the animals of this class were not the inhabitants of deep seas. Of bivalve shells there are many species; and the remains of zoophytes, particularly of sponges and alcyonia, are numerous.

The remains of vertebrated animals are rare; they consist chiefly of the teeth, palates, vertebræ, and scales of fishes. The great preservation in which some of the most delicate of these remains are frequently found, render it probable, that chalk was deposited in a deep and tranquil sea. Balls of iron pyrites with a radiated diverging structure, are frequently found in chalk; and the large spines of echini, of the genus Cidaris, are found converted into pyrites in the chalk-pits near Dorking; they resemble small fungi with a stalk and rounded head.

All the fossils in chalk are regarded as belonging to species now extinct, and several of them belong to extinct genera. Mr. Parkinson says that "hardly a single fossil has been found in the lower chalk, which has been met with in the upper or in any other stratum." Chalk extends along the northern coast of France opposite the chalk cliffs of England, of which it was no doubt a continuous formation: it extends also far into the interior of France, and may be traced through the Netherlands and part of Germany, into Poland, and to the Island of Rugen in the Baltic, and into Sweden.

The lower part of the chalk formation may also be traced to the calcareous ranges of the Alps. We have no precise information respecting the extent of chalk in Asia: it has been said, but with what truth I know not, that Jerusalem is built upon chalk. Humboldt discovered no chalk in South America,

nor has it been hitherto found in any part of the United States. Chalk is the uppermost of the strata classed as secondary; it was till very lately regarded as the most recent of rock-formations, except the volcanic.

Between the epoch when chalk was deposited, and the period when it was covered with the tertiary strata, there appears to have been a considerable interval, during which the surface of the extensive mass of chalk, was in many situations deeply furrowed, and excavated into valleys and basins, before a new series of strata were deposited upon it, destined to support a new creation of animals of a superior class, altogether different from those which have left their remains in the subjacent

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CHAPTER XIV.

ON THE TERTIARY FORMATIONS.

On the Formation of the Tertiary Strata in Lakes or inland Seas. On their subsequent destruction by external causes.On the discovery of the Tertiary Strata of France.-Alternations of Marine and Freshwater Strata.-General Classification of Tertiary Strata.-Lower Marine Strata sometimes alternating with Beds containing River Shells and Lignite. -Lower Freshwater Strata sometimes containing Marine Shells. - Upper Marine Sandstone. - Upper Freshwater Limestone.-Plastic Clay and London Clay.-Molasse.-On the Remains of Land Quadrupeds supposed to be found in Molasse. On the London Clay in the Vale of Thames and the Strata with pure Water below it. Calcaire grossier and Calcaire siliceux.-Gypseous Marle and Gypsum of Paris containing Bones of numerous extinct Species of Land Quadrupeds.-Upper Marine Sandstone of France and England.-Freshwater Limestone of Paris and the South of France. Remarkable position of the Tertiary Strata in the Isle of Wight.-Opinions respecting the alternation of Marine and Freshwater Formations.

THE tertiary formations comprise all the various regular beds of limestone, clay, marle, sandstone, or sand, that have been deposited after chalk.— They were until very recently confounded with alluvial and diluvial deposits, and were scarcely noticed by geologists. It is now however discovered, that the tertiary formations are very widely spread over the present islands and continents, and are of considerable thickness.

The most remarkable discovery that has been made respecting the tertiary deposits is, that many

of them contain the bones of mammiferous quadrupeds, as perfect in their organization as any of the existing species of land quadrupeds, but most of them belonging to genera or species that are extinct. The tertiary strata are further remarkable, for presenting the frequent alternation of beds containing the remains of marine animals, with other beds that contain the bones of land animals, or freshwater shells. It appears that the tertiary strata were chiefly formed in detached inland seas, or lakes; hence there is a considerable diversity in the thickness, number and quality of the beds, in different districts or countries.

During the deposition and consolidation of the upper secondary strata, the crust of the globe appears to have remained in a quiescent state, and to have experienced few violent concussions and derangements from internal causes. Those faults and dykes which have bent, contorted, or broken the lower strata, rarely extend to the upper secondary strata; for we find the latter arranged horizontally over them, or dipping with a very slight degree of inclination. Where the upper secondary strata have experienced any considerable disturbing force, it appears to have operated at a comparatively recent period, after the deposition of the tertiary strata; for they are frequently raised or depressed together, as we have before noticed in the Alps.

In our own island, we have instances of partial subsidences of the upper secondary and tertiary strata, which however are few and of very limited extent.

Though in England and the northern parts of

Europe, few internal disturbing causes have acted intensely or extensively on the crust of the globe, after the deposition of the upper secondary, and the tertiary strata, we have clear indications of an external force, which has torn away considerable portions of them, and transported their ruins into distant countries, or into the ocean. Many of these strata have evidently once extended beyond their present limits; and some of the tertiary strata have been so completely destroyed in many situations, that we can only infer their former existence, by a few remaining detached portions.

In France, the tertiary strata are more widely spread, and many of them more fully developed, than in England: it is indeed scarcely possible to imagine a more distinct display of the series of strata in any class of rocks, than is presented close to the very gates of Paris. In a capital so distinguished for scientific investigation, and possessing so many -able and acute observers, it does indeed seem truly extraordinary, that the strata with which they were surrounded, should never have been properly examined until so recent a period, as the early part of the present century. What is daily before our eyes seldom excites attention, or is deemed deserving of much notice; but there was another cause which long prevented the philosophers of Paris from observing the remarkable objects around them. Captivated with the generalizations of Werner, who it was firmly believed had unlocked all the hidden mysteries of Geology, and comprised in his system, all the different formations that composed the crust of the globe, they saw before them a series of strata