[meteorite-list] moldavite splashforms w/ artifacts. Inquiry?

From: Paul Heinrich <lenticulina1_at_meteoritecentral.com>
Date: Thu Apr 22 10:14:07 2004
Message-ID: <20030428142416.41511.qmail_at_web21414.mail.yahoo.com>

On Mon, 28 Apr 2003 00:12:18 -0500
Sterling K. Webb kelly_at_bhil.com Wrote:

Mrs. Webb is mixing apples and oranges and
putting words in my mouth that I did not
say as I am just talking about the moldavites
and not other types of tektites.

Many of the other tektites, which she mentions,
I would well agree retain a large degree of
their surface morphology and that I don't
dispute. I am ++not++ arguing that the surface
morphology of all tektites, as Mrs. Webb
incorrectly implies, is the result of etching.
The aerodynamic forms of australite buttons
clearly demonstrate. Again, my discussion
just applies to moldavites.++

Mrs. Webb stated:

>Frankly, I feel that the popularity of
>the "differential chemical etching"
>theory is due to its ability to dismiss
>in a single phrase a complex morphology
>that defies easy explanation and which
>has been inadequately studied.

This is not true, the popularity of the
chemicaletching explanation is the result
of the fact that the complex forms that
moldavites exhibit, and I am just talking
about the moldavites, is the type of complex
morphology that results when materials
corroded by chemical etching.

>While aerodynamic ablation is "probably"
>the answer, no one has undertaken the
>monumental job of classifying and
>thoroughly explaining the great
>variety of features that are to be
>found.

The fact that people have been able to
explain the morphology of australite
buttons using aerodynamics and nobody
has yet been able to explain the
complex form of moldavites with
aerodynamics suggests to me that it
has proven useless as explanation for
the formation of moldavites. (Again
I am just discussing moldavites,
**not*** other forms of tektites.)
In contrast, the form that moldavites
have is the classic shapes geologist
often observe in the corrosion of many
types of materials.

>Both the frequency of symmetry and the
>common orientation of features on Besednice
>"leaf" moldavites argue against "corrosion"
>as the sculpting force.

This is not true. This just means that
there was symmetry to the internal structure
of the original moldavite. If the internal
structure of the etched moldavite is
symmetrical, than the resulting etched form
will be symmetrical. This in no way proves
that the original form of a Besednice was
"leaf" shaped. The common orientation in the
moldavites just means that they have a common
internal structure, which would corrode to
produce a common orientation.

If the Besednice were originally "leaf"
shaped how did they survived intact being
transported in fluvial systems and then
deposited in the sands that they are
found? The delicate "leaf" shaped forms
could only have formed by corrosion once
they had come to rest and been encased
in the fluvial sands that they occur.
Otherwise, they would had been completely
been broken before being deposited with
the fluvial sand that they are found in.

There are other shapes, e.g., spheres, discs,
 ellipsoids (ovals), lenses, cylinders, rods,
dumb-bells, and so forth which reflect the
original, although with corroded surfaces,
form of some moldavites. As far as the
"leaf" shaped forms, geologists, with very
good reason, would find the aerodynamic
explanation extremely implausible.

>Moreover, they are found in complete
>range of forms from completely undamaged
>with every little "finger" intact to
>progressively less and less elaborate
>forms whose reduction is mechanical
>(breakage), not chemical.

It just means that there has mechanical
breakage after the etching of moldavite
has occurred. Reworking of the moldavite
deposits after they have been corroded
can easily account for this breakage.

> If chemical etching were the formative
>agent, there would be intermediately
>"etched" forms, and there are not.
>There would be pieces only partially
>"etched", and there are not. There is
>no evidence of a range of chemical
>activity, only of a range of mechanical
>damage.

This is not true. All of this means is that
the deposits containing these moldavites have
been subject to either the degree of
weathering, diagenesis, and some combination
of the two. As a result, any moldavite found
in these deposits will exhibit the same degree
of intense corrosion to the extent that
intermediate forms and fresh moldavites simply
don't exist. These moldavites are about 15 million
years old and occur very porous sands that would
have allowed intense digenatic corrosion of them.
Under these circumstances, it is would quite
remarkable and quite unexpected that they
haven't been badly corroded. The lack of
intermediate forms proves nothing about the
origin of "leaf" shaped moldavites.

Yours,

Paul
Baton Rouge, LA



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Received on Mon 28 Apr 2003 10:24:16 AM PDT