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 as we 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 of _Eocene_, _Miocene_, and _Pliocene_ have 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. [81] Lyell’s “Elements of Geology,” p. 187. [Illustration: Fig. 148.--Trigonia margaritacea. (Living form.)] THE EOCENE PERIOD. During this period _terra firma_ has 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 as _Flabellaria_ and _Palmacites_; with many evergreen trees (Conifers), for the most part belonging to genera still existing, as the _firs_, the _pines_, the _yews_, the _cypresses_, the _junipers_, and the _thuyas_ or tree of life. The _Cupanioides_, among the Sapindaceæ; the _Cucumites_, 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 genera _Pecopteris_, by the _Tæniopteris_, _Asplenium_, _Polypodium_. Of the mosses, some _Hepaticas_ formed a humble but elegant and lively vegetation alongside the terrestrial and frequently ligneous plants which we have noted. _Equiseta_ and _Charæ_ would still grow in marshy places and on the borders of rivers and ponds.