Re: Roots in coal?

Wahoo! At last, someone who knows about coal, and likely knows more than
I do. Thank you, Glenn, for introducing us.

On Mon, 15 Dec 2003 23:03:44 -0700 "Kevin and Birgit Sharman"
<ksharman@pris.bc.ca> writes:

> We won't agree on this one if you have expectations like that. When
you are
> shown roots which look identical to ones that grow in place today, you
say
> there aren't enough of them. You specify (in an older post) "intensely
and
> deeply rooted underclays" as a criterion which will convince you of
in-situ
> coal formation. This allows you to reject these as not intensely
rooted
> enough.

I'll grant you, Kevin, that I'm a moving target (i.e., responding to
evidence), which is why I realized during my last post that definitive
evidence for in situ coal will probably have to come from within the coal
rather than from the underlying strata.

Having said that, I agree that the radiating roots in your last photos
are, as far as I can tell, "identical to ones that grow in place today."
The problem I have is that your photos show only _single-plant_ root
balls. If this level at the top of the sandstone is an ancient marsh,
then when those individual plants died other shrubs should have grown
next to them and left additional radiating roots, and so on until the
entire surface of the marsh was rooted from one side to the other. By
virtue of the fact that you show only single sets of radiating roots, you
are demonstrating that the peat formed faster than the shrubs grew, yet
the shrubs are supposedly the source, in your model, for the peat. I'm
assuming that you accept the standard rate for accumulation of peat in a
swamp at the rate of 1 to 2 mm per year. So for the time being I'll
stand by what I said, that this level beneath the coal is not intensely
rooted enough to form a peat mat from shrubs thick enough to prevent tree
roots from reaching through the shrub peat to the sand below the mat. (I
hope that makes sense)

> Remember that bituminous coal is a metamorphic rock. The coal proceeds
> through a stage known as gelification which obscures the original
textures.
> The coal precursors for these seams include large (up to 20 cm
diameter)
> trees, as evidenced by log impressions in an overlying channel
sandstone.
> Just as no macroscopic remnants of these logs are found in these coals,
no
> macroscopic evidence of roots is found either - they have been
coalified
> into (predominantly) vitrinite. These coals contain 50% to 60%
vitrinite.

Ah, this sounds like Loren's parable (another recent post here). You can
explain the evidence within your model and I can explain it within mine.
:-)

I have never heard bituminous coal referred to as metamorphic. It's a
sedimentary rock which has been coalified, and I can certainly see how
the term metamorphic bolsters your position, but I am not aware that
gelification obscures the original textures. In fact, I have seen the
texture of the original bark on faces of coal split along (parallel to)
the banding (bedding) surfaces. All sorts of textures (leaves, roots,
bark, spores and pollen) are found coalified, but uncompressed in coal
balls, which are included within coal seams.

Steve Austin studied >250 vertically oriented, polished blocks of
Kentucky No. 12 coal and concluded: "Vitrain, which comprises 10% by
volume of the coal, exists as thin, sheetlike masses, and as wide,
thin-walled, flattened cylinders with extraordinary, unbroken extent
lying parallel to bedding. Microscopic analysis shows that a vitrain
sheet is a single, mummified, structural unit of a plant. The size and
shape of vitrain, and its association with abundant miospores from
Lepidodendron and Lepidophloios, indicate that vitrain sheets int he
Kentucky No. 12 coal represent ruptured cortex shed or broken from the
outer upportive structure of aborescent lycopods." (from Depositional
environment of mummified bark sheets in the Kentucky No. 12 coal bed,
Abstracts with Programs, 1980. Geological Society of America, v 12)

> See above - you are making an unwarranted leap by saying that banded
> coals without roots imply transportation.

I don't see why you say that. To continue with Austin above: "It is
extrememly difficult to imagine how abundant, horizontally extenisve bark
sheets could remain intact in an intensely root-penetrated environment
such as a swamp. Instead, the bark must have been deposited in a
subaqueous environment below a floating vegetation mat. Mechanical
abrasion of floating lycopod trunks appears to have stripped off large,
waterlogged bark segments and cylinders which were deposited at the
bottom of the water mass where rooting was absent, and where the fine
interlamination of bark with macerated plant material and clay could be
preserved."
 
> However, roots in coal are documented in the literature. Stach's
Handbook
> of Coal Petrology (1982) has this to say: "Humic colloidal solutions or
gels
> form preferentially through oxidation of peat and brown coal in the
presence
> of abundant water, e.g. around roots whose surfaces have functioned
> as water-conducting channels and oxygen carriers in the peat. Thus,
> broad partings of eugelinite can be observed around the roots of
Sequoia
> stumps in the Cologne brown coal." (p. 239, 3rd edition).

I'd need to know more about this coal, but off the top of my head - at
some point the flood ended and real swamps did in fact collect peat which
is preserved today. We have "brown coal" or lignite deposits in south
Alabama, which incidentally look nothing like banded coal. I've had a
geologist tell me he can see how to get from peat to lignite, but not
from lignite to banded coal.
 
I saw your other post. I'll get to it tomorrow (hopefully).

Thanks Kevin,

Bill

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Received on Thu Dec 18 22:42:35 2003