At Cosmictusk.com there was a comment by Terry Egolf, which triggered an idea that I posted as a comment and that I post here as well.
For those who have never heard of them or would like to know more of the basics, see here.
This was an interesting and thought-provoking idea:
As George knows, I’m a YEC, so I immediately thought of a Genesis Flood-related process. Based on some work done by Emil Silvestru, an eminent karstologist, I imagined thermal decomposition of deeply buried limestones off the east coast releasing high pressure carbon dioxide into the upward-tilted aquifers underlying the coastal plain. As the lithostatic pressure lessened, gas bubbles expanded and broke through the impermeable rock strata and burst through the surface sediments. If this had occurred near the end of the recessional stage of the Flood, and while the coast was still under water, the flow off the land could have lengthened the craters in the direction of flow. Now THAT is what I call thinking outside the box! Non-uniformitarian catastrophism at its best. Heh.
…Your bubble hypothesis IS definitely out of the box, which alone says nothing for or against it.
When the waters receded, they would have done so at a less than glacial pace. Year to year, it would have been relatively difficult to see or measure. As the coastline receded, then at some point – and for a very long time – each bay would have been straddling the high and low tides. Not only would the bay have seen the incoming and outgoing tides, but wave action every minute or two.
It seems not possible that the waves would not have completely erased the sand rim of that at-risk bay, all 360° of it. I have spent much less time on beaches than you, a submariner, would have done, but I know that any competition between sand and waves is always won by the waves. The best we would see is a high tide sand dune. How that could turn into an ellipse I can’t see.
Nice try on that aspect, but I can’t see it working. Not if the solid surface were underwater. But it takes my mind to something else…
Your bubbling idea brings to mind the hydrate fields under the coastal waters.
THIS seems like something worth looking into. We have so far only a little understanding of hydrate “patches”. It is certain that the water pressure helps keep them from bubbling up, and what allows them to bubble up is a release of the pressure for whatever reason. So far, all the studies have been focused on hydrates currently under the water. If the coastal plain was at one time under water, then one would think that hydrates were underlying those areas, too. And since they do bubble up from time to time, it makes sense that they could bubble up under above-sea-level coastal plains, too.
You suggest they bubbled up while under water, but the transition from under water to dry land I don’t think is tenable. Therefore, perhaps considering that they might have bubbled up AFTER the land emerged may make more sense.
To widen our overall picture, let’s consider the New Madrid quakes of 1811-1812. One of the phenomena of those was what are termed “sand blows.” Here is a link to an image of sand blows in the New Madrid area:
Sand blows, based on first-hand descriptions at the time of the quakes, acted like geysers, with water and gases shooting up out of the ground. Thus the part of the name “blows.” Now, those have some vague resemblance to the Carolina bays. Mostly in their dispersal, not in their particulars. Not in their shapes, because they do not have elliptical shapes. They also do not have sand rims, nor (I am certain) will there be any impactites. The sand blows occurred in a matter of minutes, though, so perhaps the speed is a factor in the eventual shape and surface contour. I am only thinking out loud here, though.
But I think you are on to something. Not necessarily as “the” solution, but as something not previously considered that might shed light on the subject. Everyone has seen the bays as either wind-formed or as coming from above, and here you are saying, “No! Look below, too, if for no other reason than to rule it out.” And why not?
Now, sand blows as seen in New Madrid and elsewhere don’t show the same characteristics, but what if the action came from hydrates, instead? What would we see? I don’t know.
But let’s speculate a bit…
If a hydrate bubble came up from below, what could cause that? Taking a lesson from the sand blows of New Madrid, we might certainly consider earthquakes. I believe that undersea tremors have been connected with hydrate blows, though I cannot recall where I got that impression. If so, then that much would And what do we find? Charleston, SC, is the site of one of the biggest quakes in U.S. history, on August 31, 1886. Like New Madrid, Charleston does not lie on a plate boundary, for what that is worth. That quake is estimated to have been 7.0 on the Richter scale, give or take a bit. But Charleston is right smack in the middle of the CBs, looked at in a north-to-south direction. It is on the coast, certainly. But the bays go all the way to the coast, so Charleston is not outside the bay region. (But it is not necessary that the epicenter be IN the CB region, but only that the hydrate region be shaken.)
Quakes are considered one of the triggers for sub-oceanic hydrate releases. I believe that both the pressures involved and the fracturing contribute to the releases, both causing and then allowing a path for the gasses to find their way upward.
Sub-oceanic hydrate releases DO occur as bubbles.
If hydrates are released as rising sub-surface bubbles under sandy coastal plains, what would the process look like?
All of this is hypothetical:
…Imagine a quake, that shakes for 30-40 seconds.
– The soil around and above the hydrates would liquefy to some extent.
– The trapped hydrates would begin ascending through the liquefied soil.
– The rising bubble would tend to assume a round shape, as viewed from above. The rising would not be terribly fast, due to resistance to flow through the sandy soil. It would be something like quicksand, but in reverse: things do not sink quickly in quicksand, but slowly – and only quicker if agitated. The quake itself would represent the agitation factor.
– If it reached the surface, what would be the effect?
– The bubble would lift the soil, more or less in the center, since the surface would act as a beam of sorts and the weakest point is the furthest from its supports (which support is at the edges of the bubble).
– The lifting would be a slow (compared, for example, to an airburst or impact) and relatively gentle billowing up.
– The bubble would burst upward and somewhat outward, throwing the more or less sandy soil into a rim, but most of it being splayed out beyond the rim. Much, but not all, would remain within the bubble area and fall back down.
– Most of the soil would not go outward, but enough so that when the bubbling is complete, the average ground elevation would be a bit lower than before.
– Over some number of decades or centuries, in flat areas the sandy soil inside would level out, from water accumulating and not having an outlet. In un-flat areas, erosion would erase the bubble and blend the surface in with the surrounding terrain. This would – like the impact hypothesis – tend to explain why the CBs are not found except in flat areas.
– What are now seen to be overlapping impacts – how do we deal with them? If a bubble came up after an earlier one, and would it not cut off the first one somewhat, just like we see?
– Now, as to the elliptical shape, how do we get that? I would suggest that the alignments of the ellipses might align to elevation, with the southeastern-most end being lower and the northwestern-most end being higher. I do NOT know this as fact, but would use it as a falsification prediction. The SE ends are the ones with the higher rims, so this would seem to make sense. I am suggesting that the alignments may not be due to anything more than the “lay of the land.” This is easily determined, isn’t it?
I admit I am probably wrong on this. It is all just taking off from Terry’s idea, but I won’t blame him for where my mind went. At the same time, it is pretty much acknowledged that there are at least NINETEEN different hypotheses about the origin of the Carolina Bays, and NONE of those is correct, either. So if I am wrong, I have PLENTY of company…LOL
Terry is absolutely RIGHT to suggest we think out of the box. And everyone who has looked up or sideways for an explanation hasn’t found the solution, so what harm is there in looking DOWN? The old saw about doing the same thing over and over, even if it doesn’t work – that that is insanity – well, then looking down can’t be too stupid. Even if it does not have the solution, perhaps it will trigger thinking toward more ingenious possible solutions.
It is absolutely clear that the existing by-the-numbers solutions are not going to arrive at a solution.
Other thoughts come to mind, but that is enough for me to at least consider this as a possible direction of inquiry.