  Subdivisions of the Eocene group in the Paris basin — Gypseous series — Extinct quadrupeds — Impulse given to geology by Cuvier's osteological discoveries — Shelly sands called sables moyens — Calcaire grossier — Miliolites — Calcaire siliceux — Lower Eocene in France — Lits coquilliers — Sands and plastic clay — English Eocene strata — Freshwater and fluvio-marine beds — Barton beds — Bagshot and Bracklesham division — Large ophidians and saurians — Lower Eocene and London Clay proper — Fossil plants and shells — Strata of Kyson in Suffolk — Fossil monkey and opossum — Mottled clays and sands below London Clay — Nummulitic formation of Alps and Pyrenees — Its wide geographical extent — Eocene strata in the United States — Section at Claiborne, Alabama — Colossal cetacean — Orbitoid limestone — Burr stone. From what was said in the two preceding chapters, it has already appeared that we have in England no true chronological representative of the Miocene faluns of the Loire, and none of the Upper Eocene group MIDDLE EOCENE.—FRANCE.Gypseous series (2. a, Table, p. 175.).—Next below the upper marine sands of the neighbourhood of Paris, we find a series of white and green marls, with subordinate beds of gypsum. These are most largely developed in the central parts of the Paris basin, and, among other places, in the Hill of Montmartre, where its fossils were first studied by M. Cuvier. The gypsum quarried there for the manufacture of plaster of Paris occurs as a granular crystalline rock, and, together with the associated marls, contains land and fluviatile shells, together with the bones and skeletons of birds and quadrupeds. Several land plants are also met with, among which are fine specimens of the fan palm or palmetto tribe (Flabellaria). The remains also of freshwater fish and of crocodiles and other reptiles, occur in the gypsum. The skeletons of mammalia are usually isolated, often entire, the most delicate extremities being preserved; as if the carcasses, clothed with their flesh and skin, had been floated down soon after death, and while they were still swoln by the gases generated by their first decomposition. The few accompanying shells are of those light kinds which frequently float on the surface of rivers, together with wood. M. Prevost has therefore suggested that a river may have swept away the bodies of animals, and the plants which lived on its borders, or in the lakes which it traversed, and may have carried them down into the centre of the gulf into which flowed the waters impregnated with sulphate of lime. We know that the Fiume Salso in Sicily enters the sea so charged with various salts that the thirsty cattle refuse to drink of it. A stream of sulphureous water, as white as milk, descends into the sea from the volcanic mountain of Idienne on the east of Java; and a great body of hot water, charged with sulphuric acid, rushed down from the same volcano on one occasion, and inundated a large tract of country, destroying, by its noxious properties, all the vegetation. Of birds, about ten species have been ascertained, the skeletons of some of which are entire. None of them are referable to existing species. The tribe of land quadrupeds most abundant in this formation is such as now inhabits alluvial plains and marshes, and the banks of rivers and lakes, a class most exposed to suffer by river inundations. Whether the disproportion of carnivorous animals can be ascribed to this cause, or whether they were comparatively small in number and dimensions, as in the indigenous fauna of Australia, when first known to Europeans, is a point on which it would be rash, perhaps, to offer an opinion in the present state of our knowledge. Fig. 162. Paleotherium magnum. The Paleothere, above alluded to, resembled the living tapir in the form of the head, and in having a short proboscis, but its molar teeth were more like those of the rhinoceros (see fig. 163.). Paleotherium magnum was of the size of a horse, 3 or 4 feet high. The annexed woodcut, fig. 162., is one of the restorations which Cuvier attempted of the outline of the living animal, derived from the study of the entire skeleton. When the French osteologist declared in the early part of the present century, that all the fossil quadrupeds of the gypsum of Paris were extinct, the announcement of so startling a Fig. 163. Upper molar tooth of Paleotherium magnum from Isle of Wight. (Owen's Brit. Foss. p. 317.) Reduced one-third. GrÈs de Beauchamp (2. b, Table, p. 175.).—In some parts of the Paris basin, sands and marls, called the GrÈs de Beauchamp, or Sables Moyens, divide the gypseous beds from the underlying Calcaire grossier. These sands contain more than 300 species of marine shells, many of them peculiar, but others common to the underlying marine deposit (No. 2. c.). Calcaire grossier (2. c, Table, p. 175.).—The formation called Calcaire grossier consists of a coarse limestone, often passing into sand. It contains the greater number of the fossil shells which characterize the Paris basin. No less than 400 distinct species have been procured from a single spot near Grignon, where they are embedded in a calcareous sand, chiefly formed of comminuted shells, in which, nevertheless, individuals in a perfect state of preservation, both of marine, terrestrial, and freshwater species, are mingled together. Some of the marine shells may have lived on the spot; but the Cyclostoma and Limnea must have been brought thither by rivers and currents, and the quantity of triturated shells implies considerable movement in the waters. Nothing is more striking in this assemblage of fossil testacea than the great proportion of species referable to the genus Cerithium (see fig. 164.). There occur no less than 137 species of this genus Fig. 164. Cerithium cinctum. EOCENE FORAMINIFERA. Fig. 165. Calcarina rarispina, Desh.
Fig. 166. Spirolina stenostoma, Desh.
Fig. 167. Triloculina inflata, Desh.
Fig. 168. Clavulina corrugata, Desh.
In some parts of the calcaire grossier round Paris, certain beds occur of a stone used in building, and called by the French geologists "Miliolite limestone." It is almost entirely made up of millions of microscopic shells, of the size of minute grains of sand, which all belong to the class Foraminifera. Figures of some of these are given in the annexed woodcut. As this miliolitic stone never occurs in the Faluns, or Miocene strata of Calcaire siliceux.—This compact siliceous limestone extends over a wide area. It resembles a precipitate from the waters of mineral springs, and is often traversed by small empty sinuous cavities. It is, for the most part, devoid of organic remains, but in some places contains freshwater and land species, and never any marine fossils. The siliceous limestone and the calcaire grossier occupy distinct parts of the Paris basin, the one attaining its fullest development in those places where the other is of slight thickness. They also alternate with each other towards the centre of the basin, as at Sergy and Osny; and there are even points where the two rocks are so blended together that portions of each may be seen in hand specimens. Thus, in the same bed, at Triel, we have the compact freshwater limestone, characterized by its LimneÆ, mingled with the coarse marine limestone, with its small multilocular shells, or "miliolites," dispersed through it in countless numbers. These microscopic testacea are also accompanied by Cerithia and other shells of the calcaire grossier. It is very extraordinary that in this instance both kinds of sediment must have been thrown down together on the same spot, yet each retains its own peculiar organic remains. From these facts we may conclude, that while to the north, where the bay was probably open to the sea, a marine limestone was formed, another deposit of freshwater origin was introduced to the southward, or at the head of the bay; for it appears that during the Eocene period, as now, the ocean was to the north, and the continent, where the great lakes existed, to the south. From that southern region we may suppose a body of fresh water to have descended, charged with carbonate of lime and silica, the water being perhaps in sufficient volume to freshen the upper end of the bay. The gypseous series (2. a, Table, p. 175.), before described, was once supposed to be entirely subsequent in origin to the two groups, called calcaire grossier and calcaire siliceux. But M. Prevost has pointed out that in some localities they alternate repeatedly with both. The gypsum, with its associated marl and limestone, is in greatest force towards the centre of the basin, where the calcaire grossier and calcaire siliceux are less fully developed. Hence M. Prevost infers, that while those two principal deposits were gradually in progress, the one towards the north, and the other towards the south, a river descending from the east may have brought down the gypseous and marly sediment. It must be admitted, as highly probable, that a bay or narrow sea, 180 miles in length, would receive, at more points than one, the waters of the adjoining continent. At the same time, we must be LOWER EOCENE, FRANCE.Lits coquilliers (3. a, Table, p. 175.).—Below the calcaire grossier are extensive deposits of sand, in the upper parts of which some marine beds, called "lits coquilliers," occur, in which M. d'Archiac has discovered 200 species of shells. Many of these are peculiar, but the larger portion appear to agree with species of the calcaire grossier, so that the line of demarcation usually adopted between the French Lower and Middle Eocene formations, seems not to be very strongly drawn. Sands and plastic clay (3. b, Table, p. 175.)—At the base of the tertiary system in France are extensive deposits of sands, with occasional beds of clay used for pottery, and called "argile plastique." Fossil oysters (Ostrea bellovacina) abound in some places, and in others there is a mixture of fluviatile shells, such as Cyrena cuneiformis (fig. 187. p. 204.), Melania inquinata (fig. 188.), and others, frequently met with in beds occupying the same position in the valley of the Thames. Layers of lignite also accompany the inferior clays and sands. Immediately upon the chalk at the bottom of all the tertiary strata there is often a conglomerate or breccia of rolled and angular chalk flints, cemented by siliceous sand. These beds appear to be of littoral origin, and imply the previous emergence of some portions of the chalk, and its waste by denudation. Fig. 169. Cardium porulosum. Paris and London basins. The lower sandy beds of the Paris basin are often called the sands of the Soissonais, from a district so named 50 miles N.E. of Paris. One of the shells of the formation is adduced by M. Deshayes as an example of the changes which certain species underwent in the successive ENGLISH EOCENE FORMATIONS.The Eocene areas of Hampshire and London are delineated in the map (fig. 153. p. 174.). The following table will show the succession of the principal deposits found in our island. The true place of the Bagshot sands, in this series, was never accurately ascertained till Mr. Prestwich published, in 1847, his classification of the English Eocene strata, dividing them into three principal formations, in which the Bagshot sands occupied the central place.
Fig. 170. Lymnea longiscata. Freshwater Eocene strata, Isle of Wight. Freshwater beds (2. a, Table, p. 175.).—In the northern part of the Isle of Wight, beds of marl, clay, and sand, and a friable limestone, containing freshwater shells, are seen, containing shells of the genera Lymnea (see fig. 170.), Planorbis, Melanopsis, Cyrena, &c., several of them of the same species as those occurring in the Eocene beds of the Paris basin. Gyrogonites, also, or seed-vessels of Chara, exhibiting a similar specific identity, occur. At Headon Hill, on the western side of the island, where these beds are seen in the sea-cliffs, some of the strata contain a few marine and estuary shells, such as CytherÆa, Corbula, &c., showing a temporary occupation of the area by brackish or salt water, after which the river or a lake seems again to have prevailed. A Several of the species of extinct quadrupeds already alluded to as characterizing the gypsum of Montmartre have been discovered by Messrs. Pratt and Fox, in the Isle of Wight, chiefly at Binstead, near Ryde, as PalÆotherium magnum, P. medium, P. minus, P. minimum, P. curtum, P. crassum, also Anoplotherium commune, A. secundarium, Dichobune cervinum, and ChÆropotamus Cuvieri. In Hordwell cliff, also on the Hampshire coast, several of these species, with other quadrupeds of new genera, such as Paloplotherium, Owen, have been met with; and remains of a remarkable carnivorous genus, HyÆnodon. These fossils are accompanied by the bones of Trionyx, and other tortoises, and by two land snakes of the genus Paleryx, Owen, from 3 to 4 feet long, also a species of crocodile, and an alligator. Among other fossils collected by Lady Hastings, Sir Philip Egerton has recognized the well-known gar or bony pike of the American rivers, a ganoid fish of the genus Lepidotus, with its hard shining scales. The shells of Hordwell are similar to those of the freshwater beds of the Isle of Wight, and among them are a few specifically undistinguishable from recent testacea, as Paludina lenta and Helix labyrinthica, the latter discovered by Mr. S. Wood, and identified with an existing N. American helix. The white and green marls of this freshwater series in Hampshire, and some of the accompanying limestones, often resemble those of France in mineral character and colour in so striking a manner, as to suggest the idea that the sediment was derived from the same region, or produced contemporaneously under very similar geographical circumstances. Barton beds.—Both in the cliffs of Headon Hill and Hordwell, already mentioned, the freshwater series rests on a mass of pure white sand without fossils, and this is seen in Barton Cliff to overlie a marine deposit, in which 209 species of testacea have been found. More than half of these are peculiar; and, according to Mr. Prestwich, only 11 of them common to the London Clay proper, being in the proportion of only 5 per cent. On the other hand, 70 of them agree with the calcaire grossier shells. As this is the newest purely marine bed of the Eocene series known in England, we might have expected that some of its peculiar fossils would be found to agree with the upper Eocene strata described in the last chapter, and accordingly some identifications have been cited with testacea, both of the Berlin and Belgian strata. It is nearly a century since Brander published, in 1766, an account of the organic remains collected from these cliffs, and his excellent figures of the shells then deposited in the British Museum are justly admired by conchologists for their accuracy. Bagshot Sands (2. c, Table, p. 197.).—These beds, consisting chiefly Fig. 171. Venericardia planicosta, Lamck. Cardita planicosta, Deshayes. At Bracklesham Bay, near Chichester, in Sussex, the characteristic shells of this member of the Eocene series are best seen; among others, the huge Cerithium giganteum, so conspicuous in the calcaire grossier of Paris, where it is sometimes 2 feet in length. The volutes and cowries of this formation, as well as the lunulites and other corals, seem to favour the idea of a warm climate having prevailed, which is borne out by the discovery of a serpent PalÆophis typhÆus, exceeding, according to Mr. Owen, 20 feet in length, and allied to the Boa, Python, Coluber, and Hydrus. The compressed form and diminutive size of certain caudal vertebrÆ indicate so much analogy with Hydrus as to induce the Hunterian professor to pronounce the extinct ophidian to have been marine. Fig. 172. Prolonged premaxillary bone or "sword" of a fossil sword-fish (CÆlorhynchus). Bracklesham. Dixon's Fossils of Sussex, pl. 8. Fig. 173. Dental plates of Myliobates Edwardsi. Bracklesham Bay. Ibid. pl. 8. Fig. 174. Nummulites (Nummularia) lÆvigatus. Bracklesham. Ibid. pl. 8.
London clay proper (3. a, Table, p. 197.).—This formation underlies the preceding, and consists of tenacious brown and blueish grey clay, with layers of concretions called septaria, which abound chiefly in the brown clay, and are obtained in sufficient numbers from the cliffs near Harwich, and from shoals of the Essex coast, to be used for making Roman cement. The principal localities of fossils in the London clay are Highgate Hill, near London, the island of Sheppey, and Bognor in Hampshire. Out of 133 fossil shells, Mr. Prestwich found only 20 to be common to the calcaire grossier (from which 600 species have been obtained), while 33 are common to the lits coquilliers (p. 196.), in which only 200 species are known in France. We may presume, therefore, that the London clay proper is older than the calcaire grossier. This may perhaps remove a difficulty which M. Adolphe Brongniart has experienced when comparing the Eocene Flora of the neighbourhoods of London and Paris. The fossil species of the island of Sheppey, he observes, indicate a much more tropical climate than the Eocene Flora of France, which has been derived principally from the "gypseous series." The latter resembles the vegetation of the borders of the Mediterranean rather than that of an equatorial region. Mr. Bowerbank, in a valuable publication on the fossil fruits and seeds of the island of Sheppey, near London, has described no less than thirteen fruits of palms of the recent type Nipa, now only Fig. 175. Nipadites ellipticus. Bow. Fossil palm of Sheppey. The contiguity of land may be inferred not only from these vegetable productions, but also from the teeth and bones of crocodiles and turtles, since these creatures, as Mr. Conybeare has remarked, must have resorted to some shore to lay their eggs. Of turtles there were numerous species referred to extinct genera, and, for the most part, not equal in size to the largest living tropical turtles. A snake, which must have been 13 feet long, of the genus PalÆophis before mentioned, has also been described by Mr. Owen from Sheppey, of a different species from that of Bracklesham. A true crocodile, also, Crocodilus toliapicus, and another Saurian more nearly allied to the gravial, accompany the above fossils. A bird allied to the vultures, and a quadruped of the new genus Hyracotherium, allied to the Hyrax, Hog, and ChÆropotamus, are also among the additions made of late years to the palÆontology of this division. FOSSIL SHELLS OF THE LONDON CLAY. Fig. 176. Mitra scabra. Fig. 177. Rostellaria macroptera, Sow. One-third of nat. size. Fig. 178. Crassatella sulcata. The marine shells of the London clay confirm the inference derivable from the plants and reptiles of a high temperature. Thus, many species of Conus, Mitra, and Voluta occur, a large CyprÆa, a Fig. 179. Nautilus centralis. Fig. 180. Voluta athleta. Fig. 181. Terebellum fusiforme. Fig. 182. Aturia zigzag. Bronn. Syn. Nautilus zigzag. Sow. London clay. Sheppey. Fig. 183. Belosepia sepiodea, De Blainv. London clay. Sheppey. The above shells are accompanied by a sword-fish (Tetrapterus priscus, Agassiz), about 8 feet long, and a saw-fish (Pristis bisulcatus, Ag.), about 10 feet in length; genera now foreign to the British seas. On the whole, no less than 50 species of fish have been described by M. Agassiz from these beds in Sheppey, and they indicate, in his opinion, a warm climate. Fig. 184. Molar of monkey (Macacus). Strata of Kyson in Suffolk.—At Kyson, a few miles east of Woodbridge, a bed of Eocene clay, 12 feet thick, underlies the red crag. Beneath it is a deposit of yellow and white sand, of considerable interest, in consequence of many peculiar fossils contained in it. Its geological position is probably the lowest part of the London clay proper. In this sand has been found the first example of a fossil quadrumanous animal discovered in Great Britain, namely, the teeth and part of a jaw, shown by Mr. Owen to belong to a monkey of the genus Macacus (see fig. 184.). The mammiferous fossils, first met with in the same bed, were those of an opossum (Didelphys) (see fig. 185.), and an insectivorous bat (fig. 186.), together with many teeth of fishes of the shark family. Fig. 185. Molar tooth and part of jaw of opossum. From Kyson. Fig. 186. Molars of insectivorous bats, twice nat. size. From Kyson, Suffolk. Mottled or Plastic Clays, &c. (3. b, Table, p. 197.).—No formations can be more dissimilar on the whole in mineral character than the Eocene deposits of England and Paris; those of our own island being almost exclusively of mechanical origin,—accumulations of mud, sand, and pebbles; while in the neighbourhood of Paris we find a great succession of strata composed of a coarse white limestone, and compact siliceous limestone with beds of crystalline gypsum and siliceous sandstone, and sometimes pure flint used for millstones. Hence it is by no means an easy task to institute an exact comparison between the various members of the English and French series, and to settle their respective ages. It is clear that a continual change was going on in the fauna and flora by the coming in of new species and the dying out of others; and contemporaneous changes of geographical conditions were also in progress in consequence of the rising and sinking of the land and bottom of the sea. A particular subdivision, therefore, of time was occasionally represented in one area by land, in another by an estuary, in a third by the sea, and even where the conditions were in both areas of a marine character, there was often shallow water in one, and deep sea in another, producing a want of agreement in the state of animal life. At the commencement, however, of the Eocene formations in France and England, we find an exception to this rule, for a marked similarity of mineral character reigns in the lowest division, whether in the basins of Paris, Hampshire, or London. This uniformity of aspect must be seen in order to be fully appreciated, since the beds consist simply of sand, mottled clays, and well-rolled flint pebbles, derived from the chalk, and varying in size from that of a pea to an egg. These strata may be seen at Reading, at Blackheath, near In several places, as at Woolwich on the Thames, at Newhaven in Sussex, and elsewhere, a mixture of marine and freshwater testacea distinguishes this member of the series. Among the latter, Melania inquinata (see fig. 188.) and Cyrena cuneiformis are very common. They probably indicate points where rivers entered the Eocene sea. Fig. 187. Cyrena cuneiformis, Min. Con. Natural size. Fig. 188. Melania inquinata, Des. Nat. size. Syn. Cerithium melanoides, Min. Con. With us as in France, clay of this formation is used in some places, as near Poole in Dorsetshire, for pottery; and hence the name of plastic clay was adopted for the group by Mr. T. Webster. Lignite also is associated with it in some spots, as in the Paris basin. Before the minds of geologists had become familiar with the theory of the gradual sinking of the land, and its conversion into sea at different periods, and the consequent change from shallow to deep water, the freshwater and littoral character of this inferior group appeared strange and anomalous. After passing through many hundred feet of London clay, proved by its fossils to have been deposited in salt water of considerable depth, we arrive at beds of fluviatile origin. Thick masses, also, of shingle indicate the proximity of land, where the flints of the chalk were rolled into sand and pebbles, and spread continuously over wide spaces, as in the Isle of The London area appears to have been upraised before that of Hampshire, so that it never became the receptacle of the Barton clays, nor of the overlying fluvio-marine and freshwater beds of Hordwell and the north part of the Isle of Wight. On the other hand, the Hampshire Eocene area seems to have emerged before that of Paris, so that no marine beds of the Upper Eocene era were ever thrown down in Hampshire. Nummulitic formation of the Alps and Pyrenees.—It has long been matter of controversy, whether the nummulitic rocks of the Alps and Pyrenees should be regarded as Eocene or Cretaceous; but the number of geologists of high authority who regard this important group as belonging to the lowest tertiary system of Europe has for many years been steadily increasing. The late M. Alex. Brongniart first declared the specific identity of many of the shells of this formation with those of the marine strata near Paris, although he obtained them from the summit of the Diablerets, one of the loftiest of the Swiss Alps, which rises more than 10,000 feet above the level of the sea. Deposits of the same age, found on the flanks of the Pyrenees, contain also a great number of shells common to the Paris and London areas, and three or four species only which are common to the cretaceous formation. The calcareous division consists often of a compact crystalline marble, full of nummulites (see fig. 189.), shells of the class Foraminifera. Fig. 189. Nummulites. Peyrehorade, Pyrenees.
The nummulitic formation, with its characteristic fossils, 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 Apennines. It is found in the Carpathians, and in full force in the north of Africa, as, for example, in Algeria and Morocco. It has also been traced from Egypt into Asia Minor, and across Persia by Bagdad to the mouths 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 farther eastward into India. Some members of this lower tertiary formation in the central Alps, including even the superior strata called flysch, have been converted into crystalline rocks, and changed into saccharoid marble, quartz, rock, and mica-schist. EOCENE STRATA IN THE UNITED STATES.In North America the Eocene formations occupy a large area bordering the Atlantic, which increases in breadth and importance as it is traced southwards from Delaware and Maryland to Georgia and Alabama. They also occur in Louisiana and other states both east and west of the valley of the Mississippi. At Claiborne in Alabama no less than four hundred species of marine shells, with many echinoderms and teeth of fish, characterize one member of this system. Among the shells the Cardita planicosta, before mentioned (fig. 171. p. 199.), is in abundance; and this fossil, and some others identical with European species, or very nearly allied to them, make it highly probable that the Claiborne beds agree in age with the central or Bracklesham group of England, and the calcaire grossier of Paris. Higher in the series is a remarkable calcareous rock, formerly called "the nummulite limestone," from the great number of discoid bodies resembling nummulites which it contains, fossils now referred by A. d'Orbigny to the genus Orbitoides, which has been demonstrated by Dr. Carpenter to belong to the Foraminifera. Fig. 190.
The lowest set of strata, No. 1., having a thickness of more than 100 feet, comprise marly beds, in which the Ostrea sellÆformis occurs, a shell ranging from Alabama to Virginia, and being a representative form of the Ostrea flabellula of the Eocene group of Europe. In others beds of No. 1., two European shells, Cardita planicosta, before mentioned, and Solarium canaliculatum are found, with a great many other species peculiar to America. Numerous corals, also, and the remains of placoid fish and of rays occur, and the "swords," as they are called, of sword fishes, all bearing a great generic likeness to those of the Eocene strata of England and France. No. 2. (fig. 190.) is a white limestone, sometimes soft and argillaceous, but in parts very compact and calcareous. It contains several peculiar corals, and a large Nautilus allied to N. zigzag, also in its upper bed a gigantic cetacean, called Zeuglodon by Owen. Zeuglodon cetoides, Owen. Fig. 191. Molar tooth, natural size. Fig. 192. Vertebra, reduced. The colossal bones of this cetacean are so plentiful in the interior of Clarke County as to be characteristic of the formation. The vertebral column of one skeleton found by Dr. Buckley at a spot visited Mr. Owen first pointed out that the huge animal was not reptilian, since each tooth was furnished with double roots (see fig. 191.), implanted in corresponding double sockets; and his opinion of the cetacean nature of the fossil was afterwards confirmed by Dr. Wyman and Professor R. W. Gibbes. That it was an extinct species of the whale tribe has since been placed beyond all doubt by the discovery of the entire skull of another fossil of the same family, found to have the double occipital condyles only met with in mammals, and the convoluted tympanic bones which are characteristic of cetaceans. Near the junction of No. 2. and the incumbent limestone, No. 3., next to be mentioned, are strata characterized by the following shells: Spondylus dumosus (Plagiostoma dumosum, Morton), Pecten Poulsoni, Pecten perplanus, and Ostrea cretacea. No. 3. (fig. 190.) is a white limestone, for the most part made up of the Orbitoides of d'Orbigny before mentioned (p. 206.), formerly supposed to be a nummulite, and called N. Mantelli, mixed with a few lunulites and small corals and shells. Some of the shells of this limestone are common to the Claiborne beds, but many of them are peculiar. It will be seen in the section (fig. 190. p. 155.) that the strata, Nos. 1, 2, 3., are, for the most part, overlaid by a dense formation of sand or clay without fossils. In some points of the bluff or cliff of the Alabama river, at Claiborne, the beds Nos. 1, 2., are exposed nearly from top to bottom, whereas at other points the newer formation, No. 4., occupies the face of nearly the whole cliff. The age of this overlying mass has not yet been determined, as it has hitherto proved destitute of organic remains. The burr-stone strata of the Southern States contain so many fossils agreeing with those of Claiborne, that it doubtless belongs to the same part of the Eocene group, though I was not fortunate enough to see the relations of the two deposits in a continuous section. Mr. Tuomey considers it as the lower portion of the series. It may, perhaps, be a form of the Claiborne beds in places where lime was wanting, and where silex, derived from the decomposition of felspar, predominated. It consists chiefly of slaty clays, quartzose sands, and loam, of a brick red colour, with layers of chert or burr-stone, used in some places for millstones. | |||||||||||||||||||||||||||||||||||
|
