The two Aspects in which. Matter can be viewed; Space and
Time.--Geological History of the Earlier Periods.--The Cambrian
System,--Its Annelids.--The Silurian System.--Its Corals, Encrinites,
Molluscs, and Trilobites.--Its Fish.--These of a high Order, and
called into Existence apparently by Myriads.--Opening Scene in the
History of the Old Red Sandstone a Scene of Tempest.--Represented by
the Great Conglomerate.--Red a prevailing Color among the Ancient
Rocks contained in this Deposit.--Amazing Abundance of Animal
Life.--Exemplified by a Scene in the Herring Fishery.--Platform of
Death.--Probable Cause of the Catastrophe which rendered it such.
"There are only two different aspects," says Dr. Thomas Brown, "in
which matter can be viewed. We may consider it simply as it exists,
in space, or as it exists in time. As it exists in space we inquire
into its composition, or, in other words, endeavor to discover
what are the elementary bodies that coexist in the space which it
occupies; as it exists in time, we inquire into its susceptibilities
or its powers, or, in other words, endeavor to trace all the various
changes which have already passed over it, or of which it may yet
become the subject."
Hitherto I have very much restricted myself to the consideration of
the Old Red Sandstone as it exists in _space_--to the consideration
of it as we now find it. I shall now attempt presenting it to the
reader as it existed in _time_--during the succeeding periods of its
formation, and when its existences lived and moved as the denizens
of primeval oceans. It is one thing to describe the appearance of a
forsaken and desert country, with its wide wastes of unprofitable
sand, its broken citadels and temples, its solitary battle-plains,
and its gloomy streets of caverned and lonely sepulchres; and quite
another to record its history during its days of smiling fields,
populous cities, busy trade, and monarchical splendor. We pass from
the dead to the living--from the cemetery, with its high piles of
mummies and its vast heaps of bones, to the ancient city, full of
life and animation in all its streets and dwellings.
Two great geological periods have already come to their close; and
the floor of a widely-spread ocean, to which we can affix no limits,
and of whose shores or their inhabitants nothing is yet known, is
occupied to the depth of many thousand feet by the remains of bygone
existences. Of late, the geologist has learned from Murchison to
distinguish the rocks of these two periods--the lower as those
of the Cambrian, the upper as those of the Silurian group. The
lower--representative of the first glimmering twilight of being--of a
dawn so feeble that it may seem doubtful whether in reality the gloom
had lightened--must still be regarded as a period of uncertainty.
Its ripple-marked sandstones, and its half coherent accumulations of
dark-colored strata, which decompose into mud, show that every one
of its many plains must have formed in succession an upper surface
of the bottom of the sea; but it remains for future discoverers to
determine regarding the shapes of life that burrowed in its ooze,
or careered through the incumbent waters. In one locality it would
seem as if a few worms had crawled to the surface, and left their
involved and tortuous folds doubtfully impressed on the stone.
Some of them resemble miniature cables, carelessly coiled; others,
furnished with what seem numerous legs, remind us of the existing
Nereidina of our sandy shores--those red-blooded, many-legged worms,
resembling elongated centipedes, that wriggle with such activity
among the mingled mud and water, as we turn over the stones under
which they had sheltered. Were creatures such as these the lords of
this lower ocean? Did they enter first on the stage, in that great
drama of being in which poets and philosophers, monarchs and mighty
conquerors, were afterwards to mingle as actors? Does the reader
remember that story in the _Arabian Nights_, in which the battle of
the magicians is described? At an early stage of the combat a little
worm creeps over the pavement; at its close two terrible dragons
contend in an atmosphere of fire. But even the worms of the Cambrian
System can scarce be regarded as established. The evidence respecting
their place and their nature must still be held as involved in some
such degree of doubt as attaches to the researches of the antiquary,
when engaged in tracing what their remains much resemble--the
involved sculpturings of some Runic obelisk, weathered by the storms
of a thousand winters. There is less of doubt, however, regarding the
existences of the upper group of rocks--the Silurian.
The depth of this group, as estimated by Mr. Murchison, is equal
to double the height of our highest Scottish mountains; and four
distinct platforms of being range in it, the one over the other,
like stories in a building. Life abounded on all these platforms,
and in shapes the most wonderful. The peculiar encrinites of the
group rose in miniature forests, and spread forth their sentient
petals by millions and tens of millions amid the waters; vast ridges
of corals peopled by their innumerable builders,--numbers without
number,--rose high amid the shallows; the chambered shells had
become abundant--the simpler testacea still more so; extinct forms of
the graptolite, or sea-pen, existed by myriads; and the formation
had a class of creatures in advance of the many-legged annelids of
the other. It had its numerous family of trilobites,--crustaceans
nearly as high in the scale as the common crab,--creatures with
crescent-shaped heads, and jointed bodies, and wonderfully
constructed eyes, which, like the eyes of the bee and the butterfly,
had the cornea cut into facets resembling those of a multiplying
glass. Is the reader acquainted with the form of the common _Chiton_
of our shores--the little boat-shaped shell-fish, that adheres to
stones and rocks like the limpet, but which differs from every
variety of limpet, inbearing as its covering a jointed, not a
continuous shell? Suppose a chiton with two of its terminal joints
cut away, and a single plate of much the same shape and size, but
with two eyes near the centre, substituted instead, and the animal,
in form at least, would be no longer a chiton, but a trilobite. There
are appearances, too, which lead to the inference that the habits of
the two families, though representing different orders of being, may
not have been very unlike. The chiton attaches itself to the rock
by a muscular sucker or foot, which, extending vent rally along its
entire length, resembles that of the slug or the snail, and enables
it to crawl like them, but still more slowly, by a succession of
adhesions. The locomotive powers of the trilobite seem to have been
little superior to those of the chiton. If furnished with legs at
all, it must have been with soft rudimentary membranaceous legs,
little fitted for walking with; and it seems quite as probable, from
the peculiarly shaped under margin of its shell, formed, like that
of the chiton, for adhering to flat surfaces, that, like the slug
and the snail, it was unfurnished with legs of any kind, and crept
on the abdomen. The vast conglomerations of trilobites for which the
Silurian rocks are remarkable, are regarded as further evidence of a
sedentary condition, Like _Ostreæ_, _Chitones_, and other sedentary
animals, they seemed to have adhered together in vast clusters,
trilobite over trilobite, in the hollows of submarine precipices, or
on the flat, muddy bottom below. And such were the master existences
of three of the four Silurian platforms, and of the greater part of
the fourth, if, indeed, we may not regard the chambered molluscs,
their contemporaries,--creatures with their arms clustered round
their heads, and with a nervous system composed of a mere knotted
cord,--as equally high in the scale. We rise to the topmost layers of
the system,--to an upper gallery of its highest platform,--and find
nature mightily in advance.
Another and superior order of existences had sprung into being at
the fiat of the Creator--creatures with the brain lodged in the
head, and the spinal cord enclosed in a vertebrated column. In the
period of the Upper Silurian, fish properly so called, and of very
perfect organization, had become denizens of the watery element,
and had taken precedence of the crustacean, as, at a period long
previous, the crustacean had taken precedence of the annelid. In
what form do these, the most ancient beings of their class, appear?
As cartilaginous fishes of the higher order. Some of them were
furnished with bony palates, and squat, firmly-based teeth, well
adapted for crushing the stone-cased zoöphytes and shells of the
period, fragments of which occur in their fœcal remains; some with
teeth that, like those of the fossil sharks of the later formations,
resemble lines of miniature pyramids, larger and smaller alternating;
some with teeth sharp, thin, and so deeply serrated that every
individual tooth resembles a row of poniards set upright against the
walls of an armory; and these last, says Agassiz, furnished with
weapons so murderous, must have been the pirates of the period. Some
had their fins guarded with long spines, hooked like the beak of
an eagle; some with spines of straighter and more slender form, and
ribbed and furrowed longitudinally like columns; some were shielded
by an armor of bony points; and some thickly covered with glistening
scales. If many ages must have passed ere fishes appeared, there was
assuredly no time required to elevate their lower into their higher
families. Judging, too, from this ancient deposit, they seem to have
been introduced, not by individuals and pairs, but by whole myriads.
"Forthwith, the sounds and seas, each creek and bay,
With fry innumerable swarmed; and shoals
Of fish, that with their fins and shining scales
Glide under the green wave in plumps and sculls,
Banked the mid sea."
The fish-bed of the Upper Ludlow Rock abounds more in osseous remains
than an ancient burying-ground. The stratum, over wide areas, seems
an almost continuous layer of matted bones, jaws, teeth, spines,
scales, palatal plates, and shagreen-like prickles, all massed
together, and converted into a substance of so deep and shining
a jet color, that the bed, when "first discovered, conveyed the
impression," says Mr. Murchison, "that it enclosed a triturated heap
of black beetles." And such are the remains of what seem to have
been the first existing vertebrata. Thus, ere our history begins,
the existences of two great systems, the Cambrian and the Silurian,
had passed into extinction, with the exception of what seem a few
connecting links, exclusively molluscs, that are found in England
to pass from the higher beds of the Ludlow rocks into the Lower
or Tilestone beds of the Old Red Sandstone.[AZ] The exuviæ of at
least four platforms of being lay entombed furlong below furlong,
amid the gray, mouldering mudstones, the harder arenaceous beds, the
consolidated clays, and the concretionary limestones, that underlay
the ancient ocean of the Lower Old Red. The earth had already become
a vast sepulchre, to a depth beneath the bed of the sea equal to at
least twice the height of Ben Nevis over its surface.
[Footnote AZ: "Upwards of eight hundred extinct species of animals
have been described as belonging to the earliest, or Protozoic and
Silurian period, and of these only about one hundred are found also
in the overlying Devonian series; while but fifteen are common to
the whole Palæozoic period, and not one extends beyond it."--(_M. de
Verneuil and Count D'Archiac_, quoted by Mr. D. T. Ansted. 1844.)]
The first scene in the _Tempest_ opens amid the confusion and turmoil
of the hurricane--amid thunders and lightnings, the roar of the
wind, the shouts of the seamen, the rattling of cordage, and the
wild dash of the billows. The history of the period represented by
the Old Red Sandstone seems, in what now forms the northern half of
Scotland, to have opened in a similar manner. The finely-laminated
lower Tilestones of England were deposited evidently in a calm sea.
During the contemporary period in our own country, the vast space
which now includes Orkney and Loch Ness, Dingwall, and Gamrie, and
many a thousand square mile besides, was the scene of a shallow
ocean, perplexed by powerful currents, and agitated by waves. A vast
stratum of water-rolled pebbles, varying in depth from a hundred feet
to a hundred yards, remains in a thousand different localities, to
testify of the disturbing agencies of this time of commotion. The
hardest masses which the stratum encloses,--porphyries of vitreous
fracture that cut glass as readily as flint, and masses of quartz
that strike fire quite as profusely from steel,--are yet polished
and ground down into bullet-like forms, not an angular fragment
appearing in some parts of the mass for yards together. The debris
of our harder rocks rolled for centuries in the beds of our more
impetuous rivers, or tossed for ages along our more exposed and
precipitous sea-shores, could not present less equivocally the marks
of violent and prolonged attrition than the pebbles of this bed. And
yet it is surely difficult to conceive how the bottom of any sea
should have been so violently and so equally agitated for so greatly
extended a space as that which intervenes between Mealforvony in
Inverness-shire and Pomona in Orkney in one direction, and between
Applecross and Trouphead in another--and for a period so prolonged,
that the entire area should have come to be covered with a stratum
of rolled pebbles of almost every variety of ancient rock, fifteen
stories' height in thickness. The very variety of its contents shows
that the period must have been prolonged. A sudden flood sweeps away
with it the accumulated debris of a range of mountains; but to blend
together, in equal mixture, the debris of many such ranges, as well
as to grind down their roughnesses and angularities, and fill up the
interstices with the sand and gravel produced in the process, must
be a work of time. I have examined with much interest, in various
localities, the fragments of ancient rock inclosed in this formation.
Many of them are no longer to be found in situ, and the group is
essentially different from that presented by the more modern gravels.
On the shores of the Frith of Cromarty, for instance, by far the most
abundant pebbles are of a blue schistose gneiss: fragments of gray
granite and white quartz are also common; and the sea-shore at half
ebb presents at a short distance the appearance of a long belt of
bluish gray, from the color of the prevailing stones which compose
it. The prevailing color of the conglomerate of the district, on the
contrary, is a deep red. It contains pebbles of small-grained, red
granite, red quartz rock, red feldspar, red porphyry, an impure red
jasper, red hornstone, and a red granitic gneiss, identical with
the well-marked gneiss of the neighboring Sutors. This last is the
only rock now found in the district, of which fragments occur in the
conglomerate. It must have been exposed at the time to the action of
the waves, though afterwards buried deep under succeeding formations,
until again thrust to the surface by some great internal convulsion,
of a date comparatively recent.[BA]
[Footnote BA: The vast beds of unconsolidated gravel with which one
of the later geological revolutions has half filled some of our
northern valleys, and covered the slopes of the adjacent hills,
present, in a few localities, appearances somewhat analogous to
those exhibited by this ancient formation. There are uncemented
accumulations of water-rolled pebbles, in the neighborhood of
Inverness, from ninety to a hundred feet in thickness. But this
stratum, unlike the more ancient one, wanted continuity. It must have
been accumulated, too, under the operation of more partial, though
immensely more powerful agencies. There is a mediocrity of size in
the enclosed fragments of the old conglomerate, which gives evidence
of a mediocrity of power in the transporting agent. In the upper
gravels, on the contrary, one of the agents could convey from vast
distances blocks of stone eighty and a hundred tons in weight. A new
cause of tremendous energy had come into operation in the geological
world.]
The period of this shallow and stormy ocean passed. The bottom,
composed of the identical conglomerate which now forms the summit
of some of our loftiest mountains, sank throughout its wide area to
a depth so profound as to be little affected by tides or tempests.
During this second period there took place a vast deposit of coarse
sandstone strata, with here and there a few thin beds of rolled
pebbles. The general subsidence of the bottom still continued, and,
after a deposit of full ninety feet had overlain the conglomerate,
the depth became still more profound than at first. A fine,
semi-calcareous, semi-aluminous deposition took place in waters
perfectly undisturbed. And here we first find proof that this ancient
ocean literally swarmed with life--that its bottom was covered with
miniature forests of algæ, and its waters darkened by immense shoals
of fish.
In middle autumn, at the close of the herring season, when the fish
have just spawned, and the congregated masses are breaking up on
shallow and skerry, and dispersing by myriads over the deeper seas,
they rise at times to the surface by a movement so simultaneous, that
for miles and miles around the skiff of the fisherman nothing may be
seen but the bright glitter of scales, as if the entire face of the
deep were a blue robe spangled with silver. I have watched them at
sunrise at such seasons on the middle of the Moray Frith, when, far
as the eye could reach, the surface has been ruffled by the splash
of fins, as if a light breeze swept over it, and the red light has
flashed in gleams of an instant on the millions and tens of millions
that were leaping around me, a handbreadth into the air, thick as
hail-stones in a thunder-shower. The amazing amount of life which
the scene included, has imparted to it an indescribable interest.
On most occasions the inhabitants of ocean are seen but by scores
and hundreds; for in looking down into their green twilight haunts,
we find the view bounded by a few yards, or at most a few fathoms;
and we can but calculate on the unseen myriads of the surrounding
expanse by the seen few that occupy the narrow space visible. Here,
however, it was not the few, but the myriads, that were seen--the
innumerable and inconceivable whole--all palpable to the sight as a
flock on a hill-side; or, at least, if all was not palpable, it was
only because sense has its limits in the lighter as well as in the
denser medium--that the multitudinous distracts it, and the distant
eludes it, and the far horizon bounds it. If the scene spoke not of
infinity in the sense in which Deity comprehends it, it spoke of it
in at least the only sense in which man can comprehend it.
Now, we are much in the habit of thinking of such amazing
multiplicity of being--when we think of it at all--with reference to
but the later times of the world's history. We think of the remote
past as a time of comparative solitude. We forget that the now
uninhabited desert was once a populous city. Is the reader prepared
to realize, in connection with the Lower Old Red Sandstone--the
second period of vertebrated existence--scenes as amazingly fertile
in life as the scene just described--oceans as thoroughly occupied
with being as our friths and estuaries when the herrings congregate
most abundantly on our coasts? There are evidences too sure to
be disputed that such must have been the case. I have seen the
ichthyolite beds, where washed bare in the line of the strata, as
thickly covered with oblong, spindle-shaped nodules as I have ever
seen a fishing bank covered with herrings; and have ascertained
that every individual nodule had its nucleus of animal matter--that
it was a stone coffin in miniature, holding enclosed its organic
mass of bitumen or bone--its winged, or enamelled, or thorn-covered
ichthyolite.
At this period of our history, some terrible catastrophe involved
in sudden destruction the fish of an area at least a hundred miles
from boundary to boundary, perhaps much more. The same platform
in Orkney as at Cromarty is strewed thick with remains, which
exhibit unequivocally the marks of violent death. The figures are
contorted, contracted, curved; the tail in many instances is bent
round to the head; the spines stick out; the fins are spread to the
full, as in fish that die in convulsions. The _Pterichthys_ shows
its arms extended at their stiffest angle, as if prepared for an
enemy. The attitudes of all the ichthyolites on this platform are
attitudes of fear, anger, and pain. The remains, too, appear to
have suffered nothing from the after attacks of predaceous fishes;
none such seem to have survived. The record is one of destruction
at once widely spread and total, so far as it extended. There are
proofs that, whatever may have been the cause of the catastrophe,
it must have taken place in a sea unusually still. The scales, when
scattered by some slight undulation, are scattered to the distance
of only a few inches, and still exhibit their enamel entire, and
their peculiar fineness of edge. The spines, even when separated,
retain their original needle-like sharpness of point. Rays, well
nigh as slender as horse-hairs, are enclosed unbroken in the mass.
Whole ichthyolites occur, in which not only all the parts survive,
but even the expression which the stiff and threatening attitude
conveyed when the last struggle was over. Destruction must have come
in the calm, and it must have been of a kind by which the calm was
nothing disturbed. In what could it have originated? By what quiet
but potent agency of destruction were the innumerable existences of
an area perhaps ten thousand square miles in extent annihilated at
once, and yet the medium in which they had lived left undisturbed
by its operations? Conjecture lacks footing in grappling with the
enigma, and expatiates in uncertainty over all the known phenomena of
death. Diseases of mysterious origin break out at times in the animal
kingdom, and well nigh exterminate the tribes on which they fall. The
present generation has seen a hundred millions of the human family
swept away by a disease unknown to our fathers. Virgil describes the
fatal murrain that once depopulated the Alps, not more as a poet than
as a historian. The shell-fish of the rivers of North America died in
such vast abundance during a year of the present century, that the
animals, washed out of their shells, lay rotting in masses beside the
banks, infecting the very air. About the close of the last century,
the haddock well nigh disappeared, for several seasons together,
from the eastern coasts of Scotland; and it is related by Creech,
that a Scotch shipmaster of the period sailed for several leagues on
the coast of Norway, about the time the scarcity began, through a
floating shoal of dead haddocks.[BB]
[Footnote BB: I have heard elderly fishermen of the Moray Frith
state, in connection with what they used to term "the haddock dearth"
of this period, that, for several weeks ere the fish entirely
disappeared, they acquired an extremely disagreeable taste, as if
they had been boiled in tobacco juice, and became unfit for the
table. For the three following years they were extremely rare on the
coast, and several years more elapsed ere they were caught in the
usual abundance. The fact related by Creech, a very curious one, I
subjoin in his own words; it occurs in his third _Letter to Sir John
Sinclair_: "On Friday, the 4th December, 1789, the ship _Brothers_,
Captain Stewart, arrived at Leith from Archangel, who reported that,
on the coast of Lapland and Norway, he sailed many leagues through
immense quantities of dead haddocks floating on the sea. He spoke
several English ships, who reported the same fact. It is certain
that haddocks, which was the fish in the greatest abundance in the
Edinburgh market, have scarcely been seen there these three years. In
February, 1790, three haddocks were brought to market, which, from
their scarcity, sold for 7s. 6d."
The dead haddocks seen by the Leith shipmaster were floating by
thousands; and most of their congeners among what fishermen term
"the white fish," such as cod, ling, and whiting, also float when
dead; whereas the bodies of fish whose bowels and air-bladders are
comparatively small and tender, lie at the bottom. The herring
fisherman, if the fish die in his nets, finds it no easy matter to
buoy them up; and if the shoal entangled be a large one, he fails at
times, from the great weight, in recovering them at all, losing both
nets and herrings. Now, if a corresponding difference obtained among
fish of the extinct period--if some rose to the surface when they
died, while others remained at the bottom--we must, of course, expect
to find their remains in very different degrees of preservation--to
find only scattered fragments of the floaters, while of the others
many may occur comparatively entire. Even should they have died
on the same beds, too, we may discover their remains separated by
hundreds of miles. The haddocks that disappeared from the coast of
Britain were found floating in shoals on the coasts of Norway. The
remains of an immense body of herrings, that weighed down, a few
seasons since, the nets of a crew of fishermen, in a muddy hollow
of the Moray Frith, and defied the utmost exertions of three crews
united to weigh them from the bottom, are, I doubt not, in the
muddy hollow still. On a principle thus obvious it may be deemed
not improbable that the ichthyolites of the Lower Old Red Sandstone
might have had numerous contemporaries, of which, unless in some
instances the same accident which killed also entombed them, we can
know nothing in their character as such, and whose broken fragments
may yet be found in some other locality, where they may be regarded
as characteristic of a different formation.]
But the ravages of no such disease, however extensive, could well
account for some of the phenomena of this platform of death. It
is rarely that disease falls equally on many different tribes
at once, and never does it fall with instantaneous, suddenness;
whereas in the ruin of this platform from ten to twelve distinct
genera seem to have been equally involved; and so suddenly did
it perform its work, that its victims were fixed in their first
attitude of terror and surprise. I have observed, too, that groups
of adjoining nodules are charged frequently with fragments of the
same variety of ichthyolite; and the circumstance seems fraught with
evidence regarding both the original habits of the creatures, and
the instantaneous suddenness of the destruction by which they were
overtaken. They seem, like many of our existing fish, to have been
gregarious, and to have perished together ere their crowds had time
to break up and disperse.
Fish, have been found floating dead in shoals beside submarine
volcanoes--killed either by the heated water, or by mephitic gases.
There are, however, no marks of volcanic activity in connection with
the ichthyolite beds--no marks, at least, which belong to nearly the
same age with the fossils. The disturbing granite of the neighboring
eminences was not upheaved until after the times of the Oolite.
But the volcano, if such was the destroying agent, might have been
distant; nay, from some of the points in an area of such immense
extent, it must have been distant. The beds abound, as has been said,
in lime; and the thought has often struck me that calcined lime, cast
out as ashes from some distant crater, and carried by the winds,
might have been the cause of the widely-spread destruction to which
their organisms testify. I have seen the fish of a small trouting
stream, over which a bridge was in the course of building, destroyed
in a single hour, for a full mile below the erection, by the few
troughfuls of lime that fell into the water when the centring was
removed.