On Mon, 22 Mar 1999 17:39:41 +1100 Jonathan Clarke
<jdac@alphalink.com.au> writes:
>However lack of numerous large roots can also suggest that there were
few
>large trees in that particular deposit (which is the point I have been
trying
>to make), and the peat forming vegetation was largely stunted, or small,
with
>very small roots.
At the construction site in Birmingham, AL, we've found several tree
trunks/stumps from one to two feet in diameter. These were unfortunately
found after blasting, they break out and were found in the rubble.
However, I have seen none in the exposed coal seams, which are exposed
over a total length of maybe 800 feet (four seams are exposed in one
highwall). What I've seen strikes me as being more consistent with a
floating mat.
>Also note that in swamps the roots of even large tress may not
penetrated deep into >the substratum, but spread horizontally at shallow
depths.
As I think I've pointed out before, Gastaldo says the axial stigmarian
root systems penetrate the substrate at 10 to 30 degrees from the
horizontal (or something like that - I can't lay my hands on his paper
right now).
>You seem to keep proposing these two as diametrically opposed
alternatives.
>Why? They are really end members on a spectrum, and you will find
examples
>of both. Most coals will fall somewhere between the two, with both
>transported and in situ components don't you think?
No. Can you think of a modern analog where an organic deposit is
partially transported and partially swamp? I suppose you might say a
river could flood and wash tree debris into a swamp, but that would not
match the features of coal seams I observe. I keep looking for coals
which display features that would indicate to me a swamp origin. When I
look at coals which are passionately believed by most Alabama geologists
to be of swamp origin, I see features which tell me they are mistaken.
And it is very, very difficult to engage them in meaningful dialogue.
There are really only two geologists (one, and probably both of them, are
agnostics) that I've met that know anything about coal that will discuss
the issue with me. I know two more geologists who are Christians (one a
YEC and one doesn't care) who agree with me that the organics were
transported.
>Why are you sympathetic to the YEC position? Because you believe that
the
>bulk of geological data (not just one coal seam) is better explained by
it
>(against the bulk of geologists in the last 200 years)? or because your
>Biblical hermeneutic favours it?
The latter. When I read "Enoch, the seventh from Adam ...." (Jude 14), I
understand God to be saying Adam was literally the first human, and there
were literally seven generations from Adam to Enoch. Given this, I tend
to think that the remaining generations were pretty much what we find in
the Bible, without any significant missing time. And if Adam was an
actual human living about 5,000 to 10,000 years ago, then it strains me
to think that the rest of the Genesis story is allegory, except for the
part about Adam being the first man. I just feel more comfortable
believing that there are explanations for what I don't understand rather
than allegorizing Scripture that seems (in light of Jude 14) to have been
intended to be taken literally.
>What is it that strains your credulity? That the Pittsburgh coal seam
might be in situ or >that all coals might be in situ?
No no, just the Pittsburgh and all the others that I have ever seen. Not
the ones that I haven't seen (yet). :-)
>Are there any references on the Pittsburgh coal more up to date than
1894? I
>am some distance from the nearest georef CD and can't find out what is
>available. We have learned a lot about coal facies and palaeoecology
in the
>last 105 years.
I'm sure that there are. If there is a student out there looking for a
subject to research, this would be a good one. The objective would be to
compare the features of the Pittsburgh to a modern swamp, and see if
there is a fit. I wasn't very concerned about the age of the reference
because the description matches what I have observed locally.
>The description that Glenn quotes sounds hard to fit into my mental
image of a >floating mat, but maybe that is a lack of imagination on my
part!
Why do you say this, because the mat would have to be so big?
>More germane is the question as to what observations would be
>required to falsify the model in your mind?
[snip]
>So, again please, what evidence would lead you to abandon your floating
mat
>model?
Coal seams generally have a razor-sharp contact with the underlying clay,
shale or sandstone. (Those underlain by sandstone generally don't have
rootlets and would likely be classified by most geologists as
transported). The rootlets, where they are found, are individually
recognizable. If this had been a swamp for thousands of years, the root
zone would have no discernable interbedding of very fine sand and shale
because the roots would have destroyed the interbeds, and I would expect
that the contact between organics and soil would be gradational due,
again, to the roots that would have lived and died in the soil. I asked
one geologist about this on a field trip, and he replied in a rather
agitated tone, "I don't know, maybe they rotted!" I didn't press him,
but I'm wondering, why would the roots rot and the organics above the
roots be preserved? And, why would the tiny rootlets be preserved but
the larger Stigmarian axial roots, from which the rootlets radiate, not
be preserved? Incidentally, I've only seen the Stigmarian axial root
systems in the rubble at the site in Birmingham. Directly beneath the
coals there, I've only seen rootlets which seem to be oriented
vertically, but no axials.
Also, the trees which formed the coal were not stunted and were not
mosses, at least not according to Bob Gastaldo, and not according to what
I understand James Mahaffe to have said. The tree stumps and trunks
which have been found associated with coals were certainly not from small
trees. If these coals were formed from the remains of large trees, and
if these trees were buried in situ, then their stumps should have
disturbed the organic mat in some way. I would expect to see the stumps
from the last generation of trees that were growing when the swamp was
flooded and buried by mud, and I would expect to see these stumps in the
coal, or, if they were uprooted, then I would expect to see the pothole
left when the stump and root ball were pulled out, which should now be
filled with the overlying sediment. I have seen stumps and tree trunks
above and below coal seams, but never in the coal, and I don't recall
ever seeing a coal seam with a "pothole" interrupting the continuity of
the seam. It looks like the stumps and trunks were floating in water and
settled out.
If the coal seam was an organic mat supporting swamp vegetation, I would
expect to see no fine laminations and interbeds of impurities
horizontally in the coal. Thin bedding is usually an indication of
sedimentation, unless it occurs in a coal seam, and then it's said to be
the result of compression. I don't buy that.
In summary, to falsify the floating mat model, I would like to see
intensely and deeply rooted underclays with little or no interbedded
structure remaining, a gradational contact between the underclay and
coal, roots connecting to the last generation of stumps in the swamp, and
the last generation of stumps still standing in the coal where they grew.
Having recently seen rootlets as deep at four feet below a coal seam, I
do not think it reasonable to suggest that the roots were shallow and
horizontal.
>Also, could you remind me in which of last year's posts did you outline
your model?
You're very kind, Jonathan, but it's not my model. Steve Austin laid the
foundation, I'm just Steve's bulldog. :-) I had posted Steve's abstract
Sept 25, 1997 to the ACG list. Here it is again:
***************
Environment of the Kentucky No. 12 Coal Bed (Middle Pennsylvanian) of
Western Kentucky, with Special Reference to the Origin of Coal
Lithotypes" - A Thesis in Geology by Steven Arthur Austin. Submitted in
Partial Fulfillment of the Requirements for the Degree of Doctor of
Philosophy, August, 1979.
ABSTRACT
The KY No. 12 coal bed (upper Desmoinesian) is a high volatile B
bituminous, high mineral, and high sulfur coal occurring within the
Providence Limestone Member at the base of the Sturgis Formation in
western KY. The coal bed was studied stratigraphically,
petrographically, mineralogically, and palynologically in order to
decipher the environment of deposition and the origin of coal
lithotypes.
In Hopkins, Muhlenberg, and part of Ohio Counties, the No. 12 coal
contains 8 thin carbonaceous shale partings (6 of which extended over an
area exceeding 1,500 sq km), 4 thin bony coal bands, and at lease 1
widespread fusain band. Partings define chronostratigraphic horizons,
divide the coal bed into benches, demonstrate the facies relationship of
the coal with the marine roof strata, and indicate that the coal was
deposited on a north-dipping surface in response to marine
transgression. The thickest coal accumulated on the highest elevations.
Partings are marine in origin because they contain marine fossils,
connect to marine roof strata, have a high ratio of illite to kaolinite,
and grade southward (upslope) into bony coal and fusain clast
conglomerate. Vitrain, "pseudovitrinite," and clay are more abundant in
the thinner, more marine-influenced coal to the north, whereas clarain,
"normal vitrinite," and liptinite are more common in the thicker, less
marine-influenced coal to the south. Some benches have distinctive
composition which can be recognized over wide areas. A statistical test
of maceral associations generally supports published concepts of the
origin of macerals. Maceral analyses of thin lithotype bands indicate
that vitran, clarain, bony coal, and carbonaceous shale form a
compositional series which can be described by quadratic equations.
Miospores of arborescent lycopods appear to be especially common in the
more marine influenced coal.
Although the coastal plain swamp environment provides a possible modern
analog for the No. 12 coal bed, it fails to explain several important
characteristics of the coal: (1) the mechanism for emplacement of thin
and widespread marine shale partings, (2) the lack of rooting of
lithotypes, (3) the abrupt succession of bright lithotypes and miospores
of arborescent plants just above partings, and (4) the unusual
intertonguing of coal with marine roof strata. These problems are best
resolved if the coal was deposited below an extensive floating mat. An
environment ideal for the production of a floating mat is indicated by
the stratigraphic data. Carbonaceous shale partings, bony coal bands,
and fusain clast conglomerate appear to have been deposited below the
mat by short-lived density currents generated by turbulent water in
marine areas marginal to the mat. Clarain, the most abundant lithotype,
was produced in quiet, shallower water generally removed from the margin
of the mat. Vitrain, which is common near intertonguing marine rocks,
appears to have formed primarily at the margin of the mat where lycopods
were dominant, and where currents and waves were stronger.
************
If you're interested in learning more, Austin's ICR video "Mt. St. Helens
- Explosive Evidence for Catastrophe" better illustrates the model.
>However there are a lot of studies, some very detailed, which indicate
that >Carboniferous coals of the northern hemisphere are predominantly in
situ. For the >sake of argument, even if the floating mat model is
applicable for the Pittsburgh coal, >this would have to be demonstrated
for quite a few deposits before you could argue >that it is generally
applicable. There are more Carboniferous coals that just the
>Pittsburgh seam and there is more to coal geology than the
Carboniferous.
Are you trying to steamroller me, my friend? :-)) Let's see how the
discussion goes on Joggins when Steven Schimmrich gets back. If I can
survive that one with my head still on my shoulders, I'll be three for
three (Pittsburgh, Gastaldo, and Joggins). How many will it take to
drain the swamp, old buddy?
God bless,
Bill
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