heat, and pressure. The assumption there, comes from the belief that such conditions can only have a subterrainian source. But the error in that assumption is revealed we come back to the ND’s. Because the atmospheric conditions of heat, and pressure required for their formation, exceed those required to produce pottasium feldspar phenocrysts. So we can say that underground is not the only place it gets that hot.
The next question I would ask is: Can you show me the vent? Or is it one of the theoretical kind that remains to be discovered?
George,I’m completely stuck. Do you have a copy of that paper in a different format? Every time I try to load it from scribed, the page locks up at about page 2. I get to read just enough to get interested. And to know I need to read the whole thing. And then the page stops responding.
~Dennis
Ok, Now that I’ve read the paper I can get a little better Idea what you’re asking. And while that is a different archeological context, the terrains there are very recognizable.
There are at present four places that I would call, without a moments hesitation, a geo-ablative terrain. The closest to me are the pristine blast effected materials near my home here in central California. The other, just as pristine, and probably formed in the same event, is central Mexico. And the ignimbrites of the Chihuahuan Desert. The third is central Australia. In the area around Alice Springs. It’s a little bit more weathered than the Geo-ablative terrains in North America. But the patterns of movement in the blast effected meterials are still legible. And the forth region with recognizable geo-ablative terrains in very good condition is Mesopotamia, and the Middle East.
If I were them, and without a possitive ID of a local vent to blame for them. I would not be so quick to assume volcanic origin for the disaster those materials describe. Do you know if anyone else has considered the possibility that the tephra might not be volcanogenic?