CHAPTER XII.

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.