Coal, Cohen and Okefenokee swamp

James Mahaffy (
Tue, 31 Aug 1999 21:44:40 -0500

On Mon, 30 Aug 1999 21:13:11 -0500 James Mahaffy <>

>Cohen has perhaps done
>more work than anyone on modern peat and much of it has been on the peat
>of the Okefenokee. .......and Richard Winston's work comparing coal
petrography to
>fossilized peat in coal balls. That would be a very direct comparison.
> Thanks, James. Could you give us some specific citations, or should we
> just search on our own.
> Bill

Sure. And maybe I was a bit strong, but probably the only reason the
Okefenokee swamp comes up in a discussion of coal formation, is because
of Cohen's work on the swamp. Not sure it will still answer the question
you and Glenn are having about if it is or is not a good model for
modern swamps. But one of the earlier references that should give you a
good feel for the swamp is: Cohen, A. D. 1975. Peats from the
Okefenokee Swamp-Marsh Complex. Geoscience and Man, 11:123-131. For a
long time cohen seemed to just expand on this study but more recently he
has been working with some coal petrographer and you might check out -
Cohen, A.D., and Stack, E.M., 1996. Some observations regarding the
potential effects of doming of tropical peat deposits on the composition
of coal beds. Int. J. Coal Geol., 29:39-65. My annotation on the last
reference is as follows: "September 28, 1996 Interesting article they
look at a lot of the modern and ancient peat-forming environment. They
warn that there may be a number of factors that affect the formation of
the type of peat and that a single coal may be just one or the other
type of coal. They suggest that the domed coals are thicker and more
uniform. That would fit with Carboniferous coals. But they also
suggest that coals should usually show a brightening up sequence and the
British Coals (with the dull upper beds of densospores) are usually a
dulling up sequence. I think there is a suggestion by Smith that there
is less mineral matter in the dull coal. But I think this may well be
due to the different plant that grows in this different habitat. They
like Winston's 1990 publication (I should check to see if I have it) and
quote DiMichele and Phillips 1994 especially about the formation of

Another good technical question is to ask what the coal petrographers
suggest causes the fine clastic laminations in Pennsylvanian coals. I
don't recall what their explanation is but I know that sometimes the
larger clastic bands (partings) like the "Blue Band" in the Herrin were
for a long time difficult to explain. Work by Johnson (unpulished Phd
thesis) shows a great thickening as one approaches the paleochannel. I
suppose that could in itself could appear rapidly - but am not too sure
how it would work if you have most of the Herrin peat floating on the
top of the swamp in a young earth model. But I would like to see a young
earther show me how they would model it. Maybe Austin could since he
worked on a coal a bit above it in Indiania if I am not mistaken.

But then most of this group probably doesn't care that much about coal
so Bill if you or anyone has any questions for me maybe we should do it
by private e-mail. But you asked for some references as did someone
else so I thought I would post this to the list.

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