"hrtbreak" writes:

"Richard I. Gibson" wrote in
message ...
hrtbreak wrote:

Would one expect to see carbonates fixed in rocks when the atmosphere
is rich in CO2? Doesn't the large-scale fixation of CO2 in our
atmosphere into rock formations require living organisms, like diatoms?

Not to criticize your other speculations, but diatoms secrete
siliceous tests, not carbonate. There are other critters, of
course, that DO turn CO2 into CO3 in rocks.
---clip---
See speculation qualifications below. My point was that if there were
carbonate-based rocks in large quantities, would there be all that free CO2
left in the atmosphere?

If Earth-life hadn't happened to accidentally stumble across the trick
of spewing out the nasty toxic poison waste-product gas called "oxygen,"
Earth's atmosphere would still have even _MORE_ CO2 in it than Mars's ---
and it took earth-life over a billion years for it to stumble across
_that_ particular trick!



-- Gordon D. Pusch

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