Re: Early Cambrian explosion

Jonathan Clarke (jdac@alphalink.com.au)
Tue, 09 Feb 1999 20:45:43 +1100

Welcome back Bill

Bill Payne wrote (in part):

> You mentioned root casts above, and I assume you would say the root zone
> below a coal seam is a paleosol. I now realize that there are roots
> below most coal seams, and I believe that these roots grew in situ.
> However, the roots are poorly developed and the root zone is generally
> only a few inches deep. The paper by Bob Gastaldo, which I critiqued
> last year at your request, persausively argues that the Carboniferous
> trees were massive (up to maybe 30 meters tall) and required long
> stigmarian axial root systems for support. Bob failed to note that we
> don't observe these long root systems beneath coal seams.
>
> Where we do see long root systems, I believe that they may have been
> eroded from their original growth site, rafted by the flood to another
> location, and reburied in growth position, similar to the numerous
> vertical fossil tree trunks we observe (without roots).
>
> The shallow roots that we do observe beneath coal seams developed after
> the still living vegetation settled out of suspension. When it touched
> firm sediment, it began to root in an attempt to gain a foothold and
> begin a new forest. The fact that these roots are so shallow is evidence
> that the vegetation quickly died as it was buried by additional sediments
> in the flood. Therefore, we have transported (allochthonous) coal with
> in situ (autohthonous) roots.
>
> Comments?
>

I am glad that you have continued to reflect on these questions. It is great
that you recognise the evidence for roots beneath at least some coal
deposits.

Your proposed allochthonous model is to my mind very unlikely. It might be
just possible in rare instances, but to expect your model to explain all
rootlet horizons beneath all coal horizons is taking special pleading to an
extreme. It fails completely to explain laterally extensive rootlet horizons
beneath paleosols where there is no evidence what so ever for floating mats
of vegetation settling on the dunes, or even for them being submerged.
Occam's razor is an important component even in geology.

In Christ

Jonathan