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ular surface of the Devonian limestone, and on one side of the
section abutting against a vertical wall of limestone about 8 feet
in height. The general relations of the two formations at this
point are shown in the photograph fig. 2. The beds marked
A are a nearly pure limestone of Onondaga age. Those marked
B are the basal beds of the Chattanooga shale, which at this
horizon includes some dark magnesian and silicious beds inter-
bedded with black shale. In the illustration the hammer
rests upon the side of the limestone ledge and the hand of
the man upon the shale. The details of this vertical contact

♦Kentucky Geol. Surv. Bull. No. 7, figs. 8, 9, 1906.



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Chattanooga Shale in Kentucky, 125

are shown more clearly in tig. 3, in which the hammer
rests with one end against the shale and the other against the
limestone. Fig. 3 also shows more clearly than fig. 2 the walls
of a small water-worn cavity in the lower half of the ledge

Fig. 3.



Fio. 3. Close view of a portion of the black shale and limestone contnct
line shown in fig. 2. A solution cavity in the limestone filled with black shale
is seen nnder the hat. The shale is marked A^ and the limestone B,

which extends nearly, if not quite, to the bottom of the lime-
stone. This cavity, tilled with a deposit of the black shale, is



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126 Kindle — Unconformity at the Base of the

seen in the photograph just above the bag. The hat rests upon
the upper part of the falling of the Chattanooga shale. Since
the Devonian limestone in the vicinity of Irvine seldom ex-
ceeds 10 feet in thickness, it is evident from the photographs
that it was locally almost, if not entirely, cut through by sub-
aerial erosion previous to Chattanooga sedimentation. Another
exposure of the contact of the two formations which occurs in
the small ravine between the town and the station at Irvine
shows a still more advanced stage of denudation of the lime-
stone than that illustrated in the photographs. Here the Devo-
nian limestone has been reduced to large disassociated bowlders.
These have been enveloped by the Chattanooga shale, which
lies upon and around them and rests directly on the subjacent
Silurian shale between the bowlders.

The significance of the remarkable and apparently haphazard
variations in the thickness of the Devonian limestone in east
central Kentucky to which Foerste* has called attention,
becomes evident in the light of the preceding examples of sub-
aerial erosion of this formation subsequent to Chattanooga
shale deposition. These variations in thickness range from a
few inches to 47 feet according to Foerste. The following
striking cases are quoted from Professor Foerste's report : f

" Another thick section of Devonian limestone occurs three
miles southwest of Cartersville, where the road to Crab Orchard
crosses the headwaters of Harmon creek. Here the Devonian
limestone is seventeen feet thick. Half wayT)etween this locality
and Crab Orchard the thickness of the Devonian limestone is only
six feet, so that the Devonian limestone appears to become thin-
ner from both areas toward this middle region. . . . Directly
north of Berea the thickness of the Devonian section is thirteen
and a half feet. Four miles north of Berea it is reduced to three
inches. Evidences of thinning are seen also in going from Berea
northeast, toward Bobtown. In the vicinity of Bobtown, and
from this region forat least three miles toward the east and north-
east, the thickness of the Devonian limestone is reduced to about
one foot or less, except at the Mat Moody Store, a mile and a
quarter toward the southt^ast of Bobtown. Here the thickness
of the Devonian limestone is at least four feet four inches, again
suggesting an irregular thinning of the Devonian limestone toward
the north."

It would seem to be a reasonable inference that the snbaerial
erosion which rendered the Devonian limestone cavernous and
in places reduced it to a bed of bowlders as at Irvine, may, where
the pre-Chattanooga relief was greater, or the drainage more

* The Silurian, Devonian, and Irrine formations of Eiast-Central Kentucky,
Kentucky Geol. Survey, BuH. No. 7, p. 89-92, 1906.
t Idem., p. 90.



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Chattanooga Shale in Kentucky, 127

deeply incised, liave removed it altogether. Tlie very irregular
and patchy distribution of the Devonian limestone which obtains
in southern Kentucky and adjacent parts of Tennessee, taken
in connection with the evidences of its partial erosion in central
and northern Kentucky, strongly suggests that this formation
has been completely removed over a considerable area near the
Kentucky-Tennessee line and over smaller areas in central
Kentucky. In the latter area the Devonian limestone is gen-
erally present where the Chattanooga shale is found, but over
certain areas, as the regions between Bardstown and New
Haven, between Raywick and Loretta, and south of Stanford,
it is entirely absent. Farther south it is not the absence but
the presence of the Devonian limestone which is exceptional.
Southwest of the southern limit of the Devonian limestone in
Kentucky, as indicated on Foerste'sf map, a detached area of
this formation occurs on the Rolling Fork River. The writer
has found another on the Green River near Edith P. O. A
third occurs south of the Tennessee line on the Harpeth River.
In the light of the evidence which has been presented of the
extensive denudation of the Devonian limestone at Irvine, it
appears nearly certain that these outlying patches of limestone
are remnants of a once continuous sheet of Devonian limestone.
Its relatively greater degree of denudation is doubtless the
result of the greater elevation of the axis of the Cincinnati
geanticline in southern Kentucky and northern Tennessee.

Time interval represented. — Any conclusion concerning the
time interval represented by the unconformity which has been
described must rest upon tlie determination of the age of the
formations involved. The complexity of this question is
apparent when we consider that the unconformity involves at
its base at least six distinct formations in Kentucky ranging in
age from Ordovician to Middle Devonian. This, of course,
raises the question whether in one part of the area land con-
ditions began as early as Ordovician and in another part as late
as post-Hamilton time, or whether differential erosion is respon-
sible for the difference in age. The evidence already given of
the nearly complete denudation of the Devonian limestone by
subaerial erosion at one locality seems to strongly support the
probability that the absence of the later formations in part of
the Kentucky area is due to denudation rather than to land
conditions having persisted in certain areas from Ordovician
to the beginning of Chattanooga sedimentation. Obviously the
question of transgression or overlap comes into the problem,
^ut we have to discover whether the transgression proceeded
rapidly and at approximately the same rate from all sides, or

*Silarian and Devonian limestones of Tennessee and Kentucky, Bull.
Geol. Soc. America, vol. xii, fig. 8, 1901.



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128 Kindle — Unconformity at the Base of the

whether it proceeded very slowly and chiefly in the direction of
the oldest rocks exposed at the base of the nnconformity. The
latter view seems to have been maintained by some geologists
as a corollary of the dogma of very slighi erosion of Silurian and
Devonian lands. The photographs and other evidence here
presented indicate the necessity of very materially modifying
this assumption. It is of course possible to have had a south-
erly transgression of the black shale across Kentucky at the
close of such a cycle of erosion as has been indicated in this
paper, but proof of this must rest on evidence of distinctly dif-
ferent age values of the basal faunas of the black shale at
the north and at the south. It is desirable here to ascertain
just what evidence there is, if any, for such differences in the
age of the shale. Prof. Edward Orton, Jr.,* appears to have
been one of the first to claim that the black shule in Kentucky
represented only the " Upper or Cleveland Division " of the
Ohio shale. His statement is as follows: '^The shale that
covers the Lower Silurian limestone in central Kentucky is the
Upper or Cleveland Division." This opinion concerning the age
of the Chattanooga shale is comparable to some which have
followed it in the poverty of evidence on which it rests and
the positive phrasing which might mislead one unfamiliar with
the subject to suppose that it represents an established fact.

No complete or entirely adequate discussion of the time
interval represented by the unconformity at the base of the
Chattanooga shale can be given until the fauna and strati-
graphy of this formation have been described in detail.
Altliough generally considered to be nearly barren of organic
remains, the writer has found the carbonaceous beds of the
Chattanooga shale to carry a conodont fauna which is quite
as abundant in the lower or Huron shale of Ohio and Kentucky
as it is in the upper or Cleveland shale. These minute but
beautifully preserved fossils may be obtained at any locality
and at any horizon in the blacK shales from Lake Erie to
Alabama. These fossils have long been known in Ohio in the
upper beds of the Ohio shale, but with the exception of a very
few species have remained undetermined and undescribedf.
When they have been described and the species which are con-
fined to the upper and lower horizons of the shale distinguished,
they will prove an invaluable aid in correlating the different
parts of the Ohio shale in Ohio with their equivalents in the
Chattanooga shale in Kentucky and farther south. Until this
has been done, however, any attempt to make use of these
fossils in correlating subdivisions of the Ohio and Chattanooga
shale must be considered premature and futile. Hence, in the
present discussion of the age of the interval represented by the
*Geol. Survey of Ohio, vol. vii, p. 28, 1893.



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Chattanooga Shale in Kentucky. 1 29

unconformity at the base of the Chattanooga shale, the previ-
ously adduced evidence of the age of the sliale will be consid-
ered chiefly.

Devonian fossils have been found by various geologists
in the lower part of the Chattanooga shale in Kentucky
and in its equivalent, the new Albany shale, in Indiana.
For a summary of the literature relating to the Devonian
age of the Ohio shale which has appeared previous to
1898, the reader is referred to Dr. George H. Girty's*
important contribution to the age of the Chattanooga snale
in eastern Kentucky. Somewhat later the writer f published
a short list of Devonian fossils obtained from the Chattanooga
shale on the western side of the Cincinnati geanticline. The
whole of the Chattanooga shale was generally considered to be
of Genesee age until Prof. H. S. WilliamsJ reported that Car-
boniferous fossils appeared in the topmost beds of the formation
at Irvine. The excellent stratigraphic work done by Foerste
and Mor8e§ in northern Kentucky has shown that these Car-
boniferous fossils at Irvine occur in beds which are the south-
ern extensions of the Berea, Bedford, and Sunbury formations
of southern Ohio. They have shown that about 4 feet of the
uppermost beds previously included in the 150 feet of the
Ohio or Chattanooga shale in east central Kentucky are the
stratigraphic equivalents of beds which in northern Ohio imme-
diately follow the Ohio shale and have a total thickness of about
150 feet. The thinning of these beds in crossing southern
Ohio and northern Kentucky, though very marked, narmonizes
fully with the attenuation which the Ohio shale suffers in being
reduced from a thickness of more than 2400 feet east of Cleve-
land to less than 150 feet at Irvine, Kentucky.

On the basis of diastrophism Grabau,|{ Schuchert,^^ and
Ulrich** have referred the Chattanooga shale in Tennessee to
the Mississippian. These authors, though differing widely as to
the direction of movement of the transgression, agree in assum-
ing that it culminated in the deposition of the Chattanooga
shale in Mississippian time. Concerning this correlation and
the method by which it was derived, it is perhaps sufficient
to quote Professor Schuchert's remarks on the diastrophic
method. He states :

* Description of a Devonian fauna found in the Devonian black ehale of
eastern Kentucky, this Journal, vol. vi, p. 385, 1898.

tBuU. U. S. Geol. Survey, No. 244, p. 20, 1905.

X This Journal, vol. iii, p. 898, 1897.

p Jour, of Geology, vol. xvii, pp. 164-167, 1909.

I Types of Sedimentary Overlap, Bull. Geol. Soc. America, vol. xvii, pp.
699-701, 1906.

^ Paleogeography of North America, Bull. Geol. Soc America, vol. xx,
p. 441, 1910.

♦* Bevision of the Paleozoic Systems, Bull. Geol. Soc. America, vol. xxii.
No. 8, p. 307, pi. 29, 1911.



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130 Kindle — Unconformity at the Base of the

" In fact, the principle of diastrophism can rarely be used before
taking the fossil evidence into account, for it is the latter that
fixes and determines physical events. Diastrophism, however, is
of much value in paleontography, but it must follow, not precede,
the evidence furnished by the fossils."

None of these authors has given us any faunal evidence for
transferring the Chattanooga shale to the Carboniferous from
the Devonian, where it had been generally placed and to which
it liad previously been referred by one of them,* and separated
from the Carboniferous by an unconformity.! Probably all
of the paleontologic evidence which the advocates of the
Carboniferous age of the Chattanooga shale might claim to
support their view has been presented by Dr. R. S. Ba6sler.:|:
Although his paper does not eschew diastrophism, it proceeds
mainly on the paleontologic basis and consequently invites
our careful consideration and critical examination. The con-
tentions which Bassler makes in his paper are reducible to
three distinct theses, which may be stated thus : (1) The Chat-
tanooga shale of central Tennessee is a distinct formation
from the Chattanooga shale of the U. S. Geological Survey
folios of eastern Tennessee. (2) The Chattanooga shale should
be correlated with the Cleveland shale of Ohio. (3) The
Cleveland shale of Ohio is of Waverlyan age.§ Inasmuch as
Dr. Bassler admits the Devonian age of tne east Tennessee
black shale, it is evident that the first proposition is of pri-
mary importance to his argument. It is stated by Bassler
as follows : " East and northeast of this Chattanooga band
of outcrop a similar black shale, but of undoubted Devonian
age, has been mapped as the Chattanooga shale."T In support
ot the distinctness of the eastern and central Tennessee Chatta-
nooga shale I find in Dr. Bassler's paper no evidence adduced
beyond the reference of the central Tennessee Chattanooga to
the Carboniferous. This reference rests primarily on evidence
submitted by Newberrv nearly forty years ago, the validity
of which I am compelled to deny for reasons to be shown
presently. During tlie past summer the writer has discovered
in the most easterly outcrops of the Chattanooga shale in

•Ulrich, E. O., Prof. Paper, U. S. Geol. Survey, No. 8«, p. 26, and Folio
U. S. G. S. No. 95.

t Hayes, C. W.. and Ulricb, E. O., Folio U. S. Geol. Survey, No. 95, 1903.

X The Waverlyan Period of Tennessee, Proc. U. S. Nat. Museum, vol. xli,.
pp. 209-224, 1911.

g Note. — In another paper| the whole of the Ohio shale in Ohio has been
referred to the Mississippian by Dr. Bassler. This reference, however, was
evidently an oversight as regards the lower division of the Ohio shale, since
no evidence has ever been offered by Bassler or any one else tending to prove
that th'e lower portion of the Ohio shale is of later age than Devonian. So
we may confine our discussion of the proposed revision to the evidence rela-
ting to the position of the Cleveland and Chattanooga shales.

I This Journal, vol. xxxi, p. 20, 1911.

IT Idem, p. 215.



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Chattanooga Shale in Kenhccky, 131

Tennessee the same conodont fauna wliich characterizes this
formation at Chattanooga, the type localit}'. In view of this
discovery of the same fauna on both sides of the bari'ier, which
some geologists have assumed to separate the black shale of
eastern and middle Tennessee, the claim of the distinctness
of the shale in the two areas appears to be no longer tenable
Since the Devonian age of the east Tennessee black shale has
already been conceded, the finding of a conodont fauna which
shows the essential faunal unity of the shale in both areas car-
ries with it the evidence of the Devonian age of both.

With the second proposition the writer does not take issue
except to state that it is probable that the Chattanooga shale
in Tennessee will be shown to be the equivalent, not only of
the Cleveland shale, but of much of the remainder of the Ohio
shale as well.

With the third proposition I am compelled to disagree. Dr.
Bassler does not claim to present any new evidence for refer-
ring the Cleveland shale to the Carboniferous but briefly
restates* the evidence which led Newberry to refer these beds
to the Waverly in 1874. It seems probable that Bassler was
not aware of the excellent reasons which have led the authors
of the official reports of the Ohio Survey since Professor New-
berry's time to discard the evidence brought forward by
Newberry and place the Cleveland shale in the Devonian. In
the space here" available it is only possible to refer briefly to
the stratigraphic mistakes made by Newberry which must
throw grave doubt upon any evidence which he presented for
the Carboniferous age of the Cleveland shale. Prof. Prosserf
has fully discussed some of these in his paper on the Sunbury
shale, to which the reader is referred. It is necessary for the
reader to recall in this connection that in northern Ohio the
Cleveland shale, which is the highest member of the Ohio shale,
is separated from a Carboniferous black shale above it, called
the Sunbury, and from a Devonian black shale, below, called
the Huron, by drab shale and sandstone formations of variable
thicknesses. It was easy in the early reconnoissance work
of the Ohio Survey to confuse these three black shales. We
have Newberry's own statement that he did confuse the Cleve-
land and Huron shales in northern Ohio. Con<;erning this
he wrote : " This dip misled us and the thinning of the Erie
shale, bringing the Cleveland down near to the Huron, caused
these two to be confounded.":|: It appears that this confusion
of the upper and lower shales was not detected by Newberry
until 1886, or twelve years after he announced the discovery

*Proc. U. S. Nat. Musetim, vol. xli, p. 218, 1911.

+ The Sacbury Shale of Ohio, Jour, of Geology, vol. x, pp. 262-312, 1902.

X Mon. U. S. Geol. Survey, xvi, p. 127, 1889.



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132 Kindle — Unconformity at the Base of the

of the Waverly fauna at the base of the Cleveland shale which
Sassier cites as evidence of the Carboniferous age of the
Cleveland.

No one who has made a detailed study of the relations of
the Carboniferous Sunbiiry to the two lower black shales from
the northern to the southern boundary of Ohio, can doubt that
the shale which Newberry called Cleveland in the 1874
Report* is the Sunbury shale. It was in this volume that
Newberry published the list of Waverly fossils, including
Syringothyris typa^ which he reported to have been found
below the Cleveland shale. It appears that the authenticity
of this find was called in question during Prof essor Newberry's
lifetime, and in a later discussionf of the matter he states that
these fossils were collected by an assistant who was not able to
relocate the horizon when requested to do so. The writer and
Mr. P. V. Roundy searched very carefully the section from
which this fauna was reported to have been obtained, but
found immediately below the Cleveland shale a Chemung
fauna without any trace of Waverly species. Many other
geologists have studied the northern Ohio sections since Wav-
erly lossils were reported by Newberry from below the Cleve-
land shale, but not one, so far as the writer is aware, claims to
have found Waverly fossils at this horizon.:]: In view of these
facts I think we may safely conclude that the collector of this
fauna incorrectly identified the formation from which his
Waverly fossils came.

If, for the reasons already stated, we dismiss from considera-
tion the Syringothyris fauna as evidence in this case, we find
that we must depend almost wholly for evidence of its age
upon the affinities of the rich fish and conodont faunas which
cnaracterize the Cleveland shale. When Professor Newberry
found himself unable to substantiate his previously published
statement of the occurrence of a Waverly fauna at the base of
the Cleveland shale, he continued to maintain the Carbonifer-
ous age of the formation chiefly on the evidence of the occur-
rence in it of three genera oif Carboniferous fishes, namely,
HcyplonchuSj Orodus^ and Polyrhizodus,% Concerning this
evidence it is well to recall that most of the fossil fishes
described by Newberry were obtained for him by collectors
on whom he depended for the correct designation of their
geologic horizon. Since Professor Newberry had himself con-
fused the Sunbury and Cleveland shales, the opportunities

* Geol. Survey of Ohio, vol. ii, Pt. 1, p. 95.

t Mon. U. S. Geol. Survey, xvi, p. 127, 1889.

X Note : It may be observed here that the Waverly fauna recently reported
in Kentucky by Foerste (Ohio Naturalist, vol. ix, No. 7, pp. 515-523, 1 pi.,
1909), was found below the Kentucky representative of the Sunbury shale.

§ The Paleozoic Fishes of North America, Mon, U. S. Geol. Survey, xvi,
p. 128, 1889.



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Chattanooga Shale in Kentucky. 133

which existed for the collectors to confuse them are too evi-
dent to require discussion. If these genera occur in the Cleve-
land shale at Bedford, as Professor Newberry believed, recent
workers in this iield should have found at least one or two of
them. TVe have, however, the testimony* of two paleoichthyol-
ogists, Dr. L. Hussakof and Prof. E. B. Branson, who have
been persistent collectors in the Cleveland shale of northern
Ohio, that they have never found any of these genera in it.
Professor Bransonf writes as follows :

" I have never collected any specimens of the genera mentioned
in your letter, from the Cleveland shale, nor have I ever seen

Carboniferous fish remains of any kind in the shales We

had quite a large collection of Cleveland shale material in Oberlin
College Museum, but all of it indicated the Devonian age of the
formation."

Dr. Hussakof indicates his experience in the following
words :

"In regard to your query about Uoplonchus, Orodus and
Polyrhizodus — I have never found any of them in the Cleveland
8hale."J

In view of this kind of testimony from paleontologists thor-
oughly familiar with the fish fauna of the Cleveland shale,
both through extended collecting and study of all the important
collections made by others, we seem forced to conclude that
the Carboniferous fishes which Newberry records from the
Cleveland shale came probably from the Sunbury instead of
the Cleveland.

When Newberry's monograph on the Paleozoic fishes of
North America was published he was not aware that any of the
twenty-eight fossil fishes which had been described from the
Cleveland shale occurred in the Huron shale of northern Ohio,
for he states§ that " none of the fossil fishes described from
northern Ohio should be credited to the Huron." Progress
has been made since this was written in our knowledge oi the
range of the Cleveland shale fishes. It has been comparatively
small, however, because the group of collectors who have made
the Cleveland shale famous for its fossil fishes, all lived on or
near outcrops of this formation and gave comparatively little
attention to the more remote area in northern Ohio in which
the Huron shale reaches the surface. Branson] has, however,
shown that at least one of the Cleveland shale fishes, Dinich-
thy% intermedivSy occurs in the Huron shale in its typical area
near Huron, Ohio. It may be pointed out, too, that one at

♦ Letters to the writer.

f Letter to the writer, Nov. 23, 1911.

1 Letter to the writer, Nov. 11, 1911.

% Mon. U. S. Geol. Survey, xvi p. 127, 1889.

I Science, n. s., vol. xxviii, p. 94, 1908.



Online LibraryJohn Elihu HallThe American journal of science → online text (page 13 of 61)