"It constrains the 'reducing atmosphere' model - pushing it back yet further
into the past."
As far as I know, no one has ever seriously suggested that a reducing
atmosphere lasted much beyond 4 billion years, whereas there has always been
evidence (as Art point out) that by 3.5 billion years ago the atmosphere was
neutral. The evidence that Art reports in the paper he cited pushes this
back to 3.8 billion years, but the informatin Mason provides confirms that
by that time the atmosphere was neutral or at least only mildly reducing.
Sounds to me like, rather than contradicting Mason, Art's cited paper
confirms Mason.
"There is no evidence which 'establishes' this, Kevin."
Of course there is. Reread those excerpts from Mason that I posted some
days back; or better yet get a copy of Mason and read it for yourself.
"This is 'theory' pretending to be data."
Obviously you need a refresher course on the basic philosophy of science. I
don't have time to go into details now, but very briefly, theory can never
"pretend" to be data, because theory cannot exist in the absence of data.
If you have a theory, then you have data to support it.
Besides, Mason is not describing theory; he is describing what we can say
the atmosphere of the primeval earth was like based on the available
evidence.
"Further comment from me, on the paper cited by Art, is at:
http://www.pages.org/bcs/Bcs074.html"
I plan to look at that page _very_ carefully. Thanks.
Kevin L. O'Brien