> Anyway, my point in posting this is to ask Bill Payne to comment on Gastaldo's
> serious critique of Austin's model. Arguing with Glenn is one thing, but he's a
> geophysicist, not an expert on lycopods and plant taphonomy (I mean no offense but
> I know how it is to try to argue an issue outside of my area of expertise).
At this point, let me say how much I appreciate Glenn hanging in here
with me. I'm on the steep side of the learning curve myself, and have
probably said some things that a more knowledgeable person than either
Glenn or me would have taken me to task on. Maybe Bob Gastaldo will
take up some of the slack in my position. :-) At any rate, Glenn's
points have been most beneficial and I appreciate his time to
thoughtfully engage me.
> Gastaldo, on the other hand, has spent his life studying plant fossils in coals and
> therefore his critiques should be seriously addressed by any young-earth creationists
> pushing a floating peat mat model for the formation of coal.
Although I do believe the Carboniferous coal data supports (or at least
suggests) a global flood, I am quite comfortable with either a young or
old age for the earth. Therefore, technically I don't consider myself a
true YEC. My interest in coal is not so much to support YEC, but to
show how strongly our paradigms influence our interpretation of data.
It should (IMHO) be a no-brainer that the data demonstrates coal to be
allochthonous, yet almost all geologists believe it to be
autochthonous. And if clear-cut evidence for the origin of coal is
misinterpreted, what about the evolution of life, which is supported by
data *much* more tenuous than that surrounding coal?
> So how about it Bill,
> want to tell us why Gastaldo is wrong? He concludes that:
>
> "An evaluation of the floating mat hypothesis in perspective demonstrates
> the untenable nature of the hypothesis." (p. 111)
Lock and load; here we go brother.
A CASE AGAINST PELAGOCHTHONY: THE UNTENABILITY OF CARBONIFEROUS
ARBORESCENT LYCOPOD-DOMINATED FLOATING PEAT MATS
by Robert A. Gastaldo, Department of Geology, Auburn University,
Alabama 36849
ABSTRACT
"In order to rectify perceived problems in the nineteenth century
autochthonous and allochthonous theories of coal formation, an
alternative theory was proposed that hypothesized that sylvo-marine,
lycopod-dominated, floating peat mats were responsible for the
development of Carboniferous coals. This pelagochthony theory was not
widely accepted at the time but recently has been resurrected in order
to explain the formation of Carboniferous coals well within the 'Bibical
time scale.' Numerous, unsubstantiated 'facts' have been proposed to
support the floating mat hypothesis including: the supposed hollow
construction of arborescent lycopods; the extensive intertwining of
stigmarian axial systems; a supposed continuous transgression of the
shallow epeiric sea; a supposed stratified water column below the
floating mat; and others. An examination of lycopod anatomy and
morphology negates the contention of hollow arborescent lycopods and
allows establishment of criteria to aid in the identification of _in
situ_ plants. An evaluation of the floating mat hpothesis in
perspective demonstrates the untenable charachter of this proposed
coal-forming mechanism. Reattachment of the floating mat is highly
probable in the shallow epeiric sea, either by stigmarian axial systems
proper, or helically arranged 'rootlets.' Isostatic adjustments of the
mat would continue downwards as more biomass is generated by mturation
of the trees. However, if this is ignored, meteoric waters introduced
onto the surface of the mat would promote rapid decay in the tropical
environment, and may preclude peat accumulation."
INTRODUCTION
In the introduction, Bob reivews the historical debate between
allochthonous [organics transported from their land-based growth site,
or living in "floating forests", which then settled to the bottom of a
shallow sea and formed a peat which eventually became a coal seam] and
autochthonous [coal from peat which accumulated _in situ_, i.e., where
it grew] models, beginning with the early 1700's through 1980. He
concludes the introduction:
"The controversy concerning the exclusivity of allochthonous or
autochthonous coals has been abandoned with the development of
interdisciplinary approaches to the study of coal formation. The vast
majority of Carboniferous coals are now understood to be autochthonous
and formed from various proportions of several plant groups (DiMeichele
and Phillips, 1981), the major coal-forming plant group is the
lycopods. Some Carboniferous coals are believed to be allochthonous and
it is generally accepted that plant debris may be transported into an
_in situ_ peat accumulating environment during periods of extensive
flooding. Stratigraphical, sedimentological, and paleobotanical studies
independently corroborate the coastal, deltaic, and floodplain
depositional environments for coal (i.e. Spackman and Cohen, 1976; Ferm
and others, 1979)."
"Recently, Kuntze's floating, arborescent lycopod-dominated, marine
vegetation mat has been resurrected to explain the unusual
characteristics of the Kentucky No. 12 coal (Austin, 1979, 1980a,
1980b). In addition, this model has been used by Scheven (1979, p 187)
to explain the allochthonous formation of coal within 'a relatively
short period, well within the Biblical time scale.' It is the purpose
of the present paper to examine the scientific merit of Carboniferous
lycopod-dominated floating peat mats."
FLOATING LYCOPOD-DOMINATED PEAT MAT THEORY
In this section, Gastaldo briefly discusses the history of the peat-mat
theory and concludes with a description of Austin's model:
"Austin (1979; Figure 1) invoked a floating mat model to account for the
development of the Kentucky No. 12 coal. This alternative working model
is used to explain the occurrence of four seam characteristics that do
not correlate with Holocene coastal-plain-swamp and marsh peats of the
proposed modern analog, sub-marl peats of Florida Bay.... The floating
mats were believed not to have been stationary but mobile structures
(Austin, personal communication 18 Feb. 83) and the clastic material,
introduced as partings, developed as density currents."
"The four important characteristics of the Kentucky No. 12 coal not
explained by a conventional, terrestrial based coastal model, and used
as evidence for supporting a floating peat mat hypothesis, include: (1)
the thin and widespread marine shale partings, (2) the lack of rooting
of lithotypes, (3) the abrupt succession of bright lithotypes and
arborescent miospores above partings, and (4) the intertonguing of coal
with marine roof strata (Austin, 1979). Austin (1979, p. 346-347)
recognized that acceptance of the model poses several problems
including: (1) the lack of a modern analog, (2) the extensive
geographical distribution of the coal, (3) the ecological tolerances of
the plants and the suitability to inhabit floating mats, (4)
distribution of plants across the floating mat, and (5) the petrographic
trends. Nevertheless, Austin (1980) speculated that this model is the
most feasible to explain the deposition of the Kentucky No. 12 coal."
To Austin's credit, he did note the problems he saw with his model. In
1979 he defended his doctoral thesis, having only bathtub models of the
floating mat theory. Less than a year later, Mt. St. Helens exploded
and created the modern analog - a huge floating mat of over 1 million
trees in Spirit Lake. So in 1980, Austin had a modern analog, and this
analog helped explain problems 2, 3, and 4 listed above. It may have
helped explain the petrographic trends also, I don't know what the
trends are.
GENERALIZED LYCOPOD MORPHOLOGY AND ANATOMY
"The two lycopod genera _Lepidodendron_ and _Lepidophloios_ contributed
the greatest amount of biomass to Early and Middle Pennslyvanian coals
(Phillips and others, 1974). Both genera are well documented and
relatively well understood. Although mature trees of different taxa
varied in maximum height attained (DiMichele, 1979a, 1981), specimens
attributable to _Lepidodendron_ have been documented that demonstrate
trees could attain heights in excess of 38 m (Thomas and Watson, 1976)
and diameters up to 2 m at the base. The erect trunks were fairly
constant in diamenter with a slight to moderate reduction in diameter
towards the top of mature individuals. Taylor (1846) recorded trunks
40-50 feet in length without any appreciable change in diameter. The
crown may have been either excurrent (in which the axis is prolonged
forming an undivided main trunk) or dentritic (in which the axis is
branched profusely to produce a large crown of leafy twigs; DiMichele,
1979a, 1981). Leaves varied in size and may have been deciduous or
persistent (DiMichiele, 1980; Chaloner and Myer-Berthand, 1983). The
organs of the plant generally accepted as the subterranean parts of
these lycopods are cruciform in shape with four dichotomizing stigmarian
axes radiating from the base (Williamson, 1887). Stigmarian axes
departed the base of the tree (positive geotropism) at varied angles
(see: Potonie, 1920; Frankenburg and Eggert, 1969), dichotomized twice,
and bore helically arranged lateral appendages sometimes referred to as
stigmarian 'rootlets' (Charlton and Watson, 1982). 'Rootlets' attained
a maxium diameter of 1 cm, and were deciduous at least near the base of
the tree (Frankenburg and Eggert, 1969, Figure 2)."
The next two pages of this section in Bob's article discuss the internal
structure of lycopods. I think he is primarily demonstrating that these
plants were not light-weight and hollow-stemmed, i.e. not well suited to
life in a floating mat. We should point out though, that in the fossil
record vertical (and horizontal or oblique) stumps and trunks are
normally filled with sediment; apparently the internal structure decayed
while the outer shell was still intact.
IN SITU LYCOPODS - Criteria for Identification
"Erect arborescent lycopods within coals rarely have been documented,
and for this reason, proponents of allochthonous coal formation have
utilized documentation of erect plants in other lithologies as evidence
for transport (Stevenson, 1912, 1913). The prevailing asumption is that
if no one saw the tree grow on a particular site, then it could not have
grown on that site. Stevenson (1913) remarked that the recognition of
lycopods in growth position has been by application of knowledge gained
through actual observation to explain conditions where actual
observation is impossible."
"It would be naive to discount the presence of some apparently
allochthonous erect stumps in the Carboniferous deposits. Transported
trunks not fixed in place by stigmarian axes and stigmarian appendages
have been infrequently reported. On the other hand, the remaining
documented erect trunks preserve characteristics that can be considered
only as representing in-place growth of these trees."
It is at this point that Bob and I begin to diverge in our
interpretations of the data. Later I will discuss his last statement
above.
"The disposition of the stigmarian axes and rootlets within their
encasing matrix is an essential criterion for determining in situ
growth. Although Rupke (1969) attempted to attribute some _Stigmaria_
occurrences to transport, Ferguson (1970) asserted that the data
provided by Rupke are insufficient to allow for acceptance of this
hypothesis. The four main stigmarian axes departing from the base of
the trunk may penetrate the matrix at various angles. The contention
that stigmarian axes always are buried shallowly, that is, lying
parallel or subparallel to bedding, is a generalization. Although
specimens have been documented where the axes are buried shallowly (i.e.
MacGregor and Walton, 1972; and others), numerous speciemns bave been
excavated which demonstrate that stigmarian axes also grew downwards at
steep angles (i.e. Potonie, 1920; Frankenburg and Eggert, 1969; and
others). Sorby (1875) suggested that the difference in angle of
penetration of stigmarian axes of individual trees might indicate
prevailing wind directions during the Carboniferous. Stigmarian axes
which cross cut bedding at angles up to, and in some cases exceeding, 30
degrees and possess perpendicularly inserted, radiating appendages
('rootlets') have been interpreted to represent preservation in a normal
subterranean attitude."
"In addition, where encountered, the stigmarian axes interlace in a
complex manner and demonstrate that the axes spread out over an immense
aerial, three-dimensional surface. Williamson (1887) figured a stump
with stigmarian axes which were distributed over an 926 square foot
area, and recorded the discovery of a single stigmarian axis of 37 feet
4 inches in length. The stumps which are attached to such systems cross
cut the encasing lithology(ies) and are commonly abruptly terminated in
the upper sediments. The heights to which trunks are preserved may be
minimal or may be in excess of 6 m (i.e. Teichmuller, 1955; Pontonid,
1920). The distribution of large numbers of erect trunks conform to
natural spacings (DiMichele and DeMaris, 1982; Gastaldo, 1983)."
"Although erect lycopod trunks are generally found without accompanying
erect vegetation, those cases in which erect vegetation has been
preserved along with lycopods demonstrate the same cross-cutting
relationships of stem and root structure. The only other plant
convincingly documented to co-exist with lycopods is _Calmites_. Binney
(1847) illustrated the positively geotropic character of calamite roots
originating from successively higher nodal areas, which cross-cut
bedding in the same horizon(s) in which erect lycopods are preserved.
Dawson (1868), Potonie (1909), Pfefferkorn and Zodrew (1982) and others
recorded the same observations, and Ward (1900) reported this condition
for _Calamites_ preserved in conglomerates of St. Etienne."
Distribution
"Erect _in situ_ lycopods have been documented in three lithotypes:
shales, sandstones, and marine limestones (Gastaldo, in prep). In
addition, studies of permineralized coals have demonstrated that
lycopod-dominated peats are permeated by stigmarian axes and lateral
appendages (Phillips, 1980). There is no report known to the present
author that documents _in situ_ lycopods within conglomerates. The
occurrence of these lycopods, then, is neither restricted to any
specific lithology nor any single facies (for additonal discussion see
Stevenson, 1912, 1913)."
"Interpretations of lithofacies in which erect lycopods have been
preserved indicate that these plants existed and were preserved within
various submerged depositional environments. Gastaldo (in prep)
suggests that lycopods were tolerant of standing or flowing fresh or
brackish waters, in addition to stangnant swamp waters."
I don't know why Bob did not include salt water in the paragraph above,
since in the preceding paragraph he states: "Erect _in situ_ lycopods
have been documented in .... marine limestones." Maybe this was
inadvertent, but it may have been because he discounts the idea of a
global flood and wanted to downplay any supporting evidence.
I'll work on part II and try to get it out in the next few days. The
rest of Bob's paper contains the Discussion, Floating Mats in
Perspective, and Conclusions. He makes some assumptions which I will
attempt to show are a straw-man argument.
Bill