North Carolina. State Geologist.

Report of Professor Emmons, on his geological survey of North Carolina [electronic resource] online

. (page 11 of 14)
Online LibraryNorth Carolina. State GeologistReport of Professor Emmons, on his geological survey of North Carolina [electronic resource] → online text (page 11 of 14)
Font size
QR-code for this ebook

retains the peculiar characteristic of that of the slates ;
it is best f-en in the conglomerates, where the masses of
quartz are larger than in sandstone. The color of the
sandstones is due to the presence of oxyde of iron. The
iron came from the same source as the sandstones. These
slates are highly charged with pyrites, which have been
thoroughly decomposed; the sulphur dissipated, or probably
it has formed rew combinations. The oxyde of iron, being
insoluble, has remained with the particles composing the
rocks ; and it has formed, of itself, no combination with
other bodies, unless it is wnh carbonic acid. The iron
forms a superficial coa ng upon the angular grains of
sands, an<J niay be removed by washing, when it leaves
a perfectly pure white sand. In the other case, it is inter-
mixed with clay and a smailt-r proportion of fine sand, and
forms the softer beds, whioh are sometimes called red marls.
It seems, therefor*., that the materials of this group of rocks
were brought from the northwest side of it, or from that por-
tion of t? e gold rocks which lie in that direction. As,
however, the area of deposit must have been basin shaped,
or trough shaped, he materials must have been derived,
also from all sides o( it; but our examinations are facili-
ta:ed upon the nor th west side by a vertical movement;
her*ce. we are able to test the truth of ihese views, rather
upon that side, than upon the southeast.

98. It is more difficult to determine the origin of the
materials composing the coal slates. These contain lime,
but no sand, except in combination with alumina. The


slates, therefore, differ so much from the sandstones, that
there can be no doubt, that the origin and source, fiom
whence they were derived, was different also They indi-
cate a total change in the direction in which the sediment
came, nnd as there is no formation to the northwest, cr
southwest, to which their oiigin can be attributed. lam
inclined to regard the source as concealed by the present

The sandstones in the United States, of the ages closely
approximating to those under consideration, were deposited
in shallow water. The ripple marks, the loo! prints, which
have been preserved, are regarded as proofs of this position.
Taking the same ground and kind of evidence, I have not yet
been able to furnish the same ground of proof for their deposi-
tion in sh illow water. I have not yet discovered footprints, or
ripple marks, and the only fact, which goes to support the
vi%w entertained, of the depth of wate,, in which the strata
were deposited, is. a single layer, which had cracked in dry-
ing. These cracks were subsequently filled with sediment.
Still, but few opportunities for a disclosure of the inte-
rior of these deposits have been furnished. The blocks
of sandstone, which have been employed jn building,
have been procured from the surface, and which were
already loosened from their beds; besides this, the strata
have not been laid oare by an inundation. The means, there-
fore, for obtaining a series ot facts, bearing upon the.-e
questions , are insufficient. They throw but little light
upon them, and we must, therefore, wait until railroads
and internal improvements have laid open the series to in-

The evidence, as it now stands, favors the view, that
these rocks were deposited in deep water; the absence of
all tipple marks, the great thickness of the deposits, and
thickness of the deeper layers, indicate for the sandstones
dtep oceanic deposits.



$ 99. The age of a rock, or of a formation, is determined
without difficulty, provided it contains fossils ; especially
those belonging to the molusca; or, if its relations to
other systems can be seen ; whether those systems are
above or below. But the sandstones and coal -stones rest
upon a series ot gold-bearing: rocks, whose age dates buck
farther than any fossiliferous rocks ; hence they cannot
be employed for comparison. The only rocks which rest
upon them are the sands of the tertiary. We have no
way boards by which their relations to other formations
can be determined, excepting those of the most general

The fossils are exceedingly scarce; and their spe3 : es
few in number, and not very distinctive. They are confined
to one species of molusca: a small posidoma or cypris ;
which is regarded as a crustacean, and which is only the
size of a grass-seed ; the teeth of two or three si>uri:ms
and the scales and teeth of one or two fish. The p'-*i-
doniu does not differ from the posidoma of the Richmond
beds, except in size : it is smaller, and resembles the
P. minutice of Gold fuss.

This iossil is remarkable for its numbers ; every layer
in portions ol ;he slate is crowded with them, and t y
range from the top to the bottom. It is usually one-eighth
of an inch in diameter ; The largest ever exceed one-
quarter. It is always fl it, in the slates, from pressure, and
always round and plump in the thin beds of impure lime-
stone. The cypris, or it may be a cytherin >, is ohnut
one line in lengih and pointed at both ends, and sun- '\.
li re>etnbK j s a hny -e d ; and so numerous is this
minute fossil, that thick layers are made up nlmosi \-
tirely of it. It is scarcely possible to touch a point with a
pin. and not mutilate one.


The presence of the cypris indicates that the slates are
a fiesh water formation they go to prove that a remark-
able change tuok pi ace alter the lower sandstones were
deposited that the ocean, in which the sandstones were
formed, was removed a.d the basin, to which sediment
hai been brought from a distant quarter, ceased to be
brought to it as formerly, and from the same as they had
been ; ari'' f in fine, thai what had been sea became a fresh
water lake. It was not until this change from red sandy
sediments to.>k | lace, that the fossils peopling the waters
appeared ; and then ihey were confined to a very limited
number of specks

Jf, however, this small tossil is a cytherina, the change
which it is suppose,! may have occuned at the close of the
oceanic sandstones, \yas only in the direction of the sedi-
ments ; a change which appears to have been sudden for
the sandstones scarcely alterr.ate with the lower slates.
They begin, as it were, at once ; but the basin or trougL
w;ts stili ocear.ic.

Ut saurian remains, in the formation, 1 can speak only
of two species in the sandstones: one below the slates,
ai.d of the crocodilian type; and one above, with long
curved teetii. And, probably, three species in the slaie
the teeth of one aie long, slcndtr, an J curve four inches;
the teeth ot another, ol a medium length, and only slightly
flatici ed, and very finely serrated on one edge ; the teeth
of she other, Distinctly serrated on both edges, and agrees
with figuies of the tkecodontu saurus of Owen.

The latter p<-i.iLs to the Permitn age ; and Sir Charles
Lyeil has observed, that tins saurian was regarded as the
oidcst animal known of that type; and, irom its pre-
sei ce in th-j older deposits, Mr. CKveii has shown that it
militates ag the doctrines of Hie Author of the Y'esti-
g > ol Creation. It ranks v\ith the highest animals of that
t \ pe ; proving that rank is not determined by the periods
in which animals have lived. The most remarkable saurian,


if saurian it is, is the species furnished with the long slen-
der teeth, of which I have seen no figures resembling them
in form or length. Tfcey are slightly flattened, giving an
oval in a transverse section ; but their sides are not armed
with serratures.

The bones in the rocks above the coal, are black. The
sandstone had become concretionary, and exfoliated in
their coats, like those of an onion; and hence, it was im-
possible, to obtain them in a good condition ; besides, the
rock had, also, become exceeding hard and tough.

The iossils, being in my opinion, new. throw no positive
light upon the age of the rocks, in which they occur.

The fish scales are quite small and smooth. Their form
is rhomboidul, some acute, others obtuse. The teeth are
small, slender and pointed, and seem to fork slightly, at
their roots. Another fossil, which might be mistaken for
a vegetable, is, undoubtedly, an appendage to a fish.

The vegetables are few in number, and differ from those
of the coal rocks of Pennsylvania, or the flora of the car-
boniferous system. An IJquiselites, differing from E Corn-
munis, is the only one of this genus 1 have seen. A lyco-
podites, and other allied forms, are all I have yet found, ex-
cept a naked aud rather spinous vegetable, which is unknown
in the carboniferous rocks. It is a cellular crytognmwus
plant. This is very common and abundant at Madison,
aud one or two layers of sJate are covered with it at
Evans' Mills.

The roots of vegetables, in the fire clay, are thin, nar-
row, ribbon-like tissues ; and have tost their vegetable
structure*. Their thinness and compressibility show, how-
ever, that the roots were spongy, of a loose texture, and
were aquatic.

The meagre list of plants and animals, then, deposited in
the slates furnish only grounds for conjecture, to what
age the formation belongs. My opinion* derived from all
the facts and circumstances known to me, inclines me to


adopt the belief, that it is the upper new red sandsstone
Still, if the Richmond coal basin is of the same age, as the
eoal rocks of North Carolina, Geologists will be disposed
to place the series along with the Oolites or Lias, a ' >
Wm B. Rodgers and Sir Ch. Lyell have done on the
ground, that the fossils are, in part, identical in species
with those of Whitby, in Ksigland, where those rocks are
well developed. Mr Lyell observes, that the sandstones
containing fish, of the Connecticut river, are of an older
date than the strata containing coal near Richmond. The
higher antiquity of the Connecticut beds cannot be proved
by direct supposition ; but the fact is presumed from the
structure of the country. That structure proves them to
be newer than ihe movements .o which the Alleghany
chain owes its movements or flexures; and this chain in-
cludes the ancient coal formations among its contorted rocks,
The uriconfonitalve position of this new red with the pri-
mary is often seen. He regards the sandstones of the
Connecticut valley as triassic ; but. to what portion of
the triassic;, which division, whether upper or lower, is
not determined

In Europe, the triassic is rich in fossils ; and different
parts oi the series are so well characterised by fossils, that
the determinations are not difficult. But here, in this
country, the Connecticut valley, the New Jersey beds, tlie
sandstones of the Potomac, and Fredericksburg, and North
Carolina, ate illobscire. from their relations, and from the
absence of characteristic fossils.



100. In Rockingham and Stokes Counties, a series of
rocks have been known for a quarter of a century, as coal-
bearing. These rocks are similar to those of Deep River,
and consist of the same members. They lie in the
sa:ne order, and have the same relations to each other, as
ti,'>se ol'Cnalham and Mnre, <>r Deep liiver.

While theie can he no doubt respecting the age and re-
lations of the entire series, compared wish tliose of Deep
River, still I have observed a fe\v peculiarities worthy ol

The. Dan river coal deposits may be divided, for the
convenience of description, into five parts:

1. Imperfect conglomerates and breccias.

2. Lower sandstones, including the soft and

3. Coal slates, with their subordinate de-

4. Uuper sandstones; including the soft and
hard kn;ds.

5. Conglomerates ; cr brecciated conglom-

The several parts, constituting a complete and perfect
system, occupy a synclinal trough, and lie in the primary
or stratified pyro crystalline tocks. Its direction is r.orih.
east, and southwest. The axis may be defined by uniting
Leak*?! He and Germanton by a line. This line will repre-
sent the direction of the coal slates


The general dip of the system is to the northwest ; the

angle of dip lies within 15 and 40. The dip is usually
above 20. In North Carolina, the rocks extend 40
miles. The breadth is between four and seven miles. The
system extends into Virginia on the north ; but how far,!
am uninformed.

This field, it will be observed, covers a smaller area than
Deep River. It is similar, in some respects, to the Rich-
mond coal fields, but is disconnected by the intervening
primary rocks.

If we consult a map of the United States, and mark
upon the map the position of the coal- field to which refer-
ence has been made, we cannot fail to notice the singular
fact, that there are three small troughs, formed in synclinal
dips of the primary slates^ and all lying with their axes di-
rected to the southwest, or nearly parallel to the present
Atlantic coast.

These troughs are now disconnected, and an examination
of the series, their outcrops, &c. go to show that each was
formed in a trough by itself, and totally disconnected with
each other. Each was formed in the bosom of its own sea,
and each remarkably deep.. The area? upon which these
rocks were deposited, have never suffered from denudation, or
from great fracture ; but are traversed by moderately sized
trap dykes- The Richmond coal beds have been disturbed
more than those of Dan River, and the Dan River lie in-
clined at a greater angle than Deep River,

When oui examination is extended to the Hudson and
Connecticut Rivers, similar rocks are found. The sandstone
is accompanied with conglomerates and slates. The latter,
however, are hard, and retain the impression of (he fish and
fossils better: than those of the Dan or Deep River. All
these beds of sandstone lie parallel to each other. They are
comparatively long, but the breadth is inconsiderable. That
these several isolated series represent one period,, is highly
probable, though not geologically proved.



Four of these isolated troughs are characterised bv out-
bursts of the pyroplastic rocks, or igneous. The Trap or
Palisades of the Hudson ; the vast fields and mountains of
trap in the Connecticut Valley, extending more than a hun-
dred and fifty miles ; and the heavy trap dykes of Deep
River, and the minor trap dykes of the Dim, belong to one
era. They all cut throng 1 ! the sandstone and slates, and
send lateral blanches of th'e once molten mass both between
and upon the layers, baking and hardening those which are
in contact or in proximity with them.

Geologists are now very much inclined to adopt, the view-
that outbursts of igneous matter, though ui distant points, but
found upon and through the same formation, happen at one
and the same period.

Proceeding still farther North, our attention will be arrested
again by a still more extensive outburst of trap in Nova
Scotia. It is not satisfactorily determined whether I he traps
of Nova Scotia are connected with the new red sandstones.
Still, it seems to have happened at a period subsequent to the
carboniferous ; and the trap lies upon, and has intruded
itself into, a rock, whose mineral characters are similar to
those of New Jersey, Deep River and Connecticut.

But the foregoing remarks may be regarded as digressions.
My object in these remarks is, to identify age by means of
phenomena, and show that, when rocks possess characters in.
common, and where certain phenomena are of the same kind,
and are observed to be common to them also, it is an indica-
tion that the rocks belong to the same period.

It is remarkable, too, that all these troughs of red sandstone
repose directly upon the primary rooks. The junction of
sandstone with primary is very distinct at Blomidon, Nova
Scotia, in the Connecticut Valley, in the Hudson River
Valley, in the Richmond basin, the Dan River, and the
Deep River. The most Southern troughs of red sandstone
are the least disturbed, and the smallest quantity of trap ha
been ejected. In Nova Scotia it has reached its maximum.
The whole outburst has extended through twenty degrees of


Whether the foregoing facts do really prove that the
rystetns are one in age, and belong to the same period or not,,
may still require proof. The facts themselves are interesting.
We may require many additional particulars to enable us to
interpret phenomena aright, and assign to those sandstones
and sl.xtes their true age.

101. The lowest mass upon the Dan River, which
belongs to the sandstone series, is a conglomerate, quite im-
perfect, at least, where it has fallen under my observation.
At Leaksville, i have not seen the lower conglomerates ; but
at Germanton, an imperfect mass, occupying the lowest place
in the series, is formed of angular pins of granite, mixed with
a gray and reddish sediment, in very unequal propor-
tions. Its appearance might easily deceive an inattentive
observer. It has an exceeding close resemblance to some
varieties of granite. After a close inspection of many large rocks
lying near the small creek at this place, rounded pebbles
were found ; and, by still farther search, roots of trees in
beds of lignite were found, also branching into the rock.
This represents the fine beds of millstone on the Deep River.
The mass is thin, and of little importance.

Immediately above this bed of brecciated conglomerate,
there is one of the finest exhibitions of an ancient forest in
this country. It consists partly of roots of trees changed into
lignite, arid partly of perfectly silicified trunks of trees, exceed-
ing two feet in diameter. The soil in which the majority of
these trees grew, is still concealed. Segments of their trunks
stand out of the soft rock, inclining at an angle to the horizon,
but lean in a direciion contrary to the dip of the vock. A
road cuts through the strata in which the forest grew. All
that remains of it are the trunks ; it was impossible to find a
leaf or stem of herbage or fruit. The softer and more per-
ishable parts and organs are destroyed by unknown agencies.
Perhaps some fortunate blow of the hammer may bring to
light the leaves and fruit. The structure of these trunks
prove them to belong to the natural family of conifers, or
the family to which the pi nes, spruces and hemlocks belong


The frees extend for half a mile or more, and no one, on
seeing the number, can doubt that here grew a forest when
the rocks were forming. Similar trunks have been found at
Madison, and pieces of trunks occur upon Deep River, near
Evans' bridge, and another forest of the same character
upon Drowning Creek, in Richmond County. They occu-
py the sa*me position in the series. These trunks are geolo-
gically important, and may be employed to assist m identify-
ing the system with any other at a distance. Numerous
fragments of trunks, also, occur in all the subsequent forma-
tions, especially with tertiaries, and in the superficial cutting
for rail-ways. I was at a loss to account for their occurrence
in positions where agencies could not be supposed to exist,
competent to silicify wood. I have been satisfied that most
of the scattered trunks were derived from the red sandstone
formation. They have been transported by rivers, and by
various agencies, which have also carried the slate rocks, and
deposited them in the green sand, and the various subsequent
beds of the tertiary. Their direction of transport is east-

102. In connection with the strata I have described, (the
breeciated conglomerate,) there occurs no clay or argillaceous
formation, which has a perfect concretionary structure. Large
concentric circles are formed ; some of which are two feet in
diameter. This part of the rock is extremely soft, and is
nothing more, nor less, than clay of a light green color. It
is rare to find a series of perfect concentric circles, and ter-
minating in a nucleus of the size of a two shilling piece, as at
this place. They are due to molicular movements^ which
have taken place, subsequent to the time of deposition. We
are obliged, from phenomena of this kind, to reckon mo-
licular force, as one of the silent geological forces, which
have been instrumental in effecting important changes in the
earth's crust.

103. These argillaceous beds lie beneath the common
sandstones of the formation, which consist of variegated and


gray masses of rock. They terminate with the coal shales.
At Leaksvil'e, a hard silicious slate intervenes between the
lower beds of sandstone and the slates. It is bluish and
flinty, approaching, however, a sandstone in its composition.
His at least two hundred feet thick. It also contains a few
layers, which externally resemble a mixture of carbonate
oxyde of iron. It was in one of these layers, I discovered
the fragments of the skeleton of a saurian.

The middle part of this formation of sandstone is occu-
pied with a soft marly slate the coal slate of the system.
It differs in no respect, from that of Deep River, bearing the
same fossils, the posidonia and cypris, in equal abundance,
through all the strata, of which il is cpmposed.

The coal beds of Leakiville lie in these slates ; the beds
in which the coal seams are exposed are two miles from the
village, on ihe plantation of Mr. Wade.

The coal appears in a long ridge, rising about sixty feet
above the meadow, which lies in the bend of the Dan, at
this place. The following section is partially exposed at
Wade's coal mine

1. Shale below the coal seams.

2. Shaly micaceous sandstones, two feet.

3. Shaly coal at the outcrop, eighteen inches

to two feet.

4. Micaceous shale, two feet.

5. Coal, two to three feet.
5. Shale, 110 feet.

7. Seams of a hard blue magnesian limestone,

intermixed with silex, four to six feet.

8. Soft, green, bluish and black shales, filled

with posidonia, sixty feet.

The shales still continue covered with soil ; the thickness
of the shales is not less than five hundred feet.

The hard calcareous layers are separated by slate at the


The calcareous layers lie above the coal seams, and as
they extend nenrly if not entirely through the formation,
they may be observed as way boards in searching for coal.
The same layers appear in Madison, and contain abundance
of septaria of the size of a goose egg.

Dip of the slates at the coal mine : N. 35 W.; anglo
of dip 25; strike S. 80 VV. It is not improbable, that thb
angle of dip will diminish as the seam is penetrated.

104. The section of rocks lying between Eagle Bridge
and Gov. Morehead's factory, is exhibited in the following
section ; though, it should be observed, that the rocks ay*
concealed, at some points, between the bridge and factory.

1. Sandstones and conglomerates, concealed at

the bridge

2. Flinty black slates, two hundred feet, with

saurian remains.

3. Coal slates, consisting of the usual green and

black slates, with the posidoniaand cypris,
and a few obscure species of plants, (Ly-
copcdiacaCj) fifty to six hundred feet.

4. Red and gray sandstones.

5. Conglomerates.

6. Shaly and green variegated sandstone.

7. Conglomerates, at least five hundred feet.

These conglomerates are hard, and contain many angular
fragments, or those which are but slightly rounded; and some
of these fragments are quite similar to the flinty slate below.
Tne beds resemble hard gray wackes of New York, except
that the masses of rounded quartz are much larger. The
superior beds of sandstone occur at the factory, and have
been employed as a building stone.

106. The series of sandstones which lie between the
bridge and the conglomerates, are better exposed upon Fac-
tory creek, about, four miles from Madison, on the road to


Martins' lime kilns. The latter predominates at this local-
ity. The creek has uncovered the strata, for half a mile.

The section upon Factory creek is represented by the fol-
lowing strata, the strike of which is S. 7U W. dip 20.

1 Soft greenish slates and shales above the
coal slates.

2. Coarse sandstone with pebbles.

3. Red and brown sandstones.

4. Porous red sandstones, or sandstone with

angular cavities, similar to those in other
rocks, which have contained a soluble

5. Green and gray hard sandstones.

6. Coarse sandstones containing rounded pel -


7. Conglomerates similar to those at Gov. More-

head's factory, at Leaksville.
8 Soft sandstones, like the red marls.
9. Slates with quartz veins, dipping beneath

the sandstones.
The thickness of the series above the coal

1 2 3 4 5 6 7 8 9 11 13 14

Online LibraryNorth Carolina. State GeologistReport of Professor Emmons, on his geological survey of North Carolina [electronic resource] → online text (page 11 of 14)