[meteorite-list] Re: Tektites II
From: Kelly Webb <kelly_at_meteoritecentral.com>
Date: Thu Apr 22 09:43:32 2004
Hi, Steve and List,
This is my reply to Steve's reply to my reply to Steve's... Wow, way
too many levels of recursion here. OK, we're going to go to the triple
interleaved posting format: my former posting (with >'s), Steve's
replies, and my replies to his replies. To help keep the sequence of the
three different texts straight, I have added the "speaker's" name to
each level respectively (WEBB1, SCHONER, WEBB2).
Got that? You can't tell the players without a program...
All spelling (typing) errors are mine (except for the ones that are
Steve's). All other errors are for the reader to judge.
> Glass's preliminary guess in 1968 that the Tunguska object had a
>"composition similar to that of tektites" has been long superseded by
>more recent and ongoing studies of the Tunguska microspherules, none of
>which bear this notion out. They are largely metallic, not glassy.
Probably, yes. I read somewhere that some of these might even be
related to industrial activity and not the impactor at all. Billy
Glass, a recognized authority on tektites made the statement, and I
quoted it. But the jury is still out and I acknowledge it.
On of the real mysteries of the Tunguska blast is how little
physical evidence it left behind, almost a case of no fingerprints. One
new way of retrieving the microspherules and dust from Tunguska is by
cutting sections out of trees that were alive at the time of the blast
and extracting residues from the tree rings associated with that date!
They show lots of exotic metallic elements.
> The microspherules themselves lend no evidence either way on
>the impactor was meteoritic or a comet chunk. Actually more
>think the Tunguska Object was a stony meteorite, while more astronomers
>think it was a comet; it seems to correspond to whichever choice is
>familiar to the theorist.
Whatever it was it was fragile. And having fallen on June 30th, and in
the morning, it might have been related to the Taurid (?) meteoroid
stream that the Earth passes through at around that time. I am not sure
if it has been correlated with a comet or an asteroid. But it does
seem coincidental that it fell at that date, and during a time of each
year when large fireballs are likely to be seen.
Not fragile (see below). 200 bars crushing pressure (3000 pounds per
square inch) are calculated for the Tunguska Object based on the air
density at the altitude of its airburst and a "reasonable" assumption
for its velocity.
I too agree it was probably a beta Taurid, a daylight meteor stream
and one of two streams associated with the decaying Comet Enke.
Personally, I'm certain it was. Well, as certain as I get. Just wait
until 2042 AD when Ken Brecher's Canterbury Swarm is supposed to come
back (or not, depending on whether it really exists). I believe in the
beta Taurids for the simplest of reasons: witnessing a daylight fireball
half as bright at the sun itself over 30 years ago (on a June 29th).
It's one thing to read about big potential impactors; it's another thing
to stand there with your mouth open watching hundreds of secondary
shadows swing around in unison as one passes overhead. It impressed the
hell out of me.
Hey, did we just agree on something?!
> The crucial issue in the possible airburst of an impactor is the
>point at which the dynamic pressure of the atmospheric resistance [p =
>0.6 x gas density x (velocity)^2] equals the crushing strength of the
>impactor material. The Tunguska object, whatever it was, exploded at a
>dynamic pressure of about 200 bars. Whatever it was, it WASN'T weak and
>fluffy. That doesn't necessarily mean it wasn't a cometary fragment. We
>don't know enough about comets to be sure.
And we don't know what the effect of impacts to their structure and
composition will be either. I would assume that they would, because
they have been hit, and are being hit by other cosmic debris, that their
composition would reflect that. But more importantly, how will such
impacts while they are out in space affect the cometary structure? How
fragile will they be after all of that bombarment? And how will they
stay together when the do enter a planet's atmosphere?
Questions not easy to answer.
What we do know is that some comets are very fragile, and they break up
by Solar wind pressure alone.
Their fragility, composition, fragmentation are all irrelevant in
that short dash through the atmosphere at cosmic velocities. I'm going
to quote you a source here, since I perceive some reluctance to take my
word for it (don't blame you; I'm the same way).
I looked in Rocks From Space and other common sources but discovered
none of these books spell it out the physics of it very clearly.
From John S. Lewis, Physics and Chemistry of the Solar System,
Chapter VIII, Meteorites and Asteroids, p. 309ff:
"Often, small bodies will be decelerated to subsonic speed before
reaching the ground. About the largest body that could possibily reach
the ground in one piece, without exploding on impact, would be a
monolithic chunk of iron, preferably extremely flattened, travelling at
the lowest possible entry speed, and entering the atmosphere at a very
shallow grazing angle. The limiting size can be calculated to lie in the
range of 30 to 100 tons..." (Webb: About the size of the Hoba meteorite,
"For a spherical stone, roughly 3 m in diameter (40 ton) for a
density of 3 gm/cm^2 is the upper limit..."
"Fragmentation is unimportant for very large impactors, irrespective
of size, because the fragments of large bodies do not have time to get
away from each other before impact with the surface... For a typical
stone, the critical size (for ignoring fragmentation) is about 300
meters. Deceleration is important for entering objects only if their
mass per unit area (essentially pd3/d2 or pd) is less than that of the
atmosphere above the Earth's surface."
Webb: Picture it this way. The atmospheric pressure is about 1 kilo
per cm^2. That means that a mass of 1 kg of air sits on each square cm
of the surface. Imagine that our incoming meteorites are, oddly enough,
perfect cubes. For a one centimeter cube to make it through the
atmosphere without slowing down much, it would have to weigh 1000 grams,
a very high specific density of 1000.
But a 10 cm cube would have to weigh 100 kilos, but its specific
density would only be 100 (100,000 grams / 1000 cm^2). A one meter cube
would have to weight 1,000,000 kilos, but its specific density would
only be 10 (10,000,000 grams / 1,000,000 cm^2). I think you can see the
A ten meter cube would only have to be as dense as ice (specific
density = 1), a 100 meter cube 1/10 as dense as water, a one kilometer
cube 1/100th as dense as water, a 10 kilometer cube only 1/1000, and so
forth. At this point, our impactor is less dense than air, which raises
other severe problems.
> The weakest fireball objects burst at 0.1 bar, so obviously there
>weak and fluffy material out there, corresponding to interplanetary
>with densities of 0.01 to 0.10 gm/cm^3. However, your assertion that a
>10 kilometer weak'n'fluff would never reach the surface of the Earth
>well, ridiculous. The factor in determining whether an object will
>suffer ANY decceleration in the atmosphere depends on the total mass
>unit area of frontal surface of the object.
Maybe my assumption might seem ridiculous to you, but it is obvious that
such may very well have happened as the tektites indicate. Impact (or
impactor) products (tektites and microtektites) scattered over areas as
broad as 10% or more of the Earth's surface and-- not a trace of a
And these strewnfield distrubutions cannot be supported by having been
formed, and ejected from the moon to Earth?
Humm... being skeptical... something is wrong in this picture.
However, there are several tektite fields that do seem to be associated
with known craters, The Ivory Coast tektites-- Bosumtui (sp),
Moldivites-- Reis, and Georgia tektites-- Chesapeake Bay crater.
But the Indochinites are the most enigmatic, for they point to some type
of atmopheric bursting event that liberated enough heat to vaproize the
impactor as well as ground rocks, throwing them far and wide of the
epicenter of the event.
> Once an object is big enough to have more than 1.057 kilgrams of
>mass for every cm^2 of frontal area, it's gonna reach the surface of
>Earth with its cosmic velocity relatively undiminished. The dynamics of
>cometary impact are as well known as that of any other kind of impact.
>That 10 kilometer fluffball of yours is just as deadly a hazard as any
>other object with its mass and velocity, whether stone, iron or pure
>neutronium [kinetic energy = mass x (velocity)^2]. A cometary fluffball
>with the density of interplanet dust particles, if there were such a
>thing, would reach enough mass to punch through essentially unimpeded
>the 500 meter size.
I do not dispute that objects of the size that produced tektites are
cosmic hazards to the Earth. Tektites clearly demonstrate that. But
the fact is that, if they were, as I am convinced that they are,
terrestrial, and no crater exists then an atmospheric burst (Tunguska
event) must be the culprit. And though I don't dispute your
mathematical reasoning, you have not proved that such a "fluff ball"
(such as are some comets that break up by Solar Wind alone) ABSOLUTELY,
and without question MUST reach the Earth's surface even if its size be
at or below 10 Km in diameter. I suspect that there are other factors to
be considered, such as the angle of entry, the velocity of the impactor,
as well as its composition.
The question really is, how fluffy can the fluffball get and hold
itself together as an object. A density of 1/100th of water is out of
the question. That is the density of a Brownlee particle 10 microns
across. Brownlee particles are that size because that represents the
maximum size an object that "fluffy" can get. But Brownlee particles are
soot-like mineral oxides from which the volatiles have escaped. They are
found floating in the upper atmosphere and, although cometary in origin,
they cannot be a model for a low-density comet
I don't know where you got the idea of comets "broken apart" by the
solar wind. I've been through every book on comets I've got handy
(Yeomanns, Delsemme, etc.) with lots of material on solar wind
interaction with cometary ion tails, etc., but have yet to encounter any
such instance of "breakup" cited or suggested. I doubt the idea, but I'd
like to know if you have a specific source.
At any rate, in a fluffball the size you suggest the tidal forces
(differential force of solar gravity between the near and far sides of
the object) are more than enough to rip the fluffball to shreds unless
it has sufficient structural strength to resist. At the size you are
talking about, the object would also have to resist crushing by its own
gravity. Your fluffballs have to be able to survive in their own free
orbits for long periods. I won't even go into another mystery, how such
a critter might form in the first place.
Some years ago, I saw a very interesting abstract by a Russian
researcher looking into the dymamics of the bolide that created the
Tunguska event. His analysis of it, using computer and mathematical
models incorporating data gleaned from hydorgen bomb tests produced very
nteresting results. As the impactor broke up, according to him, it had
a "cascade effect" In other words the breakup caused more break up, and
it progressed exponentilly in the span of a millisecond or less, so that
the energy release was as equal to that of a hydrogen bomb explosion in
the air(airburst), not only in energy release but in effect as well.
The key point in his analysis as I remember was the total energy
released in relation to the time element of the release, and the medium
(air) in which that energy was released.
His conclusion was that the impactor made a "crater" in the Earth's
atmosphere rather than the ground. Though not a very large body, if this
was so then impactors do not have to reach the ground to produce
craters. "Craters in the air" is what can be produced by an impactor if
the conditions are right.
IN the case of tektites, they are evidence of such events on a much,
much larger scale than the 1908 Tunguska event.
Of course, that is exactly how airbursts happen. No one doubts that
or has suggested anything else. We can all agree to your craters in the
air. But how big can they be?
> Ignoring the numerical coefficients, we have a factor here composed
>of density x diameter^3 / diameter^2. This reduces to density x
>diameter. Even a little simple arithmetic would have revealed that your
>fluffball would have a volume of 5 x 10^29 cm^3 and a frontal area of 8
>x 10^11 cm^2 and hence would have to have a density of less than 10^-13
>gm/cm^3 to be unable to penetrate the atmosphere, or in other words, a
>density essentially similar to space itself or a very good laboratory
>vacuum. So, in a way, you're right: balls of vacuum do not penetrate
NO, NO, NO! I think you had better go back to the drawing board on that
one. A cometary "fluff ball" does not mean a vacuum.
My point is that your fluffballs in the size you're talking about,
in order to not reach the ground but aurburst instead, would have to be
virtually a vacuum or at the least an "airball." Refer to the
step-by-step density reduction in my previous comment.
Let me give you this analogy. I think that it is a good one and
illustrates the point well.
Suppose that you take a bullet-- a solid bullet and fire it from a gun
at a set velocity at a target composed of ballistic jelly. The solid
bullet will penetrate deeply into it leaving a bullet track in its wake
as it expends energy. It will either pass through, or come to a stop,
but all the while expending its kinetic energy until it comes to a stop.
Now use one of the "stinger" rounds, of the same weight, but composed of
a bullet made of tiny lead shot contained in a polycarbonate shell.
This round will travel at the same velocity, and strike the ballistic
putty with exactly the same amount of force and energy yield-- HOWEVER--
because its structure is not consolidiated it spreads out on impact and
expends its energy much facter and closer to the impact point in the
ballistic putty, and more importantly it does not pass through. The
hole "crater" it produces is in the ballistic jelly, and the majority of
its damage is inflicted at, or very close to the point of entry.
The amount of kinetic energy of both rounds is identical. What is
different is how they expend that energy on impact with the target and
this is related
to the *structure* of the round AND NOT its mass.
The same effect I think applies to cosmic impactors. Structure is what
determines how they release their energy in the Earth's atmosphere.
(And whether they even reach the ground).
The analogy of bullets and targets is a very poor one. Cosmic
velocities are orders of magnitudes greater than what's produced by
human popguns. Kinetic energy goes up as the square of the velocity. The
kinetic energy of the fastest bullet is only great enough to deform or
shatter it. A gram of material moving at 72 km/sec, the highest possible
intercept velocity at the Earth's orbital distance, has 1000 times more
kinetic energy per gram than the energy released by the explosion of a
gram of the most powerful chemical explosive known. In fact, when this
amount of kinetic energy per gram is released in an impact, less than
0.2% is used up vaporizing the impactor; the rest goes into the force of
the explosion. We measure the impact energy in tons of TNT equivalent,
but a one-ton body moving at this speed has more kinetic energy than the
ton of TNT has explosive energy, by a thousand-fold!
The point here is that kinetics on this energy level is, in fact,
totally unlike conventional earthly events, like bullets. Composition
matters little. Density shades the results (an iron can be a little
smaller than a stone and an ice can be a little bigger), but doesn't
affect the outcome much. Composition affects the outcome less and less
as the impactor gets bigger and bigger.
(It's difficult to realize how potent kinetic energy alone can be. A
gram of anything moving at 7000 km/sec would have more kinetic energy
than the energy produced by the nuclear fission of one gram of
plutonium. In other words, shooting a chunk of rock at a planet at this
speed would be just as effective as a nuclear bomb with the same weight
in fissionables. At this speed, a one kilogram rock would equal the
Hiroshima bomb in energy release!)
Most larger impactors as you pointed out will reach the surface, but
even a stony object of the same size as those that do, but that is
highly fragmented can explode in a Tunguska type event in the Earth's
atmosphere rather than on the ground.
What is the pressure of the center of an explosion as the blast wave
radiates out? Correct me if I am wrong, but I read somwhere that in the
case of nuclear airbusts at 60,000 feet, that such an explosion produces
a very strong blast wave which then radiates out from the epicenter, and
milliseconds after that, the dynamic pressure at the center of that
super heated plasma fireball is *close* to a perfect vacuum. Then in
the wake of the blast the air rushes back to fill the void. (Take note
of the old atomic blast footage of the blast wave-- it radiates out,
then a moment later rushes back.)
The question is how big an object can airburst? The lower its
density, the bigger it can be and still airburst. But there is an upper
limit to an airburst imposed by the lower limit on density.
Fiddling with the limits set by tidal forces, self-gravity, and
structural limitations (below the densities of frozen gasses, only voids
will lower the density further), I'm willing to postulate that an object
with a density of 1/10th that of water could conceivably exist.(Frankly,
I doubt it, but I notice you never say how fluffy you think fluffy is,
just that it's fluffy enough.) Such an object would be about 85% voids.
That's really foamy.
Huge, mega-Tunguska events also produce blast waves that are "exactly"
like thermonuclear blast waves, but on a much, much larger scale. And
this is why in the early 50's that Dr. Lincoln Lapaz and others though
that the Tunguska event was caused by an "anti-matter" impactor rather
than a meteoroid expending all of its kinetic energy in the Earth's
atmosphere rather than on the ground. At the time, and with the limited
information and data that was available to them they could not grasp the
dynamics of a meteoroid disrupting in a cascade of fragmentation in the
Earth's atmosphere. To get an idea of this, imagine the thing
shattering instantaneously, and in so doing coming to a complete stop
high in the air. All of the impactor's kinetic energy would be
converted to heat, and infrared radiation, and visible light. Instead
of making the release of such energy in the solid ground it does so in
the air. There will then be a bright and very intense flash-- just as
in a thermonuclear explosion. In this regard, Dr. Roddy and previous to
that, the late Dr. Shoemaker both told me that the energy release
dynamics of Tunguska type events, are "identical" to the energy release
dynamics of thermonuclear airburst explosions.
No one disagrees with this, Steve. You're making my point for me. In
a sufficiently energetic event, nothing matters but the raw parameters
of energy. There's no difference; energy is energy. Whether the energy
comes from a fast dumb rock or a sophisticated gadget like a super bomb.
If it's a kinetic event, above a certain energy level it just doesn't
matter about its composition or structure or anything, whether it's a
million tons of iron or a million tons of goose feathers.
The question is, as always, how big? Ok, I gave you your 1/10th of
water density. That reduces to the following maximum airburst, that is,
it just barely fails to hit the surface. The object is about 130 meters
in diameter. It weighs about 90,000 tons. The impact energy is around
5,000,000 tons of TNT equivalent. That 5 megaton burst is sort of medium
for a fusion or boosted fission bomb. (The biggest "H-bomb" ever
exploded was 60 megatons, by the Russians.) That's the top yield for a
low density object possible in an airburst. The object could be much
bigger, of course, but then it would reach the surface and create that
crater you're trying to avoid.
The real Tunguska object produced a much bigger explosion (about 5
times bigger). Its burst pressure of 3000 pounds per square inch
(compared to the much lower bursting pressure on your low-density
object) is what created the higher yield.
IN this regard a mega-Tunguska event in the Earth's atmosphere would
most certainly generate enough energy to "blow away the Earth's
atmsophere" and create a virtual supperheated vacuum as the fireball
expanded, and additionally, the wake of the fireball (its track through
the Earth's atmosphere) would also serve as a "conduit" for any impact
generated materials that would be ejected into space as the flanged
Australaisian tektites indicate.
There can't be a mega airburst. Airbursts, as the physics of the
situation limit it, are confined to a narrow range. That range lies
between, on the one hand, airbursts that occur so high up the blast is
dissipated and unnoticed at the Earth's surface (likely very weak
objects and/or very fast ones) and airbursts that occur just short of
the surface and which transmit most of their force to the Earth below.
Tunguska is an example of that. The many nearly megaton blasts at very
high altitudes detected by early warning satellites like the DSP-647's
(hush, hush) are examples of the former. These weak objects, whatever
they were, are probably the closest thing in the real world to your
hypothetical low density objects, Steve, but don't rush to the DoD to
get the data, because they threw the data away after they decided they
weren't weapons. Military... intelligence?
Study the dynamics of the Comet Shoemaker-Levy impactors to the planet
Jupiter to get a grasp of the process. The impactors expoded in the
Jovian atmosphere and the blast plume then went up through the bolides
wake. So if such happened there, such could and most likely did happen
here on Earth.
Tektites serve as the evidence of such events.
> But, hey, we knew that already. That's what the backs of envelopes
>are for. When we get these great notions, like, I'll bet there are big
>comets so fluffy they won't penetrate the atmosphere, we do the
>arithmetic first to find out whether it's in the ballpark (or even if
>there is a ballpark). This notion is a complete non-starter.
As I pointed out, Kelly. I am no "arithmatic expert" (spelling either),
but I think that the basis of your calculations are wrong. If you start
out with the wrong assumptions, you will get wrong answers.
All science is at bottom quantitative. Verbal analogies and images
are more often misleading than helpful. Only crunching the numbers, or
even just approximating them, produces a clear mental picture.
The fact is that Tunguska type events happen. And in the case of the
Tunguska event, with impactors that may very well be much more
substantial in structure than most comets. And I think that if you go
back and plug into your equations some figures that show angle of entry
variables, velocity of known comets, and also factoring in suspected
struture based upon ovservation of fragmenting comets-- I am confident
that your arithmatic will show that such impactors DO NOT necessarilly
HAVE to reach the ground just because they are large.
They produce their craters in the air, and close to the ground, but not
so much in it.
And impactor solids, along with that from the ground that was vaporized
or melted by the air blast is then blown far and wide over the surface
of the Earth, as the tektites and microtektites are found today.
> As for Michael Pain's article answering my questions, it was
>Pain's article that was summarized in the CCNet post which raised the
>questions for me. I repeat, the notion of an impact of this magnitude
>--- 10,000,000,000,000 tons of TNT equivalent --- having occurred so >
>recently and without leaving unequivocal and substantial evidence,
>obvious traces, is ludicrous.
Air bursts. Mega- Tunguska events, just as I explained, and as he
explained could and most likely are the cause for tektites.
> It reveals the increasing intellectual poverty of impact dogma to
>require an impact of this magnitude to create the Australasian field
>be unable to find any trace of that fresh hole --- 70 miles across and
>12,000 to 20,000 feet deep --- in Indochina or anywhere else.
Craters in the air. Try to grasp the concept.
A crater in the air with the bottom of it reaching, but not penetrating
into the ground.
That is what I and others think created tektites. It is a process that
apparently happens only very rarely on the Earth.
34 million years ago in what is now Texas, and about the same time for
the Georgia tektites.
14 million years ago for the Moldivites
800,000 years ago for the Indochinites.
Oh, and I forgot the Ivory Coast tektites-- was that 6 million years
No. 1.3 million years ago.
How many ground impacts have happened over that span of time? Many more
than that. So I think that "air burst" events that produce their
"craters in the air" are not nearly as common as those events that
produce their craters on the ground.
> You can't bury all traces of a crater 1/3 the size of Chicxulub in
> than a million years. (Back to arithmetic: it would take depositation
> 1-2 meters of sediment per century to fill the damn thing in and bury
> it in so short a time.)
Again, Kelly, your assumption evaporates and has no validity when one
considers that Mega-Tunguska events produce their Craters in the *air*.
And the dynamics of air rushing back to fill that void is the
explanation for the distribution of tektites as they are found on the
I repeat-- You won't find a crater for the largest tektite field because
the crater was in the air, and not on the ground. The atmosphere was,
as I previously said, "splashed away" by the impact event, vaporizing
both the impactor and the ground close to the bottom of the atmospheric
crater itself. The crater is gone, filled in by air returning to fill
the void, and the tektites are left as the only evidence that such an
Again, airbursts occur in the range between a few kilotons of TNT
equivalent and perhaps as high as 50 megatons (dense, slow, weak
objects) and I sure wouldn't want to stand under one. But these energies
are insufficient to create tektites. Since airbursts this size are not
that uncommon, if they created tektites, even little fields of them,
there would be many small tektite fields all over the planet. But there
ain't. And since airbursts are limited in maximum size, they couldn't
have produced the big fields of tektites either.
I know John Wasson (1991) first floated the idea of cometic
airbursts to explain the Muong Nong glasses, but you'll notice that he
hypothesized a huge number of airbursts all in the same place to do it.
The one big airburst can't occur. The problem with the many little
bursts is that it's a hell of a coincidence.
But the "experts" quoted in the M. Pain article are saying that to
create the Australasian field an energy release of 10,000,000,000,000
tons of TNT equivalent are required, that's 10 million megatons. That's
a 100,000 times bigger than the biggest airburst possible. It's bigger
than big. It's 2000 times bigger than a full nuclear exchange. It's
bigger than a Hollywood movie about asteroids. It's a major piece of
planetary asskicking. Big.
It had to leave a mark... if it happened. Glass and Lee's 114-km
crater --- if it existed --- would be the fourth biggest crater on
Earth. And it's too new to hide.
> And, tektites do not have the "composition" of terrestial rocks, any
On the composition there is no disparity between terrestrial rocks and
tektites. Water is virtually absent, and that is about it.
The presence or absence of water is part of its composition, isn't
it? I call that a major disparity. Earth got water; Venus don't ---
makes a big difference to me. If I go to Venus, I don't pack my beach
As I quoted, Billy Glass, (a noted expert on tektites) said as much.
And others that I have spoken to that are currently doing research on
the tektite problem have also said as much.
> There is no match for tektites anywhere on Earth. Even
>if by "composition," you mean "bulk composition," there is no match.
>What you are referring to is a set of plausible hypotheses that certain
>mixtures of terrestial materials subjected to certain very extreme
>conditions might produce something like a tektite. It's quite possible
>that they're produced that way, but it's hypothesis, not proof.
I am glad that you can admit this, Kelly-- because that is most likely
the case. The proof will come, sooner or later. But I think probably
in the next ten years the question will be resolved.
And the answer will be that they are terrestrial impact products caused
by "air burst" events.
> Go grab >some rocks and a big electric vacuum furnace and cook me up a
>tektite. That I'll believe. That would be proof. It's been tried, by
>many times, and nobody's ever succeeded in making a tektite. Unique and
>perverse little things, that's why they're so interesting.
Until the middle of the last century no one could create diamonds in the
lab either. Man had an understanding as to how they might have been
but did not have the tools to actually make them.
And to date, I don't think that anyone has been able to re-create the
conditions that would occurr during an air burst Tunguska type event.
Conditions at, or most likely exceeding a Tunguska event are required to
form tektites. We simply do not know enough about it, or the conditions
of such an event to bring about the creation of tektites in the lab.
Just because we can't at this time re-create them, does not mean that we
cannot come to an understanding as to the processes that created them.
This is what science is doing now, and the evidence is mounting that
they were created in terrestrial impact events.
Actually, we have conducted experiments that could be considered
tektite forming tests: nuclear bomb tests. Bomb tests were conducted in
places with plenty of sandy soils (Nevada, atoll islands) to provide the
silica. The temperatures are certainly high enough! Billy Glass has
written about nuclear glasses and compared them to tektites. The low
water content of 70 ppm of the driest nuclear glasses is bandied about
as "proof" that any really energetic event on the face of the Earth
could produce tektites. But if you looked at bomb glasses, you would
never mistake them for any kind of tektite; they are rotten with
xenoliths, structurally dissimilar in almost every way. (Even the ones
produced by airbursts.)
I must add, that I am not an "expert" on tektites. In the past I sided
with Harvey Nininger in his thoughts that they came from the Moon. But
in discussions with Dr. John Wasson and others who have spent many
years in the field and the lab studying them, my opinon has changed.
(And I might also add, that Harvey Nininger's position changed, too.
More than a decade after the Apollo Missions, and in one of the last
conversations that I had with him, when the subject of tektites came up
he felt that they were not from the Moon as he had previously proposed,
but as the mounting evidence at that time indicated from impact events
to the Earth.)
We talk about speculation?
The fact of the matter is, and as I pointed out before, there is
ABSOLUTELY NO solid evidence that they came from the Moon, and there is
ABSOLUTELY NO solid evidence for a tektite parent body, and or
I never said they came from the Moon.
As for the possibly of an unique impactor of tektite-like
composition, its chief virtue as a theory is that it would explain the
total absence of any trace "contamination" of extra-terrestial
(meteoritic) materials in tektites. In the standard (Melosh et al.)
model of impact, the highest velocity ejecta is produced from the back
central portion of the impactor as it is crushing the target surface and
before the impactor itself vaporizes and explodes. This is the only
ejecta that leaves the scene without mixing with "target material." If
the tektites are produced from the terrestial "target" material by a
common impactor (meteoritic) they will be inevitably be contaminated to
some degree with impactor material. And they are not.
The chief objection to the tektite impactor theory is the absence of
small randomly falling pieces of tektite-like meteorites all over the
Earth. Unless you can figure out how there can only be big tektite
impactors and no little ones, it's a pretty good objection.
I am only surprised that fewer theorists see that the absence of
impactor contaminants is a fatal flaw in the impact theory of tektite
origin, and that nobody much has pushed the tektite-like impactor
theory. (I get soft-hearted over orphan theories.) Bob Haag's '97
catalog says a good word for it.
BUT-- there is mounting evidence for a terrestrial origin.
So, based on the information at hand, what conclusion can we at this
I think that the answer is becoming clear.
>The isotopic compositions do indicate that tektites are derived from
>a differentiated body with a secondary crust. But the Earth is not the
>only such body, only the one we're most familiar with.
Yes, that is where they came from-- The Earth after impact events to the
Earth's atmosphere created them.
One piece of evidence that shoots all tektite meteorite theories, and
Lunar origin theories down are as I originally proposed-- the very rare
After very luckily acquiring the one that inspired all of this
discussion at the last Tucson Gem and Mineral Show and going back to the
Macovich Meteorite room to admire it in a brief quite moment-- it hit me
like a revelation-- the significance of the is form in the tektite
Looking at it, and knowing the mystery, it hit me, it struck me in an
instant as I saw it.
These are the "smoking guns" in favor of terrestrial origin-- for there
is absolutely no way that such a form could have survived falling from
the Moon or anywhere else in space passing through the Earth's
atmosphere at 7+ miles per'second.
NO WAY-- it is logically impossible. And Darryl Pitt's meteorites, in
the displays around me, fusion crusted, and ablated were evidence as to
what the atmosphere does to bodies traveling through it at hypersonic
speed. The flanged buttion tektites, too. Even they, ablated as they
are and directly related to and contrasting with the "stretch" form
indicated what happens when such objects travel through the Earth's
atmosphere at hypersonic speed.
One would really have to "stretch" logic as well as science to explain
them falling from space and then arrive on the Earth and still retain
that stretch form. And the extraordinary stretch tektite that I have in
front of me at this moment, with stretched bubble holes almost touching
the surface, and a few breaking that surface, show absolutely no
ablation that one would expect to see had such an object formed in the
vicinty of the Moon or space and then fell to
Nor do I buy the notion that stretch forms were formed by a "tektite
meteoroid" breaking up in the Earth's atmosphere. Distribution problems
exist with that notion. For to spread them out in the known
strewnfields as they are would have also created the "crater" on the
ground that everyone seems to be looking for. Also in this regard,
tektites are much stronger material than comets. A tektite impactor
would would therefore have a much greater likelihood of reaching the
ground than an icy, "fluff ball" comet that breaks up under the influnce
of the Solar wind.
So, the bottom line, the final piece of evidence that shoots down all
Lunar, and tektite meteoroid theories is the rarest of tektites-- the so
called "Stretch" tektites. Where they are found, close to the epicenter
of the presumed air burst event, and their condition, lacking ablation,
speaks volumes as to the origin of these strange objects.
And if not, then I challenge one, anyone far and wide, to explain how
such a form could be produced on any other cosmic body, other than the
Earth, then fall to Earth at hypersonic velocity, yet still retain its
form which was clearly, and beyond doubt formed at or very near its
point of origin.
I repeat it again-- The "smoking gun" for terrestrial origin of tektites
are stretch tektites, and I think that tektite researchers should
closely examine these forms in their quest to resolve the tektite
Now we're on a completely different subject. The surface features of
tektites and their causes has been an unresolved quarrel for nearly a
century. One school holds that the pits, grooves, and myriad surface
features are all the result of terrestial etching, acidic erosion eating
away at glasses of differing composition at differing rates to produce
the features. Another school holds that the surface features are
ablative in origin, the most obvious ablative form being the flanged
button, of course. Shapes have been explained, successfully I think, by
the rotation of molten spheres on single and multiple axes.
The "stretch" form was still virtually molten liquid glass inside
with a thin, newly solidified surface when it landed, cracking its
"shell" and exposing the molten "taffy" inside. The problem is that I
can think of many scenarios that could end this same way. I understand
that Nininger eventually decided that the "stretch" forms couldn't have
stayed molten all the way from the Moon and so couldn't support lunar
origin but rather refuted it. But it does prove that the surface
features are not terrestial etching.
The ablative theory appeals to me, but I'll be damned if I can see
how this crazy variety of surface features could be produced by
ablation. I keep trying to, though.
And since this is a completely different subject, let's save it for
the next round of the tektite wars. Even I think this is enough... Hey,
at this point, if anybody still reading this post? Show of hands...
In summary, I see major flaws of one kind or another in ALL the
major (and minor) theories of tektite origin. Since I am not by nature a
negative nitpicker about most things, I think that is because some
important element is missing or has been overlooked or has not yet been
thought of. But I can't tell you what it is. Since I've been puzzling
over these odd rocks for many years, I'd like to know the answer.
The fact that I'm writing this on a Saturday night proves one thing,
to me at least, and that is, I've really got to get a life...
Sterling K. Webb
Received on Sun 15 Jul 2001 03:08:27 PM PDT