From: asa-owner@lists.calvin.edu
Date: Tue Dec 03 2002 - 14:07:02 EST
From: "D. F. Siemens, Jr." <dfsiemensjr@juno.com>
On Tue, 3 Dec 2002 09:44:29 -0600 "Darryl Maddox" <dpmaddox@arn.net>
writes:
> I think this is the wrong question. I think the correct question is
> not how
> fast corals grow but rather how fast do coral reefs accumulate.
>
> But to attempt to answer the question - as I understand it, we know
> how fast
> corals grow because some of them at least have daily growth rings
> and monthly
> and annual growth variations of some type so that as you come up
> through the
> geologic record we see more and more days per year. But keeping in
> mind the
> daily, monthly, and annular variations in growth pattern, if I were
> wanting
> to answer the question of how fast a coral grows I would not only
> measure
> the current growth rate of live corals but also measure the change
> in the
> size of the various species of fossil corals per unit of time -
> daily,
> monthly, and annual and continue doing this for enough of
> individuals of
> various species to get specie specific averages and standard
> deviations and
> see how much variation there is between various species, genera etc.
> I
> suspect this has already been done. But even if it has been done it
> is
> irrelevant to the question of how fast a reef builds because of the
> previously pointed out continuous interaction between the growth
> process of
> the live corals and the destruction/accumulation process of wave
> action,
> storms, and variations in sea level. How to answer the question of
> how fast
> coral reefs have accumulated in the past I leave to others because
> other
> than guessing it might be done somehow with isotope geochemistry or
> some of
> the newer radioactive decay schemes I have no idea how to do it
> except in
> the unusual case where you might have the base of a coral on a well
> established time horizon and the top sticking slightly through
> another well
> established time horizon.
>
> <snip>
>
> Darryl
Oh, Darryl, don't you know that all geochronology is based on mistakes?
;-) As for growth rings, I recall an article in one of the YEC
publications that claimed that the bristle cone pines sometimes produced
two growth rings in a year. I figured that there had to be at least one
extra ring every other year (3 rings in 2 years) to fit the record in
living and dead trees. With all data subject to such manipulation and
misrepresentation, rational analysis is hopeless.
Dave
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