Let us give a glance at the continents whose growth we have been following, and see what these more recent geological epochs have done for their completion.  In Europe they have filled the basin in Central France, and converted all that region into dry land:  they have filled also the channel between France and Spain; they have united Central Russia with the rest of Europe by the completion of Poland, and have greatly enlarged Austria and Turkey; they have completed the promontories of Italy and Greece, and have converted the inland sea at the foot of the Jura into the plain of Switzerland.  But this fruitful period in the progress of the world, when the character of organic life was higher and the physical features of the earth more varied than ever before, was not without its storms and convulsions.  The Pyrenees, the Apennines, the Alps, and with them the whole range of the Caucasus and Himalayas, were raised either immediately after the Cretaceous epoch, or in the course of the Tertiaries.  Indeed, with this most significant passage in her history, Europe acquired all her essential characters.  There remained, it is true, much to be done in what is called by geologists “modern times.”  The work of the artist is not yet finished when his statue is blocked out and the grand outline of his conception stands complete; and there still remained, after the earth was rescued from the water, after her framework of mountains was erected, after her soil was clothed with field and forest, processes by which her valleys were to be made more fruitful, her gulfs to be filled with the rich detritus poured into them by the rivers, her whole surface to be rendered more habitable for the higher races who were to possess it.

We left America at the close of the Carboniferous epoch.  A glance at the geological map will show the reader that during the Permian, Triassic, and Jurassic epochs little was added to the United States, though here and there deposits belonging to each of them crop out.  In the Cretaceous epoch, however, large tracts of land were accumulated, chiefly in the South and West; and during the Tertiaries the continent was very nearly completed, leaving only a narrow gulf running up to the neighborhood of St. Louis to be filled by modern detritus, and the peninsula of Florida to be built by the industrious Coral-Workers of our own period.  The age of the Alleghany chain is not yet positively determined, but it was probably raised at the close of the Carboniferous epoch.  Up to that time, only the Laurentian Hills, the northern side of that mountainous triangle which now makes the skeleton, as it were, of the United States, existed.  The upheaval of the Alleghanies added its eastern side, raising the central part of the continent so as to form a long slope from the base of the Alleghanies to the Pacific Ocean; but it was not until the Tertiary Age that the upheaval of the great chain at the West completed the triangle, and transformed that wide westerly slope into the Mississippi Valley, bounded on one side by the Alleghanies, and on the other by the Rocky Mountains.