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From: pamp@bcsaic.UUCP (pam pincha)
Newsgroups: net.origins
Subject: Re: archeopteryx: THE PILTDOWN CHICKEN
Message-ID: <350@bcsaic.UUCP>
Date: Mon, 28-Oct-85 12:57:37 EST
Article-I.D.: bcsaic.350
Posted: Mon Oct 28 12:57:37 1985
Date-Received: Wed, 30-Oct-85 06:35:39 EST
References: <420@imsvax.UUCP> <880@gitpyr.UUCP> <336@bcsaic.UUCP> <814@psivax.UUCP>
Reply-To: pamp@bcsaic.UUCP (pam pincha)
Organization: Boeing Computer Services AI Center, Seattle
Lines: 58
Summary: 

In article <814@psivax.UUCP> friesen@psivax.UUCP (Stanley Friesen) writes:
>In article <336@bcsaic.UUCP> pamp@bcsaic.UUCP (pam pincha) writes:
>>
>>I would also like to note that the claims have not been even slightly
>>accepted. The comments made about the specimens would be highly unlikely
>>given the unusual type of limestone they are found in. It is a very fine
>>grained micritic limestone. It has such an even surface that it makes
>>an excellant base for printing lithographic prints -- hence its common
>>name of lithostone. To do what Sir Hoyle(who has little experience in
>>micro-petrology) claims was done would be quite a feat indeed.
>
>	What exactly does Hoyle claim to have done?

Hoyle claims that the feather impressions were added later in a
manner similar to the Piltdown Hoax. The method he proposes is
a cement-like mixture.

>>I'd like to see some electron microscope work (AND some
>>micro-petrographic studies done first) these would show up differences
>>that would be much more difinitive.
>
>	Ditto!
>>
>>I'm not convinced that a cosmologist could tell the difference
>>between different limestone types that occur naturally - let alone
>>if cement had been used. 
>>
>	Hold it! Isn't cment essentially just crushed limestone in
>water?!?! If he is trying to claim that part of the specimen is in
>artificial cement he is on shaky ground! I doubt *I* could tell the
>difference between fine grain cement and micritic limestone, and I am
>more qualified in that area than Dr Hoyle.

There is a definite difference between crushed regular limestone
and micrite -- especially the micricrystalline quality of the
limestone discussed here. Remember micrite rarely has what could
br called a good granualr texture -- hence the microcrystalline
texture it's usually described as in the literature. Crushed cement
is not just limestone. It contains alumina,silica,iron oxide and
magnesia that haas been burned together in a kiln,then finely
pulverized. That is the only way it will react with water to form
the hard matrix. The limestone has to undergo a calcining process
(heating to high temperatures ,just below fusing, in order to
drive off the volatiles and/or oxidizing the material) in order
to change it to lime. Lime is the major reactant with water.
After all these changes the calcium carbonate would not be the
same structure or make up that a fine micritic ls would be. This
would show up uder a microscope. One would have to be a carbonate
petrologist to tell, but it is distinguishable. (Note I am basing
this on the fact that the limestone that these fossils are found
is an unusually distinctive limestone that would be very difficult
to fake. A detrital limestone would be difficult. But all descriptions
I've run across indicate that this limestone is nearly a pure micrite.
This means almost no allochems or detrital material in it. Have
you run across anything to the contrary?)(Carbonates are a favorite
field of mine. Any info would be appreciated.)

			P.M.Pincha-Wagener