Re: coal again!

Keith B Miller (
Tue, 13 Apr 1999 22:22:10 -0500

Bill wrote:

>If, as you indicated, you agree with Gastaldo that stigmarian axial root
>systems do penetrate the subsurface at varying angles, and coal seams are
>formed by in situ trees, then it would follow that coal seams should be
>underlain by stigmarian axial root systems. However, you have stated:
>"I replied that such would not be expected because rooting is not readily
>preserved, and the evidence for paleosols rest with the macro- and
>microstructural features. Saturated soils are characteristically not
>deeply or intensely rooted soils."

You are trying to apply my comments in a different context than that in
which they were given. I was specifically responding to your statement
that "intensely rooted" soils below coals would disprove your ideas.
Furthermore you state that you have not observed such "intensely rooted
soils." I responded that for several reasons intensely rooted soils are not
expected under saturated conditions. You also stated that you often see
lamination and bedding below the coals. I respnded that saturated soils
often preserve some original bedding because the pedogenic processes that
destroy bedding are inhibited under saturated conditions. Rooting is not
the basis for recognizing soils. Saturated or gleyed soils can be
recognized by diagnostic microstructural features which you refuse to
consider. Many (most?) underclays are soils.

>How do you reconcile your statement that "Saturated soils are
>characteristically not
>deeply or intensely rooted soils" (your post of Mon, 29 Mar 1999 22:24:48
>-0600) with Gastaldo's statements that shallow rooting is a
>generalization and rooting cross cutting bedding and even exceeding 30
>degrees is not uncommon?

The absence of "intensely rooted soils" with well-developed soil structure
does not imply that roots do not occur. Roots _are_ difficult to preserve
within any soil profile. Typically, unless there is mineral accumulation
in association with the roots, which results in nodules or rhizocretions,
any permanent record of most rooting is destroyed. The preservation we
commonly see is from the last generation of plants living on the land
surface before it is buried or flooded. In the case of paleosols
underlying coals, the connection between the conditions during soil
formation (and the plants rooted in that soil) with the overlying coal is
not at all obvious. There are some clear cases where the paleosols
underlying the coals were formed under very different conditions than the
coals. The base of the coal is essentially an unconformity.


Keith B. Miller
Department of Geology
Kansas State University
Manhattan, KS 66506