TERTIARY PERIOD.

Fig. 144Fig. 144.—Cypris Valdensis.

Fig. 144.—Cypris Valdensis.

The Cretaceous series is not interesting for its fossils alone; it presents also an interesting subject for study in a mineralogical point of view. The white Chalk, examined under the microscope by Ehrenberg, shows a curious globiform structure. The green part of its sandstone and limestone constitutes very singular compounds. According to the result of Berthier’s analysis, we must consider them as silicates of iron. The iron shows itself here not in beds, as in the Jurassic rocks, but in masses, in a species of pocket in the Orgonian beds. They are usually hydrates in the state of hematites, accompanied by quantities of ochre so abundant that they are frequently unworkable. In the south of France these veins weremined to a great depth by the ancient monks, who were the metallurgists of their age. But for the artist the important Orgonian beds possess a special interest; their admirable vertical fractures, their erect perpendicular peaks, each surpassing the other in boldness, form his finest studies. In the Var, the defiles of Vésubia, of the Esteron, and Tinéa, are jammed up between walls of peaks, for many hundreds of yards, between which there is scarcely room for a narrow road by the side of the roaring torrent. “In the Drôme,” says Fournet, “the entrance to the beautiful valley of the Vercors is closed during a part of the year, because, in order to enter, it is necessary to cross the two gullies, theGreatandLittle Goulet, through which the waters escape from the valley. Even during the dry season, he who would enter the gorge must take a foot-bath.

“This state of things could not last; and in 1848 it was curious to see miners suspended on the sides of one of these lateral precipices, some 450 feet above the torrent, and about an equal distance below the summit of the Chalk. There they began to excavate cavities or niches in the face of the rock, all placed on the same level, and successively enlarged. These were united together in such a manner as to form a road practicable for carriages; now through a gallery, now covered by a corbelling, to look over which affords a succession of surprises to the traveller.

“This is not all,” adds M. Fournet: “he who traverses the high plateaux of the country finds at every step deep diggings in the soil, designated pits orscialets, the oldest of which have their sides clothed with a curious vegetation, in which theAucolinpredominates; shelter is found in these pits from the cutting winds which rage so furiously in these elevated regions. Others form a kind of cavern, in which a temperature obtains sufficient to freeze water even in the middle of summer. These cavities form naturalglaciers, which we again find upon some of the table-lands of the Jura.

“The cracks and crevasses of the limestone receive the waters produced by falling rain and melted snow; true to the laws of all fluid bodies, they filter through the rocks until they reach the lower and impervious marly beds, where they form sheets of water, which in course of time find some outlet through which they discharge themselves. In this manner subterranean galleries, sometimes of great extent, are formed, in which are assembled all the marvels which crumbling stalactites, stalagmites, placid lakes, and headlong torrents can produce; finally, these waters, forcing their way through the external orifices, give rise to those fine cascades which, with the first gushing torrent, form an actual river.”

TheAlbienof Alc. D’Orbigny, which Lyell considers to be the equivalent of theGault, French authors treat as the “glauconie” formation, the name being drawn from a rock composed of chalk with greenish grains ofglauconite, or silicate of iron, which is often mixed with the limestone of this formation. The fossils by which it is identified are very varied. Among its numerous types, we find Crustaceans belonging to the generaArcaniaandCorystes; many new Mollusca,Buccinum,Solen,Pterodonta,Voluta,Chama, &c.; great numbers of molluscous Brachiopods, forming highly-developed submarine strata; some Echinoderms, unknown up to this period, and especially a great number of Zoophytes; some Foraminifera, and many Polyzoa (Bryozoa). The glauconitic formation consists of two groups of strata: theGaultClay and theglauconiticchalk, or Upper Greensand and Chloritic Marl.

During this phase of the terrestrial evolutions, the continents, to judge from the fossilised wood which we meet with in the rocks which now represent it, would be covered with a very rich vegetation, nearly identical, indeed, with that which we have described in the preceding sub-period; according to Adolphe Brongniart, the “age of angiosperms” had fairly set in; the Cretaceous flora displays, he considers, a transitional character from the Secondary to the Tertiary vegetation; that the line between the gymnosperms, or naked-seeded plants, and the angiosperms, having their seeds enclosed in seed-vessels, runs between the Upper and Lower Cretaceous formations. “We can now affirm,” says Lyell, “that these Aix-la-Chapelle plants, called Credneria, flourished before the rich reptilian fauna of the secondary rocks had ceased to exist. The Ichthyosaurus, Pterodactyle, and Mosasaurus were of coeval date with the oak, the walnut, and the fig.”[80]

The terrestrial fauna, consisting of some new Reptiles haunting the banks of rivers, and Birds of the genus Snipe, have certainly only reached us in small numbers. The remains of the marine fauna are, on the contrary, sufficiently numerous and well preserved to give us a great idea of its riches, and to enable us to assign to it a characteristic facies.

The sea of the Upper Cretaceous period bristled with numerous submarine reefs, occupying a vast extent of its bed—reefs formed ofRudistes (Lamarck), and of immense quantities of various kinds of corals which are everywhere associated with them. The Polyps, in short, attain here one of the principal epochs of their existence, and present a remarkable development of forms; the same occurs with the Polyzoa (Bryozoa) and Amorphozoa; while, on the contrary, the reign of the Cephalopods seems to end. Beautiful types of these ancient reefs have been revealed to us, and we discover that they have been formed under the influence of submarine currents, which accumulated masses of these animals at certain points. Nothing is more curious than this assemblage ofRudistes—still standing erect, isolated or in groups—as may be seen, for instance, at the summit of the mountains of theCornesin the Corbières, upon the banks of the pond of Berre in Provence, and in the environs of Martigues, at La Cadière, at Figuières, and particularly above Beausset, near Toulon.

“It seems,” says Alcide D’Orbigny, “as if the sea had retired in order to show us, still intact, the submarine fauna of this period, such as it was when in life. There are here enormous groups ofHippuritesin their places, surrounded by Polyps, Echinoderms, and Molluscs, which lived in union in these animal colonies, analogous to those which still exist in the coral-reefs of the Antilles and Oceania. In order that these groups should have been preserved intact, they must first have been covered suddenly by sediment, which, being removed by the action of the atmosphere, reveals to us, in their most secret details, this Nature of the past.”

In the Jurassic period we have already met with these isles or reefs formed by the accumulation of Coral and other Zoophytes; they even constituted, at that period, an entire formation called theCoral-rag. The same phenomenon, reproduced in the Cretaceous seas, gave rise to similar calcareous formations. We need not repeat what we have said already on this subject when describing the Jurassic period. The coral or madrepore isles of the Jurassic epoch and the reefs of Rudistes and Hippurites of the Cretaceous period have the same origin, and theatollsof Oceania are reproductions in our own day of precisely similar phenomena.

The invertebrate animals which characterise the Cretaceous age are among

Cephalopoda.Nautilus sublævigatusandN. Danicus; Ammonites rostratus; Belemnitella mucronata.Gasteropoda.Voluta elongata; Phorus canaliculatus; Nerinea bisulcata; Pleurotomaria Fleuriausa, andP. Santonensis; Natica supracretacea.Acephala.Trigonia scabra; Inoceramus problematicusandI. Lamarckii; Clavigella cretacea; Pholadomya æquivalvis; Spondylus spinosus; Ostrea vesicularis; Ostrea larva; Janira quadricostata; Arca Gravesii; Hippurites ToucasianusandH. organisans; Caprina Aguilloni; Radiolites radiosus, andR. acuticostus.Brachiopoda.Crania Ignabergensis; Terebratula obesa.Polyzoa (Bryozoa) and Eschinodemata.Reticulipora obliqua; Ananchytes ovatus; Micraster cor-anguinum, Hemiaster bucardiumandH. Fourneli; Galerites albogalerus; Cidaris Forchammeri; Palæocoma Furstembergii.1.Polypi; 2.Foraminifera; 3.Amorphozoa.1.Cycollites elliptica; Thecosmilia rudis; Enallocœnia ramosa; Meandrina Pyrenaica; Synhelia Sharpeana. 2.Orbitoides media; Lituola nautiloidea; Flabellina rugosa. 3.Coscinopora cupuliformis; Camerospongia fungiformis.

Cephalopoda.

Nautilus sublævigatusandN. Danicus; Ammonites rostratus; Belemnitella mucronata.

Gasteropoda.

Voluta elongata; Phorus canaliculatus; Nerinea bisulcata; Pleurotomaria Fleuriausa, andP. Santonensis; Natica supracretacea.

Acephala.

Trigonia scabra; Inoceramus problematicusandI. Lamarckii; Clavigella cretacea; Pholadomya æquivalvis; Spondylus spinosus; Ostrea vesicularis; Ostrea larva; Janira quadricostata; Arca Gravesii; Hippurites ToucasianusandH. organisans; Caprina Aguilloni; Radiolites radiosus, andR. acuticostus.

Brachiopoda.

Crania Ignabergensis; Terebratula obesa.

Polyzoa (Bryozoa) and Eschinodemata.

Reticulipora obliqua; Ananchytes ovatus; Micraster cor-anguinum, Hemiaster bucardiumandH. Fourneli; Galerites albogalerus; Cidaris Forchammeri; Palæocoma Furstembergii.

1.Polypi; 2.Foraminifera; 3.Amorphozoa.

1.Cycollites elliptica; Thecosmilia rudis; Enallocœnia ramosa; Meandrina Pyrenaica; Synhelia Sharpeana. 2.Orbitoides media; Lituola nautiloidea; Flabellina rugosa. 3.Coscinopora cupuliformis; Camerospongia fungiformis.

Among the numerous beings which inhabited the Upper Cretaceous seas there is one which, by its organisation, its proportions, and the despotic empire which it would exercise in the bosom of the waters, is certainly most worthy of our attention. We speak of theMosasaurus, which was long known as the great animal ofMaestricht, because its remains were found near that city in the most modern of the Cretaceous deposits.

In 1780 a discovery was made in the quarries of Saint Peter’s Rocks, near Maestricht, of the head of a great Saurian, which may now be seen in the Museum of Natural History in Paris. This discoverybaffled all the science of the naturalists, at a period when the knowledge of these ancient beings was still in its infancy. One saw in it the head of a Crocodile; another, that of a Whale; memoirs and monographs rained down, without throwing much light on the subject. It required all the efforts of Adrian Camper, joined to those of the immortal Cuvier, to assign its true zoological place to the Maestricht animal. The controversy over this fine fossil engaged the attention of the learned for the remainder of the last century and far into the present.

Maestricht is a city of the Netherlands, built on the banks of the Meuse. At the gates of this city, in the hills which skirt the left or western bank of the river, there rises a solid mass of cretaceous formation known as Saint Peter’s Rocks. In composition these beds correspond with the Meudon chalk beds, and they contain similar fossils. The quarries are about 100 feet deep, consisting in the upper part of twenty feet abounding in corals and Polyzoa, succeeded by fifty feet of soft yellowish limestone, furnishing a fine building stone, which has been quarried from time immemorial, and extends up to the environs of Liège; this is succeeded by a few inches of greenish soil with Encrinites, and then by a very white chalk with layers of flints. The quarry is filled with marine fossils, often of great size.

These fossil remains, naturally enough, attracted the attention of the curious, and led many to visit the quarries; but of all the discoveries which attracted attention the greatest interest attached to the gigantic animal under consideration. Among those interested by the discovery of these strange vestiges was an officer of the garrison of Maestricht, named Drouin. He purchased the bones of the workmen as the pick disengaged them from the rock, and concluded by forming a collection in Maestricht, which was spoken of with admiration. In 1766, the trustees of the British Museum, hearing of this curiosity, purchased it, and had it removed to London. Incited by the example of Drouin, Hoffmann, the surgeon of the garrison, set about forming a similar collection, and his collection soon exceeded that of Drouin’s Museum in riches. It was in 1780 that he purchased of the quarrymen the magnificent fossil head, exceeding six feet in length, which has since so exercised the sagacity of naturalists.

Hoffman did not long enjoy the fruits of his precious prize, however; the chapter of the church of Maestricht claimed, with more or less foundation, certain rights of property; and in spite of all protest, the head of theCrocodile of Maestricht, as it was already called, passed into the hands of the Dean of the Chapter, named Goddin,who enjoyed the possession of his antediluvian trophy until an unforeseen incident changed the aspect of things. This incident was nothing less than the bombardment and surrender of Maestricht to the Army of the North under Kleber, in 1794.

The Army of the North did not enter upon a campaign to obtain the crania of Crocodiles, but it had on its staff a savant who was devoted to such pacific conquests. Faujas de Saint-Fond, who was the predecessor of Cordier in the Zoological Chair of the Jardin des Plantes, was attached to the Army of the North as Scientific Commissioner; and it is suspected that, in soliciting this mission, our naturalist had in his eye the already famous head of the Crocodile of the Meuse. However that may be, Maestricht fell into the hands of the French, and Faujas eagerly claimed the famous fossil for the French nation, which was packed with the care due to a relic numbering so many thousands of ages, and dispatched to the Museum of Natural History in Paris. On its arrival, Faujas undertook a labour which, as he thought, was to cover him with glory. He commenced the publication of a work entitled “The Mountain of Saint Peter of Maestricht,” describing all the fossil objects found in the Dutch quarry there, especially theGreat Animalof Maestricht. He endeavoured to prove that this animal was a Crocodile.

Unfortunately for the glory of Faujas, a Dutch savant had devoted himself to the same study. Adrian Camper was the son of a great anatomist of Leyden, Pierre Camper, who had purchased of the heirs of the surgeon Hoffman some parts of the skeleton of the animal found in the quarry of Saint Peter. He had even published in thePhilosophical Transactionsof London, as early as 1786, a memoir, in which the animal is classed as a Whale. At the death of his father, Adrian Camper re-examined the skeleton, and in a work which Cuvier quotes with admiration, he fixed the ideas which were until then floating about. He proved that the bones belonged neither to a Fish, nor a Whale, nor to a Crocodile, but rather to a particular genus of Saurian Reptiles, or marine lizards, closely resembling in many important structural characters, existing Monitors and Iguanas, and peculiar to rocks of the Cretaceous period, both in Europe and America. Long before Faujas had finished the publication of his work onLa Montagne de Saint-Pierrethat of Adrian Camper had appeared, and totally changed the ideas of the world on this subject. It did not, however, hinder Faujas from continuing to call his animal the Crocodile of Maestricht. He even announced, some time after, that Adrian Camper was also of his opinion. “Nevertheless,” says Cuvier, “it is as far from the Crocodile as it is from the Iguana; and these twoanimals differ as much from each other in their teeth, bones, and viscera, as the ape differs from the cat, or the elephant from the horse.”

Fig. 145Fig. 145.a, skull of Monitor Niloticus;b, under-jaw of same.

Fig. 145.a, skull of Monitor Niloticus;b, under-jaw of same.

The masterly memoir of Cuvier, while confirming all the views of Camper, has restored the individuality of this surprising being, which has since received the name of Mosasaurus, that is to say, Saurian or Lizard of the Meuse. It appears, from the researches of Camper and Cuvier, that this reptile of the ancient world formed an intermediate genus between the group of the Lacertilia, which comprehends the Monitors (represented inFig. 145), and the ordinary Lizards; and the Lacertilia, whose palates are armed with teeth, a group which embraces theIguanaand theAnolis. In respect to the Crocodiles, the Mosasaurus resembles them in so far as they all belong to the same class of Reptiles.

The idea of a lizard, adapted for living and moving with rapidity at the bottom of the water, is not readily conceived; but a careful study of the skeleton of the Mosasaurus reveals to us the secret of this anatomical mechanism. The vertebræ of the animal are concave in front and convex behind; they are attached by means of orbicular or arched articulations, which permitted it to execute easily movements of flexion in any direction. From the middle of the back to the extremity of the tail these vertebræ are deficient in the articular processes which support and strengthen the trunk of terrestrial vertebrated animals: they resemble in this respect the vertebræ of the Dolphins; an organisation necessary to render swimming easy. The tail, compressed laterally at the same time that it was thick in a vertical direction, constituted a straight rudder, short, solid, and of great power. An arched bone was firmly attached to the body of each caudal vertebra in the same manner as in Fishes, for the purpose ofgiving increased power to the tail; finally, the extremities of the animal could scarcely be called feet, but rather paddles, like those of the Ichthyosaurus, the Plesiosaurus, and the Whale. We see inFig. 146that the jaws are armed with numerous teeth, fixed in their sockets by an osseous base, both large and solid. Moreover, an altogether peculiar dental system occupies the vault of the palate, as in the case of certain Serpents and Fishes, where the teeth are directed backwards, like the barb of a hook, thus opposing themselves to the escape of prey. Such a disposition of the teeth sufficiently proves the destructive character of this Saurian.

Fig. 146Fig. 146.—Head of Mosasaurus Camperi.

Fig. 146.—Head of Mosasaurus Camperi.

The dimensions of this aquatic lizard, estimated at twenty-four feet, are calculated to excite surprise. But, as we have already seen, the Ichthyosauri and Teleosauri were of great dimensions, as were also the Iguanodon and Megalosaurus, which were ten times the size of living Iguanas. In all these colossal forms we can only see a difference of dimensions, the aggrandisement of a type; the laws which affected the organisation of all these beings remain unchanged, they were not errors of Nature—monstrosities, as we are sometimes tempted to call them—but simply types, uniform in their structure, and adapted by their dimensions to the physical conditions with which God had surrounded them.

Plate XXIIXXII.—Ideal Landscape of the Cretaceous Period.

XXII.—Ideal Landscape of the Cretaceous Period.

InPlate XXII.is represented an ideal view of the earth during theUpper Cretaceousperiod. In the sea swims the Mosasaurus; Molluscs, Zoophytes, and other animals peculiar to the period areseen on the shore. The vegetation seems to approach that of our days; it consists of Ferns and Cycadeæ (Pterophyllums), mingled with Palms, Willows, and some dicotyledons of species analogous to those of our present epoch. Algæ, then very abundant, composed the vegetation of the sea-shore.

We have said that the terrestrial flora of the Upper Cretaceous period was nearly identical with that of the Lower. The marine flora of these two epochs included some Algæ, Confervæ, and Naïadæ, among which may be noted the following species:Confervites fasciculatus,Chondrites Mantelli,Sargassites Hynghianus. Among the Naïadæ,Zosterites Orbigniana,Z. lineata, and several others.

TheConfervæare fossils which may be referred, but with some doubt, to the filamentous Algæ, which comprehend the great group of the Confervæ. These plants were formed of simple or branching filaments, diversely crossing each other; or subdivided, and presenting traces of transverse partitions.

TheChondritesare, perhaps, fossil Algæ, with thick, smooth branching fronds, pinnatifid, or divided into pairs, with smooth cylindrical divisions, and resemblingChondrus,Dumontia, andHalymeniaamong living genera.

TheSargassites, finally, have been vaguely referred to the genusSargassum, so abundant in tropical seas. These Algæ are distinguished by a filiform, branched, or ramose stem, bearing foliaceous appendages, regular, often petiolate, and altogether like leaves, and globular vesicles, supported by a small stalk.

The rocks which actually represent theUpper Cretaceous perioddivide themselves naturally into six series; but British and French geologists make some distinction: the former dividing them into 1,MaestrichtandFaxoebeds, said not to occur in England; 2,White Chalk, withflints; 3,White Chalk, withoutflints; 4,Chalk Marl; 5,Upper Greensand; and 6,Gault. The latter four are divided by foreign geologists into 1,Turonian; 2,Senonian; 3,Danian.

TheGaultis the lowest member of the Upper Cretaceous group. It consists of a bluish-black clay mixed with greensand, which underlies the Upper Greensand. Near Cambridge, where the Gault is about 200 feet thick, a layer of shells, bones, and nodules, called the “Coprolite Bed,” from nine inches to a foot thick, represents the Upper Greensand, and rests on the top of the Gault Clay. These nodules and fossils are extensively worked on account of the phosphatic matter they contain, and when ground and converted into superphosphate of lime they furnish a very valuable agricultural manure.The Gault attains a thickness of about 100 feet on the south-east coast of England. It extends into Devonshire, Mr. Sharpe considering the Black Down beds of that country as its equivalents. It shows itself in the Departments of the Pas-de-Calais, the Ardennes, the Meuse, the Aube, the Yonne, the Ain, the Calvados, and the Seine-Inférieure. It presents very many distinct mineral forms, among which two predominate: green sandstone and blackish or grey clays. It is important to know this formation, for it is at this level that the Artesian waters flow in the wells of Passy and Grenelle, near Paris.

Theglaucouschalk, or Upper Greensand, which is represented typically in the departments of the Sarthe, of the Charente-Inférieure, of the Yonne and the Var, is composed of quartzose sand, clay, sandstone, and limestone. In this formation, at the mouth of the Charente, we find a remarkable bed, which has been described as a submarine forest. It consists of large trees with their branches imbedded horizontally in vegetable matter, containing kidney-shaped nodules of amber, or fossilised resin.

TheTuronianbeds are so named because the province of Touraine, between Saumur and Montrichard, possesses the best-developed type of this strata. The mineralogical composition of the beds is a fine and grey marly chalk, as at Vitry-le-François; of a pure white chalk, with a very fine grain, slightly argillaceous, and poor in fossils, in the Departments of the Yonne, the Aube, and the Seine-Inférieure; granular tufaceous chalk, white or yellowish, mixed with spangles of mica, and containing Ammonites, in Touraine and a part of the Department of the Sarthe; white, grey, yellow, or bluish limestone, inclosing Hippurites and Radiolites. In England the Lower Chalk passes also into Chalk Marl, with Ammonites, and then into beds known as the Upper Greensand, containing green particles of glauconite, mixed, in Hampshire and Surrey, with much calcareous matter. In the Isle of Wight this formation attains a thickness of 100 feet. TheSenonianbeds take their name from the ancientSenones. The city of Sens is in the centre of the best-characterised portion of this formation; Epernay, Meudon, Sens, Vendôme, Royau, Cognac, Saintes, are the typical regions of the formation in France. In the Paris basin, inclusive of the Tours beds, it attains a thickness of upwards of 1,500 feet, as was proved by the samples brought up, during the sinking of the Artesian well, at Grenelle, by the borings.

In its geographical distribution the Chalk has an immense range; fine Chalk of nearly similar aspect and composition being met with in all directions over hundreds of miles, alternating in its lower bedswith layers of flints. In England the higher beds usually consist of a pure-white calcareous mass, generally too soft for building-stone, but sometimes passing into a solid rock.

TheDanianbeds, which occupy the summit of the scale in the Cretaceous formation, are finely developed at Maestricht, on the Meuse; and in the Island of Zeeland, belonging to Denmark; where they are represented by a slightly yellowish, compact limestone, quarried for the construction of the city of Faxoe. It is slightly represented in the Paris basin at Meudon, and Laversines, in the Department of the Oise, by a white and often rubbly limestone known aspisolitic limestone. In this formationAmmonites Danicusis found. The yellowish sandy limestone of Maestricht is referred to theDaniantype. Besides Molluscs, Polyps, and Polyzoa (Bryozoa), this limestone contains remains of Fishes, Turtles, and Crocodiles. But what has rendered this rock so celebrated was that it contained the remains of thegreat animal of Mæstricht, the Mæsasaurus.

At the close of the geological period, whose natural physiognomy we have thus traced, Europe was still far from displaying the configuration which it now presents. A map of the period would represent the great basin of Paris (with the exception of a zone of Chalk), the whole of Switzerland, the greater part of Spain and Italy, the whole of Belgium, Holland, Prussia, Hungary, Wallachia, and Northern Russia, as one vast sheet of water. A band of Jurassic rocks still connected France and England at Cherbourg—which disappeared at a later period, and caused the separation of the British Islands from what is now France.

Fig. 147Fig. 147.—Exogym conica. Upper Greensand and Gault, from Blackdown Hill.

Fig. 147.—Exogym conica. Upper Greensand and Gault, from Blackdown Hill.

[54]“The Physical Geography and Geology of Great Britain,” 2nd ed., p. 60.[55]A. C. Ramsay,Quart. Jour. Geol. Soc., vol. 27, p. 191.[56]See A. C. Ramsay, “On the Physical Relations of the New Red Marl, Rhætic Beds, and Lower Lias,”Quart. Jour. Geol. Soc., vol. 27, p. 189.[57]Quart. Jour. Geol. Soc., vol. xx., p. 396.[58]Ibid, vol. xvii., p. 483.[59]Ibid, vol. xvi., p. 374.[60]Ibid, vol. xx., p. 103.[61]Lyell, “Elements of Geology,” p. 413.[62]De la Beche’s “Geological Manual,” 3rd ed., p. 447.[63]“Geological Manual,” by H. T. De la Beche, 3rd ed., p. 346.[64]Professor Buckland on the Pterodactylus. “Trans. Geol. Soc.,” 2nd series, vol. iii., p. 217.[65]“Elements of Geology,” p. 399.[66]See Bristow in Descriptive Catalogue of Rocks, inMus. Pract. Geol., p. 134.[67]President’s Address, by Professor A. C. Ramsay.Quart. Jour. Geol. Soc., 1864, vol. xx., p. 4.[68]“Elements of Geology,” p. 400.[69]For a full account of the Ceteosaurus, see “The Geology of the Thames Valley,” by Prof. John Phillips, F.R.S. 1871.[70]“Elements of Geology,” p. 393.[71]For details respecting these strata the reader may consult, with advantage, the useful handbook to the geology of Weymouth and Portland, by Robert Damon.[72]See Bristow and Whitaker “On the Chesil Bank,”Geol. Mag., vol. vi., p. 433.[73]“Elements of Geology,” p. 389.[74]Ibid, p. 391.[75]“Elements of Geology,” p. 349.[76]Ibid, p. 350.[77]“The Physical Geology and Geography of Great Britain,” by A. C. Ramsay, F.R.S., p. 64.[78]Lyell’s “Elements of Geology,” p. 349.[79]Ibid, p. 340.[80]Lyell’s “Elements of Geology,” p. 333.

[54]“The Physical Geography and Geology of Great Britain,” 2nd ed., p. 60.

[55]A. C. Ramsay,Quart. Jour. Geol. Soc., vol. 27, p. 191.

[56]See A. C. Ramsay, “On the Physical Relations of the New Red Marl, Rhætic Beds, and Lower Lias,”Quart. Jour. Geol. Soc., vol. 27, p. 189.

[57]Quart. Jour. Geol. Soc., vol. xx., p. 396.

[58]Ibid, vol. xvii., p. 483.

[59]Ibid, vol. xvi., p. 374.

[60]Ibid, vol. xx., p. 103.

[61]Lyell, “Elements of Geology,” p. 413.

[62]De la Beche’s “Geological Manual,” 3rd ed., p. 447.

[63]“Geological Manual,” by H. T. De la Beche, 3rd ed., p. 346.

[64]Professor Buckland on the Pterodactylus. “Trans. Geol. Soc.,” 2nd series, vol. iii., p. 217.

[65]“Elements of Geology,” p. 399.

[66]See Bristow in Descriptive Catalogue of Rocks, inMus. Pract. Geol., p. 134.

[67]President’s Address, by Professor A. C. Ramsay.Quart. Jour. Geol. Soc., 1864, vol. xx., p. 4.

[68]“Elements of Geology,” p. 400.

[69]For a full account of the Ceteosaurus, see “The Geology of the Thames Valley,” by Prof. John Phillips, F.R.S. 1871.

[70]“Elements of Geology,” p. 393.

[71]For details respecting these strata the reader may consult, with advantage, the useful handbook to the geology of Weymouth and Portland, by Robert Damon.

[72]See Bristow and Whitaker “On the Chesil Bank,”Geol. Mag., vol. vi., p. 433.

[73]“Elements of Geology,” p. 389.

[74]Ibid, p. 391.

[75]“Elements of Geology,” p. 349.

[76]Ibid, p. 350.

[77]“The Physical Geology and Geography of Great Britain,” by A. C. Ramsay, F.R.S., p. 64.

[78]Lyell’s “Elements of Geology,” p. 349.

[79]Ibid, p. 340.

[80]Lyell’s “Elements of Geology,” p. 333.

A new organic creation makes its appearance in the Tertiary period; nearly all the animal life is changed, and what is most remarkable in this new development is the appearance, in larger numbers, of the great class of Mammifera.

During the Primary period, Crustaceans and Fishes predominated in the animal kingdom; in the Secondary period the earth was assigned to Reptiles; but during the Tertiary period the Mammals were kings of the earth; nor do these animals appear in small number, or at distant intervals of time; great numbers of these beings appear to have lived on the earth, and at the same moment; many of them being, so to say, unknown and undescribed.

If we except the Marsupials, the first created Mammals would appear to have been the Pachyderms, to which the Elephant belongs. This order of animals long held the first rank; it was almost the only representative of the Mammal during the first of the three periods which constitute the Tertiary epoch. In the second and third periods Mammals appear of species which have now become extinct, and which were alike curious from their enormous proportions, and from the singularity of their structure. Of the species which appeared during the latter part of the epoch, the greater number still exist. Among the new Reptiles, some Salamanders, as large as Crocodiles, and not very distinct from existing forms, are added to the animal creation during the three periods of the Tertiary epoch. Chelonians were abundant within the British area during the older epoch. During the same epoch Birds are present, but in much fewer numbers than the Mammalia; here songsters, there birds of prey, in other cases domestic—or, rather, some appear to wait the yoke and domestication from man, the future supreme lord of the earth.

The seas were inhabited by a considerable number of beings of all classes, and nearly as varied as those now living; but we no longer find in the Tertiary seas those Ammonites, Belemnites, andHippurites which peopled the seas and multiplied with such astonishing profusion during the Secondary period. Henceforth the testaceous Mollusca approximate in their forms to those of the present time. The older and newer Tertiary Series contain few peculiar genera. But genera now found in warmer climates were greatly developed within the British area during the earlier Tertiary times, andspeciesof cold climates mark the close of the later Tertiaries.

What occurs to us, however, as most remarkable in the Tertiary epoch is the prodigious increase of animal life; it seems as if it had then attained its fullest extension. Swarms of testaceous Mollusca of microscopic proportions—Foraminifera and Nummulites—must have inhabited the seas, crowding together in ranks so serried that the agglomerated remains of their shells form, in some places, beds hundreds of feet thick. It is the most extraordinary display which has appeared in the whole range of creation.

Vegetation during the Tertiary period presents well-defined characteristics. The Tertiary flora approaches, and is sometimes nearly identical with, that of our days. The class of dicotyledons shows itself there in its fullest development; it is the epoch of flowers. The surface of the earth is embellished by the variegated colours of the flowers and fruits which succeed them. The white spikes of the Gramineæ display themselves upon the verdant meadows without limit; they seem provocative of the increase of Insects, which now singularly multiply. In the woods crowded with flowering trees, with rounded tops, like our oak and birch, Birds become more numerous. The atmosphere, purified and disembarrassed of the veil of vapour which has hitherto pervaded it, now permits animals with such delicate pulmonary organs to live and multiply their race.

During the Tertiary period the influence of the central heat may have ceased to make itself felt, in consequence of the increased thickness of the terrestrial crust. By the influence of the solar heat, climates would be developed in the various latitudes; the temperature of the earth would still be nearly that of our present tropics, and at this epoch, also, cold would begin to make itself felt at the poles.

Abundant rains would, however, continue to pour upon the earth enormous quantities of water, which would give rise to important rivers; new lacustrine deposits of fresh water were formed in great numbers; and rivers, by means of their alluvial deposits, began to form new land. It is, in short, during the Tertiary epoch that we trace an alternate succession of beds containing organic beings of marine origin, with others peculiar to fresh water. It is at the end of this period that continents and seas take their respective places aswe now see them, and that the surface of the earth received its present form.

The Tertiary epoch, or series, embraces three very distinct periods, to which the names ofEocene,Miocene, andPliocenehave been given by Sir Charles Lyell. The etymology of these names is derived—Eocene, from the Greek ηως,dawn, and καινος,recent; Miocene, from μειον,less, καινος,recent; and Pliocene, from πλειον,more, καινος,recent; by which it is simply meant to express, that each of these periods contains a minor or greater proportion of recent species (of Testacea), or is more or less remote from the dawn of life and from the present time;[81]the expressions are in one sense forced and incorrect, but usage has consecrated them, and they have obtained universal currency in geological language, from their convenience and utility.

Fig. 148Fig. 148.—Trigonia margaritacea. (Living form.)

Fig. 148.—Trigonia margaritacea. (Living form.)

During this periodterra firmahas vastly gained upon the domain of the sea; furrowed with streams and rivers, and here and there with great lakes and ponds, the landscape of this period presented the same curious mixture which we have noted in the preceding age, that is to say, a combination of the vegetation of the primitive ages with one analogous to that of our own times. Alongside the birch, the walnut, the oak, the elm, and the alder, rise lofty palm-trees, of species now extinct, such asFlabellariaandPalmacites; with many evergreen trees (Conifers), for the most part belonging to genera still existing, as thefirs, thepines, theyews, thecypresses, thejunipers, and thethuyasor tree of life.

TheCupanioides, among the Sapindaceæ; theCucumites, among the Cucurbitaceæ (species analogous to our bryony), climb the trunks of great trees, and hang in festoons of aerial garlands from their branches.

The Ferns were still represented by the generaPecopteris, by theTæniopteris,Asplenium,Polypodium. Of the mosses, someHepaticasformed a humble but elegant and lively vegetation alongside the terrestrial and frequently ligneous plants which we have noted.EquisetaandCharæwould still grow in marshy places and on the borders of rivers and ponds.

It is not without some surprise that we observe here certain plants of our own epoch, which seem to have had the privilege of ornamenting the greater watercourses. Among these we may mention the Water Caltrop,Trapa natans, whose fine rosettes of green and dentated leaves float so gracefully in ornamental ponds, supported by their spindle-shaped petioles, its fruit a hard coriaceous nut, with four horny spines, known in France aswater-chestnuts, which enclose a farinaceous grain not unpleasant to the taste; the pond-weed,Potamogeton, whose leaves form thick tufts of green, affording food and shelter to the fishes;Nympheaceæ, which spread beside their large round and hollow leaves, so admirably adapted forfloating on the water, now the deep-yellow flowers of theNenupharnow the pure white flowers of theNymphæa. Listen to Lecoq, as he describes the vegetation of the period:—“The Lower Tertiary period,” he says, “constantly reminds us of the tropical landscapes of the present epoch, in localities where water and heat together impress on vegetation a power and majesty unknown in our climates. The Algæ, which have already been observed in the marine waters at the close of the Cretaceous period, represented themselves under still more varied forms, in the earlier Tertiary deposits, when they have been formed in the sea. Hepaticas and Mosses grew in the more humid places; many pretty Ferns, asPecopteris,Tæniopteris, and theEquisetum stellare(Pomel) vegetated in cool and humid places. The fresh waters are crowded withNaiades,Chara,Potamogeton,Caulinites, withZosterites, and withHalochloris. Their leaves, floating or submerged, like those of our aquatic plants, concealed legions of Molluscs whose remains have also reached us.

“Great numbers of Conifers lived during this period. M. Brongniart enumerates forty-one different species, which, for the most part, remind us of living forms with which we are familiar—of Pines, Cypresses, Thuyas, Junipers, Firs, Yews, and Ephedra. Palms mingled with these groups of evergreen trees; theFlabellaria Parisiensisof Brongniart,F. raphifoliaof Sternberg,F. maximaof Unger; and somePalmacites, raised their widely-spreading crowns near the magnificentHightea; Malvaceæ, orMallows, doubtless arborescent, as many among them, natives of very hot climates, are in our days.

“Creeping plants, such as theCucumites variabilis(Brongn.), and the numerous species ofCupanioïdes—the one belonging to the Cucurbitaceæ, and the other to the Sapindaceæ—twined their slender stems round the trunks, doubtless ligneous, of various Leguminaceæ.

“The family of Betulaceæ of the order Cupuliferæ show the form, then new, ofQuercus, the Oak; the Juglandeæ, and Ulmaceæ mingle with the Proteaceæ, now limited to the southern hemisphere.Dermatophyllites, preserved in amber, seem to have belonged to the family of the Ericineæ, andTropa Arcturæof Unger, of the group Œnothereæ, floated on the shallow waters in which grew theCharaand thePotamogeton.

“This numerous flora comprises more than 200 known species, of which 143 belonged to the Dicotyledons, thirty-three to the Monocotyledons, and thirty-three to the Cryptogams.

“Trees predominate here as in the preceding period, but the great numbers of aquatic plants of the period are quite in accordance with the geological facts, which show that the continents andislands were intersected by extensive lakes and inland seas, while vast marine bays and arms of the sea penetrated deeply into the land.”

Fig. 149Fig. 149.—Branch of Eucalyptus restored.

Fig. 149.—Branch of Eucalyptus restored.

It is moreover a peculiarity of this period that the whole of Europe comprehended a great number of those plants which are now confined to Australasia, and which give so strange an aspect to that country, which seems, in its vegetation, as in its animals, to have preserved in its warm latitudes the last vestiges of the organic creations peculiar to the primitive world. As a type of dicotyledonous trees of the epoch, we present here a restored branch ofEucalyptus(Fig. 149), with its flowers. All the family of the Proteaceæ,which comprehends theBanksia, theHakea, theGerilea protea, existed in Europe during the Tertiary period. The family of Mimosas, comprising theAcaciaandInga, which in our age are only natives of the southern hemisphere, abounded in Europe during the same geological period. A branch ofBanksia, with its fructification, taken from impressions discovered in rocks of the period, isrepresented inFig. 150—it is different from any species of Banksia living in our days.

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