[meteorite-list] Atmospheric ablation marks on Tektites?

Sat Apr 5 11:33:49 EDT 2008

On "regmaglypts" in LDG...

Sean M. wrote:

"I called them "Pseudo" in the description, because, well, there is 
still a lot of debate about them being formed from traveling through 
the atmosphere"

Hello,

"Still a lot of debate"?  Could you kindly elaborate where atmospheric 
aerodynamic shaping for LDG ever was (maybe) or stilli is (huh??) being 
seriously debated by anyone who can tell the difference between a 
tektite and a chard of a beer bottle?

==>With so many tons and never an inkling of any fusion crust or other 
surface shaping?
==>With a water content indicating the glass was not formed in space 
like other tektites.

In answer to the prior question, regmaglypts are usually formed dues to 
differences in material as the theory goes (edges of sharp breaks get 
rounded, but those shapes aren't regmaglypts - and variation of true 
regmaglypting rates during its removal during ablation.  Meanwhile, 
tektites, and for that matter LDG is essentially uniform so the 
mechanism to form regmaglypts would have to be by thinking a bit more 
out of the box...

Best wishes,
Doug

-----Original Message-----
From: Sean T. Murray <stm at bellsouth.net>
To: meteorite-list at meteoritecentral.com
Sent: Fri, 4 Apr 2008 9:13 pm
Subject: Re: [meteorite-list] Atmospheric ablation marks on Tektites?

Ok folks - I want plenty of comments on this mess :) One of my favorite 
topics... Let's see if I can ramble through this... 

Most tektites, by definition, have passed through the atmosphere at 
least once. Some material (depending on the theory you believe in) just 
is spit out in the form of blobs of glass, but others take the long 
trip through the atmosphere to gain their unique shapes. 

There are still people on both sides of the fence as to the origin of 
tektites. The majority of the folks think they happen on impact here on 
earth and that the material is thrown out of the atmosphere and then 
re-enters to create many of the aerodynamic shapes we see in typical 
tektites. The other theory is that tektites were formed from lunar 
events (such as volcanic eruptions) and enter the atmosphere on earth 
and gain much of their shapes on the trip through. 

There is a lot of reading material out there that talk about both 
theories. The main flaw in the impact theory has to do with Stokes Law 
(for creating glass) and the lack of a discovered crater for the 
Australasian event (the crater should be massive considering tektites 
 from that event covered about 20% of the planet). The lunar theory has 
it's share of problems as well. You should read Hal Povenmire's book. 
It's got a lot of interesting information on tektites. I also love this 
website: http://www.tektites.co.uk/index.html - there is a good set of 
pages that describe the formation of the shapes and features on 
tektites (http://www.tektites.co.uk/22.html). 

However, in the case of LDG, a point to make is that I've seen multiple 
people argue that they are not actually tektites, but are instead 
impact glass. Most impact glass definitions that I have seen don't 
require that the material has been in and out of the atmosphere at 
least once. However, it is hard to argue with the features on the LDGs. 
I have a piece that has "regmaglypts" that rival any Sikote you can 
find (thanks to Mike as well! 
http://www.rocksfromspace.org/March_23_2008.html). I called them 
"Pseudo" in the description, because, well, there is still a lot of 
debate about them being formed from traveling through the atmosphere, 
or just weathering out due to natural weaknesses imposed by the 
cooling, impact, and subsequent chemical etching (fresh water mainly) 
and/or sandblasting over the years. 

I'd love to hear some other opinions. There is another source that I 
have not started reading yet - Joe McCall's book on tektites. He does 
have a chapter that singles out Darwin glass and LDG. 

Sean. 

----- Original Message ----- From: "Michael Gilmer" 
<michael_w_gilmer at yahoo.com> 
To: <meteorite-list at meteoritecentral.com> 
Sent: Friday, April 04, 2008 10:36 PM 
Subject: [meteorite-list] Atmospheric ablation marks on Tektites? 

> Hi Group! 
> 
> While reading through another Meteorite-related 
> message board on the WWW, I ran across a statement by 
> an IMCA member that puzzles me somewhat. A discussion 
> about Libyan Desert Glass was ongoing, and we were 
> sharing photos of our LDG specimens. (and I showed 
> off my new 9+ gram piece of dark-veined glass from 
> Michael Farmer - thanks Mike!) 
> 
> So the guy says : 
> 
> "This is one of my favorites and is fully oriented 
> with regmaglypts (yes, tektite impactites can have 
> atmospheric ablation patterns too)." 
> 
> Ok, here is my confusion - I was under the impression 
> that tektites were formed on impact - on Earth. So, 
> doesn't this mean they cannot have atmospheric 
> ablation patterns? Assuming the tektite never passed 
> through the atmosphere, I don't see how this is 
> possible. 
> 
> I have seen tektites with features that resemble 
> regmaglypts and orientation, but this is just chance 
> occurence, right? 
> 
> Or do I need to be schooled here? 
> 
> Thanks in advance! 
> 
> MikeG 
> 
> 
> 
> > 
_________________________________________________________________________
___________ 
> You rock. That's why Blockbuster's offering you one month of 
Blockbuster > Total Access, No Cost. 
> http://tc.deals.yahoo.com/tc/blockbuster/text5.com 
> ______________________________________________ 
> http://www.meteoritecentral.com 
> Meteorite-list mailing list 
> Meteorite-list at meteoritecentral.com 
> http://six.pairlist.net/mailman/listinfo/meteorite-list 
>  
______________________________________________ 
http://www.meteoritecentral.com 
Meteorite-list mailing list 
Meteorite-list at meteoritecentral.com 
http://six.pairlist.net/mailman/listinfo/meteorite-list 