Re: coal again!(1)

Jonathan Clarke (
Sat, 27 Mar 1999 17:15:36 +1100

Hi Bill

Bill Payne wrote:

> I apologize for the length of this post.

Because of this length I will respond in two parts (1) your email and (2)
Steve Austin's abstract. I too apologise for the length.

> 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.

Why? All it is consistent with is an absence of preservation of large tree
stumps in the coal. This might because they were never there, or are not
easy to recognise. Closer examination should lead you to which one is more

> 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).

Obviously I need to read the dreaded Gastaldo! Where is this paper found? I
am not sure of the relevance of this citation though. My understanding of
the roots of vegetation growing in waterlogged ground is that they are
commonly (though not always) shallow. The citation you give seems consistent
to me with that. What is your point?

> >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.

The coals I have seen and most of those I read about have splits and dirt
bands. They also have zones where there is coaly sediment, shale, sandstone
etc., with coal debris in it, but surrounded by clastic sediment. To me that
indicates a complex interplay of autochthonous and allochthonous processes.
They might not exist in the coals you are familiar with of course. You know
them better than I.

> 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.

Which coals have you examined? What features lead you to think you are
mistaken? How confident are you in your own observations? Last year you
hadn't recognised rootlet horizons, one of the simplest and most important
things to look for in any succession of coaly sediments. I don't want to
sound too critical here, but what else are you missing? Other geologists had
known about roots etc. beneath Carboniferous coals for over 100 years.

> 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.

Unless they others are all idiots, the weight of opinion should always count
for something. Of course, you might be right for individual seams. Maybe
you are right about the seams you are talking about. There is nothing wrong
with some coals being transported, if you read the coal literature (and I
have posted this before about the Permian coals of Australia) there is a
diversity of coal forming environments and processes.

> >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.

Thank you for being so honest. So let me ask you another question. If it
were not for this hermeneutic, would you really feel pushed towards the YEC
position? Or would you be comfortable with the geological evidence for an
old earth?

If you don't want to take Genesis 1-3 figuratively, that is fine, so long as
you acknowledge that the Church fathers and the Jewish rabbis thought
differently. Gordon Brown has pointed out the most likely way Jude 14 was
meant to be taken.

We have to be careful about what we mean by the word "literal". The literal
meaning is the actual meaning, the meaning that the author intended. What is
the actual meaning of the book of Revelation? The parable of the net? The
Song of Solomon? However, most people use "literal" to mean "historical"
which may be quite different from the meaning intended by the author.

> >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.

Data is data, regardless of the age of reference. However it would be nice
to have some more recent observations to collaborate this early work. I am
interested so see that you haven't followed the issue further yourself. The
only information you cite other than your own observations is this ancient

> Why do you say this, because the mat would have to be so big?

To my understanding, a floating vegetation mat would have to be very pure to
produce coal. Such peat mats exist in some lakes. These are typically very
low energy environments. They have to be, for the mats to survive as they are
very weak. Even so, the mat often breaks up and forms floating islands.
Shades of Perelandra! A 15,000 square mile peat mat would require a very
large and very protected lake. Not impossible, but unlikely.

The other interpretation is that it represents a catastrophic collection of
floating plant debris. I have seen rafts of this type on rivers, shorelines
and in the geological record.. But they don't have the density of organic
mater to form coal. Such agglomerates of plant debris are also quite weak
structurally, and it is hard to imagine a raft of that size forming in a
turbulent environment. They could survive in a low energy environment. But
when they sink their relatively low organic content would not result in them
forming coal, only a wood rich sediment.

> >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?

I like the following section, because in it you mention specifics. You need
to be more specific though. Which coals are you referring to in it?

> 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).

I agree with your first statement. Contacts are usually sharp. This is true
from my experience of Eocene, Miocene, Triassic, and Permian coals. I would
qualify your second statement. Absence of rootlets in the underlying stratum
is good (though not conclusive) evidence for a coal being allochthonous
deposit. In my experience the nature of the underlying lithology is not
significant. I have seen transported plan material overlying both sandstone
and shale. I have also seen rootlets in sandstone as well in shale. However
you should remember blurring of boundaries in soils is largely due to
bioturbation by soil invertebrates. I would think these are rare in
waterlogged soil beneath peat. The environment is too hostile -water
saturated, low oxygen, and low pH.

> 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 don't see why this is a problem. The rootlets you see are the last ones to
have formed. This is true whether you are looking at a modern soil, a
historically buried one, or an ancient ones in the geological record. When
you look at a soil in a the side of a ditch you only see the roots currently
present (and perhaps a few relicts). These will only be a small proportion
of all the roots that have infiltrated the soil. Also remember the surface of
peat accretes upwards. So there is not an infinite amounts of time for roots
to penetrate into the underlying substratum. Eventually the root zone will
be entirely within the peat.

> 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.

If only small rootlets are preserved, then the plants growing there had only
small roots. If large roots are preserved, then plants with large roots are
preserved. We must go by what the evidence says. I can't see the problem
here. Peat can form in many ways. Dense swamp forest, open swamp forest,
stunted boggy heaths, mossy bogs, shallow lakes from algae, yes, even
floating vegetation.

> 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.

That is fine. Some peat bogs have stunted trees, some have large trees,
some have no trees. Some stunted tress may be short but quite thick. Once
again, it varies according to the evidence from each coal deposit.

> 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.

That is a good point, however, if the hole is filled by peat, it would be
hard to see. It would only clearly show up if the overlying sediment was
distinctive in character.

> 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.

There is layering and layering. Layering formed by physical sedimentary
processes looks very different to that formed by compression. The coal thin
sections I have seen are layered. The layers are defined by compressed plant
material, such as cuticle, not by transported sediments. What is the nature
of the laminae that you have seen, are they mainly the result of traction
currents, or compression of compressive material? Have you seen them in thin

> 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,

That sounds fair enough. But please define "intensely" and "deeply
rooted". The literature would suggest that such horizons are common. Is the
"little or no interbedded material" in the substrate or in the coal? Partial
preservation of lamination in the underlying material simply means that there
was insufficient root activity to destroy it. All the clastic partings in
the coal means that there were clastic influxes. That is why coals vary so
much in their content mineral matter, some have common influxes of
terrigenous matter, some did not.

> 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.

As I mentioned, the lack of a soil fauna in peat would minimise the mixing
between the peat and the underlying material. I have commonly seen sharp
contacts between modern peats and underlying substrates. Whether any stumps
are left standing in the top of the coal depends on how energetic the
overlying event is. If the subsequent sediments were laid down in energetic
environments few stumps would be left standing. Stumps do sometimes occur at
the top of seams, and again, I have seen them in the Eocene of WA.

> 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.

So what is the problem? Four feet (1.2 m in real measurements) suggests that
there were some deeply rooted plants in the overlying seam. I have no
problem with that, do you? Os this "deeply rooted" enough to meet your

> >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?

Not trying to steamroller anybody, just trying to help you see your
methodology and the task ahead of you. If you believe the Pittsburgh seam is
transported and want to demonstrate it, good luck. I still don't know
enough about this seam to have an opinion. I am sceptical though, based on
what I know about coals and what I have read about Carboniferous ones.

If you are successful then want to go and say that most coals everywhere are
the result of such a mat, then you have a big job ahead of you. You will
have to define general criteria which allow people to recognise such mats (as
opposed to peat swamps). A coal facies model, in other words. You would
then have to demonstrate how your model works better than other models for a
wide range of different coals. this will have to be done in the literature
and defended by discussion. Even if you have a case with the Pittsburgh
seam, one unusual deposit does not a rule make. A friend of mine did a PhD
on the Skillogolee Dolomite in South Australia, and presented good evidence
that it was deposited in a marginal marine lagoon or lacustrine environment
from waters with an unusual composition. She did not try and say that all,
or even most carbonates in the geological record are the result of such
processes. It is a matter of the evidence.

Three for three? You haven't convinced me about the Pittsburgh yet (and I am
trying to keep an open mind), Gastaldo I have not read, and so reserve
judgement, and Joggins isn't even in yet. Don't forget the rootlets either.

> God bless,
> Bill

You too