Chapter II: Part 2

The monuments of this era of profuse vegetation reveal themselves in the precious Coal-measures of England and Scotland. These give us some idea of the rich verdure which covered the surface of the earth, newly risen from the bosom of its parent waves. It was the paradise of terrestrial vegetation. The grand _Sigillaria_, the _Stigmaria_, and other fern-like plants, were especially typical of this age, and formed the woods, which were left to grow undisturbed; for as yet no living Mammals seem to have appeared; everything indicates a uniformly warm, humid temperature, the only climate in which the gigantic ferns of the Coal-measures could have attained their magnitude. Conifers have been found of this period with concentric rings, but these rings are more slightly marked than in existing trees of the same family, from which it is reasonable to assume that the seasonal changes were less marked than they are with us.

Everything announces that the time occupied in the deposition of the Carboniferous Limestone was one of vast duration. Professor Phillips calculates that, at the ordinary rate of progress, it would require 122,400 years to produce only sixty feet of coal. Geologists believe, moreover, that the upper Coal-measures, where bed has been deposited upon bed for ages upon ages, were accumulated under conditions of comparative tranquillity, but that the end of this period was marked by violent convulsions--by ruptures of the terrestrial crust, when the carboniferous rocks were upturned, contorted, dislocated by faults, and subsequently partially denuded, and thus appear now in depressions or basin-shaped concavities; and that upon this deranged and disturbed foundation a fourth geological system, called Permian, was constructed.

Coal, as we shall find, is composed of the mineralized remains of the vegetation which flourished in remote ages of the world. Buried under an enormous thickness of rocks, it has been preserved to our days, after being modified in its inward nature and external aspect. Having lost a portion of its elementary constituents, it has become transformed into a species of carbon, impregnated with those bituminous substances which are the ordinary products of the slow decomposition of vegetable matter.

Thus, coal is the substance of the plants which formed the forests, the vegetation, and the marshes of the ancient world, at a period too distant for human chronology to calculate with anything like precision.

It is a remarkable circumstance that conditions of equable and warm climate, combined with humidity, do not seem to have been limited to any one part of the globe, but the temperature of the whole globe seems to have been nearly the same in very different latitudes. From the equatorial regions up to Melville Island, in the Arctic Ocean, where in our days eternal frost prevails--from Spitzbergen to the centre of Africa, the carboniferous flora is identically the same. When nearly the same plants are found in Greenland and Guinea; when the same species, now extinct, are met with of equal development at the equator as at the pole, we can not but admit that at this epoch the temperature of the globe was nearly alike everywhere. What we now call _climate_ was unknown in these geological times. There seems to have been then only one climate over the whole globe. It was at a subsequent period, that is, in later Tertiary times, that the cold began to make itself felt at the terrestrial poles. Whence, then, proceeded this general superficial warmth, which we now regard with so much surprise? It was a consequence of the greater or nearer influence of the interior heat of the globe. The earth was still so hot in itself that the heat which reached it from the sun may have been inappreciable.

Another hypothesis, which has been advanced with much less certainty than the preceding, relates to the chemical composition of the air during the Carboniferous period. Seeing the enormous mass of vegetation which then covered the globe, and extended from one pole to the other; considering, also, the great proportion of carbon and hydrogen which exists in the bituminous matter of coal, it has been thought, and not without reason, that the atmosphere of the period might be richer in carbonic acid than the atmosphere of the present day. It has even been thought that the small number of (especially air-breathing) animals, which then lived, might be accounted for by the presence of a greater proportion of carbonic acid gas in the atmosphere than is the case in our own times. This, however, is pure assumption, totally deficient in proof. What we can remark, with certainty, as a striking characteristic of the vegetation of the globe during this phase of its history, was the prodigious development which it assumed. The Ferns, which in our days and in our climate are most commonly only small perennial plants, in the Carboniferous age sometimes presented themselves under lofty and even magnificent forms.

Every one knows those marsh-plants with hollow, channeled, and articulated cylindrical stems; whose joints are furnished with a membranous, denticulated sheath, and which bear the vulgar name of “mare’s-tail”; their fructification forming a sort of catkin composed of many rings of scales, carrying on their lower surface sacs full of _spores_ or seeds. These humble _Equiseta_ were represented during the coal-period by herbaceous trees from twenty to thirty feet high and four to six inches in diameter. Their trunks, channeled longitudinally, and divided transversely by lines of articulation, have been preserved to us: they bear the name of _Calamites_.

The _Lycopods_ of our age are humble plants, scarcely a yard in height, and most commonly creepers; but the Lycopodiaceæ of the ancient world were trees of eighty or ninety feet in height. It was the _Lepidodendrons_ which filled the forests. Their leaves were sometimes twenty inches long, and their trunks a yard in diameter. Such are the dimensions of some specimens of _Lepidodendron carinatum_ which have been found. Another Lycopod of this period, the _Lomatophloyos crassicaule_, attained dimensions still more colossal. The _Sigillarias_ sometimes exceeded 100 feet in height. Herbaceous Ferns were also exceedingly abundant, and grew beneath the shade of these gigantic trees. It was the combination of these lofty trees with such shrubs (if we may so call them) which formed the forests of the Carboniferous period.

How this vegetation, so imposing, both on account of the dimensions of the individual trees and the immense space which they occupied, so splendid in its aspect, and yet so simple in its organization, must have differed from that which now embellishes the earth and charms our eyes! It certainly possessed the advantage of size and rapid growth; but how poor it was in species--how uniform in appearance! No flowers yet adorned the foliage or varied the tints of the forests. Eternal verdure clothed the branches of the Ferns, the Lycopods, and Equiseta, which composed to a great extent the vegetation of the age. The forests presented an innumerable collection of individuals, but very few species, and all belonging to the lower types of vegetation. No fruit appeared fit for nourishment; none would seem to have been on the branches. Suffice it to say that few terrestrial animals seem to have existed yet; animal life was apparently almost wholly confined to the sea, while the vegetable kingdom occupied the land, which at a later period was more thickly inhabited by air-breathing animals. Probably a few winged insects (some coleoptera, orthoptera, and neuroptera) gave animation to the air while exhibiting their variegated colors; and it was not impossible but that many pulmoniferous mollusca (such as land-snails) lived at the same time.

The vegetation which covered the numerous islands of the Carboniferous sea consisted, then, of Ferns, of Equisetaceæ, of Lycopodiaceæ, and dicotyledonous Gymnosperms. The Annularia and Sigillariæ belong to families of the last-named class, which are now completely extinct.

The _Annulariæ_ were small plants which floated on the surface of fresh-water lakes and ponds; their leaves were verticillate, that is, arranged in a great number of whorls, at each articulation of the stem with the branches. The _Sigillariæ_ were, on the contrary, great trees, consisting of a simple trunk, surmounted with a bunch or panicle of slender drooping leaves, with the bark often channeled, and displaying impressions or scars of the old leaves, which, from their resemblance to a seal, _sigillum_, gave origin to their name.

The _Stigmariæ_, according to palæontologists, were roots of Sigillariæ, with a subterranean fructification; all that is known of them is the long roots which carry the reproductive organs, and in some cases are as much as sixteen feet long.

Two other gigantic trees grew in the forests of this period: these were _Lepidodendron carinatum_ and _Lomatophloyos crassicaule_, both belonging to the family of Lycopodiaceæ, which now includes only very small species. The trunk of the Lomatophloyos threw out numerous branches, which terminated in thick tufts of linear and fleshy leaves. The Ferns composed a great part of the vegetation of the Coal-measure period.

The seas of this epoch included an immense number of Zoophytes, nearly 400 species of Mollusca, and a few Crustaceans and Fishes. Among the Fishes, _Psammodus_ and _Coccosteus_, whose massive teeth inserted in the palate were suitable for grinding; and the _Holoptychius_ and _Megalichthys_, are the most important. The Mollusca are chiefly Brachiopods of great size. The _Bellerophon_, whose convoluted shell in some respects resembles the Nautilus of our present seas, but without its chambered shell, were then represented by many species.

Crustaceans are rare in the Carboniferous Limestone strata; the genus Phillipsia is the last of the Trilobites, all of which became extinct at the close of this period. As to the Zoophytes, they consist chiefly of Crinoids and Corals. We also have in these rocks many Polyzoa.

Among the corals of the period we may include the genera _Lithostrotion_ and _Lonsdalea_. Among the Polyzoa are the genera _Fenestrella_ and _Polypora_. Lastly, to these we may add a group of animals which will play a very important part and become abundantly represented in the beds of later geological periods, but which already abounded in the seas of the Carboniferous period. We speak of the _Foraminifera_, microscopic animals, which clustered either in one body or divided into segments, and covered with a calcareous, many-chambered shell, as _Fusulina cylindrica_. These little creatures, which, during the Jurassic and Cretaceous periods, formed enormous banks and entire masses of rock, began to make their appearance in the period which now engages our attention.

This terrestrial period is characterized, in a remarkable manner, by the abundance and strangeness of the vegetation which then covered the islands and continents of the whole globe. Upon all points of the earth, as we have said, this flora presented a striking uniformity. In comparing it with the vegetation of the present day, the learned French botanist, M. Brongniart, who has given particular attention to the flora of the Coal-measures, has arrived at the conclusion that it presented considerable analogy with that of the islands of the equatorial and torrid zone, in which a maritime climate and elevated temperature exist in the highest degree. It is believed that islands were very numerous at this period; that, in short, the dry land formed a sort of vast archipelago upon the general ocean, of no great depth, the islands being connected together and formed into continents as they gradually emerged from the ocean.

This flora, then, consists of great trees, and also of many smaller plants, which would form a close, thick turf, or sod, when partially buried in marshes of almost unlimited extent. M. Brongniart indicates, as characterizing the period, 500 species of plants which now attain a prodigious development. The ordinary dicotyledons and monocotyledons--that is, plants having seeds with two lobes in germinating and plants having one seed-lobe--are almost entirely absent; the cryptogamic, or flowerless plants, predominate; especially Ferns, Lycopodiaceæ, and Equisetaceæ--but of forms insulated and actually extinct in these same families. A few dicotyledonous gymnosperms, or naked-seed plants forming genera of Conifers, have completely disappeared, not only from the present flora, but since the close of the period under consideration, there being no trace of them in the succeeding Permian flora. Such is a general view of the features most characteristic of the coal-period, and of the Primary epoch in general. It differs, altogether and absolutely, from that of the present day; the climatic condition of these remote ages of the globe, however, enables us to comprehend the characteristics which distinguish its vegetation. A damp atmosphere, of an equable rather than an intense heat like that of the tropics, a soft light veiled by permanent fogs, were favorable to the growth of this peculiar vegetation, of which we search in vain for anything strictly analogous in our own days. The nearest approach to the climate and vegetation proper to the geological period which now occupies our attention would probably be found in certain islands, or on the littoral of the Pacific Ocean--the island of Chloë, for example, where it rains during 300 days in the year, and where the light of the sun is shut out by perpetual fogs; where arborescent Ferns form forests, beneath whose shade grow herbaceous Ferns, which rise three feet and upward above a marshy soil; which gives shelter also to a mass of cryptogamic plants, greatly resembling, in its main features, the flora of the Coal-measures. This flora was, as we have said, uniform and poor in its botanic genera, compared to the abundance and variety of the flora of the present time; but the few families of plants which existed then included many more species than are now produced in the same countries. The fossil Ferns of the coal-series in Europe, for instance, comprehend about 300 species, while all Europe now only produces fifty. The gymnosperms, which now muster only twenty-five species in Europe, then numbered more than 120.

Calamites are among the most abundant fossil plants of the Carboniferous period, and occur also in the Devonian. They are preserved as striated, jointed, cylindrical, or compressed stems, with fluted channels or furrows at their sides, and sometimes surrounded by a bituminous coating, the remains of a cortical integument. They were originally hollow, but the cavity is usually filled up with a substance into which they themselves have been converted.

If, during the coal-period, the vegetable kingdom had reached its maximum, the animal kingdom, on the contrary, was poorly represented. Some remains have been found, both in America and Germany, consisting of portions of the skeleton and the impressions of the footsteps of a Reptile, which has received the name of Archegosaurus. Among the animals of this period we find a few Fishes, analogous to those of the Devonian formation. These are the _Holoptychius_ and _Megalichthys_, having jawbones armed with enormous teeth. Scales of _Pygopterus_ have been found in the Northumberland Coal-shale at Newsham Colliery, and also in the Staffordshire Coal-shale. Some winged insects would probably join this slender group of living beings. It may then be said with truth that the immense forests and marshy plains, crowded with trees, shrubs, and herbaceous plants, which formed on the innumerable isles of the period a thick and tufted sward, were almost destitute of animals.

Coal, as we have said, is only the result of a partial decomposition of the plants which covered the earth during a geological period of immense duration. No one, now, has any doubt that this is its origin. In coal-mines it is not unusual to find fragments of the very plants whose trunks and leaves characterize the Coal-measures, or Carboniferous era. Immense trunks of trees have also been met with in the middle of a seam of coal. In order to explain the presence of coal in the depths of the earth, there are only two possible hypotheses. This vegetable débris may either result from the burying of plants brought from afar and transported by river or maritime currents, forming immense rafts, which may have grounded in different places and been covered subsequently by sedimentary deposits; or the trees may have grown on the spot where they perished, and where they are now found.

Can the coal-beds result from the transport by water, and burial under ground, of immense rafts formed of the trunks of trees? The hypothesis has against it the enormous height which must be conceded to the raft, in order to form coal-seams as thick as some of those which are worked in our collieries. If we take into consideration the specific gravity of wood, and the amount of carbon it contains, we find that the coal-deposits can only be about seven-hundredths of the volume of the original wood and other vegetable materials from which they are formed. If we take into account, besides, the numerous voids necessarily arising from the loose packing of the materials forming the supposed raft, as compared with the compactness of coal, this may fairly be reduced to five-hundredths. A bed of coal, for instance, sixteen feet thick, would have required a raft 310 feet high for its formation. These accumulations of wood could never have arranged themselves with sufficient regularity to form those well-stratified coal-beds, maintaining a uniform thickness over many miles, and that are seen in most coal-fields to lie one above another in succession, separated by beds of sandstone or shale. And even admitting the possibility of a slow and gradual accumulation of vegetable débris, like that which reaches the mouth of a river, would not the plants in that case be buried in great quantities of mud and earth? Now, in most of our coal-beds the proportion of earthy matter does not exceed fifteen per cent of the entire mass. If we bear in mind, finally, the remarkable parallelism existing in the stratification of the coal-formation, and the state of preservation in which the impressions of the most delicate vegetable forms are discovered, it will, we think, be proved to demonstration that those coal-seams have been formed in perfect tranquillity. We are, then, forced to the conclusion that coal results from the mineralization of plants which has taken place on the spot; that is to say, in the very place where the plants lived and died.

It was suggested long ago by Bakewell, from the occurrence of the same peculiar kind of fireclay under each bed of coal, that it was the soil proper for the production of those plants from which coal has been formed.

The clay-beds, “which vary in thickness from a few inches to more than ten feet, are penetrated in all directions by a confused and tangled collection of the roots and leaves, as they may be, of the _Stigmaria ficoides_, these being frequently traceable to the main stem (_Sigillaria_), which varies in diameter from about two inches to half a foot. The main stems are noticed as occurring nearer the top than the bottom of the bed, as usually of considerable length, the leaves or roots radiating from them in a tortuous irregular course to considerable distances, and as so mingled with the under-clay that it is not possible to cut out a cubic foot of it which does not contain portions of the plant.”

It is a natural inference to suppose that the present indurated under-clay is only another condition of that soft, silty soil, or of that finely levigated muddy sediment--most likely of still and shallow water--in which the vegetation grew, the remains of which were afterward carbonized and converted into coal.

In order thoroughly to comprehend the phenomena of the transformation into coal of the forests and of the herbaceous plants which filled the marshes and swamps of the ancient world, there is another consideration to be presented. During the coal-period, the terrestrial crust was subjected to alternate movements of elevation and depression of the internal liquid mass, under the impulse of the solar and lunar attractions to which they would be subject, as our seas are now, giving rise to a sort of subterranean tide, operating at intervals, more or less widely apart, upon the weaker parts of the crust, and producing considerable subsidences of the ground. It might, perhaps, happen that, in consequence of a subsidence produced in such a manner, the vegetation of the coal-period would be submerged, and the shrubs and plants which covered the surface of the earth would finally become buried under water. After this submergence new forests sprung up in the same place. Owing to another submergence, the second forests were depressed in their turn, and again covered by water. It is probably by a series of repetitions of this double phenomenon--this submergence of whole regions of forest, and the development upon the same site of new growths of vegetation--that the enormous accumulations of semi-decomposed plants, which constitute the Coal-measures, have been formed in a long series of ages.

But, has coal been produced from the larger plants only--for example, from the great forest-trees of the period, such as the Lepidodendra, Sigillariæ, Calamites, and Sphenophylla? That is scarcely probable, for many coal-deposits contain no vestiges of the great trees of the period, but only of Ferns and other herbaceous plants of small size. It is, therefore, presumable that the larger vegetation has been almost unconnected with the formation of coal, or, at least, that it has played a minor part in its production. In all probability there existed in the coal-period, as at the present time, two distinct kinds of vegetation: one formed of lofty forest-trees, growing on the higher grounds; the other, herbaceous and aquatic plants, growing on marshy plains. It is the latter kind of vegetation, probably, which has mostly furnished the material for the coal; in the same way that marsh-plants have, during historic times and up to the present day, supplied our existing peat, which may be regarded as a sort of contemporaneous incipient coal.

To what modification has the vegetation of the ancient world been subjected to attain that carbonized state which constitutes coal? The submerged plants would, at first, be a light, spongy mass, in all respects resembling the peat-moss of our moors and marshes. While under water, and afterward, when covered with sediment, these vegetable masses underwent a partial decomposition--a moist, putrefactive fermentation, accompanied by the production of much carbureted hydrogen and carbonic acid gas. In this way, the hydrogen escaping in the form of carbureted hydrogen, and the oxygen in the form of carbonic acid gas, the carbon became more concentrated, and coal was ultimately formed. This emission of carbureted hydrogen gas would, probably, continue after the peat-beds were buried beneath the strata which were deposited and accumulated upon them. The mere weight and pressure of the superincumbent mass, continued at an increasing ratio during a long series of ages, have given to the coal its density and compact state.

The heat emanating from the interior of the globe would also exercise a great influence upon the final result. It is to these two causes--that is to say, to pressure and to the central heat--that we may attribute the differences which exist in the mineral characters of various kinds of coal. The inferior beds are _drier_ and more compact than the upper ones; or less bituminous, because their mineralization has been completed under the influence of a higher temperature, and at the same time under a greater pressure.

THE PALÆONTOLOGICAL HISTORY OF ANIMALS
--HUGH MILLER

However much the faunas of the various geologic periods may have differed from each other, or from the fauna which now exists, in their general aspect and character, they were all, if I may so speak, equally underlaid by the great leading ideas which still constitute the master types of animal life. And these leading ideas are four in number. _First_, there is the _star-like_ type of life--life embodied in a form that, as in the corals, the sea-anemones, the sea-urchins, and the star-fishes, radiates outward from a centre; _second_, there is the _articulated_ type of life--life embodied in a form composed, as in the worms, crustaceans, and insects, of a series of rings united by their edges, but more or less movable on each other; _third_, there is the bilateral or _molluscan_ type of life--life embodied in a form in which there is a duality of corresponding parts, ranged, as in the cuttle-fishes, the clams, and the snails, on the sides of a central axis or plane; and _fourth_, there is the _vertebrate_ type of life--life embodied in a form in which an internal skeleton is built up into two cavities placed the one over the other; the upper for the reception of the nervous centres, cerebral and spinal--the lower for the lodgment of the respiratory, circulatory, and digestive organs. Such have been the four central ideas of the faunas of every succeeding creation, except, perhaps, the earliest of all, that of the Lower Silurian System, in which, so far as is yet known, only three of the number existed--the radiated, articulated, and molluscan ideas or types.

The fauna of the Silurian System bears in all its three great types the stamp of a fashion peculiarly antique, and which, save in a few of the mollusca, has long since become obsolete. Its radiate animals are chiefly corals, simple or compound, whose inhabitants may have somewhat resembled the sea-anemones; with zoophytes, akin mayhap to the sea-pens, though the relationship must have been a remote one; and numerous crinoids, or stone lilies, some of which consisted of but a sculptured calyx without petals, while others threw off a series of long flexible arms, that divided and subdivided like the branches of a tree, and were thickly fringed by hair-like fibres.

The articulata of the Silurian period bore a still more peculiar character. They consisted mainly of the Trilobites--a family in whose nicely jointed shells the armorer of the Middle Ages might have found almost all the contrivances of his craft anticipated, with not a few besides which he had failed to discover; and which, after receiving so immense a development during the middle and later times of the Silurian period that whole rocks were formed almost exclusively of their remains, gradually died out in the times of the Old Red Sandstone, and disappeared forever from creation after the Carboniferous Limestone had been deposited. The mollusca of the Silurians ranged from the high cephalopoda, represented in our existing seas by the nautili and the cuttle-fishes, to the low brachiopods, some of whose cogeners may still be detected in the terebratulæ of the Highland lochs and bays, and some in the lingulæ of the Southern Hemisphere. The cephalopods of the system are all of an obsolete type, that disappeared myriads of ages ago. At length, in an upper bed of the system, immediately under the base of the Old Red Sandstone, the remains of the earliest known fishes appear, blended with what also appears for the first time--the fragmentary remains of a terrestrial vegetation. The rocks beneath this ancient bone-bed have yielded no trace of any plant higher than the Thallogens, or at least not higher than the Zosteraceæ--plants whose proper habitat is the sea; but, through an apparently simultaneous advance of the two kingdoms, animal and vegetable--though, of course, the simultaneousness may be but merely apparent--the first land-plants and the first vertebrates appear together in the same deposit. The earliest fishes--first-born of their family--seem to have been all placoids. The Silurian System has not yet afforded trace of any other vertebral animal. With the Old Red Sandstone the ganoids were ushered upon the scene in amazing abundance; and for untold ages, comprising mayhap millions of years, the entire ichthyic class consisted, so far as is yet known, of but these two orders. During the times of the Old Red Sandstone, of the Carboniferous, of the Permian, of the Triassic, and of the Oolitic Systems, all fishes, though apparently as numerous individually as they are now, were comprised in the ganoidal and placoidal orders. The period of these orders seems to have been nearly correspondent with the reign, in the vegetable kingdom, of the Acrogens and Gymnogens, with the intermediate classes, their allies. At length, during the ages of the Chalk, the Cycloids and Ctenoids were ushered in, and were gradually developed in creation until the human period, in which they seem to have reached their culminating point, and now many times exceed in number and importance all other fishes. The delicate Salmonidæ and the Pleuronectidæ--families to which the salmon and turbot belong--were ushered into being as early as the times of the Chalk; but the Gadidæ or cod family--that family to which the cod proper, the haddock, the dorse, the whiting, the coal-fish, the pollock, the hake, the torsk, and the ling belong, with many other useful and wholesome species--did not precede man by at least any period of time appreciable to the geologist. No trace of the family has yet been detected in even the Tertiary rocks.

Of the ganoids of the second age of vertebrate existence--that of the Old Red Sandstone--some were remarkable for the strangeness of their forms, and some for constituting links of connection, which no longer exist in nature, between the ganoid and placoid orders. The Acanth family, which ceased with the Coal-measures, was characterized, especially in its Old Red species, by a combination of traits common to both orders; and among the extremer forms, in which palæontologists for a time failed to detect that of the fish at all, we reckon those of the genera Coccosteus, Pterichthys, and Cephalaspis. The more aberrant genera, however, even while they consisted each of several species, were comparatively short-lived. The Coccosteus and Cephalaspis were restricted to but one formation apiece; while the Pterichthys, which appears for the first time in the lower deposits of the Old Red Sandstone, becomes extinct at its close. On the other hand, some of the genera that exemplified the general type of their class were extremely long-lived. The Celacanths were reproduced in many various species, from the times of the Lower Old Red Sandstone to those of the Chalk; and the Cestracions, which appear in the Upper Ludlow Rocks as the oldest of fishes, continue in at least one species to exist still.

The ancient fishes seem to have received their fullest development during the Carboniferous period. Their number was very great: some of them attained to an enormous size, and, though the true reptile had already appeared, they continued to retain till the close of the System the high reptilian character and organization. Nothing, however, so impresses the observer as the formidable character of the offensive weapons with which they were furnished, and the amazing strength of their defensive armature. I need scarce say that the palæontologist finds no trace in nature of that golden age of the world, of which the poets delighted to sing, when all creatures lived together in unbroken peace, and war and bloodshed were unknown. Ever since animal life began upon our planet there existed, in all the departments of being, carnivorous classes, who could not live but by the death of their neighbors, and who were armed, in consequence, for their destruction, like the butcher with his axe and knife, and the angler with his hook and spear. But there were certain periods in the history of the past during which these weapons assumed a more formidable aspect than at others; and never were they more formidable than in the times of the Coal-measures. The teeth of the Rhizodus--a ganoidal fish of our coal-fields--were more sharp and trenchant than those of the crocodile of the Nile, and in the larger specimens fully four times the bulk and size of the teeth of the hugest reptile of this species that now lives. The dorsal spine of its contemporary, the Gyracanthus, a great placoid, much exceeded in size that of any existing fish; it was a mighty spearhead, ornately carved like that of a New Zealand chief, but in a style that, when he first saw a specimen in my collection, greatly excited the admiration of Mr. Ruskin. But one of the most remarkable weapons of the period was the sting of the Pleuracanthus, another great placoid of the age of gigantic fishes. It was sharp and polished as a stiletto, but, from its rounded form and dense structure, of great strength; and along two of its sides, from the taper point to within a few inches of the base, there ran a thickly set row of barbs, hooked downward, like the thorns that bristle on the young shoots of the wild rose, and which must have rendered it a weapon not merely of destruction, but also of torture. The defensive armor of the period, especially that of its ganoids, seems to have been as remarkable for its powers of resistance as the offensive must have been for their potency in the assault; and it seems probable that in the great strength of the bony and enameled armature of this order of fishes we have the secret of the extremely formidable character of the teeth, spines, and stings that coexisted along with it.

The oldest known reptiles appear just a little before the close of the Old Red Sandstone, just as the oldest known fishes appeared just a little before the close of the Silurian System. What seems to be the Upper Old Red of Great Britain, though there still hangs a shade of doubt on the subject, has furnished the remains of a small reptile, equally akin, it would appear, to the lizards and the batrachians; and what seems to be the Upper Old Red of the United States has exhibited the foot-tracks of a larger animal of the same class, which not a little resemble those which would be impressed on recent sand or clay by the alligator of the Mississippi, did not the alligator of the Mississippi efface its own footprints (a consequence of the shortness of its legs) by the trail of its abdomen. In the Coal-measures the reptiles hitherto found are all allied, though not without a cross of the higher crocodilian or lacertian nature, to the batrachian order--that lowest order of the reptiles to which the frogs, newts, and salamanders belong. It was not, however, until the Permian and Triassic Systems had come to a close, and even the earlier ages of the Oolitic System had passed away, that the class received its fullest development in creation. And certainly very wonderful was the development which it then did receive. Reptiles became everywhere the lords and masters of this lower world. When any class of the air-breathing vertebrates is very largely developed, we find it taking possession of all the three old terrestrial elements--earth, air, and water. The human period, for instance, like that which immediately preceded it, is peculiarly a period of mammals; and we find the class _free_, if I may so express myself, of the three elements, disputing possession of the sea with the fishes, in its Cetaceans, its seals and its sea-lions, and of the air with the birds, in its numerous genera of the bat family. Further, not until the great mammaliferous period is fairly ushered in do either the bats or the whales make their appearance in creation. Remains of Oolitic reptiles have been mistaken in more than one instance for those of Cetacea; but it is now generally held that the earliest known specimens of the family belong to the Tertiary ages, while those of the oldest bats occur in the Eocene of the Paris basin, associated with the bones of dolphins, lamantines, and morses. Now, in the times of the Oolite it was the reptilian class that possessed itself of all the elements. Its gigantic enaliosaurs, huge reptilian whales mounted on paddles, were the tyrants of the ocean, and must have reigned supreme over the already reduced class of fishes; its pterodactyles--dragons as strange as were ever feigned by romancer of the Middle Ages, and that to the jaws and teeth of the crocodile added the wings of a bat and the body and tail of an ordinary mammal--had the “power of the air,” and, pursuing the fleetest insects in their flight, captured and bore them down; its lakes and rivers abounded in crocodiles and fresh-water tortoises of ancient type and fashion; and its woods and plains were the haunts of a strange reptilian fauna of what has been well termed “fearfully great lizards”--some of which, such as the iguanodon, rivaled the largest elephant in height, and greatly more than rivaled him in length and bulk. Judging from what remains, it seems not improbable that the reptiles of this Oolitic period were quite as numerous individually, and consisted of wellnigh as many genera and species as all the mammals of the present time. In the cretaceous ages, the class, though still the dominant one, is visibly reduced in its standing: it had reached its culminating point in the Oolite and then began to decline; and with the first dawn of the Tertiary division we find it occupying, as now, a very subordinate place in creation. Curiously enough, it is not until its times of humiliation and decay that one of the most remarkable of its orders appears--an order itself illustrative of extreme degradation, and which figures largely in every scheme of mythology that borrowed through traditional channels from Divine revelation, as a meet representative of man’s great enemy, the Evil One. I, of course, refer to the ophidian or serpent family. The earliest ophidian remains known to the palæontologist occur in that ancient deposit of the Tertiary division known as the London Clay, and must have belonged to serpents, some of them allied to the Pythons, some to the sea-snakes, which, judging from the corresponding parts of recent species, must have been from fourteen to twenty feet in length.

Birds make their first appearance in a Red Sandstone deposit of the United States in the valley of the Connecticut, which was at one time supposed to belong to the Triassic System, but which is now held to be at least not older than the times of the Lias. No fragments of the skeletons of birds have yet been discovered in formations older than the Chalk; the Connecticut remains are those of footprints exclusively; and yet they tell their extraordinary story, so far as it extends, with remarkable precision and distinctness. They were apparently all of the Grallæ or stilt order of birds--an order to which the cranes, herons, and bustards belong, with the ostriches and cassowaries, and which is characterized by possessing but three toes on each foot (one species of ostrich has but two), or, if a fourth toe be present, so imperfectly is it developed in most of the cases that it fails to reach the ground. And in almost all the footprints of the primeval birds of the Connecticut there are only three toes exhibited. The immense size of some of these footprints served to militate for a time against belief in their ornithic origin. The impressions that are but secondary in point of size greatly exceed those of the hugest birds which now exist; while those of the largest class equal the prints of the bulkier quadrupeds. There are tridactyle footprints in the Red Sandstones of Connecticut that measure eighteen inches in length from the heel to the middle claw, nearly thirteen inches in breadth from the outer to the inner toe, and which indicate, from their distance apart in the straight line, a stride of about six feet in the creature that impressed them in these ancient sands--measurements that might well startle zoologists who had derived their experience of the ornithic class from existing birds exclusively. In a deposit of New Zealand that dates little if at all in advance of the human period, there have been detected the remains of birds scarce inferior in size to those of America in the Liassic ages. The bones of the _Dinornus giganteus_, exhibited by Dr. Mantell in Edinburgh in 1850, greatly exceeded in bulk those of the largest horse. The larger thigh-bone referred to must have belonged, it was held, to a bird that stood from eleven to twelve feet high--the extreme height of the great African elephant. Such were the monster birds of a comparatively recent period; and their remains serve to render credible the evidence furnished by the great footprints of their remote predecessors of the Lias. The huge feet of the greatest Dinornus would have left impressions scarcely an inch shorter than those of the still huger birds of the Connecticut.

With the Stonesfield slates--a deposit which lies above what is known as the Inferior Oolite--the remains of mammaliferous animals first appear.

The Eocene ages were peculiarly the ages of the Palæotheres--strange animals of, that pachydermatous or thick-skinned order to which the elephants, the tapirs, the hogs, and the horses belong. It had been remarked by naturalists that there are fewer families of this order in living nature than of almost any other, and that of the existing genera not a few are widely separated in their analogies from the others. But in the Palæotheres of the Eocene, which ranged in size from a large horse to a hare, not a few of the missing links have been found--links connecting the tapirs to the hogs, and the hogs to the Palæotheres proper; and there is at least one species suggestive of a union of some of the more peculiar traits of the tapirs and the horses. It was among these extinct Pachydermata of the Paris basin that Cuvier effected his wonderful restorations, and produced those figures in outline which are now as familiar to the geologist as any of the forms of the existing animals. The London Clay and the Eocene of the Isle of Wight have also yielded numerous specimens of these pachyderms, whose identity with the Continental ones has been established by Owen; but they are more fragmentary, and their state of keeping less perfect than those furnished by the gypsum quarries of Velay and Montmartre.

In the Middle or Miocene Tertiary, pachyderms, though of a wholly different type from their predecessors, are still the prevailing forms. The Dinotherium, one of the greatest quadrupedal mammals that ever lived, seems to have formed a connecting link in this middle age between the Pachydermata and the Cetaceæ. Each ramus of the under jaw, which in the larger specimens are fully four feet in length, bore at the symphysis a great bent tusk turned downward, which appears to have been employed as a pick-axe in uprooting the aquatic plants and liliaceous roots on which the creature seems to have lived. The head, which measured about three feet across--a breadth sufficient, surely, to satisfy the demands of the most exacting phrenologist--was provided with muscles of enormous strength, arranged so as to give potent effect to the operations of this strange tool. The hinder part of the skull not a little resembled that of the Cetaceæ; while, from the form of the nasal bones, the creature was evidently furnished with a trunk like the elephant. It seems not improbable, therefore, that this bulkiest of mammaliferous quadrupeds constituted, as I have said, a sort of uniting tie between creatures still associated in the human mind, from the circumstances of their massive proportions, as the greatest that swim the sea or walk the land--the whale and the elephant The Mastodon, an elephantoid animal, also furnished, like the elephant, with tusks and trunk, but marked by certain peculiarities which constitute it a different genus, seems in Europe to have been contemporary with the Dinotherium; but in North America (the scene of its greatest numerical development) it appears to belong to a later age. In height it did not surpass the African elephant, but it considerably exceeded it in length--a specimen which could not have stood above twelve feet high indicating a length of about twenty-five feet: it had what the elephants want--tusks fixed in its lower jaw, which the males retained through life, but the females lost when young; its limbs were proportionally shorter, but more massive, and its abdomen more elongated and slim; its grinder teeth, too, some of which have been known to weigh from seventeen to twenty pounds, had their cusps elevated into great mammæ-like protuberances, to which the creature owes its name, and wholly differ in their proportions and outline from the grinders of the elephant. The much greater remoteness of the mastodontic period in Europe than in America is a circumstance worthy of notice, as it is one of many facts that seem to indicate a general transposition of at least the later geologic ages on the opposite sides of the Atlantic.

EUROPEAN AND ASIATIC DELUGES
--LOUIS FIGUIER

The Tertiary formations, in many parts of Europe of more or less extent, are covered by an accumulation of heterogeneous deposits, filling up the valleys, and composed of very various materials, consisting mostly of fragments of the neighboring rocks. The erosions which we remark at the bottoms of the hills, and which have greatly enlarged already existing valleys; the mounds of gravel accumulated at one point, and which is formed of rolled materials, that is to say, of fragments of rocks worn smooth and round by continual friction during a long period, in which they have been transported from one point to another--all these signs indicate that these denudations of the soil, these displacements and transports of very heavy bodies to great distances, are due to the violent and sudden action of large currents of water. An immense wave has been thrown suddenly on the surface of the earth, making great ravages in its passage, furrowing the earth and driving before it débris of all sorts in its disorderly course.

To what cause are we to attribute these sudden and apparently temporary invasions of the earth’s surface by rapid currents of water? In all probability to the upheaval of some vast extent of dry land, to the formation of some mountain or mountain range in the neighborhood of the sea, or even in the bed of the sea itself. The land, suddenly elevated by an upward movement of the terrestrial crust, or by the formation of ridges and furrows at the surface, has, by its reaction, violently agitated the waters, that is to say, the more mobile portion of the globe. By this new impulse the waters have been thrown with great violence over the earth, inundating the plains and valleys, and for the moment covering the soil with their furious waves, mingled with the earth, sand, and mud, of which the devastated districts have been denuded by their abrupt invasion.

There have been, doubtless, during the epochs anterior to the Quaternary period many deluges such as we are considering. Mountains and chains of mountains were formed by upheaval of the crust into ridges, where it was too elastic or too thick to be fractured. Each of these subterranean commotions would be provocative of momentary irruptions of the waves.

But the visible testimony to this phenomenon--the living proofs of this denudation, of this tearing away of the soil--is found nowhere so strikingly as in the beds superimposed, far and near, upon the Tertiary formations, and which bear the geological name of _diluvium_. This term was long employed to designate what is now better known as the “bowlder” formation, a glacial deposit which is abundant in Europe north of the 50th, and in America north of the 40th, parallel, and reappearing again in the Southern Hemisphere; but altogether absent in tropical regions. It consists of sand and clay, sometimes stratified, mixed with rounded and angular fragments of rock, generally derived from the same district; and their origin has generally been ascribed to a series of diluvial waves raised by hurricanes, earthquakes, or the sudden upheaval of land from the bed of the sea, which had swept over continents, carrying with them vast masses of mud and heavy stones, and forcing these stones over rocky surfaces so as to polish and impress them with furrows and striæ. Other circumstances occurred, however, to establish a connection between this formation and the glacial drift. The size and number of the erratic blocks increase as we travel toward the Arctic regions; some intimate association exists, therefore, between this formation and the accumulations of ice and snow which characterize the approaching glacial period.

There is very distinct evidence of two successive deluges in our hemisphere during the Quaternary epoch. The two may be distinguished as the _European Deluge_ and the _Asiatic_. The two European deluges occurred prior to the appearance of man; the Asiatic deluge happened after that event; and the human race, then in the early days of its existence, certainly suffered from this cataclysm.

The first occurred in the north of Europe, where it was produced by the upheaval of the mountains of Norway. Commencing in Scandinavia, the wave spread and carried its ravages into those regions which now constitute Sweden, Norway, European Russia, and the north of Germany, sweeping before it all the loose soil on the surface, and covering the whole of Scandinavia--all the plains and valleys of Northern Europe--with a mantle of transported soil. As the regions in the midst of which this great mountainous upheaval occurred--as the seas surrounding these vast spaces were partly frozen and covered with ice, from their elevation and neighborhood to the pole--the wave which swept these countries carried along with it enormous masses of ice.

The physical proof of this _deluge of the north of Europe_ exists in the accumulation of unstratified deposits which covers all the plains and low grounds of Northern Europe. On and in this deposit are found numerous blocks which have received the characteristic and significant name of erratic blocks, and which are frequently of considerable size. These become more characteristic as we ascend to higher latitudes, as in Norway, Sweden, and Denmark, the southern borders of the Baltic, and in the British Islands generally, in all of which countries deposits of marine fossil shells occur, which prove the submergence of large areas of Scandinavia, of the British Isles, and other regions during parts of the glacial period. Some of these rocks, characterized as _erratic_, are of very considerable volume; such, for instance, is the granite block which forms the pedestal of the statue of Peter the Great at St. Petersburg. This block was found in the interior of Russia, where the whole formation is _Permian_, and its presence there can only be explained by supposing it to have been transported by some vast iceberg, carried by a diluvial current. This hypothesis alone enables us to account for another block of granite, weighing about 340 tons, which was found on the sandy plains in the north of Prussia, an immense model of which was made for the Berlin Museum. The last of these erratic blocks deposited in Germany covers the grave of King Gustavus Adolphus, of Sweden, killed at the battle of Lutzen, in 1632. He was interred beneath the rock. Another similar block has been raised in Germany into a monument to the geologist Leopold von Buch.

These erratic blocks, which are met with in the plains of Russia, Poland, and Prussia, and in the eastern parts of England, are composed of rocks entirely foreign to the region where they are found. They belong to the primary rocks of Norway; they have been transported to their present sites, protected by a covering of ice, by the waters of the northern deluge.

The second European deluge is supposed to have been the result of the formation and upheaval of the Alps. It has filled with débris and transported material the valleys of France, Germany, and Italy over a circumference which has the Alps for its centre. The proofs of a great convulsion at a comparatively recent geological date are numerous. The Alps may be from eighty to one hundred miles across, and the probabilities are that their existence is due, as Sir Charles Lyell supposes, to a succession of unequal movements of upheaval and subsidence; that the Alpine region had been exposed for countless ages to the action of rain and rivers, and that the larger valleys were of pre-glacial times, is highly probable. In the eastern part of the chain some of the Primary fossiliferous rocks, as well as Oolitic and Cretaceous rocks, and even Tertiary deposits, are observable; but in the central Alps these disappear, and more recent rocks, in some places even Eocene strata, graduate into metamorphic rocks, in which Oolitic, Cretaceous, and Eocene strata have been altered into granular marble, gneiss, and other metamorphic schists; showing that eruptions continued after the deposit of the Middle Eocene formations. Again, in the Swiss and Savoy Alps, Oolitic and Cretaceous formations have been elevated to the height of 12,000 feet, and Eocene strata 10,000 feet above the level of the sea; while in the Rothal, in the Bernese Alps, occurs a mass of gneiss 1,000 feet thick between two strata containing Oolitic fossils.

Besides these proofs of recent upheaval, we can trace effects of two different kinds, resulting from the powerful action of masses of water violently displaced by this gigantic upheaval. At first broad tracks have been hollowed out by the diluvial waves, which have, at these points, formed deep valleys. Afterward these valleys have been filled up by materials derived from the mountain and transported into the valley, these materials consisting of rounded pebbles, argillaceous and sandy mud, generally calcareous and ferriferous. This double effect is exhibited, with more or less distinctness, in all the great valleys of the centre and south of France. The valley of the Garonne is, in respect to these phenomena, classic ground, as it were.