Re: Whimpy Roots

On Thu, 4 Mar 2004 23:50:08 -0700 "Kevin Sharman" <ksharman@pris.bc.ca>
writes:

> Yes, preservation would be favored by keeping them underwater or at the
> water surface. They would not need to above the water table by much.
> Intense rooting would be expected to destroy them, but less intense
rooting
> would not.

That's a very precise water level you require to preserve partings from
eroding, and if there is any uneven topography the highs will be
exposed/eroded or the lows will be under water and the pioneering
vegetation won't take hold. "Less intense rooting" from pioneering
vegetation might not bioturbate the thin partings, but a single
generation of less intense rooting will not produce enough vegetation to
support the mat and prevent further root bioturbation. In the absence of
a modern analog, which I've asked for before and you have yet to offer,
you have too many conditions to make this a workable solution.

> >Will you agree that grass, shrubs and trees growing in swamps
> > do have roots that sink into and bioturbate their substrate?
>
> Yes, they can grow into the substrate. Do they have to bioturbate it?
I
> say no - my photo of roots in the parting has at least two possible
> explanations. One, your "stand up roots vertically in a turbidity
current"
> explanation, and my "in situ growth" explanation, with evidence of no
> extensive bioturbation.

No, Kevin, there is a third possibility which I have offered several
times: an opportunistic growth spurt, followed by flooding and
deposition from a floating mat. This would explain the vertical roots
and the lack of bioturbation. Continued growth in situ will certainly
result in bioturbation by the time enough vegetation is piled up to
support the tree roots and keep them out of the parting.

> There are many examples of floors of coal seams with tree stumps having
> roots spreading horizontally. These roots do not have to penetrate the
> substrate to grow, and they do not need to be supported by a layer of
> pioneering vegetation. The top surface of thin inseam partings is
usually
> not exposed for any great area, but I would not be surprised if roots
> radiating horizontally from stumps were found on the top of some of
these.
> I know you will say that these are transported stumps in growth
position,
> but these stump horizons do not have mostly prostrate logs with the odd
> stump in growth position, which is what one sees when this material is
> transported.

Pennsylvanian roots are often Stigmarian axial roots, which look similar
to a bottle brush. If the central axial root grows parallel to the
surface then the radial rootlets will be perpendicular to and penetrate
the parting. You can't grow these tree roots on top of a parting without
penetrating the parting. Also, the weight of the tree would compress the
soft mud/peat and cause a depression beneath the stump, squeezing the
parting out from beneath the tree stump. Furthermore, if these were in
situ swamps, why aren't the tree stumps ubiquitous? Why do we only find
the occasional tree stump in growth position? And if the stump horizons
do NOT have mostly prostrate logs, then why not? Where did all of the
logs from the stumps go?

> Yes, this is a simple explanation, but you are not addressing some
problems
> with this. How can a thin parting avoid being squished by falling
vegetation?
> I have never seen partings with soft sediment deformation from
> the overlying plants that would land on them in your scenario. Where
are
> the randomly oriented pieces of vegetation that would be jabbed into
the top
> surface of a very soft mud?

When you were arguing against my detrital vertical roots, you said we
would expect to see horizontal to sub-horizontal roots if they floated
in. Now you are calling on randomly-oriented pieces of vegetation to be
jabbed into the mud. You can't have it both ways, Kevin. Also, if one
of your in situ trees falls over, wouldn't those horizontal roots be
pushed into the mud on one side (the side beneath where the tree fell),
and wouldn't the limbs of the tree be plunged into the thin, soft layer
of mud? Even if you were able to grow trees on soft mud without
disturbing the layer of mud, which is impossible, you still have the
problem of getting the tree down when it dies without mashing the
parting.

> Bill, I agree with you that my explanation for partings is not 100%
satisfactory.

Thank you for that admission, Kevin. I think we both need to be more
ready to admit when we are propounding a weak argument.

> I might even say that partings without roots may have been
> covered by allochthonous peat IN THE SWAMP,

This is called "hypo allochthonous" - and it won't help unless you cover
the parting with a meter or so of vegetation, and where are you going to
get that much vegetation to cover >200,000 square miles (three times,
once for each parting in the Herren coal!)?

> then normal swamp plant growth
> prevailed. Those partings that have roots support an insitu origin.

Partings with roots but no bioturbation? Trees with roots that don't
penetrate the parting? Partings that are not squeezed out beneath trees?
 You are engaged in vague arm waving (if I may borrow a term from you
:-).

> But, we must look at the big picture here.

You really don't like these detailed analyses when they go against you,
do you Kevin? I can tell when I'm on the right track because that is
when you guys always run for the big picture.

> Your Biblical floating mat
> scenario is simply unsupportable for the many reasons that I've
outlined and
> you have not addressed, and an in situ origin for coal IS supportable.
As
> Glenn has said, even if one horizon in the middle of so-called Flood
> deposits contains in situ roots, your idea is falsified.

We're in the Pennsylvanian, now. You're going to have to start over with
your in situ proofs.
>
> You have not buttressed your explanation of partings, especially
tonsteins,
> as turbidites with any further support, have you Bill? As I keep
pointing
> out: until you do, I don't consider it a viable mechanism.

We agree that tonsteins are subaqueous deposits. As to whether they
settled vertically out of suspension as you say, or whether they flowed
horizontally as I have suggested, is beside the point. The tonsteins are
there and they are not bioturbated. You can't grow a swamp on a tonstein
or any other parting without bioturbation. Until you can show me a
modern swamp with intact layers of mud, you have not demonstrated the
viability of your model. Mature swamps do not have whimpy roots. Trees
have roots which grow beneath the water table. Your model needs a little
work, my friend.

Bill

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Received on Tue Mar 9 00:13:05 2004