CENTRAL FRANCE, consisting of the districts of Auvergne, Velay, and Viverais, is universally admitted by geologists to be of volcanic origin. The most cursory glance at the dome-shaped hills, the basalt, trachyte, and scoriaccous ingredients of which they are composed, at once satisfies the student of nature as to the class of rocks among which he here treads. This region lies upon the river Rhone, nearly in the angle formed by it with the Mediterranean, and covers an area of forty or fifty leagues in diameter. Here are associated, perhaps, the earliest and the latest products of Plutonic action, the primary granites, and the basaltic lavas of comparatively recent times. The granite is flanked on the south and west by immense overliers of gneiss. It may be described as the highlands of the country, whence all the great rivers, the Seine, the Loire, the Gironde, and their principal feeders, take their rise. The mountains, though not remarkable for elevation, now that we are approaching true Alpine peaks, reach the height of four, five, and six thousand, and the Aurillac group to nearly seven thousand feet above the level of the sea; but what a geological series of events is embraced within the period of their physical history! The great depository arrangements of the globe have, one and all, succeeded to those paroxysmal movements that raised their tops above the primeval seas. Race after race of living creatures have enjoyed their span of existence, to be mixed up with the strata which during the interval have been collected and arranged in their various systems. The crust of the earth from time to time was disrupted. The depressions and fissures were as repeatedly replaced with new matter. The tertiary period dawned upon Creation, when plain, lake, and seas, were all teeming with an exuberance of terrestrial and aquatic life,—and when again all in the region of Central France was disturbed, and these newer molten rocks were erupted from beneath. The subterranean fires, wherever seated, were thus, after the lapse of geological epochs, still glowing with intense vigor. And, just bordering on the advent of man, the two classes of rocks would seem to have been placed in the closest proximity, as if to remind him, that the same Omnipotent agency which created every single atom of his earthly habitation, likewise determines every movement and advance of the structure, and makes the near and the remote equally manifest the thunder of his power.