Lying immediately between the oolite and the chalk, is a small formation of fresh water, and not of marine deposit, to which the term Wealden has been given. This name has been given to it because it has been found developed chiefly in the Wealds, or Wolds,^[98] of Sussex, Surrey, and Kent; and to Dr. Mantell belongs the honour of investigating this singularly interesting formation, and of giving us its history, after months of patient research and laborious toil conducted on the spot, just as Hugh Miller has become the historian and explorer of the Old Red Sandstone of Cromarty. But although the Wealden is small when compared with the vast extent of some other formations, previously or subsequently added to the material of this “great globe’s” crust, it possesses unusual interest on account of the strange organic remains that are found in it, and of the evidence which these remains supply of vast changes in the conditions and characters of the living beings, found at that period roaming at large in the once tropical swamps of the Wealden.

The Wealden is almost if not wholly of fresh water origin; and a word or two on the formation of the deltas of great rivers, now going on in various parts of the world, will help us rightly to appreciate the character of this formation. It is seldom, some one remarks, that we “can catch a mountain in process of making,” and hence we have much difficulty in arriving at definite ideas concerning the times that the sedimentary rocks occupied in their deposit. But we can catch deltas in the process of manufacture,—the deltas of the Nile, the Mississippi, the Amazon, and other huge rivers that pour down, not their “golden streams,” but their muddy accumulations, gathered from the mountain sides whose slopes they wash into the great ocean basin waiting to receive them. “All the rivers run into the sea, yet the sea is not full.”

These deltas,—for we wish to explain as we go along, and would rather fall into the error of explaining where there is no necessity, than of leaving one word that might prove a stumbling-block unexplained,—these deltas are all the mouths, (les embouchères,) of oceanic rivers, that is, of rivers that pursue their impetuous course towards their native ocean bed; and the character of these deltas necessarily varies with the character of the coast through which they pursue the uneven “tenor of their way.” As the level of the sea is approached, the rapidity of the mountain stream is necessarily checked. No longer dashing down steep mountain precipices, as it did in the heyday of its youth, it finds itself grown into a majestic breadth and depth; and as it nears its maternal home, leaving the high land of its origin far behind, it traverses with slow and measured pace the slightly descending planes by which it falls into the ocean. This gradual process enables it to deposit on each side the alluvial soil, and decayed vegetable matter, and so on, that have been held by it in suspension during its rapid progress; and as the current slackens still more as it approaches its final destiny, portions of land gradually rise into view, the results of these deposits, which from their triangular shape have received the name of deltas, from their likeness to the Greek letter Δ.

Thus the mouths of the Ganges form a vast breadth of waters, with intervening islands and strips of land, 200 miles in width. Into this delta the river Ganges runs laden with the rich spoils of clay, sand, vegetable matter, &c., gathered from the Himalaya Mountains, and thus those dismal-looking islands have been formed in the mouth of this river, that have become the home of tigers, crocodiles, &c.

In North America, that “father of waters,” the Mississippi, sometimes called the Missouri, runs through a glorious valley of unexhausted and inexhaustible wealth of 3,000 miles, and runs out into the sea at least fifty miles, while its currenmiles further. “Like all other great rivers, the Mississippi does not empty itself into the sea in one continuous channel, but in a great variety of arms or mouths, which intersect in sluggish streams the great alluvial delta, which is formed by the perpetual deposit of the immense volume of water which rolls into the ocean. Between these mouths of the river a vast surface, half land, half water, from 50 to 100 miles in width, and 300 in length, fringes the whole coast; and there the enormous mass of vegetable matter constantly brought down by the Mississippi is periodically deposited. A few feet are sufficient to bring it above the level of the water, except in great floods; and as soon as that is done, vegetation springs up with the utmost rapidity in that prolific slime. No spectacle can be conceived so dreary and yet so interesting, as the prospect of these immense alluvial swamps in the course of formation. As far as the eye can reach, over hundreds of square leagues, nothing is to be seen but marshes bristling with roots, trunks, and branches of trees. In winter and spring, when the floods come down, they bring with them an incalculable quantity of these broken fragments, technically called logs, which not only cover the whole of this immense semi-marine territory, but, floating over it, strew the sea for several miles off to such an extent, that ships have often no small difficulty in making their way through them. Thus the whole ground is formed of a vast network of masses of wood, closely packed and rammed together to the depth of several fathoms, which are gradually cemented by fresh deposits, till the whole acquires by degrees a firm consistency. Aquatic birds, innumerable cranes and storks, water serpents, and huge alligators, people this dreary solitude. In a short time a kind of rank cane or reed springs up, which, by retarding the flow of the river, collects the mud of the next season, and so lends its share in the formation of the delta. Fresh logs, fresh mud, and new crops of cane or reed, go on for a series of years, in the course of which the alligators, in enormous multitudes, fix in their new domain, and extensive animal remains come to mingle with the vegetable deposits. Gradually, as the soil accumulates and hardens, a dwarfish shrub begins to appear above the surface; larger and larger trees succeed with the decay of their more stunted predecessors; and at length, on the scene of former desolation, the magnificent riches of the Louisianian forest are reared.”^[99]

To this glowing description we might add what we ourselves have witnessed on the coast of South America, where the great Amazon, the Orinoco, and the Essequibo, roll their mud-laden waters into the Atlantic, and form vast accumulations of alluvial deposit all along its northern coast; indeed, the coast line of all the Guianas of South America, averaging some five to ten miles in width, and at least 1,000 miles in length,—Venezuela, British Guiana, Surinam, and Cayenne,—are nothing more than the deposit formed at the base of the mountains by these and other rivers of smaller note. Buried in this mud are pebbles, trunks of trees, animal remains, and so on; and if these in process of time should be elevated and afterwards hardened, or submerged and pressed into clayey slate or sandy stone, the fauna and the flora of these deltas would then be brought to light, just as the leaves of plants are exhibited between the pages of a botanist’s collecting book.

In some such method as this was once formed a delta, now constituting the Wealden formation in our own country. What is now the south-east of England, including the Weald clay, the Hastings sand, and the Purbeck beds of limestone and marls, in short, the greater part of the counties already named, with part of Dorsetshire, was once the delta of a mighty river, that so long and so uninterruptedly flowed through this then uninhabited part of the planet, that its accumulated deposits average 1,000 feet in thickness. We have but to pause over those words—one thousand feet thick;—once mud, or rather fluviatile deposits of mud and sand, a thousand feet thick in order to receive fresh evidence of the high antiquity of the globe, and of the recent creation of man. We have but for a moment to remember that these deposits consist of innumerable layers of mollusks and crustaceans, a prodigious accumulation of the bones of reptiles and fishes, and of the trunks, branches, and foliage of a long extinct vegetable world, all quietly brought down by “the rivers of waters” of that era, and carefully and without injury deposited in what were then the bottoms of bays or the rising land of deltas, in order to appreciate the evidence which this one deposit alone affords of the immense period of time occupied in its accumulation.

Our next section, the cretaceous division of the secondary rocks, presents us with an exclusively marine deposit. The Wealden, as we have said, is a fresh-water deposit. “Many a long and weary journey,” says Dr. Mantell, “have I undertaken to examine the materials thrown up from a newly-made well, or the section exposed by recent cuttings on the roadside, in the hope of obtaining the data by which this problem is now completely settled.” The data referred to are such as these—the absence of all ammonites, encrinites, corals, terebratulæ, and other marine organisms, which form so large a portion of the cretaceous and other sea deposits.

Here, again, we may anticipate future remarks. It may be thought—by some it has been roundly asserted—that these fossils were placed in their present situations by the deluge. Without entering into the theological question, as to the universality or partiality of the Noachian flood, although, as we shall hereafter see, there is but one opinion on that subject held by our best geologists, namely, that the deluge recorded in the Bible was simply the subsidence or submerging of so much of the earth, and no more, as was then inhabited by man, and that so partial and so limited was its character, and so brief its duration, compared with those vast geological epochs we have been considering, that there are no traces in nature of that event at all, i.e. that we have no one single fossil that can be referred to that event,—without, we repeat, entering upon the investigation of this subject, which will be done in a subsequent part of this volume, we would merely remark, in reply to this absurd notion, that the Wealden is evidently an alluvial, and not a diluvial formation; and as these terms are so frequently used as if they were synonymous, we shall venture upon our old habit of explanation. An alluvial deposit is formed by the ordinary, but a diluvial deposit by the extraordinary action of water. Thus all the straths and carses of Scotland, and our English dales or dells, (may not the remote etymology be delta?) are all of alluvial formation; while, as owing their origin to diluvial, or the violent action of water, we are to ascribe the heaps of rubbish, gravel, sand and boulders, that are found in firm compact together.

Thus, if we take a basin of water holding a quantity of earthy matter in solution, and place it on a quiet table, and allow the earthy matter gradually to subside, that which is found at the bottom of the basin is an alluvial formation, deposited by the quiet and ordinary action of water.

But when, as sometimes here in Royston, a sudden and heavy rain occurs, when for a while “the windows of heaven” seem opened, and the surrounding hills pour down their rushing streams through the town, filling, as unfortunately they do on such occasions, the cellars of our neighbours in the bottom of the town, with sticks, stones, flint, gravel, bits of chalk, paper, bones, cloth, and a variety of intermingled sundries too numerous to mention, and all huddled together in wild confusion, then is formed in such ill-fated cellars a diluvial deposit, occasioned by the extraordinary action of water.

Now, the Scripture flood (and we may be allowed to say, we are not trying to explain away the fact of the deluge,^[100] nor to weaken the strength of the Mosaic narrative, but the very contrary) was a most extraordinary event. Not only were the “windows of heaven opened,” but the “fountains of the great deep” were broken up, and if it had left any traces of its action, they would have been of a heterogeneous and diluvial character; whereas in the Wealden, as elsewhere, the fossils occur in the most orderly and quiet manner, preserving in many cases those exquisite forms of beauty which distinguished them during life.

Without entering more fully into details of the fossil remains of this period, we shall conclude this chapter by a reference to one of the vast saurians whose remains have been disinterred from the Wealden. Many years ago Dr. Mantell discovered, in a quarry at Cuckfield in Sussex, a tooth, which he took up to the Geological Society of London; it was altogether unlike any tooth he had hitherto found, but yet it was so common, that the quarrymen had broken many of them up to mend the roads. The most eminent geologists of the day were puzzled extremely with this tooth. One thought it belonged to a fish; another, that it belonged to an unknown herbivorous mammal; and a third, who was right, that it belonged to a herbivorous reptile. Sir Charles Lyell was at that time about to visit Paris, and the tooth, and that alone, was shown to Cuvier, who at once pronounced it to be the tooth of a rhinoceros. In the process of time other fossil remains were found, portions of jaws, cervical, dorsal, and caudal vertebræ; and on Cuvier seeing these, with the magnanimity of a truly great mind, he frankly avowed his error, and said, “I am entirely convinced of my error in pronouncing it to be the tooth of a rhinoceros.” Shortly after, Dr. Mantell was fortunate enough to procure the skeleton of an iguana,^[101] and he found that the fossil teeth found in Tilgate forest bore a close resemblance to the teeth of the iguana. The teeth of the iguana were found to be small, closely set, and serrated like the edge of a saw, not so much for crushing victims, as for champing and grinding its vegetable food; this corresponded precisely with the fossil teeth found, and after long and careful deliberation, the name given to this crocodile lizard, and the name which it retains, was Iguanodon, or the reptile with teeth like the iguana.

The probable size of the Iguanodon was thirty feet in length, though probably some exceeded these enormous proportions. Seventy species have been discovered in the quarries opened at Tilgate forest; and this gives us some idea of the conspicuous part these mighty creatures once played in the eras happily before man was an inhabitant of this planet. Why these remains should generally be found in the same locality we cannot certainly tell, though the previous extract from Alison may shed some light on this curious fact; but it appears beyond doubt that particular spots were selected by these beasts as hospitals and dying places, where, undisturbed by their enemies, they retired to die unseen.

The drawing on page 195, representing the restored fauna of this period, that is, inclusive of the Lias, Oolite, and Wealden formations, will not only illustrate our previous remarks, but enable our readers thoroughly to appreciate the following vivid description of the life of that remote era, which we do not like to abridge. Should any feel sceptical as to whether there were ever such “goings on” in this globe of ours, especially in our eastern counties, now the resort of tourists and invalids having no dread of such creatures before their eyes, we ask them not to reject all this as fable until they have gone to the British Museum, and in Room 3, and in Wall-case C, they will there see some of the magnificent specimens, obtained by Dr. Mantell, of these extinct deinosaurians.^[102] On reading this description, it seems quite justifiable to congratulate ourselves upon the era in which we live. Strange forms and monsters vast have been in the old time before us, and their disinterred remains teach us again and again the good and wholesome lesson of the king of Israel, prefixed as a motto to this chapter.

“Two of these saurians have more especially attracted attention, in consequence of their great abundance in a fossil state in our own country, but they are by no means the only ones known. Of these two, one was more exclusively a tenant of the deep, while the other was probably more frequently met with on the mud banks or on the shore. Both were truly marine in their habits, and both seem to have served as the representatives of the great Cetacean tribe—the whales, the porpoises, and other similar animals now existing.

“It is not easy to imagine the conditions of existence of such animals. We know their form, their proportions, their strange contrivances of structure, their very skin, and the nature of the food which they devoured; and yet, knowing with absolute certainty these points, we hardly dare draw the conclusions which are suggested. I will, however, venture to offer a sketch of the appearance of the sea and its inhabitants during this portion of the Reptilian epoch.

“There were then, perhaps, existing on or near the land, some of those reptiles which I shall describe in the next chapter; and with them were associated true crocodilians, not much unlike the fresh water gavial inhabiting the Ganges. These, also, might occasionally swim out to sea, and be found in the neighbouring shoals.

“But these shoals were alive with myriads of invertebrated animals; and crowds of sharks hovered about, feeding upon the larger tribes. There were also numerous other animals, belonging to those remarkable groups which I have attempted to describe in some detail. Imagine one of these monstrous animals, a plesiosaurus, some sixteen or twenty feet long, with a small wedge-shaped crocodilian head, a long, arched, serpent-like neck, a short compact body, provided with four large and powerful paddles, almost developed into hands; an animal not covered with brilliant scales, but with a black slimy skin. Imagine for a moment this creature slowly emerging from the muddy banks, and, half walking, half creeping along, making its way towards the nearest water. Arrived at the water, we can understand from its structure that it was liable to exhibit greater energy. Unlike the crocodile tribe, however, in all its proportions, it must have been equally dissimilar in habit. Perhaps, instead of concealing itself in mud or among rushes, it would swim at once boldly and directly to the attack. Its enormous neck stretched out to its full length, and its tail acting as a rudder, the powerful and frequent strokes of its four large paddles would at once give it an impulse, sending it through the water at a very rapid rate. When within reach of its prey, we may almost fancy that we see it drawing back its long neck as it depressed its body in the water, until the strength of the muscular apparatus with which this neck was provided, and the great additional impetus given by the rapid advance of the animal, would combine to produce a stroke from the pointed head which few living animals could resist. The fishes, including perhaps even the sharks, the larger cuttle-fish, and innumerable inhabitants of the sea, would fall an easy prey to this monster.

“But now let us see what goes on in the deeper abysses of the ocean, where a free space is given for the operations of that fiercely carnivorous marine reptile, the ichthyosaurus. Prowling about at a great depth, where the reptilian structure of its lungs, and the bony apparatus of the ribs would allow it to remain for a long time without coming to the air to breathe, we may fancy we see this strange animal, with its enormous eyes directed upwards, and glaring like globes of fire. Its length is some thirty or forty feet, its head being six or eight feet long; and it has paddles and a tail like a shark; its whole energies are fixed on what is going on above, where the plesiosaurus or some giant shark is seen devouring its prey. Suddenly striking with its short but compact paddles, and obtaining a powerful impetus by flapping its large tail, the monster darts through the water at a rate which the eye can scarcely follow towards the surface. The vast jaws, lined with formidable rows of teeth, soon open wide to their full extent; the object of attack is approached—is overtaken. With a motion quicker than thought the jaws are snapped together, and the work is done. The monster, becoming gorged, floats languidly near the surface, with a portion of the top of its head and its nostrils visible, like an island covered with black mud, above the water.

“But a description of such scenes of carnage, enacted at former periods of the earth’s history, may perhaps induce some of my readers to question the wisdom that permitted them, and conclude rashly that they are opposed to the ideas which we are encouraged to form of the goodness of that Being, the necessary action of whose laws, enforced on all living beings, gives rise to them. By no means, however, is this the case. These very results are perfectly compatible with the greatest wisdom and goodness and even according to our limited views of the course of nature, they may be shown not to involve any needless suffering. To us men, constituted as we are, and looking upon death as a punishment which must be endured, premature and violent destruction seems to involve unnecessary pain. But such is not the law of nature as it relates to animal life in general. The very exuberance and abundance of life is at once obtained and kept within proper bounds by this rapacity of some great tribes. A lingering death—a natural decay of those powers which alone enable the animal to enjoy life—would, on the contrary, be a most miserable arrangement for beings not endowed with reason, and not assisting each other. It would be cruelty, because it would involve great and hopeless suffering. Death by violence is to all unreasoning animals the easiest death, for it is the most instantaneous; and therefore, no doubt, it has been ordained that throughout large classes there should be an almost indefinite rate of increase, accompanied by destruction rapid and complete in a corresponding degree, since in this way the greatest amount of happiness is ensured, and the pain of misery and slow decay of the vital powers prevented. All nature, both living and extinct, abounds with facts proving the truth of this view; and it would be as unreasonable to doubt the wisdom and goodness of this arrangement, as it would be to call in question the mutual adaptation of each part in the great scheme of creation. No one who examines nature for himself, however superficially, can doubt the latter; and no one certainly, who duly considers the laws ordained for the general government of the world, can believe it possible for these laws to have acted without a system of compensation, according to which the vital energies of one tribe serve to prepare food for the development of higher powers in another.”^[103]