> 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 has been a significant literature that has attempted to find
evidences of a reducing atmosphere in the data obtained from BIFs,
from uraninite and from various other sources. None of these are now
acceptable interpretations.
I wrote of the reducing atmosphere hypothesis:
> "There is no evidence which 'establishes' this, Kevin."
Kevin wrote back:
> 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.
Because of the tremendous number of posts, I was reading selectively.
I am unable to read the excerpts from Mason - and would appreciate
receiving this again. I am sufficiently confident of what I am
saying to stick with the comment I made above.
I wrote:
> "This is 'theory' pretending to be data."
Keving replied:
> 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.
Maybe I do need such a refresher course. However, I am of the
opinion that it is not infrequent for people to confuse theory with
data. Note that I did not say "theory can exist in the absence of
data", but that this is a case where 'theory' is pretending to be
data. I suppose the test of this argument is to be explicit as to
what data supports the existence of a reducing atmosphere on earth.
The existence of reducing atmospheres in the outer planets is data,
but it can only be regarded as data supporting this particular thesis
by the imposition of an interpretative model of planetary origins -
which itself needs to be tested and validated. More importantly,
where are the geological evidences for a reducing atmosphere on
Earth?
Best regards,
David J. Tyler.