[meteorite-list] Part2: Professor Rejects Meteor Theory of CarolinaBays' Origin

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Thu Mar 30 11:56:13 2006
Message-ID: <003501c653c9$89ff0000$5aea8c46_at_ATARIENGINE>

Paul,

    Depends on what you mean by "common."
Rather than parallel orientation, I referred to
orientation relative to a "radiant" point, which
orientation is more consistent. I also was not
wed to the notion of a single cometary event
breaking up into 500,000 objects! It is quite
possible to have a cometary stream that intersects
the Earth's orbit at regular intervals. Or to have
an object or objects captured by the Earth in
low orbit decaying on successive passes, events
unlikely but not impossible. It's a big universe.
In any event, the radiants of multiple impact
events need not be any more regular than the
orientation of the Bays. It's not diagnostic.
    Their "regularity of form" is quite remarkable
for a "natural" feature, however. The Alaska lakes
Eric Olsen provided a link to are very much more
irregular than the Bays and indeed most lakes
and ponds are.
    The paleowind theory that is so popular as
the cause of the elipticity doesn't seem to account
for the fact that to get perfect elipses you have to
start with perfect circles just as regular. Wind stretching
would exaggerate prior irregularities. This leaves
the regularity problem untouched.
    Geometric regularity is not characteristic of
local features, formed locally, and influenced by
local factors. Simple mathematical forms are rare:
the cone of a new ashy volcano, the circularity of
coral atolls, the geometry of dune fields. True,
lakes in low lying, flat, uniformly soft soils are
more regular, but the Bays are oddly too regular.
    Those rim dates correspond to re-glaciation
(36,000 yr), cold peak (25,000 yr), melting (11,600
yr), so maybe the Bays are a glacial feature whose
mechanism we just haven't figured out yet. At the
time, this was a cold, windy place, with much less
plant cover, particularly trees, more like the northern
Great Plains than the semi-tropical Carolinas
of today.
    Does anybody like giant Pleistocene beavers as
a candidate? If you assume certain behavioral
differences from the modern species, like building
regular embayments out of gravel, sand, and mud
instead of log dams (no trees!). I suppose you could
easily hypothesize any behavior, since Pleistocene
beavers are extinct and can hardly object to our
speculations!

Sterling K. Webb
-------------------------------------------------
----- Original Message -----
From: "Paul" <bristolia_at_yahoo.com>
To: <meteorite-list_at_meteoritecentral.com>
Sent: Wednesday, March 29, 2006 1:53 PM
Subject: [meteorite-list] Part2: Professor Rejects Meteor Theory of
CarolinaBays' Origin


> Susan Web wrote:
NOTE:
> STERLING WEBB wrote:
>
> "Their key mysterious features are their
> number (half a million of them), their
> regularity of form, their common
> orientation, their extreme shallowness,
> their low rim heights."
>
> Their "common orientation" is not as consistent as the
> proponents of an impact origin falsely claim them to be.
> In the southern and northern ends of their distribution,
> the long axis of Carolina Bays actually show a wide
> range of orientations, which fails to support either an
> air-burst or impact origin. Within the middle range of
> their distribution, the orientation of the Carolina Bays
> are consistent with Pleistocene paleowind directions as
> determined from ancient dune fields, loess distribution
> patterns, and paleoclimate models. I would find it quite
> remarkable that either a meteorite or comet would take
> the time and trouble to plan its impact as to perfectly
> coincide with the prevailing winds at the time it hit like
> an airplane landing at an airport. The wide spread of
> orientations at the northern and southern ends of their
> distributions is also consistent with what is known about
> the variability of Pleistocene paleowind patterns over
> time.
>
> Another and major problem, which the proponents of either
> an impact or air-burst origin is that the shape, orientation,
> and depth of the Carolina Bays have been altered by over
> a 100,000 years of modification by eolian and lacustrine
> processes. For example, Ivester et al. (2003) found that
> the multiple sand rims found within Big Bay in South
> Carolina become progressively younger towards the center
> of this Carolina Bay. In this case, Optically Stimulated
> Luminescence (OSL) dates from sand rims starting from
> the outer rim to the inner rim produced a perfectly
> chronologically consistent set dates of 35,660?2600;
> 25,210?1900; 11,160?900; and 2,150?300 years BP. In
> this case, the Big Bay has shrunk by 1.6 km over the last
> 36,000 years, with rims being produced about 36,000 BP,
> 25,000 BP, 11,000 BP, and 2,000 BP as it shrunk. If a
> person wants to argue that these sand rims are of impact or
> air-burst origin, they need to explain how either impacts or
> air-bursts managed to precisely excavate tens of thousand
> of years apart sucessive craters in precise center of Big Bay
> and similar Carolina Bays and with ever decreasing energy
> as to produce sand rims of smaller and smaller diameter,
> which are nicely nested within each other.
>
> Their nothing mysterious about these rims as (Ivester et al.
> 2004a) studied the sedimentology and stratigraphy of these
> rims and found them to be "composed of both shoreface
> and eolian deposits". Eolian and lacustrine processes are
> perfectly capable of producing the low rims processes by
> Carolina Bays. The low rims can be easily explained by a
> combination of eolian and lacustrine processes.
>
> As a result of the OSL dating of the rims of numerous Carolina
> Bays, Ivester et al (2004b) concluded:
>
> "The optical dating results indicate that
> present-day bay morphology is not the
> result of a single event, catastrophic
> formation, but rather they have evolved
> through multiple phases of activity and
> inactivity over tens of thousands of years.
> This is evidenced both by multiple rims
> of differing ages along the same bay, and
> by multiple ages within single rims."
>
> Because the Carolina Bays have been modified for over a
> 100,000 years by both eolian and lacustine processes, their
> form, orientation, shallowness, and sand rims are useless as
> evidence of how they were originally created.
>
> References Cited:
>
> Ivester, A.H., Godfrey-Smith, D. I., Brooks, M. J., and
> Taylor, B. E., 2003, Concentric sand rims document the
> evolution of a Carolina bay in the Middle Coastal Plain
> of South Carolina. Geological Society of America
> Abstracts with Programs. vol. 35, no. 6, pp. 169.
>
> Ivester, A. H., Godfrey-Smith, D. I., Brooks, M. J., and
> Taylor B. E., 2004a, The timing of Carolina Bay and
> inland activity on the Atlantic coastal plain of Georgia
> and South Carolina. Geological Society of America
> Abstracts with Programs. vol. 36, no. 5, p. 69
>
> Ivester, A. H., Godfrey-Smith, D. I., Brooks, M. J., and
> Taylor B. E., 2004b, Chronology of Carolina bay sand
> rims and inland dunes on the Atlantic Coastal Plain, USA.
> The 3rd New World Luminescence Dating Workshop. July
> 4 - 7, 2004, Department of Earth Science, Dalhousie
> University, Halifax, Nova Scotia.
>
> Mrs. Webb also wrote:
>
> "It is also worth noting that all the
> geological theories of their origins
> are based on the erroneous notion
> that the Carolina Bays are all to be
> found in only one type of geological
> terrain, the coastal plains. But they
> have since been found in other terrain
> types, which effectively rules out
> most of the prior geological theories
> (except for those fish fins, of course)."
>
> Unfortunately, the only "erroneous notion" here is the
> pervasive Internet folklore about Carolina Bays having
> been found on a variety of geologic terrains. The fact
> of the matter is that Carolina Bays are **not** found in
> a diverse assortment geologic terrains. The Internet
> fiction about Carolina Bays being found in a wide range
> of geologic terrains was soundly refuted by the detailed
> analysis, which May and Warme (1999) did of Carolina
> Bays, including those found within the coastal plains of
> Mississippi and Alabama. They found that these bays
> are restricted to deeply weathered, very low relief, and
> very poorly drained, geomorphic surfaces.
>
> Reference Cited:
>
> May, James H., and Warne, Andrews G., 1999, Hydrogeologic
> and Chemical Factors Required for the Development of
> Carolina Bays Along the Atlantic and Gulf of Mexico Coastal
> Plain, USA. Environmental Engineering and Geoscience.
> vol. 5, no. 3, pp. 261-270.
>
> The abstract for May and Warme (1999) can be found at:
>
> http://eeg.geoscienceworld.org/cgi/content/abstract/5/3/261
>
> Best,
>
> Paul
>
>
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Received on Thu 30 Mar 2006 02:14:08 AM PST