Bill,
I really don't have much time to respond, but I will see what I can do
in about half an hour before the responsibilities for getting the last
minute things done before vacation catch up with me. That also means I
will not be around to respond to anyone for about a week, since I am not
taking my computer to the Black Hills.
Bill thanks for posting your bibliography. It really helps to know
more about a person than what you sometimes get in their posts. The
rest of you should be aware that (since I know something about coal), I
responded to Bill once and if you lost that post you can read it in the
archives at url:http://www.calvin.edu/archive/asa/200206/0081.html
Bill responded to me but since he responded three weeks later and since
I only read ASA via the archives, I missed his post at url:
http://www.calvin.edu/archive/asa/200206/0389.html until today. I would
urge anyone interested in the discussion to look at both of the previous
posts. Bill has done some good homework and responded to some of the
criticisms I had of his model. If all YEC folks had read the recent
GSA special publication on modern and ancient coal environments (as Bill
has) we would have more basis for discussion. For those of you who
don't know too much about me, my PhD thesis and a couple of publications
that came from this work (see
http://homepages.dordt.edu/~mahaffy/homepage/profact3.htm) dealt with
intraseam palynology of two major midcontinent Pennsylvanian age coals.
One of these the Herrin No. 6 has a persistent clastic (mud or clay
parting with usually no coal in it) band in the bottom third of the seam
called the "blue band".
First Bill you seemed to have been be frustrated that no one was taking
up your discussion of coal (although since then both Morton and Campbell
responded). But Bill that shouldn't really surprise you. Remember you
are approaching coal from a YEC (flood model perspective). You must
realize that is a different paradigm than is shared by most on this
list. Although I like to see Christians trying different paradigms and
have sometimes been critical of folks on this list that tend to be
automatically very harsh on ID or YEC, I would need to be shown that the
flood model offered a better model for explaining coal deposition before
I would use your paradigm. Bear in mind that there are also not that
many soft rock geology types on this list that have studied coal. Most
of them assume the standard geological interpretation is right. You
really can't expect them to comment when they may never have looked at
coal seams in the field or even had geology courses. You have however,
pointed out some of the areas where coal sedimentary structures while
they fit with current models, do not on the surface fit real well. The
main ones you are currently talking about are the sharp transition
between coal and shale and lack of evidence of vegetation material
causing an irregular surface at the top of a coal seam on in a clastic
band like the blue band.
Let me ask a few questions so we can at least see how your model would
apply to some of the coals (Herrin and Springfield Coal) that I know
well.
In my first point of my last post, I asked, "Is the model of rafted peat
any better for explaining a sharp contact between coal and the clastic
layers?" And you responded with Steve Austin's model of vegetation
raining down organics and then as the water rose and the organic mat
moved landward getting clastic sedimentation from the open water.
Thanks for explaining the model but I see a few problems. Why would
this result in a sharp transition and not a gradual transition at the
top of the coal? Mind you sometimes there are more clastics in the
upper part of coal seams but not that much. Also this ought to
generally result in a dark shale immediately above the coal. While it
differs in different areas, both the Herrin and Springfield Coals and a
number of others have a grey (low in organics) non-marine shale right
above the coal and then a marine back shale above that. It seems that
Austin's model should have these reversed.
You are right that the widespread "blue-band", which is apparently NOT a
volcanic ash is quite an amazing feature. If you believe Wanless (and
you should), you can trace it in the Herrin for maybe several hundred
miles and it is usually the same thickness and at about the same
position in the coal seam [I think it is in his 1961 reference below,
but I would need to check to be sure]. And yes the contacts at the top
and bottom are usually sharp and planar, but as Dave Campbell noted in a
recent post the compression associated with coalification should
decrease the irregularity of the surfaces. I am not sure how Austin's
model explains this widespread clastic pulse. Can you explain it when
you have a vegetation mat floating on top? Remember it is also low in
organics (not that black), but you could always I suppose postulate some
oxidation of the organics. For what it is worth, I showed in my thesis
that the miospores of this band are closer to the coal above rather than
below this "blue band" And then to complicate matters Johnson (1972)
showed that it seems to thicken as you approach the contemporaneous
Walshville Channel.
Which brings me to another point. In the Herrin and in the Springfield
there are large channel structures that have been mapped and studied
well enough to be quite sure that they were active structures at the
time of deposition of the coal. One article on them is by Deb Willard in
the GSA spec paper (#286) on coal forming environments that you have,
although a latter paper of her's with others in 1995 is more
comprehensive. How can the channel sediments and their associated
vegetation be made to fit with the floating vegetation model? While
obviously the authors did not consider the floating mat model, that
model, if it is going to compete, must be able to give a reasonable
explanation for the sedimentation and vegetation patterns. And just to
complicate matters Peppers has looked at loads of channel samples (of
the whole seam) and has shown (Peppers in Phillips et al., 1985) in the
Herrin Lycospora (the spore of one of the dominant lycopods) increasing
from 65% to 85% near the channel. The same paper shows that a similar
but more pronounced difference is seem in the samples close to the
channel in the Springfield Coal. So Bill I really need to know how the
vegetation model would try (I would not expect it to have worked it out
as well yet) to explain the features that are interpreted as a
contemporaneous paleochannel and the associated change in spores in the
coal.
And then there are the nasty problems like how do you explain
biostratigraphy to work with your model in the numerous coals in the
Illinois Basin (Peppers, 1964 and 1970). Some miospores are only found
in certain coals and their ranges can and are used for the
biostratigraphy of the coal. That for me was one of the main reasons
why I find the flood model just unusable You could ask the same question
of course for invertebrates in the fossil record. I don't think
differential settling can explain the differences in miospores all
extracted from coals.
Also not all coals are wide and flat in the Illinois Basin. Some have
patterns that look like they fill lows in the topography. So you have
to be careful that your model is not formed just from one of these
widespread coals (Austin studied one of the widespread ones).
Bill, I am really not trying to be hard on you, but the model can not be
used to explain just one sedimentary feature. It has to work fairly
well for explaining most of what you see in order to be useful. Even if
you can explain how some of these could be explained in a broad way, it
would help me appreciate the model. To overturn the paradigm, you must
not only show a few areas where current models lack some explanatory
power, you must show that the new paradigm work preferably better in
most areas. You know I appreciate the reading you have done and when I
finally read it, I appreciated your specific responses to the questions
I raised in my last post.
And now I have spent most of the afternoon, in between running around
working on this. But at least I think I showed that I have considered
and will consider your model but currently do not see it having enough
explanatory power.
----- References -----
Johnson, D.O., 1972. Stratigraphic analysis of the interval between the
Herrin (No. 6) Coal and the Piasa Limestone in southwestern Illinois.
Ph.D. Thesis (unpublished) University of Illinois at Urbana-Champaign,
105 p.
Mahaffy, J.F., 1999. Vegetational patterns in the Herrin and Springfield
coals (Middle Pennsylvanian of Illinois), based on miospore profiles
with comparison to coal-ball patterns. Ph.D. Thesis University of
Illinois at Urbana-Champaign, 211 p.
Peppers, R.A., 1964. Spores in strata of late Pennsylvanian cyclothems
in the Illinois Basin. Ill. Geol. Surv. Bull. 90 89p.
Peppers, R.A., 1970. Correlation and palynology of coals in the
Carbondale and Spoon Formation (Pennsylvanian) of the northeastern part
of Illinois Basin. Ill. Geol. Surv. Bull. 93 173p.
Phillips, T.L., Peppers, R., and DiMichele, W., 1985. Stratigraphic
and interregional changes in Pennsylvanian coal-swamp vegetation:
Environmental Inferences. Int. J. Coal Geol., 5:43-109.
Willard, D.A, 1993, Vegetational patterns in the Springfield Coal
(Middle Pennsylvanian, Illinois Basin): Comparison of miospore and
coal-ball records. In: Cobb, J.C., and Cecil C.B., (Editors), Modern
and ancient Coal forming Environments. Geol. Soc. Am. Spec. Pap.
286:139-152.
Willard, D.A., DiMichele, W.A., Eggert, D.L., Hower, J.C., Rexroad,
C.B., and Scott, A.C., 1995. Paleoecology of the Springfield Coal
Member (Desmoinesian, Illinois Basin) near the Leslie Cemetery
paleochannel, southwestern Indiana. Int. J. Coal Geol. 27:59-98.
Wanless, H.R., 1961. Depositional basins of some widespread
Pennsylvanian coal beds in the United States. Nova Scotia Dept. Mines.
Origin and Constitution of Coal, 1956. p. 95-128.
-- James and Florence Mahaffy 712 722-0381 (Home) 227 S. Main St. 712 722-6279 (Office) Sioux Center, IA 51250
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