The Crag, divided into three portions, is a local deposit of limited extent. It consists of variable beds of sand, gravel, and marl; sometimes it is a sh.e.l.ly ferruginous grit, as the Red Crag; at others a soft calcareous rock made up of sh.e.l.ls and bryozoa, as the Coralline Crag.

The _Coralline Crag_, of very limited extent in this country, ranges over about twenty miles between the rivers Stour and Alde, with a breadth of three or four. It consists of two divisions--an upper one, formed chiefly of the remains of Bryozoa, and a lower one of light-coloured sands, with a profusion of sh.e.l.ls. The upper division is about thirty-six feet thick at Sudbourne in Suffolk, where it consists of a series of beds almost entirely composed of comminuted sh.e.l.ls and remains of Bryozoa, forming a soft building-stone. The lower division is about forty-seven feet thick at Sutton; making the total thickness of the Coralline Crag about eighty-three feet.

Many of the Coralline Crag Mollusca belong to living species; they are supposed to indicate an equable climate free from intense cold--an inference rendered more probable by the prevalence of northern forms of sh.e.l.ls, such as _Glycimeris_, _Cyprina_, and _Astarte_. The late Professor Edward Forbes, to whom science is indebted for so many philosophical deductions, points out some remarkable inferences drawn from the fauna of the Pliocene seas.[95] It appears that in the glacial period, which we shall shortly have under consideration, many sh.e.l.ls, previously established in the temperate zone, retreated southwards, to avoid an uncongenial climate. The Professor gives a list of fifty which inhabited the British seas while the Coralline and Red Crag were forming, but which are all wanting in the glacial deposits;[96] from which he infers that they migrated at the approach of the glacial period, and returned again northwards, when the temperate climate was restored.[97]

[95] Edward Forbes in "Memoirs of the Geological Survey of Great Britain," vol. i., p. 336.

[96] For full information on these deposits the reader is referred to the "Memoirs on the Structure of the Crag-beds of Norfolk and Suffolk," by J. Prestwich, F.R.S., in the _Quart. Jour. Geol.

Soc._, vol. xxvii., pp. 115, 325, and 452 (1871). Also to the many Papers by the Messrs. Searles Wood published in the _Quar.

Jour. Geol. Soc._, the _Ann. Nat. Hist._, the _Phil. Mag._, &c.

[97] Lyell's "Elements of Geology," p. 203.

In the Upper or Mammaliferous (or Norwich) Crag, of which there is a good exposure in a pit near the asylum at Thorpe, bones of Mammalia are found with existing species of sh.e.l.ls. The greater number of the Mammalian remains have been supposed, until lately, to be extraneous fossils; but they are now considered by Mr. Prestwich as truly contemporaneous. The peculiar mixture of southern forms of life with others of a more northern type lead to the inference that, at this early period, a lowering of temperature began gradually to set in from the period of the Coralline Crag to that of the Forest Bed, which marks the commencement of the Glacial Period.

The distinction between the Mammaliferous Crag of Norwich and the Red Crag of Suffolk is purely palaeontological, no case of superposition having yet been discovered, and they are now generally considered as contemporaneous. Two Proboscidians abundant during the Crag period were the _Mastodon Arvernensis_ and the _Elephas meridionalis_. In the Red Crag the Mastodon is stated by the Rev. John Gunn to be more abundant than the Elephant, while in the Norwich beds their proportions are nearly equal.

At or near the base of the Red Crag there is a remarkable acc.u.mulation, varying in thickness from a few inches to two feet, of bones, teeth, and phosphatic nodules (called coprolites), which are worked for making superphosphate of lime for agricultural manure.

The foreign equivalents of the older Pliocene are found in the _sub-Apennine strata_. These rocks are sufficiently remarkable in the county of Suffolk, where they consist of a series of marine beds of quartzose sand, coloured red by ferruginous matter.

At the foot of the Apennine chain, which forms the backbone, as it were, of Italy, throwing out many spurs, the formations on either side, and on both sides of the Adriatic, are Tertiary strata; they form in many cases, low hills lying between the Apennines of Secondary formation and the sea, the strata generally being a light-brown or bluish marl covered with yellow calcareous sand and gravel, with some fossil sh.e.l.ls, which, according to Brocchi, are found all over Italy. But this wide range includes some older Tertiary formations, as in the strata of the Superga near Turin, which are Miocene.

The _Antwerp_ Crag, which is of the same age with the Red and Coralline Crag of Suffolk, forms great acc.u.mulations upon divers points of Europe: at Antwerp in Belgium, at Carentan and Perpignan, and, we believe, in the basin of the Rhone, in France. The thickest deposits of this rock consist of clay and sand, alternating with marl and arenaceous limestone. These const.i.tute the sub-Apennine hills, alluded to above as extending on both slopes of the Apennines. This deposit occupies the Upper Val d'Arno, above Florence. Its presence is recognised over a great part of Australia. Finally, the seven hills of Rome are composed, in part, of marine Tertiary rocks belonging to the Pliocene period.

In PLATE XXV. an ideal landscape of the Pliocene period is given under European lat.i.tudes. In the background of the picture, a mountain, recently thrown up, reminds us that the period was one of frequent convulsions, in which the land was disturbed and upheaved, and mountains and mountain-ranges made their appearance. The vegetation is nearly identical with the present. We see a.s.sembled in the foreground the more important animals of the period--the fossil species, as well as those which have survived to the present time.

At the close of the Pliocene period, and in consequence of the deposits left by the seas of the Tertiary epoch, the continent of Europe was nearly what it is now; few permanent changes have occurred since to disturb its general outline. Although the point does not admit of actual proof, there is strong presumptive evidence that in this period, or in that immediately subsequent to it, the entire European area, with some trifling exceptions, including the Alps and Apennines, emerged from the deep. In Sicily, Newer Pliocene rocks, covering nearly half the surface of the island, have been raised from 2,000 to 3,000 feet above the level of the sea. Fossil sh.e.l.ls have been observed at the height of 8,000 feet in the Pyrenees; and, as if to fix the date of upheaval, there are great ma.s.ses of granite which have penetrated the Lias and the Chalk. Fossil sh.e.l.ls of the period are also found at a height of 10,000 feet in the Alps, at 13,000 feet in the Andes, and at 18,000 feet in the Himalayas.

[Ill.u.s.tration: XXV.--Ideal Landscape of the Pliocene Period.]

In the mountainous regions of the Alps it is always difficult to determine the age of beds, in consequence of the disturbed state of the strata; for instance, the lofty chain of the Swiss Jura consists of many parallel ridges, with intervening longitudinal valleys; the ridges formed of contorted fossiliferous strata, which are extensive in proportion to the number and thickness of the formations which have been exposed on upheaval. The proofs which these regions offer of comparatively recent elevation are numerous. In the central Alps, Cretaceous, Oolitic, Lia.s.sic, and Eocene strata are found at the loftiest summits, pa.s.sing insensibly into metamorphic rocks of granular limestone, and into talcose and mica-schists. In the eastern parts of the chain the older fossiliferous rocks are recognised in similar positions, presenting signs of intense Plutonic action. Oolitic and Cretaceous strata have been raised 12,000 feet, Eocene 10,000, and Miocene 4,000 and 5,000 feet above the level of the sea. Equally striking proofs of recent elevation exist in the Apennines; the celebrated Carrara marble, once supposed--from its crystalline texture and the absence of fossils, and from its resting--1. on talcose schists, 2. on quartz and gneiss--to be very ancient, now turns out to be an altered limestone of the Oolitic series, and the underlying crystalline rocks to be metamorphosed Secondary sandstones and shales. Had all these rocks undergone complete metamorphism, another page in the earth's history would have been obscured. As it is, the proofs of what we state are found in the gradual approach of the rocks to their unaltered condition as the distance from the intrusive rock increases. This intrusive rock, however, does not always reach the surface, but it exists below at no great depth, and is observed piercing through the talcose gneiss, and pa.s.sing up into Secondary strata.

At the close of this epoch, therefore, there is every probability that Europe and Asia had pretty nearly attained their present general configuration.

QUATERNARY EPOCH.

The Quaternary epoch of the history of our globe commences at the close of the Tertiary epoch, and brings the narrative of its revolutions down to our own times.

The tranquillity of the globe was only disturbed during this era by certain cataclysms whose sphere was limited and local, and by an interval of cold of very extended duration; the _deluges_ and the _glacial_ period--these are the two most remarkable peculiarities which distinguished this epoch. But the fact which predominates in the Quaternary epoch, and distinguishes it from all other phases of the earth's history is the appearance of man, the culminating and supreme work of the Creator of the universe.

In this last phase of the history of the earth geology recognises three chronological divisions:--

1. The European Deluges.

2. The Glacial Period.

3. The creation of man and subsequent Asiatic Deluge.

Before describing the three orders of events which occurred in the Quaternary epoch, we shall present a brief sketch of the organic kingdoms of Nature, namely, of the animals and vegetables which flourished at this date, and the new formations which arose. Lyell, and some other geologists, designate this the POST-TERTIARY EPOCH, which they divide into two subordinate groups.--1. _The Post-Pliocene Period_; 2. _The Recent or Pleistocene Period._

POST-PLIOCENE PERIOD.

In the days of Cuvier the Tertiary formations were considered as a mere chaos of superficial deposits, having no distinct relations to each other. It was reserved for the English geologists, with Sir Charles Lyell at their head, to throw light upon this obscure page of the earth's history; from the study of fossils, science has not only re-animated the animals, it has re-constructed the theatre of their existence. We see the British Islands now a straggling archipelago, and then the mouth of a vast river, of which the continent is lost; for, says Professor Ramsay, "We are not of necessity to consider Great Britain as having always been an island; it is an accident that it is an island now, and it has been an island many times before." In the Tertiary epoch we see it surrounded, then, by shallow seas swarming with numerous forms of animal life; islands covered with bushy Palms; banks on which Turtles basked in the sun; vast basins of fresh or brackish water, in which the tide made itself felt, and which abounded with various species of sharks; rivers in which Crocodiles increased and multiplied; woods which sheltered numerous Mammals and some Serpents of large size; fresh-water lakes which received the spoils of numerous sh.e.l.ls. Dry land had increased immensely. Groups of ancient isles we have seen united and become continents, with lakes, bays, and perhaps inland seas. Gigantic Elephants, vastly larger than any now existing, close the epoch, and probably usher in the succeeding one; for we are not to suppose any sudden break to distinguish one period from another in Nature, although it is convenient to arrange them so for the purposes of description. If we may judge from their remains, these animals must have existed in great numbers, for it is stated that on the coast of Norfolk alone the fishermen, in trawling for oysters, dredged up between 1820 and 1833, no less than 2,000 molar teeth of Elephants. If we consider how slowly these animals multiply, these quarries of ivory, as we may call them, must have required many centuries for their production and acc.u.mulation.

The same lakes and rivers were at this time occupied, also, by the Hippopotamus, as large and as formidably armed as that now inhabiting the African solitudes; also the two-horned Rhinoceros; and three species of Bos, one of which was hairy and bore a mane. Some Deer of gigantic size, as compared with living species, bounded over the plains. In the same savannahs lived the Reindeer, the Stag, a Horse of small size, the a.s.s, the Bear, and the Roe, for Mammals had succeeded the Ichthyosauri of a former age. Nevertheless, the epoch had its tyrants also. A Lion, as large as the largest of the Lions of Africa, hunted its prey in the British jungles. Another animal of the feline race, the _Machairodus_ (Fig. 179), was probably the most ferocious and destructive of Carnivora; bands of Hyaenas and a terrible Bear, surpa.s.sing in size that of the Rocky Mountains, had established themselves in the caverns; two species of Beaver made their appearance on the scene.

[Ill.u.s.tration: Fig. 179.--_a_, Tooth of Machairodus, imperfect below, natural size; _b_, outline of cast of tooth, perfect, half natural size; _c_, tooth of Megalosaurus, natural size.]

The finding of the remains of most of these animals in caverns was perhaps among the most interesting discoveries of geology. The discovery was first made in the celebrated Kirkdale Cave in Yorkshire, which has been described by Dr. Buckland; and afterwards at Kent's Hole, near Torquay. This latter pleasant Devonshire town is built in a creek, shut out from exposure on all sides except the south. In this creek, hollowed out of the rocks, is the great fissure or cavern known as Kent's Hole; like that of Kirkdale, it has been under water, from whence, after a longer or shorter interval, it emerged, but remained entirely closed till the moment when chance led to its discovery. The princ.i.p.al cavern is 600 feet in length, with many crevices or fissures of smaller extent traversing the rock in various directions. A bed of hard stalagmite of very ancient formation, which has been again covered with a thin layer of soil, forms the floor of the cavern, which is a red sandy clay. From this bed of red loam or clay was disinterred a ma.s.s of fossil bones belonging to extinct species of Bear, Lion, Rhinoceros, Reindeer, Beaver, and Hyaena.

Such an a.s.semblage gave rise to all sorts of conjectures. It was generally thought that the dwelling of some beasts of prey had been discovered, which had dragged the carcases of elephants, deer, and others into these caves, to devour them at leisure. Others asked if, in some cases, instinct did not impel sick animals, or animals broken down by old age, to seek such places for the purpose of dying in quiet; while others, again, suggested that these bones might have been engulfed pell-mell in the hole during some ancient inundation. However that may be, the remains discovered in these caves show that all these Mammals existed at the close of the Tertiary epoch, and that they all lived in England. What were the causes which led to their extinction?

It was the opinion of Cuvier and the early geologists that the ancient species were destroyed in some great and sudden catastrophe, from which none made their escape. But recent geologists trace their extinction to slow, successive, and determinative action due to local causes, the chief one being the gradual lowering of the temperature. We have seen that at the beginning of the Tertiary epoch, in the older Eocene age, palms, cocoa-nuts, and acacias, resembling those now met with in countries more favoured by the sun, grew in our island. The Miocene flora presents indications of a climate still warm, but less tropical; and the Pliocene period, which follows, contains remains which announce an approach to our present climate. In following the vegetable productions of the Tertiary epoch, the botanist meets with the floras of Africa, South America, and Australia, and finally settles in the flora of temperate Europe. Many circ.u.mstances demonstrate this decreasing temperature, until we arrive at what geologists call the _glacial period_--one of the winters of the ancient world.

But before entering on the evidences which exist of the glacial era we shall glance at the picture presented by the animals of the period; the vegetable products we need not dwell on--it is, in fact, that of our own era, the flora of temperate regions in our own epoch. The same remark would apply to the animals, but for some signal exceptions. In this epoch Man appears, and some of the Mammals of the last epoch, but of larger dimensions, have long disappeared. The more remarkable of these extinct animals we shall describe, as we have those belonging to anterior ages. They are not numerous; those of our hemisphere being the Mammoth, _Elephas primigenius_; the Bear, _Ursus spelaeus_; gigantic Lion, _Felis spelaea_; Hyaena, _Hyaena spelaea_; Ox, _Bison priscus_, _Bos primigenius_; the gigantic Stag, _Cervus megaceros_; to which we may add the _Dinornis_ and _Epiornis_, among birds. In America there existed in the Quaternary epoch some Edentates of colossal dimensions and of very peculiar structure, these were _Megatherium_, _Megalonyx_, and _Mylodon_; we shall pa.s.s these animals in review, beginning with those of our own hemisphere.

The Mammoth, the skeleton of which is represented in Fig. 180, surpa.s.sed the largest existing Elephants of the tropics in size, for it was from sixteen to eighteen feet in height. The teeth, and the size of the monstrous tusks, much curved, and with a spiral turn outwards, and which were from ten to fifteen feet in length, serve to distinguish the Mammoth from the two Elephants living at the present day, the African and the Indian. The form of its teeth permits of its being distinguished from its ally, the Mastodon; for while the teeth of the latter have rough mammillations on their surface, those of the Mammoth, like those of the living Indian Elephant, have a broad united surface, with regular furrowed lines of large curvature. The teeth of the Mammoth are four in number, like the Elephants, two in each jaw when the animal is adult, its head is elongated, its forehead concave, its jaws curved and truncated in front. It has been an easy task, as we shall see, to recognise the general form and structure of the Mammoth, even to its skin. We know beyond a doubt that it was thickly covered with long s.h.a.ggy hair, and that a copious mane floated upon its neck and along its back; its trunk resembled that of the Indian Elephant; its body was heavy, with a tail naked to the end, which was covered with thick tufty hair, and its legs were comparatively shorter than those of the latter animal, many of the habits of which it nevertheless possessed.

Blumenbach gave it the specific name of _Elephas primigenius_.

[Ill.u.s.tration: Fig. 180.--Skeleton of the Mammoth, Elephas primigenius.]

In all ages, and in almost all countries, chance discoveries have been made of fossil bones of elephants in the soil. Pliny has transmitted to us a tradition, recorded by the historian Theophrastus, who wrote 320 years before Jesus Christ, of the existence of bones of fossil ivory in the soil of Greece, that the bones were sometimes transformed into stones. "These bones," the historian gravely tells us, "were both black and white, and born of the earth." Some of the elephant's bones having a slight resemblance to those of man, they have often been mistaken for human bones. In the earlier historic times these great bones, accidentally disinterred, have pa.s.sed as having belonged to some hero or demiG.o.d; at a later period they were thought to be the bones of giants.

We have already spoken of the mistake made by the Greeks in taking the patella of a fossil elephant for the knee-bone of Ajax; in the same manner the bones revealed by an earthquake, and attributed by Pliny to a giant, belonged, no doubt, to a fossil elephant. To a similar origin we may a.s.sign the pretended body of Orestes, thirteen feet in length, which was discovered at Tegea by the Spartans; those of Asterius, the son of Ajax, discovered in the Isle of Ladea, of ten cubits in length (about eighteen feet), according to Pausanius; finally, such were the great bones found in the Isle of Rhodes, of which Phlegon of Tralles speaks in his "Mundus Subterraneus."

[Ill.u.s.tration: Fig. 181.--Tooth of the Mammoth.]

We might fill volumes with the history of the remains of pretended giants found in ancient tombs. The books, in fact, which exist, formed a voluminous literature in the middle ages--ent.i.tled _Gigantology_. All the facts, more or less real, true or imaginative, may be explained by the accidental discovery of the bones of some of these gigantic animals.

We find in works on Gigantology, the history of a pretended giant, discovered in the 4th century, at Trapani in Sicily, of which Boccaccio speaks, and which may be taken for Polyphemus; of another, found in the 16th century, according to Fasellus, near Palermo; others, according to the same author, at Melilli between Leontium and Syracuse, Calatrasi and Petralia, at each of which places the bones of supposed giants were disinterred. P. Kircher speaks of three other giants being found in Sicily, of which only the teeth remained perfect.

In 1577, a storm having uprooted an oak near the cloisters of Reyden, in the Canton of Lucerne, in Switzerland, some large bones were exposed to view. Seven years after, the celebrated physician and Professor at Basle, Felix Platen, being at Lucerne, examined these bones, and declared they could only be those of a giant. The Council of Lucerne consented to send the bones to Basle for more minute examination, and Platen thought himself justified in attributing to the giant a height of nineteen feet. He designed a human skeleton on this scale, and returned the bones with the drawing to Lucerne. In 1706 there only remained of these bones a portion of the scapula and a fragment of the wrist bone; the anatomist Blumenbach, who saw them at the beginning of the century, easily recognised in them the bones of an Elephant. Let us not omit to add, as a complement to this story, that since the sixteenth century, the inhabitants of Lucerne have adopted the image of this fabulous giant as the supporter of the city arms.

Spanish history preserves many stories of giants. The supposed tooth of St. Christopher, shown at Valence, in the church dedicated to the saint, was certainly the molar tooth of a fossil Elephant; and in 1789, the canons of St. Vincent carried through the streets in public procession, to procure rain, the pretended arm of a saint, which was nothing more than the femur of an Elephant.

In France, in the reign of Charles VII. (1456), some of these bones of imaginary giants appeared in the bed of the Rhone. A repet.i.tion of the phenomenon occurred near Saint-Peirat, opposite Valence, when the Dauphin, afterwards Louis XI., then residing at the latter place, caused the bones to be gathered together and sent to Bourges, where they long remained objects of public curiosity in the interior of the Sainte-Chapelle. In 1564 a similar discovery took place in the same neighbourhood. Two peasants observed on the banks of the Rhone, along a slope, some great bones sticking out of the ground. They carried them to the neighbouring village, where they were examined by Ca.s.sanion, who lived at Valence. It was no doubt apropos to this that Ca.s.sanion wrote his treatise "De Gigantibus." The description given by the author of a tooth sufficed, according to Cuvier, to prove that it belonged to an Elephant; it was a foot in length, and weighed eight pounds. It was also on the banks of the Rhone, but in Dauphiny, as we have seen, that the skeleton of the famous Teutobocchus, of which we have spoken in a previous chapter, was found.

In 1663 Otto de Guericke, the ill.u.s.trious inventor of the air-pump, witnessed the discovery of the bones of an Elephant, buried in the sh.e.l.ly limestone, or Muschelkalk. Along with it were found its enormous tusks, which should have sufficed to establish its zoological origin.

Nevertheless they were taken for horns, and the ill.u.s.trious Leibnitz composed, out of the remains, a strange animal, carrying a horn in the middle of its forehead, and in each jaw a dozen molar teeth a foot long.

Having fabricated this fantastic animal, Leibnitz named it also--he called it the _fossil unicorn_. In his "Protogaea," a work remarkable besides as the first attempt at a theory of the earth, Leibnitz gave the description and a drawing of this imaginary animal. During more than thirty years the unicorn of Leibnitz was universally accepted throughout Germany; and nothing less than the discovery of the entire skeleton of the Mammoth in the valley of the Unstrut was required to produce a change of opinion. This skeleton was at once recognised by Tinzel, librarian to the Duke of Saxe-Gotha, as that of an Elephant, and was established as such; not, however, without a keen controversy with adversaries of all kinds.

In 1700 a soldier of Wurtemberg accidentally observed some bones showing themselves projecting out of the earth, in an argillaceous soil, near the city of Canstadt, not far from the banks of the Necker. Having addressed a report to the reigning Duke, the latter caused the place to be excavated, which occupied nearly six months. A veritable cemetery of elephants was discovered, in which were not less than sixty tusks. Those which were entire were preserved; the fragments were abandoned to the court physician, and they became a mere vulgar medicine. In the last century the fossil bones of bears, which were abundant in Germany, were administered in that country medicinally, as an absorbent, astringent, and sudorific. It was then called by the German doctors the _Ebur fossile_, or _Unicornu fossile_, _Licorn fossil_. The magnificent tusks of the Mammoth found at Canstadt helped to combat fever and colic. What an intelligent man this court physician of Wurtemberg must have been!

Numerous discoveries like those we have quoted distinguished the 18th century; but the progress of science has now rendered such mistakes as we have had to relate impossible. These bones were at length universally recognised as belonging to an Elephant, but erudition now intervened, and helped to obscure a subject which was otherwise perfectly clear.