buried the previous topography and extended as vast lavaplains, like those of younger date, which form so impressive a feature in the scenery of Montana, Idaho, and Oregon, in Western North America.

In the Paris basin, the Oligocene strata follow immediately upon the Eocene group described on p. 433. They consist of (1) a lower division of gypsum (65 feet) and marls, with terrestrial shells, and remains of palæotheres and anoplotheres; (2) a middle band of marl, limestone, and sand, with lacustrine and estuarine shells; and (3) an upper division, in which the most conspicuous members are the sands and hard siliceous sandstone of Fontainebleau.

In Northern Germany the subjoined succession of strata in descending order has been noted.

{

Marine marls, clays, and sands.
Brown coal of the Lower Rhine, with abundant terrestrial

CHAPTER XXV.

MIOCENE-PLIOCENE.

THE geological period at which we are now arrived, one of the most important in the history of the configuration of the existing continents, embraced that portion of geological time during which the great mountain-chains of the globe were uplifted into their present commanding positions. There is good reason to believe that these lines of elevation are of great geological antiquity, and that they have again and again been pushed upward during great terrestrial disturbances. But the intervals between these successive upthrusts were probably often of immense duration, so that the mountains, being exposed to continuous and prolonged denudation, were worn down, sometimes perhaps almost to the very roots. In all probability the nucleus of the line of the Alps, for example, dates back to a remote geological period. But only in Tertiary time did it attain its present dimensions. We have seen that, during the Eocene period, the sea of the nummulitic limestone extended over at least a considerable part of the Alpine region, and that, as the limestone now forms crumpled and dislocated mountainous masses, the great upheaval of the chain must have taken place after Eocene time. Not improbably the process was a prolonged one, advancing in successive uplifts with intervals of rest. The final upheaval that gave the Alps their colossal bulk did not take place until the Miocene period or later, for the Miocene strata have been involved in the earth-movements, and have been thrust up, bent, and broken. Nor were the terrestrial convulsions confined to Central Europe, all over the globe there seem to have been extensive disturbances. The Eocene sea-bed with its thick accumulations of nummulite-limestone was ridged up into land, and portions of it were carried upward on the flanks of the mountains, in the Himalayas to a height of 16,500 feet above the sea.

While these revolutions were taking place in its topography, Europe continued to enjoy a climate which, to judge from the remains of plants and animals preserved in the Miocene rocks, must still have been of a somewhat tropical character. The flora that clothed the slopes of the Alps was not unlike that of the forests of India and Australia at the present time. Palms of various kinds still flourished all over Central and Western Europe, mingled with conifers, laurels, evergreen oaks, magnolias, myrtles, mimosas, acacias, sumachs, figs, oaks, and various still living genera of proteaceous shrubs (Fig. 198). But there is evidence of the incoming of a more temperate climate, for, in the higher parts of the Miocene series of strata, the vegetation was characterised by the abundance of its beeches, poplars, hornbeams, elms, laurels, pondweeds, etc.

Remains of the terrestrial fauna have been well preserved in the deposits that gathered over the floors of the lakes. We know, for instance, that in the woodlands surrounding the large Miocene lake of Switzerland insect life was remarkably abundant. From the porportions of the different kinds that have been exhumed, it has been inferred

that the total insect population was then more varied in some respects than it is now in any part of Europe, wood

FIG. 198.- Miocene Plants; (a) Magnolia Inglefieldi (3); (b) Rhus Meriani (natural size); (c) Ficus decandolleana (1⁄2); (d) Quercus ilicoides ().

beetles being especially numerous and large. In the thick underwood, frogs, toads, lizards, and snakes found their food. Through the forests there roamed antelopes, deer, and three-toed horses, while opossums, apes, and monkeys (Pliopithecus, Dryopithecus, Oreopithecus) gamboled among the branches. Wild cats, bears (Hyænarctos), and sabretoothed lions (Machairodus) were among the prominent carnivores of the time. But the most striking denizens of these scenes were undoubtedly the huge proboscidian creatures among which the Mastodon and Deinotherium took the lead. The mastodon (Fig. 199) was a large and long extinct form of elephant, which, besides tusks in the upper jaw, had often also a pair in the lower jaw. The deinotherium

FIG. 199.-Mastodon augustidens (2).

(Fig. 200) possessed two large tusks in the lower jaw which

FIG. 200.-Skull of Deinotherium giganteum (reduced).

were curved downwards.

This huge animal probably fre

quented the rivers of the

time, using its powerful curved