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

From: N Lehrman <nlehrman_at_meteoritecentral.com>
Date: Thu Apr 22 10:14:08 2004
Message-ID: <00d401c30de2$19f89f80$cc04fea9_at_homeportal.2wire.net>

List,

I've been out in the field and missed the first part of this discussion.
There are several subjects going on here, all favorites with me.

Aerodynamic pitting vs. terrestrial etching: Regardless of which you
choose, if you view this as an either/or issue, you will be wrong. The
answer is certainly "both". I have examined Nininger's stretch tektite
casts and have found three other examples (pictured on our website
http://tektitesource.com ). Nininger's argument is absolutely
compelling:most of the characteristic Indochinite pitting has to be
flight-related and very little is happening in the soil. Note also that
this "stretch" phenomenon is more common than most realize, in that
starburst-ray (skin-split) splatforms also provide a window into interiors
that have seen soil juices, but not flight exposure.

However, Besednice hedgehogs demonstrate the converse. It cannot be a
coincidence that the famous ornamentation in this case is found in one tiny
area a few hundred feet square, and even within that area, only the
specimens at the water-table show the extreme etching. Moldavites found
even a meter or so higher in the alluvial profile are not so etched. There
is a very precise chemical environment at play. This would present a great
research opportunity.

Colombites provide another case for terrestrial etching, in this case being
a terrestrial obsidian with tektite-like ornamentation. Ditto Arizonaites.
Again see images on our website. Along the same line, examples of deeply
etched man-made glass are known. Terrestrial etching is a certainty.

Age is a factor. The oldest known well-preserved tektites (Georgiaites &
Bediasites) both do have examples with depth of etching approaching that of
Besednice moldavites (In both cases, all known specimens have been reworked
from their parent formation and are mostly working on round 2 of surface
pitting. In rare cases, very deeply etched character remains, and I presume
these specimens have not had stage 1 etching removed by erosional abrasion.)
(I'll be posting some spectacular new Bediasites as soon as I've paid the
finder----)However, the youngest of the events, the Australasians, never
show anything significantly like their older relatives with the limited
exception of the Billitonites and Javanites. The latter both provide
examples of ornamentation so fragile and paper-thin that it could only have
formed in-situ. Not really a look-alike for Besednice, but equally fragile.

As for impact draping over substrate objects, it continues to baffle me why
not a single example of an embedded substrate object is known. Clearly,
some of the splatforms were still very fluid on impact. One sees teardrops
that telescoped into flat puddles with only concentric rings and a bit of
the tail protruding. Interestingly, there is a style of ornamentation very
specific to these extreme splatforms. The upper surface is distended and
stretched or wrinkled, often entirely erasing aerodynamic pitting. The
basal surface is deeply and irregularly pitted, reminiscent of the pattern
you see on the base of the metal when molten lead is poured on wet clay.

It's admittedly a stretch (of another sort), but could it be that the
australasian event happened at a moment in the wet season when all surfaces
in the splatform area were saturated? In this event, a vapor barrier would
form as the wet substrate sizzled beneath the blobs of hot glass. This
would preclude adhesions of pebbles or preservation of substrate detail (and
would generate the peculiar basal pitting at the same time).

Out of several hundred thousand specimens we have examined, only two or
three have geometries that look like they draped over something
three-dimensional. The rest appear to have conformed to a flat surface. No
fine details of that surface have ever been observed.

Obviously this needs to be a chapter in a book, if not a book in itself.
Sorry to ramble on, but this is a hot button. I'm just getting started.
I'll quit now, but would be glad to continue the discussion on or off list
as you may see appropriate.

Norm Lehrman
IMCA #4946

----- Original Message -----
From: "E.L. Jones" <jonee_at_epix.net>
Cc: <meteorite-list_at_meteoritecentral.com>
Sent: Monday, April 28, 2003 3:12 PM
Subject: Re: [meteorite-list] moldavite splashforms w/ artifacts. Inquiry?


> Ok Sterling, I agree that the two (now three if you count Michael
> Blood's) specimens show an unpitted interior plastic surface while the
> external surface is pitted. This doesn't rule out aerodynamic pitting
> but tends to discount post landing etching. BUT.......
>
> As to pitting occurances, look at the Georgiasites which show no pitting
> (if I recall correctly). At this point, I am not inclined to believe
> that soil content in the separate fields can be discounted but might
> work in tandem with other effects. The diffrences in terrestrial ages
> might account for a different rate of weathering in given soil. Season
> cycles might also play a part.
>
> I don't see this hedgehog form in any other occurrence. This makes me
> think a third specific effect may be acting on the moldavites in
> particular. As to moldivites,if the form was caused by surface impact,
> what would you surmise the impact surface was that allowed
> stalactite-like, fingers? Surely not snow, one would expect intant
> chilling.
>
> I was pondering a third effect; The Thaw-Freeze cycle. This field, and
> the rare tektite occurance from Tibet, are the two fields that lie in
> heavy winter climates. Granted the Tibetan stones don't show moldavites
> hedgehog forms but, it are also in a cold desert climate. Tektite glass
> being very dry, would weather more slowly than common minerals near the
> surface..one would think.
>
> Thoughts?
> Elton
>
>
>
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Received on Mon 28 Apr 2003 07:58:43 PM PDT