On Fri, 23 Feb 2001 17:34:40 -0500 "bivalve"
<bivalve@mail.davidson.alumlink.com> writes:
> >The the swamp model for the origin of coal fails to explain the
> >features of banded coals of the eastern US. The alternate model,
> >which more readily fits the data, is that coal seams are the result
> >of floating mats of organic debris which settled out of water.
>
> I think there are probably many additional possible explanations, so
> a weakness in a swamp model does not necessarily mean that the mat
> model is better.
But in this case I would say that the weaknesses in the swamp model are
fatal, unless you can quantify some of the "many additional possible
explanations."
> On the other hand, it is perfectly possible that a
> poorly drained swampland would have an accumulation of floating
> debris or, perhaps more importantly, sunken debris. I have seen
> extensive accumulations of soggy wood in modern bays, for example.
Soggy wood in a bay would be an example of a transported organic mat. A
poorly-drained swampland would have to cover thousands of square miles
and have roots so shallow that they didn't penetrate the organic mat
(which would put them above the mat floating in water). I critiqued a
paper by Robert Gastaldo, in which Bob went to extremes to make the point
that the Carboniferous trees were heavy, with deep roots, and therefore
not from floating mats. I did not agree even with his observations, much
less his conclusions. The critique may be referenced at:
http://www.calvin.edu/archive/asa/199804/0389.html
http://www.calvin.edu/archive/asa/199805/0030.html
http://www.calvin.edu/archive/asa/199805/0119.html
> I am somewhat familiar with a few lignite-rich deposits, but do not
> know details of the beds that particularly interest you. These
> typically have in-place stumps, roots, stray twigs, etc. and no
> abrupt boundaries.
We have lignite beds in south Alabama which I have seen, but it has been
too long for me to remember what they looked like. However, based upon
your description above, if these lignite beds were coalified I cannot
imagine that they would look like the bitumenous, banded, Carboniferous
coals of the eastern US. They were possibly post-flood swamp deposits.
> I do know that modern swampland trees typically have shallow root
> systems, so bioturbation by roots is less deep than in typical
> soils. Roots need plenty of oxygen, not stagnant water.
The GSA Special Paper 286 I referenced said the Indonesian swamp root
zones are 50 to 80 cm deep. I have seen axial root systems lying flat on
top of the underclay after the coal was removed. However, the adjacent,
still in-place coal seam did not show any evidence of vertical trunks
which should have been there had the roots been in situ and not
transported. Shallow root systems do not satisify the lack of
concurrence of the swamp model with the data (see my other post for a
list of observations that don't fit).
> (If you think there is anything of interest to the list, I have no
> objection to it being forwarded.)
I know interest in this subject is very limited and we have discussed
these things previously. Unless Jonathan, Steve or anyone else has
something interesting to offer, I suppose we can let this thread snap, or
they can contact us offline.
Thanks for your input.
Bill
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