Re: [asa] Polonium Halos

>
> I know that this has been answered before on this forum, but I didn't save
> it. What is the fallacy in the YEC argument about polonium halos? Someone
> in the Sunday School class that I attend has forwarded an e-mail to the
> class from some YEC organization entitled "Polonium Halos: Unrefuted
> Evidence for Earth's Instant Creation!", and so I would be interested to
> know if there is a simple way to explain what is wrong with the argument
> besides that it comes from a source that is not credible.

http://www.csun.edu/~vcgeo005/revised8.htm deals with some of the technical
geological evidence.

The basic problem is that Gentry is a physicist with no particular geologic
background and so has no competence to support his claim that these are
primordial unmodified rocks. Not only (as the article points out) is the
occurrence of the halos very localized, in specific geologic settings and
not in all granite, but it is in uranium-rich granite that clearly shows,
through cross-cutting relationships and mineralogy, that it is younger than
other rocks. Gentry would have to endorse an Omphalos-like scenario of God
creating the rocks with evidence of history in place, thereby contradicting
his claim that they show evidence of no history.

I saw a bit of video by Gentry supporters claiming that several other
features of granite fit with his scenario and are unexplained by
conventional geologic ideas. As these features are explained by
conventional geologic ideas, those responsible for the claims (I don't know
if Gentry himself makes these claims) are either lying about conventional
geology or lying about having checked conventional geology. They could
claim to have a better explanation (though they need to be honest about
their criteria for "better"), but to claim that conventional geology is
mystified is untrue.

Another problem is that, for Gentry's argument to hold, radiometric dating
must be valid. He would actually prove that granite formed very quickly
very long ago if he were consistent. In order to show that a halo is
actually a polonium halo, and to show that polonium should have all decayed
before the granite could form conventionally, the laws of radiometric decay
must not have changed since the halo formed. In order to show that the halo
has anything to do with the formation of the rock, it is necessary to be
able to rule out later contamination or modification. If the laws of
radiometric decay have not changed, and contamination and alteration can be
ruled out, then radiometric dating is valid.

There's also a problem with the assumption that, in a conventional geologic
model, the polonium had to be present in the initial melt and would have all
decayed away by the time of crystallization of the granite. Since polonium
is continually produced by radioactive decay of longer-lived isotopes, there
would be a little Po being formed as long as crystallization occurred. The
above article claims that the halo-rich granites were formed through
modification of existing rock, rather than crystallizing directly from melt,
so the formation time was not overly long. I'm not much of an igneous
expert myself, so I can only say that there was a big fight about cooling
magma versus replacement origin of granite about 50 years ago or so, and I
would not be surprised if it in part reflected some granites being
replacement and some being cooled magma.

> --
> Dr. David Campbell
> 425 Scientific Collections
> University of Alabama
> "I think of my happy condition, surrounded by acres of clams"

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Received on Mon Jun 19 12:56:37 2006