Upper Formations of the Old Red Sandstone.--Room, enough for each
and to spare.--Middle, or Cornstone Formation.--The _Cephalaspis_
its most characteristic Organism.--Description.--The Den of
Balruddery richer in the Fossils of this middle Formation than
any other Locality yet discovered.--Various Contemporaries
of the _Cephalaspis_.--Vegetable Impressions.--Gigantic
Crustacean.--_Seraphim._--Ichthyodorulites.--Sketch of the Geology
of Forfarshire.--Its older Deposits of the Cornstone Formation.--The
Quarries of Carmylie.--Their Vegetable and Animal Remains.--The
Upper Formation.--Wide Extent of the Fauna and Flora of the earlier
Formations.--Probable Cause.
Hitherto I have dwelt almost exclusively on the fossils of the Lower
Old Red Sandstone, and the history of their discovery: I shall
now ascend to the organisms of its higher platforms. The system
in Scotland, as in the sister kingdom, has its middle and upper
groups, and these are in no degree less curious than the inferior
group already described, nor do they more resemble the existences
of the present time. Does the reader remember the illustration of
the pyramid employed in an early chapter--its three parallel bars,
and the strange hieroglyphics of the middle bar? Let him now imagine
another pyramid, inscribed with the remaining and later history of
the system. We read, as before, from the base upwards, but find the
broken and half-defaced characters of the second erection descending
into the very soil, as in those obelisks of Egypt round which the
sands of the desert have been accumulating for ages. Hence a hiatus
in our history for future excavators to fill; and it contains
many such blanks, every unfossiliferous bar in either pyramid
representing a gap in the record. Three distinct formations the
group undoubtedly contains--perhaps more; nor will the fact appear
strange to the reader who remembers how numerous the formations are
that lie over and under it, and that its vast depth of ten thousand
feet equals that of the whole secondary system from top to bottom.
Eight such formations as the Oolite, or ten such formations as the
Chalk, could rest, the one over the other, in the space occupied by a
group so enormous. To the evidence of its three distant formations,
which is of a very simple character, I shall advert as I go along.
The central or Cornstone division of the system in England is
characterized throughout its vast depth by a peculiar family of
ichthyolites, which occur in none of the other divisions. I have
already had occasion to refer to the _Cephalaspis_. Four species of
this fish have been discovered in the Cornstones of Hereford, Salop,
Worcester, Monmouth, and Brecon;[AL] "and as they are always found,"
says Mr. Murchison, "in the same division of the Old Red System,
they have become valuable auxiliaries in enabling the geologist to
identify its subdivisions through England and Wales, and also to
institute direct comparisons between the different strata of the
Old Red Sandstone of England and Scotland." The _Cephalaspis_ is
one of the most curious ichthyolites of the system. (See Plate X.,
fig. 1.) Has the reader ever seen a saddler's cutting knife?--a tool
with a crescent-shaped blade, and the handle fixed transversely in
the centre of its concave side. In general outline the _Cephalaspis_
resembled this tool--the crescent-shaped blade representing the head,
the transverse handle the body. We have but to give the handle
an angular, instead of a rounded shape, and to press together the
pointed horns of the crescent, till they incline towards each other,
and the convex, or sharpened edge, is elongated into a semi-ellipse,
cut in the line of its shortest diameter, in order to produce the
complete form of the _Cephalaspis_. The head, compared with the body,
was of great size--comprising fully one third the creature's entire
length. In the centre, and placed closely together, as in many of the
flat fish, were the eyes. Some of the specimens show two dorsals,
and an anal and caudal fin. The thin and angular body presents a
jointed appearance, somewhat like that of a lobster or trilobite.
Like the bodies of most of the ichthyolites of the system, it was
covered with variously formed scales of bone; the creature's head
was cased in strong plates of the same material, the whole upper
side lying under one huge buckler--and hence the name _Cephalaspis_,
or buckler-head. In proportion to its strength and size, it seems
to have been amply furnished with weapons of defence. Such was the
strength and massiveness of its covering, that its remains are found
comparatively entire in arenaceous rocks impregnated with iron, in
which few other fossils could have survived. Its various species, as
they occur in the Welsh and English Cornstones, says Mr. Murchison,
seem "not to have been suddenly killed and entombed, but to have
been long exposed to submarine agencies, such as the attacks of
animals, currents, concretionary action," &c.; and yet, "though much
dismembered, the geologist has little difficulty in recognizing even
the smallest portions of them." Nor does it seem to have been quite
unfurnished with offensive weapons. The sword-fish, with its strong
and pointed spear, has been known to perforate the oaken ribs of the
firmest built vessels; and, poised and directed by its lesser fins,
and impelled by its powerful tail, it may be regarded either as an
arrow or javelin flung with tremendous force, or as a knight speeding
to the encounter with his lance in rest. Now there are missiles
employed in Eastern warfare, which, instead of being pointed like
the arrow or javelin, are edged somewhat like the crooked falchion
or saddler's cutting-knife, and which are capable of being cast
with such force, that they have been known to sever a horse's leg
through the bone; and if the sword-fish may be properly compared to
an arrow or javelin, the combative powers of the _Cephalaspis_ may be
illustrated, it is probable, by a weapon of this kind--the head all
around its elliptical margin presenting a sharp edge, like that of
a cutting-knife, or falchion. Its impetus, however, must have been
comparatively small, for its organs of motion were so: it was a bolt
carefully fashioned, but a bolt cast from a feeble bow. But if weak
in the assault, it must have been formidable when assailed. "The
pointed horns of the crescent," said Agassiz to the writer, "seem
to have served a similar purpose with the spear-like wings of the
_Pterichthys_,"--the sole difference consisting in the circumstance,
that the spears of the one could be elevated or depressed at
pleasure, whereas those of the other were ever fixed in the warlike
attitude. And such was the _Cephalaspis_ of the Cornstones--not only
the most characteristic, but in England and Wales almost the sole
organism of the formation.
[Footnote AL: _Cephalaspis Lewisii_, _C. Lloydii_, _C. Lyellii_, and
_C. rostratus_.]
Now of this curious ichthyolite we find no trace among the fossils
of the Lower Old Red Sandstone. It occurs neither in Orkney nor
Cromarty, Caithness nor Gamrie, Nairnshire nor the inferior
ichthyolite beds of Moray. Neither in England nor in Scotland is it
to be found in the Tilestone formation, or its equivalent. It is
common, however, in the Old Red Sandstone of Forfarshire; and it
occurs at Balruddery, in the Gray Sandstones which form on both
sides the Tay, where the Tilestone formation seems wanting, the
apparent base of the system. It is exclusively a medal of the middle
empire.
In the last-mentioned locality, in a beautifully wooded dell, known
as the Den of Balruddery, the _Cephalaspis_ is found associated
with an entire group of other fossils, the recent discovery of Mr.
Webster, the proprietor, who, with a zeal through which geological
knowledge promises to be materially extended, and at an expense of
much labor, has made a collection of all the organisms of the Den yet
discovered. These the writer had the pleasure of examining in the
company of Mr. Murchison and Dr. Buckland: he was afterwards present
when they were examined by Agassiz; and not a single organism of the
group could be identified on either occasion, by any member of the
party, with those of the lower or upper formations. Even the genera
are dissimilar. The fossils of the Lias scarce differ more from
those of the Coal Measures, than the fossils of the Middle Old Red
Sandstone from the fossils of the formations that rest over and under
them. Each formation has its distinct group--a fact so important
to the geologist, that he may feel an interest in its further
verification through the decision of yet another high authority. The
superior Old Red Sandstones of Scotland were first ascertained to be
fossiliferous by Professor Fleming, of King's College, Aberdeen,[AM]
confessedly one of the first naturalists of the age, and who,
to his minute acquaintance with existing forms of being, adds an
acquaintance scarcely less minute with those forms of primeval life
that no longer exist. He it was who first discovered, in the Upper
Old Red Sandstones of Fifeshire, the large scales and plates of that
strikingly characteristic ichthyolite of the higher formation, now
known as the _Holoptychius_--of which more anon; and, unquestionably,
no one acquainted with his writings, or the character of his mind,
can doubt that he examined carefully.
[Footnote AM: The Upper Old Red Sandstones of Moray were ascertained
to be fossiliferous at nearly the same time by Mr. Martin, of the
Anderson Institution, Elgin. There is a mouldering conglomerate
precipice termed the _Scat-Craig_, about four miles to the south of
the town, more abundant in remains than perhaps any of the other
deposits of the formation yet discovered; and in this precipice
Mr. Martin first commenced his labors in the lied Sandstone of the
district, and found it a mine of wonders. It is a place of singular
interest--a rock of sepulchres; and its teeth, scales, and single
bones occur in a state of great entireness; though, ere the deposit
was formed, the various ichthyolites whose remains it contains seem
to have been broken up, and their fragments scattered. Accumulations
of larger and smaller pebbles alternate in the strata; and the
bulkier bones and teeth are found invariably among the bulkier
pebbles, thus showing that they were operated upon by the same laws
of motion which operated on the inorganic contents of the deposit.
At a considerably later period the fossils of the upper group were
detected in the precipitous and romantic banks of the Findhorn, by
Dr. Malcolmson, of Madras, when prosecuting his discoveries of the
organisms of the lower formation. He found them, also, though in less
abundance, in a splendid section exhibited in the Burn of Lethen, a
rivulet of Moray, and yet again in the neighborhood of Altyre. The
Rev. Mr. Gordon, of Birnie, and Mr. Robertson, of Inverugie, have
been also discoverers in the district. To the geological labors
of Mr. Patrick Duff, of Elgin, in the same field, I have already
had occasion incidentally to refer. The patient inquiries of this
gentleman have been prosecuted for years in all the formations of the
province, from the Weald of Linksfield, with its peculiar lacustrine
remains--lignites, minute fresh-water shells, and the teeth, spines,
and vertebræ of fish and saurians--down to the base of the Old Red
Sandstone, with its _Coccostei_, _Dipteri_, and _Pterichthyes_. His
acquaintance with the organisms of the _Scat-Craig_ is at once more
extensive and minute than that of, perhaps, any other geologist;
and his collection of them very valuable, representing, as it does,
a formation of much interest, still little known. Mr. Duff is at
present engaged on a volume descriptive of the Geology of the
province of Moray, a district extensively explored of late years, and
abundant in its distinct groups of organisms, but of which general
readers have still much to learn; and from no one could they learn
more regarding it than from Mr. Duff. It is still only a few months
since the Upper Old Red Sandstones of the southern districts of
Scotland were found to be fossiliferous; and the writer is chiefly
indebted for his acquaintance with their organisms to a tradesman of
Berwickshire, Mr. William Stevenson, of Dunse, who, on perusing some
of the geological articles which appeared in the Witness newspaper
during the course of the last autumn, sent him a parcel of fossils
disinterred from out the deep belt of Red Sandstone which leans to
the south in that locality, against the grauwacke of the Lammermuirs.
Mr. Stevenson had recently discovered them, he stated, near
Preston-haugh, about two miles north of Dunse, in a fine section of
alternating Sandstone and conglomerate strata that lie unconformably
on the grauwacke. They consist of scales and occipital plates of the
_Holoptychius_, with the remains of a bulky, but very imperfectly
preserved ichthyodorulite; and the coarse, arenaceous matrices which
surround them seem identical with the red gritty Sandstones of the
Findhorn and the _Scat-Craig_,]
Now, a few years since, I had the pleasure of introducing Professor
Fleming to the Organisms of the Lower Old Red Sandstone, as they
occur in the neighborhood of Cromarty; and, notwithstanding his
extensive acquaintance with the upper fossils of the system, he
found himself, among the lower, in an entirely new field. His
knowledge of the one group served but to show him how very different
it was from the other. With the organisms of the lower he minutely
acquainted himself; he collected specimens from Gamrie, Caithness,
and Cromarty, and studied their peculiarities; and yet, on being
introduced last year to the discoveries of Mr. Webster at Balruddery,
he found his acquaintance with both the upper and lower groups
stand him in but the same stead that his first acquired knowledge
of the upper group had stood him a few years before. He agreed
with Agassiz in pronouncing the group at Balruddery essentially a
new group. Add to this evidence the well weighed testimony of Mr.
Murchison regarding the three formations which the Old Red Sandstone
contains in England, where the entire system is found continuous, the
Cornstone overlying the Tilestone, and the Quartzose conglomerate the
Cornstone; take into account the fact that, there, each formation has
its characteristic fossil, identical with some characteristic fossil
of the corresponding formation of Scotland--that the Tilestones of
the one, and the lower group of the other, have their _Dipterus_
in common--that the Cornstones of the one, and the middle group of
the other, have their _Cephalaspis_ in common--that the Quartzose
conglomerate of the one, and the upper group of the other, have their
_Holoptychius_ in common; and then say whether the proofs of distinct
succeeding formations can be more surely established. If, however,
the reader still entertain a doubt, let him consult the singularly
instructive section of the entire system, from the Carboniferous
Limestone to the Upper Silurian, given by Mr. Murchison, in his
_Silurian System_, (Part II., Plate XXXI., fig. 1,) and he will find
the doubt vanish. But to return to the fossils of the Cornstone group.
The characteristic fossil of this deposit, the _Cephalaspis_, occurs
in considerable abundance in Forfarshire, and in a much more entire
state than in the Cornstones of England and Wales. The rocks to
which it belongs are also developed, though more sparingly, in
the northern extremity of Fife, in a line parallel to the southern
shores of the Tay. But of all the localities yet known, the Den of
Balruddery is that in which the peculiar organisms of the formation
may be studied with best effect. The oryctology of the Cornstones
of England seems restricted to four species of the _Cephalaspis_.
In Fife, all the organisms of the formation yet discovered are
exclusively vegetable--darkened impressions of stems like those
of the inferior ichthyolite beds, confusedly mixed with what seem
slender and pointed leaflets drawn in black, and numerous circular
forms, which have been deemed the remains of the seed-vessels of
some unknown sub-aerial plant. "These last occur," says Professor
Fleming, the original discoverer, "in the form of circular flat
patches, not equalling an inch in diameter, and composed of numerous
smaller contiguous circular pieces;" the _tout ensemble_ resembling
"what might be expected to result from a compressed berry, such
as the bramble or the rasp." In Forfarshire, the remains of the
_Cephalaspis_ are found associated with impressions of a different
character, though equally obscure--impressions of polished surfaces
carved into seeming scales; but in Balruddery alone are the vegetable
impressions of the one locality, and the scaly impressions of the
other, together with the characteristic ichthyolites of England and
Forfarshire, found associated with numerous fossils besides, many of
them obscure, but all of them of interest, and all of them new to
Geology.
One of the strangest organisms of the formation is a fossil lobster,
of such huge proportions, that one of the average sized lobsters,
common in our markets, might stretch its entire length across the
continuous tail-flap in which the creature terminated. And it is a
marked characteristic of the fossil, that the terminal flap should
be continuous; in all the existing varieties with which I am
acquainted, it is divided into angular sections. The claws nearly
resembled those of the common lobster; their outline is similar;
there is the same hawk-bill curvature outside, and the inner sides of
the pincers are armed with similar teeth-like tubercles. The immense
shield which covered the upper part of the creature's body is more
angular than in the existing varieties, and resembles, both in form
and size, one of those lozenge-shaped shields worn by knights of the
middle ages on gala days, rather for ornament than use, and on which
the herald still inscribes the armorial bearing of ladies who bear
title in their own right. As shown in some of the larger specimens,
the length of this gigantic crustacean must have exceeded four feet.
Its shelly armor was delicately fretted with the forms of circular or
elliptical scales. On all the many plates of which it was composed we
see these described by gracefully waved lines, and rising apparently
from under one another, row beyond row. They were, however, as much
the mere semblance of scales as those relieved by the sculptor on the
corslet of a warrior's effigy on a Gothic tomb--mere sculpturings
on the surface of the shell. This peculiarity may be regarded as
throwing light on the hitherto doubtful impressions of the sandstone
of Forfarshire--impressions, as has been said, of smooth surfaces
carved into seeming scales. They occur as impressions merely, the
sandstone retaining no more of the original substance of the organism
than the impressed wax does of the substance of the seal; and the
workmen in the quarries in which they occur, finding form without
body, and struck by the resemblance which the delicately waved
scales bear to the sculptured markings on the wings of cherubs--of
all subjects of the chisel the most common--fancifully termed them
_Seraphim_. They have turned out, as was anticipated, to be the
detached plates of some such crustacean as the lobster of Balruddery.
The ability displayed by Cuvier in restoring, from a few broken
fragments of bone, the skeleton of the entire animal to which
the fragments had belonged, astonished the world He had learned
to interpret signs as incomprehensible to every one else as the
mysterious handwriting on the wall had been to the courtiers of
Belshazzar. The condyle of a jaw became in his hands a key to
the character of the original possessor; and in a few mouldering
vertebræ, or in the dilapidated bones of a fore-arm or a foot, he
could read a curious history of habits and instincts. In common
with several gentlemen of Edinburgh, all men known to science, I
was as much struck with the skill displayed by Agassiz in piecing
together the fragments of the huge crustacean of Balruddery, and
in demonstrating its nature as such. The numerous specimens of Mr.
Webster were opened out before us. On a previous morning I had
examined them, as I have said, in the company of Mr. Murchison and
Dr. Buckland; they had been seen also by Lord Greenock, Dr. Traill,
and Mr. Charles M'Laren; and their fragments of new and undescribed
fishes had been at once recognized with reference to at least their
class. But the collection contained organisms of a different kind,
which seemed inexplicable to all--forms of various design, but so
regularly mathematical in their outlines that they might be all
described by a ruler and a pair of compasses, and yet the whole were
covered by seeming scales. There were the fragments of scaly rhombs,
of scaly crescents, of scaly circles, with scaly parallelograms
attached to them, and of several other regular compound figures
besides. Mr. Murchison, familiar with the older fossils, remarked the
close resemblance of the seeming scales to those of the _Seraphim_
of Forfarshire, but deferred the whole to the judgment of Agassiz; no
one else hazarded a conjecture. Agassiz glanced over the collection.
One specimen especially caught his attention--an elegantly
symmetrical one. It seemed a combination of the parallelogram and
the crescent: there were pointed horns at each end; but the convex
and concave lines of the opposite sides passed into almost parallel
right lines towards the centre. His eye brightened as he contemplated
it. "I will tell you," he said, turning to the company--"I will tell
you what these are--the remains of a huge lobster." He arranged
the specimens in the group before him with as much apparent ease
as I have seen a young girl arranging the pieces of ivory or
mother-of-pearl in an Indian puzzle. A few broken pieces completed
the lozenge-shaped shield; two detached specimens, placed on its
opposite sides, furnished the claws; two or three semi-rings, with
serrated edges, composed the jointed body; the compound figure,
which but a minute before had so strongly attracted his attention,
furnished the terminal flap; and there lay the huge lobster before
us, palpable to all. There is homage due to supereminent genius,
which nature spontaneously pays when there are no low feelings of
envy or jealousy to interfere with her operations; and the reader may
well believe that it was willingly rendered on this occasion to the
genius of Agassiz.
[Illustration: _PLATE IX._]
The terminal flap of this gigantic crustacean was, as I have said,
continuous. The creature, however, seems to have had contemporaries
of the same family, whose construction in the divisions of the
flap resembled more the lobsters of the present day; and the
reader may see in the subjoined print the representation of a very
characteristic fragment of an animal of this commoner type, from
the Middle Sandstones of Forfarshire. (See Plate IX., fig. 1.) It
is a terminal flap--one of several divisions--curiously fretted by
scale-like markings, and bearing on its lower edge a fringe, cut
into angular points, somewhat in the style of the Vandyke edgings
of a ruff or the lacings of a dead-dress. It may be remarked, in
passing, that our commoner lobsters bear, on the corresponding edge,
fringes of strong, reddish-colored hair. The form altogether, from
its wing-like appearance, its feathery markings, and its angular
points, will suggest to the reader the origin of the name given it by
the Forfarshire workmen. With another such flap spreading out in the
contrary direction, and a periwigged head between them, we would have
one of the sandstone cherubs of our country churchyards complete.
There occur among the other organisms of Balruddery numerous
ichthyodorulites--fin-spines, such as those to which I have called
the attention of the reader in describing the thorny-finned fish of
the lower formation. But the ichthyodorulites of Balruddery differ
essentially from those of Caithness, Moray, and Cromarty. These
last are described on both sides, in every instance, by either
straight, or slightly curved lines; whereas one of the describing
lines in a Balruddery variety is broken by projecting prickles, that
resemble sharp, hooked teeth set in a jaw, or, rather, the entire
ichthyodorulite resembles the sprig of a wild rose-bush, bearing
its peculiar aquiline shaped thorns on one of its sides. Buckland,
in his _Bridgewater Treatise_, and Lyell, in his _Elements_, refer
to this peculiarity of structure in ichthyodorulites of the latter
formations. The hooks are invariably ranged on the concave or
posterior edge of the spine, and were employed, it is supposed,
in elevating the fin. Another ichthyodorulite of the formation
resembles, in the Gothic cast of its roddings, those of the
_Diplacanthus_ of the Lower Old Red Sandstone described in pages 125
and 126 of the present volume, and figured in Plate VIII., fig. 2,
except that it was proportionally stouter, and traversed at its base
by lines running counter to the striæ that furrow it longitudinally.
Of the other organisms of Balruddery I cannot pretend to speak with
any degree of certainty. Some of them seem to have belonged to the
_Radiata_; some are of so doubtful a character that it can scarce
be determined whether they took their place among the forms of the
vegetable or animal kingdoms. One organism in particular, which was
at first deemed the jointed stem of some plant resembling a calamite
of the Coal Measures, was found by Agassiz to be the slender limb
of a crustacean. A minute description of this interesting deposit,
with illustrative prints, would be of importance to science: it would
serve to fill a gap in the scale. The geological pathway, which
leads upwards to the present time from those ancient formations in
which organic existence first began, has been the work of well nigh
as many hands as some of our longer railroads: each contractor has
taken his part; very extended parts have fallen to the share of some,
and admirably have they executed them; but the pathway is not yet
complete, and the completion of a highly curious portion of it awaits
the further labors of Mr. Webster, of Balruddery.
A considerable portion of the rocks of this middle formation in
Scotland are of a bluish-gray color: in Balruddery, they resemble
the mudstones of the Silurian System; they form at Carmylie the
fissile, bluish-gray pavement, so well known in commerce as the
pavement of Arbroath; they occur as a hard, micaceous building-stone
in some parts of Fifeshire; in others they exist as beds of friable,
stratified clay, that dissolve into unctuous masses where washed by
the sea. In England, the formation consists, throughout its entire
depth, of beds of red and green marl, with alternating beds of the
nodular limestones, to which it owes its name, and with here and
there an interposing band of indurated sandstone.
The Cornstone formation is more extensively developed in Forfarshire
than in any other district in Scotland; and from this circumstance
the result of the writer's observations regarding it, during the
course of a recent visit, may be of some little interest to the
reader. About two thirds the entire area of this county is composed
of Old Red Sandstone. It forms a portion of that great belt of the
system which, extending across the island from the German Ocean to
the Frith of Clyde, represents the southern bar of the huge sandstone
frame in which the Highlands of Scotland is set. The Grampians run
along its inner edge--composing part of the primary nucleus which the
frame encloses: the Sidlaw Hills run through its centre in a line
nearly parallel to these, and separated from them by Strathmore, the
great valley of Angus. The valley and the hills thus form, if I may
so express myself, the mouldings of the frame--mouldings somewhat
resembling the semi-recta of the architect. There is first, reckoning
from the mountains downwards, an immense concave curve--the valley;
then an immense convex one--the hills; and then a half curve bounded
by the sea. The illustration may further serve to show the present
condition of the formation: it is a frame much worn by denudation,
and--just as in a _bona fide_ frame--it is the higher mouldings that
have suffered most. Layer after layer has been worn down on the
ridges, exactly as on a raised moulding we may see the gold leaf, the
red pigment, and the whiting, all ground down to the wood; while in
the hollow moulding beside it, on the contrary, the gilt is still
fresh and entire. We find in the hollows the superior layers of the
frame still overlying the inferior ones, and on the heights the
inferior ones laid bare. To descend in the system, therefore, we have
to climb a hill--to rise in it, we have to descend into a valley. We
find the lowest beds of the system any where yet discovered in the
county on the moory heights of Carmylie; its newer deposits may be
found on the sea-shore, beside the limeworks of Hedderwick, and in
the central hollows of Strathmore.
The most ancient beds in the county yet known belong, as
unequivocally shown by their fossils, to but the middle formation of
the system. They have been quarried for many years in the parish of
Carmylie; and the quarries, as may be supposed, are very extensive,
stretching along a moory hill-side for considerably more than a mile,
and furnishing employment to from sixty to a hundred workmen. The
eye is first caught, in approaching them, as we surmount a long,
flat ridge, which shuts them out from the view of the distant sea,
by what seems a line of miniature windmills, the sails flaring with
red lead, and revolving with the lightest breeze at more than double
the rate of the sails of ordinary mills. These are employed--a
lesson probably borrowed from the Dutch--in draining the quarries,
and throw up a very considerable body of water. The line of the
excavations resembles a huge drain, with nearly perpendicular
sides--a consequence of the regular and well-determined character of
the joints with which the strata are bisected. The stone itself is
a gray, close-grained fissile sandstone, of unequal hardness, and
so very tough and coherent--qualities which it seems to owe in part
to the vast abundance of mica which it contains--that it is quite
possible to strike a small hammer through some of the larger flags,
without shattering the edges of the perforation. Hence its value for
various purposes which common sandstone is too brittle and incoherent
to serve. It is extensively used in the neighborhood as a roofing
slate; it is employed, too, in the making of water cisterns, grooved
and jointed as if wrought out of wood, and for the tops of lobby and
billiard tables. I have even seen snuff-boxes fashioned out of it,
as a sort of mechanical feat by the workmen,--a purpose, however,
which it seems to serve only indifferently well,--and single slabs
of it cut into tolerably neat window frames for cottages. It is most
extensively used, however, merely as a paving-stone for lobbies and
lower floors, and the footways of streets. When first deposited,
and when the creatures whose organic remains it still preserves
careered over its numerous platforms, it seems to have existed as
a fine, muddy sand, formed apparently of disintegrated grauwacke
rocks, analogous in their mineral character to the similarly colored
grauwacke of the Lammermuirs, or of primary slates ground down by
attrition into mud, and mixed up with the pulverized fragments of
schistose gneiss and mica schist.
I was first struck, on descending among the workmen, by the
comparative abundance of the vegetable remains. In some parts of the
quarries almost every layer of the strata is covered by carbonaceous
markings--irregularly grooved stems, branching oat into boughs
at acute angles, and that at the first glance seem the miniature
semblances of the trunks of gnarled oaks and elms, blackened in a
morass, and still retaining the rough bark, chapped into furrows:
oblong, leaf-like impressions, too, and impressions of more slender
form, that resemble the narrow, parallel edged leaves of the
sea-grass weed. I observed, in particular, one large bunch of
riband-like leaflets converging into a short stem, so that the whole
resembled a scourge of cords; and I would fain have detached it from
the rock, but it lay on a mouldering film of clay, and broke up with
my first attempt to remove it. A stalk of sea-grass weed plucked up
by the roots, and compressed in a herbarium, would present a somewhat
similar appearance. Among the impressions there occur irregularly
shaped patches, reticulated into the semblance of polygonal meshes.
They remind one of pieces of ill-woven lace; for the meshes are
unequal in size, and the polygons irregular. (See Plate IX., fig.
2.) When first laid open, every mesh is filled with a carbonaceous
speck; and from their supposed resemblance to the eggs of the frog,
the workmen term them _puddock spawn_. They are supposed by Mr.
Lyell to form the remains of the eggs of some gasteropodous mollusc
of the period. I saw one flagstone, in particular, so covered with
these reticulated patches, and so abundant, besides, in vegetable
impressions of both the irregularly furrowed and grass-weed-looking
class, that I could compare it to only the bottom of a ditch beside
a hedge, matted with withered grass, strewed with blackened twigs of
the hawthorn, and mottled with detached masses of the eggs of the
frog. All the larger vegetables are resolved into as pure a coal
as the plants of the Coal Measures themselves--the kind of data,
doubtless, on which unfortunate coal speculators have often earned
disappointment at large expense. None of the vegetables themselves,
however, in the least resemble those of the carboniferous period.
The animal remains, though less numerous, are more interesting. They
are identical with those of the Den of Balruddery. I saw, in the
possession of the superintendent of the quarries, a well-preserved
head of the _Cephalaspis Lyellii_. The crescent-shaped horns were
wanting, and the outline a little obscure; but the eyes were better
marked than in almost any other specimen I have yet seen, and the
circular star-like tubercles which roughen the large occipital
buckler, to which the creature owes its name, were tolerably well
defined. I was shown the head of another individual of the same
species in the centre of a large slab, and nothing could be more
entire than the outline. The osseous plate still retained the
original brownish-white hue of the bone, and its radiated porous
texture; and the sharp crescent-shaped horns were as sharply defined
as during the lifetime of the strangely organized creature which they
had defended. In both specimens the thin angular body was wanting.
Like almost all the other fish of the Old Red Sandstone, the bony
skeleton of the _Cephalaspis_ was external--as much so as the shell
of the crab or lobster: it presented at all points an armor of bone,
as complete as if it had been carved by the ivory-turner out of a
solid block; while the internal skeleton, which in every instance
has disappeared, seems to have been composed of cartilage. I have
compared its general appearance to a saddler's cutting-knife;--I
should, perhaps, have said a saddler's cutting-knife divested of
the wooden handle--the broad, bony head representing the blade, and
the thin angular body the iron stem usually fixed in the wood. No
existence of the present creation at all resembles the _Cephalaspis_.
Were we introduced to the living creatures which now inhabit the
oceans and rivers of Mars and Venus, we could find nothing among them
more strange in appearance, or more unlike our living acquaintances
of the friths and streams, than the _Cephalaspides_ of Carmylie.
I observed, besides, in the quarry, remains of the huge crustacean
of Balruddery. The plates of the _Cephalaspis_ retain the color of
the original bone; the plates of the crustacean, on the contrary,
are of a deep red tint, which contrasts strongly with the cold gray
of the stone. They remind one, both in shape and hue, of pieces of
ancient iron armor, fretted into semi-elliptical scales, and red
with rust. I saw with one of the workmen what seemed to have been
the continuous tail-flap of an individual of very considerable size.
It seemed curiously puckered where it had joined to the body, much
in the manner that a gown or Highlander's kilt is puckered where
it joins to the waistband; and the outline of the whole plate was
marked by what I may venture to term architectural elegance. The
mathematician could have described it with his ruler and compasses.
The superintendent pointed out to me another plate in a slab
dressed for a piece of common pavement. It was a regularly formed
parallelogram, and had obviously composed one of the jointed plates
which had covered the creature's body. I could not so easily assign
its place to yet a third plate in the possession of the Rev. Mr.
Wilson, of Carmylie. It is colored, like the others, and like them,
too, fretted into minute scales, but the form is exactly that of
a heart--not such a heart as the anatomist would draw, but such
a heart, rather, as we see at times on valentines of the humbler
order, or on the ace of hearts in a pack of cards. Possibly enough
it may have been the breastplate of this antique crustacean of
the Cornstones. The spawn of our common blue lobster is composed
of spherical black grains, of nearly the size of mustard-seed. It
struck me as not very improbable that the reticulated markings of the
flagstones of Carmylie may have been produced by the minute eggs of
this fossil crustacean, covered up by some hastily deposited layer of
mingled mud and sand, and forced into the polygonal form by pressing
against each other, and by the weight from above.
The gray fissile bed in which these organisms occur was perforated
to its base on two several occasions, and in different parts of the
quarries--in one instance, merely to ascertain its depth; in the
other, in the course of excavating a tunnel. In the one case it was
found to rest on a bed of trap, which seemed to have insinuated
itself among the strata with as little disturbance, and which lay
nearly as conformably to them as the greenstone bed of Salisbury
Crags does to the alternating sandstones and clays which both
underlie and overtop it. In the other instance the excavators arrived
at a red, aluminous sandstone, veined by a purplish-colored oxide of
iron. The upper strata of the quarry are overlaid by a thick bed of
grayish-red conglomerate.
Leaving behind us the quarries of Carmylie, we descend the hill-side,
and rise in the system as we lower our level and advance upon the
sea. For a very considerable distance we find the rock covered up by
a deep-red diluvial clay, largely charged with water-worn boulders,
chiefly of the older primary rocks, and of the sandstone underneath.
The soil on the higher grounds is moory and barren--a consequence,
in great part, of a hard, ferruginous pan, which interposes like
a paved floor between the diluvium and the upper mould, and which
prevents the roots of the vegetation from striking downwards into
the tenacious subsoil. From its impervious character, too, it has
the effect of rendering the surface a bog for one half the year,
and an arid, sun-baked waste for the other. It seems not improbable
that the heaths which must have grown and decayed on these heights
for many ages, may have been main agents in the formation of this
pavement of barrenness. Of all plants, they are said to contain most
iron. According to Fourcroy, a full twelfth part of the weight of
oak, when dried, is owing to the presence of this almost universally
diffused metal; and the proportion in our common heaths is still
larger. It seems easy to conceive how that, as generation after
generation withered on these heights, and were slowly resolved into
a little mossy dust, the minute metallic particles which they had
contained would be carried downwards by the rains through the lighter
stratum of soil, till, reaching the impermeable platform of tenacious
clay beneath, they would gradually accumulate there, and at length
bind its upper layer, as is the nature of ferruginous oxide, into a
continuous stony crust. Bog iron, and the clay ironstone, so abundant
in the Coal Measures, and so extensively employed in our iron-works,
seem to have owed their accumulation in layers and nodules to a
somewhat similar process, through the agency of vegetation. But I
digress.
The rock appears in the course of the Elliot, a few hundred yards
above the pastoral village of Arbirlot. We find it uptilted on
a mass of claystone amygdaloid, that has here raised its broad
back to the surface amid the middle shales and sandstones of the
system. The stream runs over the intruded mass; and where the latter
terminates, and the sandstones lean against it, the waters leap
from the harder to the softer rock, immediately beside the quiet
parish burying-ground, in a cascade of some eight or ten feet. From
this point, for a full mile downwards, we find an almost continuous
section of the sandstone--stratum leaning against stratum--in an
angle of about thirty. The portion of the system thus exhibited must
amount to many hundred yards in vertical extent; but as I could
discover no data by which to determine regarding the space which
may intervene between its lowest stratum and the still lower beds
of Carmylie, I could form no guess respecting the thickness of
the whole. In a bed of shale, about a quarter of a mile below the
village, I detected several of the vegetable impressions of Carmylie,
especially those of the grass-weed looking class, and an imperfectly
preserved organism resembling the parallelogramical scale of a
_Cephalaspis_. The same plants and animals seem to have existed on
this high platform as on the Carmylie platform far beneath.
A little farther down the course of the stream, and in the immediate
neighborhood of the old weather-worn tower of the Ouchterlonies,
there occurs what seems a break in the strata. The newer sandstones
seem to rest unconformably on the older sandstones which they
overlie. The evening on which I explored the course of the Elliot
was drizzly and unpleasant, and the stream swollen by a day of
continuous rain, and so I could not examine so minutely as in other
circumstances I would have done, or as was necessary to establish
the fact. In since turning over the _Elements_ of Lyell, however, I
find, in his section of Forfarshire, that a newer deposit of nearly
horizontal strata of sandstone and conglomerate lies unconformably,
in the neighborhood of the sea, on the older sandstones of the
district; and the appearances observed near the old tower mark, it is
probable, one of the points of junction--a point of junction also,
if I may be so bold as venture the suggestion, of the formation
of the _Holoptychius nobilissimus_ with the formation of the
_Cephalaspis_--of the quartzose conglomerate with the Cornstones. In
my hurried survey, however, I could find none of the scales or plates
of the newer ichthyolite in this upper deposit, though the numerous
spherical markings of white, with their centrical points of darker
color, show that at one time the organisms of these upper beds must
have been very abundant.
We pass to the upper formation of the system. Over the belt of
mingled gray and red there occurs in the pyramid a second deep belt
of red conglomerate and variegated sandstone, with a band of lime
a-top, and over the band a thick belt of yellow sandstone, with
which the system terminates.[AN] Thus the second pyramid consists
mineralogically, like the first, of three great divisions, or
bands; its two upper belts belonging, like the three belts of the
other, to but one formation--the formation known in England as the
Quartzose Conglomerate. It is largely developed in Scotland. We
find it spread over extensive areas in Moray, Fife, Roxburgh, and
Berwick shires. In England, it is comparatively barren in fossils;
the only animal organic remains yet detected in it being a single
scale of the _Holoptychius_ found by Mr. Murchison; and though it
contains vegetable organisms in more abundance, so imperfectly
are they preserved, that little else can be ascertained regarding
them than that they were land plants, but not identical with the
plants of the Coal Measures. In Scotland, the formation is richly
fossiliferous, and the remains belong chiefly to the animal kingdom.
It is richly fossiliferous, too, in Russia, where it was discovered
by Mr. Murchison, during the summer of last year, spread over areas
many thousand square miles in extent. And there, as in Scotland, the
_Holoptychius_ seems its most characteristic fossil.
[Footnote AN: There still exists some uncertainty regarding the
order in which the upper beds occur. Mr. Duff, of Elgin, places the
limestone band above the yellow sandstone; Messrs. Sedgwick and
Murchison assign it an intermediate position between the red and
yellow. The respective places of the gray and red sandstones are also
disputed, and by very high authorities; Dr. Fleming holding that the
gray sandstones overlie the red, (see _Cheek's Edinburgh Journal_
for February, 1831,) and Mr. Lyell, that the red sandstones overlie
the gray, (see _Elements of Geology_, first edit., pp. 99-100.) The
order adopted above consorts best with the results of the writer's
observations, which have, however, been restricted chiefly to the
north country. He assigns to the limestone band the middle place
assigned to it by Messrs. Sedgwick and Murchison, and to the gray
sandstone the inferior position assigned to it by Mr. Lyell; aware,
however, that the latter deposit has not only a coping, but also a
basement, of red sandstone--the basement forming the upper member of
the lower formation.]
The fact seems especially worthy of remark. The organisms of some of
the newer formations differ entirely, in widely separated localities,
from their contemporary organisms, just as, in the existing state
of things, the plants and animals of Great Britain differ from the
plants and animals of Lapland or of Sierra Leone. A geologist who
has acquainted himself with the belemnites, baculites, turrilites,
and sea-urchins of the Cretaceous group in England and the north
of France, would discover that he had got into an entirely new
field among the hippurites, sphærulites, and nummulites of the same
formations, in Greece, Italy, and Spain; nor, in passing the tertiary
deposits, would he find less striking dissimilarities between the
gigantic, mail-clad megatherium and huge mastodon of the Ohio and
the La Plate, and the monsters, their contemporaries, the hairy
mammoth of Siberia, and the hippopotamus and rhinoceros of England
and the Continent. In the more ancient geological periods, ere the
seasons began, the case is essentially different; the contemporary
formations, when widely separated, are often very unlike in
mineralogical character, but in their fossil contents they are almost
always identical. In these earlier ages, the atmospheric temperature
seems to have depended more on the internal heat of the earth, only
partially cooled down from its original state, than on the earth's
configuration or the influence of the sun. Hence a widely spread
equality of climate--a greenhouse equalization of heat, if I may
so speak; and hence, too, it would seem, a widely spread Fauna and
Flora. The greenhouses of Scotland and Sweden produce the same plants
with the greenhouses of Spain and Italy; and when the world was one
vast greenhouse, heated from below, the same families of plants,
and the same tribes of animals, seem to have ranged over spaces
immensely more extended than those geographical circles in which,
in the present time, the same plants are found indigenous, and the
same animals native. The fossil remains of the true Coal Measures
are the same to the westward of the Alleghany Mountains as in New
Holland, India, Southern Africa, the neighborhood of Newcastle, and
the vicinity of Edinburgh. And I entertain little doubt that, on a
similar principle, the still more ancient organisms of the Old Red
Sandstone will be found to bear the same character all over the
world.