Part 37

The Calcaire grossier, consisting of marine limestones of various kinds, and with a coarse, sometimes compact, grain, is suitable for mason-work. These deposits, which form the most characteristic member of the Paris basin, naturally divide themselves into three groups of strata, characterised, the first, by Nummulites; the second by Miliolites; and the third or upper beds by Cerithia. The beds are also sometimes named Nummulite limestone, Miliolite limestone, and Cerithium limestone. Above these a great mass, generally sandy, is developed. It is marine at the base, and there are indications of brackish water in its upper parts; it is called Beauchamp Sandstone, or Sables Moyens (Grès de Beauchamp). These sands are very rich in shells. The siliceous limestone, or lower travertin, is a compact siliceous limestone extending over a wide area, and resembles a precipitate from mineral waters. The gypseous formation consists of a long series of marly and argillaceous beds, of a greyish, green, or white colour, in the intervals between which a thick deposit of gypsum, or sulphate of lime, is intercalated. This gypsum bed is found in its greatest thickness in France at Montmartre and Pantin near Paris. The formation of this gypsum is probably due to the action of free sulphuric acid upon the carbonate of lime of the formation; the sulphuric acid itself being produced by the transformation of the gaseous masses of sulphuretted hydrogen emanating from volcanic vents, into that acid, by the action of air and water. It was, as we have already said, in the gypsum-quarries of Montmartre that the numerous bones of Palæotherium and Anoplotherium were found. It is exclusively at this horizon that we find the remains of these animals, which seem to have been preceded by the Coryphodon, and afterwards by the Lophiodon; the order of succession in the appearance of these animals is now perfectly established. It may be added that round Paris the Eocene formation, from its lowest beds to the highest, is composed of beds of plastic clay, of the Calcaire grossier with its Nummulites, Miliolites, and Alveolites, followed by the gypseous formation; the series terminating in the Fontainebleau Sandstone, remarkable for its thickness and also for its fine scenery, as well as for its usefulness in furnishing paving-stone for the capital. In Provence the same series of rocks are continued, and attain an enormous thickness. This upper part of the Eocene deposit is entirely of lacustrine formation. Grignon has procured from a single spot, where they were embedded in a calcareous sand, no less than 400 fossils, chiefly formed of comminuted shells, in which, however, were well-preserved species both of marine, terrestrial, and fresh-water shells. Of the Paris basin, Sir Charles Lyell says: “Nothing is more striking in this assemblage of fossil testacea than the great proportion of species referable to the genus Cerithium. There occur no less than 137 species of this genus in the Paris basin, and almost all of them in the Calcaire grossier. Most of the living Cerithia (Figs. 157 and 168) inhabit the sea near the mouths of rivers, where the waters are brackish; so that their abundance in the marine strata now under consideration is in harmony with the hypothesis that the Paris basin formed a gulf into which several rivers flowed.”

“Elements of Geology,” p. 300.

To give the reader some idea of the formation, first come the limestones and lower marls, which contain fine lignite or wood-coal produced from vegetable matter buried in moist earth, and excluded from all access of air, a material which is worked in some parts of the south of France as actively as a coal-mine. In these lignites Anodon and other fresh-water shells are found.

From the base of Sainte-Victoire to the other side of Aix, we trace a conglomerate characterised by its red colour, but which dies away in its prolongation westward. This conglomerate contains land-snails (Helix) of various sizes, mixed with fresh-water shells. Upon this conglomerate, comprising therein the marls, rests a thick deposit of limestone with the gypsum of Aix and Manosque, which is believed to correspond with that of Paris. Some of the beds are remarkably rich in sulphur. The calcareous marly laminæ which accompany the gypsum of Aix contain Insects of various kinds, and Fishes resembling Lebias cephalotes. Finally, the whole terminates at Manosque in a fresh series of marls and sandstones, alternating with beds of limestone with Limnæa and Planorbis. At the base of this series are found three or four beds of lignite more inflammable than coal, which also give out a very sulphurous oil. We may form some estimate of the thickness of this last stage, if we add that, above the beds of fusible lignite, we may reckon sixty others of dry lignite, some of them capable of being very profitably worked if this part of Provence were provided with more convenient roads.

“The Nummulitic formation, with its characteristic fossils,” says Lyell, “plays a far more conspicuous part than any other Tertiary group in the solid framework of the earth’s crust, whether in Europe, Asia, or Africa. It often attains a thickness of many thousand feet, and extends from the Alps to the Carpathians, and is in full force in the north of Africa, as, for example, in Algeria and Morocco. It has been traced from Egypt, where it was largely quarried of old for the building of the Pyramids, into Asia Minor, and across Persia, by Bagdad, to the mouth of the Indus. It occurs not only in Cutch, but in the mountain ranges which separate Scinde from Persia, and which form the passes leading to Caboul; and it has been followed still further eastward into India, as far as eastern Bengal and the frontiers of China.”

Ibid., p. 305.

“When we have once arrived at the conclusion,” he adds, “that the Nummulitic formation occupies a middle place in the Eocene series, we are struck with the comparatively modern date to which some of the greatest revolutions in the physical geography of Europe, Asia, and northern Africa must be referred. All the mountain chains, such as the Alps, Pyrenees, Carpathians, and Himalayas, into the composition of whose central and loftiest parts the Nummulitic strata enter bodily, could have had no existence till after the Middle Eocene period.”

The Eocene strata, Professor Ramsay thinks, extended in their day much further west, “because,” he says, “here, at the extreme edge of the chalk escarpments, you find outlying fragments of them,” from which he argues that they were originally deposited all over the Chalk as far as these points, but being formed of soft strata they were “denuded” backwards.

The Beloptera represented in Fig. 195 are curious Belemnite-like organisms, occurring in Tertiary strata, and evidently the internal bone of a Cephalopod, having a wing-like projection or process on each side. As a genus it holds a place intermediate between the Cuttle-fish and the Belemnite.

(Living form.)]

THE MIOCENE PERIOD.

The Miocene formation is not present in England; unless we suppose, with Sir Charles Lyell, that it is represented by the Hempstead beds of the Isle of Wight.

It is on the European continent that we find the most striking characteristics of the Miocene period. In our own islands traces of it are few and far between. In the Island of Mull certain beds of shale, interstratified with basalt and volcanic ash, are described by the Duke of Argyll as of Miocene date; and Miocene clay is found interstratified with bands of imperfect coal at Bovey Tracey. The vegetation which distinguished the period is a mixture of the vegetable forms peculiar to the burning climate of the present tropical Africa, with such as now grow in temperate Europe, such as Palms, Bamboos, various kinds of Laurels, Combretaceæ (Terminalia), with the grand Leguminales of warm countries (as Phaseolites, Erythrina, Bauhinia, Mimosites, Acacia); Apocyneæ analogous to the genera of our tropical regions; a Rubiacea altogether tropical (Steinhauera) mingle with some Maples, Walnut-trees, Beeches, Elms, Oaks, and Wych-elms, genera now confined to temperate and even cold countries.

Quarterly Journal of Geol. Soc., vol. vii., p. 89.

Besides these, there were, during the Miocene period, mosses, mushrooms, charas, fig-trees, plane-trees, poplars, and evergreens. “During the second period of the Tertiary epoch,” says Lecoq, “the Algæ and marine Monocotyledons were less abundant than in the preceding age; the Ferns also diminished, the mass of Conifers were reduced, and the Palms multiplied in species. Some of those cited in the preceding period seem still to belong to this, and the magnificent Flabellaria, with the fine Phœnicites, which we see now for the first time, gave animation to the landscape. Among the Conifers some new genera appear; among them we distinguish Podocarpens, a southern form of vegetation of the present age. Almost all the arborescent families have their representatives in the forests of this period, where for the first time types so different are united. The waters are covered with Nymphæa Arithnæa (Brongniart); and with Myriophyllites capillifolius (Unger); Culmites animalis (Brongniart); and C. Gœpperti (Munster), spring up in profusion upon their banks, and the grand Bambusinites sepultana throws the shadow of its long articulated stem across them. Some analogous species occupy the banks of the great rivers of the New World; one Umbellifera is even indicated, by Unger, in the Pimpinellites zizioides.

Of this period date some beds of lignite resulting from the accumulation, for ages, of all these different trees. It seems that arborescent vegetation had then attained its apogee. Some Smilacites interlaced like the wild vines with these grand plants, which fell on the ground where they grew, from decay; some parts of the earth, even now, exhibit these grand scenes of vegetation. They have been described by travellers who have traversed the tropical regions, where Nature often displays the utmost luxury, under the screen of clouds which does not allow the rays of the sun to reach the earth. M. D’Orbigny cites an interesting instance which is much to the point. “I have reached a zone,” he says (speaking of Rio Chapura in South America), “where it rains regularly all the year round. We can scarcely perceive the rays of the sun, at intervals, through the screen of clouds which almost constantly veils it. This circumstance, added to the heat, gives an extraordinary development to the vegetation. The wild vines fall on all sides, in garlands, from the loftiest branches of trees whose summits are lost in the clouds.”

The fossil species of this period, to the number of 133, begin to resemble those which enrich our landscapes. Already tropical plants are associated with the vegetables of temperate climates; but they are not yet the same as existing species. Oaks grow side by side with Palms, the Birch with Bamboos, Elms with Laurels, the Maples are united to the Combretaceæ, to the Leguminales, and to the tropical Rubiaceæ. The forms of the species, belonging to temperate climates, are rather American than European.

The luxuriance and diversity of the Miocene flora has been employed by a German savant in identifying and classifying the Middle Tertiary or Miocene strata of Switzerland. We are indebted to Professor Heer, of Zurich, for the restoration of more than 900 species of plants, which he classified and illustrated in his “Flora Tertiaria Helvetiæ.” In order to appreciate the value of the learned Professor’s undertaking, it is only necessary to remark that, where Cuvier had to study the position and character of a bone, the botanist had to study the outline, nervation, and microscopic structure of a leaf. Like the great French naturalist, he had to construct a new science at the very outset of his great work.

The Miocene formations of Switzerland are called Molasse (from the French mol, soft), a term which is applied to a soft, incoherent, greenish sandstone, occupying the country between the Alps and the Jura, and they may be divided into lower, middle, and upper Miocene; the middle one is marine, the other two being fresh-water formations. The upper fresh-water Molasse is best seen at Œningen, in the Rhine valley, where, according to Sir Roderick Murchison, it ranges ten miles east and west from Berlingen, on the right bank, to Waugen and to Œningen, near Stein, on the left bank. In this formation Professor Heer enumerates twenty-one beds. No. 1, a bluish-grey marl seven feet thick, without organic remains, resting on No. 2, limestone, with fossil plants, including leaves of poplar, cinnamon, and pond-weed (Potamogeton). No. 3, bituminous rock, with Mastodon angustidens. No. 5, two or three inches thick, containing fossil Fishes. No. 9, the stone in which the skeleton of the great Salamander Andrias Scheuchzeri (Fig. 158) was found. Below this, other strata with Fishes, Tortoises, the great Salamander, as before, with fresh-water Mussels, and plants. In No. 16, Sir R. Murchison obtained the fossil fox of Œningen, Galacynus Œningensis (Owen). In these beds Professor Heer had, as early as 1859, determined 475 species of fossil plants, and 900 insects.

The plants of the Swiss Miocene period have been obtained from a country not one-fifth the size of Switzerland, yet such an abundance of species, which Heer reckons at 3,000, does not exist in any area of equal extent in Europe. It exceeds in variety, he considers, after making every allowance for all not having existed at the same time, and from other considerations, the Southern American forests, and rivals such tropical countries as Jamaica and Brazil. European plants occupy a secondary place, while the evergreen Oaks, Maples, Poplars, and Plane-trees, Robinias, and Taxodiums of America and the smaller Atlantic islands, occupy such an important place in the fossil flora that Unger was induced to suggest the hypothesis, that, in the Miocene period the present basin of the Atlantic was dry land--and this hypothesis has been ably advocated by Heer.

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The terrestrial animals which lived in the Miocene period were Mammals, Birds, and Reptiles. Many new Mammals had appeared since the preceding period; among others, Apes, Cheiropteras (Bats), Carnivora, Marsupials, Rodents, Dogs. Among the first we find Pithecus antiquus and Mesopithecus; the Bats, Dogs, and Coati inhabited Brazil and Guiana; the Rats North America; the Genettes, the Marmots, the Squirrels, and Opossums having some affinity to the Opossums of America. Thrushes, Sparrows, Storks, Flamingoes, and Crows, represent the class Birds. Among the Reptiles appear several Snakes, Frogs, and Salamanders. The lakes and rivers were inhabited by Perches and Shad. But it is among the Mammals that we must seek for the most interesting species of animals of this period. They are both numerous and remarkable for their dimensions and peculiarities of form; but the species which appeared in the Miocene period, as in those which preceded it, are now only known by their fossil remains and bones.

The Dinotherium (Fig. 159), one of the most remarkable of these animals, is the largest terrestrial Mammal which has ever lived. For a long time we possessed only very imperfect portions of the skeleton of this animal, upon the evidence of which Cuvier was induced erroneously to place it among the Tapirs. The discovery of a lower jaw, nearly perfect, armed with defensive tusks descending from its lower jaw, demonstrated that this hitherto mysterious animal was the type of an altogether new and singular genus. Nevertheless, as it was known that there were some animals of the ancient world in which both jaws were armed, it was thought for some time that such was the case with the Dinotherium. But in 1836, a head, nearly entire, was found in the already celebrated beds at Eppelsheim, in the Grand Duchy of Hesse Darmstadt. In 1837 this fine fragment was carried to Paris, and exposed to public view. It was nearly a yard and a half long, and above a yard wide. The defences, it was found, were enormous, and were carried at the anterior extremity of the lower maxillary bone, and much curved inwards, as in the Morse. The molar teeth were in many respects analogous to those of the Tapir, and the great suborbital apertures, joined to the form of the nasal bone, rendered the existence of a proboscis or trunk very probable. But the most remarkable bone belonging to the Dinotherium which has yet been found is an omoplate or scapula, which by its form reminds us of that of the Mole.

This colossus of the ancient world, respecting which there has been so much argument, somewhat approaches the Mastodon; it seems to announce the appearance of the Elephant; but its dimensions were infinitely greater than those of existing Elephants, and superior even to those of the Mastodon and of the Mammoth, both fossil Elephants, the remains of which we shall have to describe presently.

From its kind of life, and its frugal regimen, this Pachyderm scarcely merited the formidable name of Dinotherium which has been bestowed on it by naturalists (from δεινος, terrible, θηριον, animal). Its size was, no doubt, frightful enough, but its habits seem to have been peaceful. It is supposed to have inhabited fresh-water lakes, or the mouths of great rivers and the marshes bordering their banks by preference. Herbivorous, like the Elephant, it employed its proboscis probably in seizing the plants which hung suspended over the waters, or floated on their surface. We know that the elephants are very partial to the roots of herbaceous plants which grow in flooded plains. The Dinotherium appears to have been organised to satisfy the same tastes. With the powerful natural mattock which Nature had supplied him for penetrating the soil, he would be able to tear from the bed of the river, or lake, feculent roots like those of the Nymphæa, or even much harder ones, for which the mode of articulation of the jaws, and the powerful muscles intended to move them, as well as the large surface of the teeth, so well calculated for grinding, were evidently intended (Fig. 160).

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The Mastodon was, to all appearance, very nearly of the size and form of our Elephant--his body, however, being somewhat longer, while his limbs, on the contrary, were a little thicker. He had tusks, and very probably a trunk, and is chiefly distinguished from the existing Elephant by the form of his molar teeth, which form the most distinctive character in his organisation. These teeth are nearly rectangular, and present on the surface of their crown great conical tuberosities, with rounded points disposed in pairs to the number of four or five, according to the species. Their form is very distinct, and may be easily recognised. They do not bear any resemblance to those of the carnivora, but are like those of herbivorous animals, and particularly those of the Hippopotamus. The molar teeth are at first sharp and pointed, but when the conical points are ground down by mastication, they assume the appearance presented in Fig. 161. When, from continued grinding, the conical teat-like points are more deeply worn, they begin to assume the appearance shown in Fig. 160. In Fig. 162 we represent the head and lower jaw of the Miocene Mastodon; from which it will appear that the animal had two projecting tusks in the lower jaw, corresponding with two of much larger dimensions which projected from the upper jaw.

It was only towards the middle of the last century that the Mastodon first attracted attention in Europe. About the year 1705, it is true, some bones of this animal had been found at Albany, now the capital of New York, but the discovery attracted little attention. In 1739, a French officer, M. de Longueil, traversed the virgin forests bordering the great river Ohio, in order to reach the great river Mississippi, and the savages who escorted him accidentally discovered on the borders of a marsh various bones, some of which seemed to be those of unknown animals. In this turfy marsh, which the natives designated the Great Salt Lake, in consequence of the many streams charged with salt which lose themselves in it, herds of wild ruminants still seek its banks, attracted by the salt--for which they have a great fondness--such being the reason probably which had caused the accumulation, at this point, of the remains of so large a number of quadrupeds belonging to these remote ages in the history of the globe. M. de Longueil carried some of these bones with him, and, on his return to France, he presented them to Daubenton and Buffon; they consisted of a femur, one extremity of a tusk, and three molar teeth. Daubenton, after mature examination, declared the teeth to be those of a Hippopotamus; the tusk and the gigantic femur, according to his report, belonged to an Elephant; so that they were not even considered to be parts of one and the same animal. Buffon did not share this opinion, and he was not long in converting Daubenton, as well as other French naturalists, to his views. Buffon declared that the bones belonged to an Elephant, whose race had lived only in the primitive ages of the globe. It was then, only, that the fundamental notion of extinct species of animals, exclusively peculiar to ancient ages of the world, began to be entertained for the first time by naturalists--a notion which laid dormant during nearly a century, before it bore the admirable fruits which have since so enriched the natural sciences and philosophy.