Terrestrial Evidence of a Nuclear Catastrophe in Paleoindian Times

Mammoth Trumpet ^ | March 2001 | Firestone/Topping

[ForGod'sSake]

I hope this makes things a little clearer.

A good try I suspect but, ahem, I probably need to go find a better graphic. I'll work on that tomorrow; the toothpicks holding the eyelids open are starting weaken...

[gleeaikin]

Ah, yes. Toothpicks for night owls, a great product. I too need to put my toothpicks away and get some sleep. Goodnight.

[Renfield]

I'm a soil scientist, not a geologist, and when the subject turns to tectonism, we're venturing out of my field of competence. That's why I wanted to direct you to Helaine Markewich.

I can tell you -- and in this case I am very competent to answer -- that the sediments in the portions of the Wando formation that I worked on in Darlington, Marlboro, and Dillon Counties, in South Carolina, were deposited in a tidal-marsh enviroment. Those sediments are silty and very uniform, and the geomorphic surface there has virtually no topographic relief. In that part of the world, there isn't any other means of deposition that could produce such sediments. A terrestrial riverine system wouldn't do it..there would be too much spatial variation in soil texture, and there would be oxbow/paleochannel scars, splay deposits, lag deposits, etc. So the only question is the date of deposition, and that question is best answered by a geologist.

[Renfield]

OOPS! After reviewing Owen's map, I realize I was confusing the Wando and the Soccastee formations. Owens gives a date of 200,000 ka for the Socastee. Your blue-line graph shows sea level at that date being lower than it is today, so the same conundrum still applies. (The Wando in that area of the Pee Dee is riverine).

There is a marine (littoral) facies of the Socastee formation that stretches to about 30 km inland from the present coastline that exhibits bays. The area I referenced earlier does not exhibit them. I think Owens interprets that area as a backswamp; I do not, for reasons I posted previously. But let us not lose sight of the original purpose of this discussion. Extrapolating from your sea-level graph, the Socastee must have been exposed subaerially somewhere between 200,000 and 180,000 years ago. That upper portion of the Socastee (in the Pee Dee region) does not exhibit bays, while immediately adjacent areas of the older Duplin formation do. If meteor or cometary impact at any time in the last 180,000 years had caused the bays, then bays should exist on the aforementioned area; but they do not.

[Renfield]

This morning I pulled some old soil surveys to look for pre-Holocene surfaces on the Coastal Plain of SC that do not harbor Carolina Bays, or upon which they are exceedingly rare. I found such areas to be extensive; the lower (seaward) half of Dorchester County, most of Georgetown County, etc. Other areas (such as the lower portion of Marion County, for example) that presumably are of the same geologic age, have bays that are well expressed. This gave me an idea. I don't know exactly how I'll do it, or how long it will take, but I think I'll construct a map of the CP of SC that shows those surfaces, with a data overlay showing the geologic formations and their ages. I think it would be revealing.

[ForGod'sSake]

Owens gives a date of 200,000 ka for the Socastee. Your blue-line graph shows sea level at that date being lower than it is today, so the same conundrum still applies.

Maybe not. I went back to have another look at the abstract(?) of the study I posted in #225. Ran across this little jewel I recall reading but dismissed(?) because I had found what I was looking for in the previous sentence. From that abstract:

It follows that the present elevation of the substage 5a shoreline cannot be explained by uplift or subsidence, and that relative sea-level positions for substage 5a along the South Carolina coast were approximately the same as MIS 5e or the present day.

You'll need to reread #225 to get the whole picture but essentially what this 2005 study concluded, amongst other things, is the 5a layer(ca. 82 ka.) and the 5e(ca. 130-116 ka.), were virtually the same. I don't quite know what to make of that given the "blue line" graph indicating otherwise, except that the blue line graph is possibly/likely wrong? IOW, your arguments are holding up, at least under this layman's scrutiny. Bravo........so far.

[ForGod'sSake]

I want to make sure I'm following you: You found areas where you would NOT expect to find bays basically bayless, but other areas of the same geologic age with bays? Vedy interestink(if I'm following)!

I think it would be revealing.

Can you post that this evening.......heh,heh. Seriously, I would love to see what you're able to come up with. I'm a novice graphic artiste so if I can be of assistance, please let me know. This is actually exciting............ahem.

[Renfield]

"....Can you post that this evening...." I think a very optimistic date for completion of this map might be 12-18 months. I do this sort of thing for a living (only with maps of much, much smaller area). I know what it entails. It might have to wait until I go back to grad school...if I decide to do so.

[Renfield]

Oops again...forgot to finish up my html coding...that post should have appeared as,

"....Can you post that this evening...."

I think a very optimistic date for completion of this map might be 12-18 months. I do this sort of thing for a living (only with maps of much, much smaller area). I know what it entails. It might have to wait until I go back to grad school...if I decide to do so.

[ForGod'sSake]

BTW, what, if any ideas do you have about bays being located in areas you wouldn't or didn't expect them?

I think a very optimistic date for completion of this map might be 12-18 months.

Well gawrsh! I suppose yesterday is out of the question???

My computin' time is limited for a couple of days by grandbabies' visit, but I intend to go searching for additional maps/charts to see if I can come up with anything better than what I've posted.

[gleeaikin]

"given the blue line graph indicating otherwise"

Actually it doesn't appear to me that the blue line graph does indicate otherwise. At 82ka the sea level was about -45m, from 130-116ya sea level was rising rapidly and passed through the -45m level, so depending on the precise date of the deposition of the 5e, or the area analyzed, they both could have been at the -45m level. If you have the graphic skills, perhaps you could stretch out the blue line graph on the horizontal to get a more precise fix on when the 130-116ya line crossed the same level as the -82ka line.

[ForGod'sSake]

I'm not sure I'm following, but indeed the -45m level would have been the same on at least two other occasions surrounding the ~120,000 years ago peak. Once on the way up and again on the way down.

However, the point I was trying to make was, given the information I had, the bays could not have been formed by sea level fluctations prior to the present because they would now be under water. They would have to be exceptionally old otherwise; like something approaching ~120,000 years. BUT, the information I sortof bypassed in the study I posted indicates sea levels may have been approximately the same ~80,000 years ago as they are now. If I'm missing something(entirely possible), please point it out.

That said, I haven't been able to find any corroboration of that ~80,000 year old sea level, so who's to say??? This particular study is very recent(2005?) and may in fact be on the mark. I suppose time will tell.

[ForGod'sSake]

BTTTOMPP ;^)

[Renfield]

This paper is the best I've seen on Carolina Bays. It mirrors my own thinking on the formation being due to hydrologic discharge, wave action loosening sands, and subsequent aeolian deflation during seasonal water level drop.

http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6V93-3XBTS7K-7-1&_cdi=5887&_user=1355690&_orig=search&_coverDate=04%2F30%2F1998&_sk=999779996&view=c&_alid=444909418&_rdoc=1&wchp=dGLbVzz-zSkWW&md5=2dce2b5621b04c89d304bd2689282649&ie=/sdarticle.pdf

[blam]

If you do not have a User Name and Password, click the Register to Purchase button to purchase this article.

Price: US $ 30.00

No Thanks.

[Renfield]

What are you talking about? I just cliked on the link, and it opened up. I even copied it to my hard drive. If you'll PM me with your e-mail address, I'll send it to you as an attachment. It's a PDF file.

[ForGod'sSake]

I had the same problem as blam; I couldn't view the file either. I'm interested in taking a look at it and will send you an email addy via Freepmail. I was able to look at the ABSTRACT, but it wasn't all that helpful.

Now, I ran across another graphic I had to do some work on to get it sized to fit a standard(800 X 600 resolution) window. You'll notice re our previous discussion a possible(?) sea level "spike" at ~80,000ya. This more or less coincides with a previous argument about the age(s) of the bays being ~70,000ya. HOWEVER, the sea level indicated at that time was only ~30' above present level(s).

I know you have stated you believe the bays were formed within a marine environment, and if you're correct, something is amiss. What are the chances these marine sediments could have been deposited in existing bays by something like a "mega" tsunami? Or possibly some other process??? Or are there actual sediments deposited over a long period of time?

Anyway, getting late, so here's the graphic witout further comment. Original found HERE.

[Renfield]

I din't say that bays were "deposited in a marine environment". They formed subaerially on marine sediments after marine regression. I forwarded the paper on to you. Read it carefully, especially the last section wherein the authors propose a mechanism for bay formation. I think they've nailed it.

[ForGod'sSake]

I din't say that bays were "deposited in a marine environment". They formed subaerially on marine sediments after marine regression.

Is that anything like being formed by "hydrologic" processes???

I forwarded the paper on to you. Read it carefully, especially the last section wherein the authors propose a mechanism for bay formation.

Well, they offer up several possibilites(so I'm not sure which one you refer to), while excluding only one: a metorite/asteroid impact. Maybe they overlooked the possibility of a really big snowball. Some excerpts from the paper I found interesting as they relate to the discussion re bay formation:

Comparison between surface topography and expression of the Upland Unit surface using coring and elevation data reveal that the surface of the Upland Unit generally lies above the level of the basin interiors. The Upland Unit is typically flat-lying beneath the east and south portions of the bay rims and often rises to the west-northwest of the basins.

Well, ok; this isn't speculation, opinion or conjecture, but some hard data apparently. It's not altogether clear from this statement, but it seems to imply there's a "bulge" towards the NW and a "depression" towards the SE in the Upland Unit layer within the bays. But it doesn't appear to help in the how or when department.

The bays themselves may occupy pre-existing depressions in the Upland Unit surface, but also reflect at least some erosion of the Upland Unit surface. Moreover, the regional sand sheet thickens towards the southeast sides of the bays, but is largely absent from within bays. It is possible, therefore, that excavation of the sand sheet after emplacement of the Upland Unit created the present bay depressions and that subsequent deposition of the excavated sands formed the observed bay rims. This statement is supported by significant differences in the age and degree of pedogenic development between the Upland Unit and bay rim and interior deposits that have been cored/excavated and dated (Brooks et al., 1996).

The point of this statement was lost on me. In fact, it doesn't make any sense to me.

Processes including dissolution, meteorite impact, and eolian deflation have been proposed to account for initial formation of the depressions (e.g., Johnson, 1942; Prouty, 1952; Thorn, 1970; Kaczorowski, 1977; Colquhoun, 1982; Blair, 1986) sometime during the period ~ 10-100 ka (Schalles et al., 1989). Investigations have been impeded, however, by the subdued topographic expression of the bays, the dense vegetative cover (e.g., Knight et al., 1989; Richardson and Gibbons, 1993), typically extensive historic era modification (Van Doren, 1928; Brooks et al., 1996; Kirkman et al., 1996), and a paucity of preserved organic material for accurately dating the formation. As a result, it remains uncertain whether some or all bays share a common age or how the present expression reflects the processes responsible for initial formation of the depressions versus subsequent modification. The GPR and supporting data presented herein provide clues to the subsequent modification of the bays that resulted in a common topographic expression, but does not specifically address the initial formation of the depressions.

I see.

Although not specifically addressed in the current study, a number of processes could account for generation of the initial basin that eventually evolves into a Carolina Bay. These processes might include, among others, spring activity, solution, deflation, abandonment of channel segments, and/or excavation of original relief on the surface of the Upland Unit. No evidence was found to support basin formation by meteorite impact as suggested by Johnson(1942), and others.

Uh huh.

Stratigraphy from the surface down in the vicinity of all four bays is similar (to first-order) and begins with a thin, regional, medium-to-coarse-grained sand sheet (typically ~ 1-3 m thick) that exhibits minimal pedogenic alteration, but whose emplacement likely predates bay formation (Willoughby, 1997).

So, the sand was there before the bays formed??? How long? If the bays are of differing ages(thousands of years even?), it just seems odd to me there's still a certain consistency to it all.

I think they've nailed it.

Maybe for you ;^)

FGS

[MHGinTN]

placemarker, just a marker