With respect to the first point above named, the earth's crust was subjected in the Permian period to some of the grandest movements which have occurred in the whole course of geologic time, and we can fix the limits of these, in Europe and America at least, with some distinctness. If we examine the Permian rocks in England and Germany, we shall find that everywhere they lie on the upturned edges of the preceding Carboniferous beds. In other words, the latter have been thrown into a series of folds, and the tops of these folds have been more or less worn away before the Permian beds were placed on them. But if we pass on to the eastward, in the great plain between the Volga and the Ural mountains, where, in the "ancient kingdom of Perm," the greatest known area of these rocks is found, an area equal in extent to twice that of France, and which Sir R. I. Murchison, who first proposed the name, took as the typical district, we find, on the contrary, that the Permian and Carboniferous are conformable to one another. If now we cross the Atlantic and inquire how the case stands in America, we shall find it precisely the same. Here the great succession of earth-waves constituting the Appalachian Mountains rises abruptly at the eastern edge of the continent, and becomes flatter and flatter, until, in the broad plains west of the Mississippi, the Permian beds appear, as in Russia, resting upon the Carboniferous so quietly that it is not always easy to draw a line of separation between them. As Dana has remarked, we find at the western side of Europe and the eastern side of America, great disturbances inaugurating the Permian period; and in the interior of both, in the plains between the Volga and the Ural in one, and between the Mississippi and Rocky Mountains in the other, an entire absence of these disturbances. The main difference is, that in eastern America the whole Carboniferous areas have apparently been so raised up that no Permian was deposited on them, while in Europe considerable patches of the disturbed areas became or remained submerged. Another American geologist has largely illustrated the fact that the movements which threw up the Appalachian folds were strongest to the eastward, and that the ridges of rock are steepest on their west sides, the force which caused them acting from the direction of the sea. It seems as if the Atlantic area had wanted elbow-room, and had crushed up the edges of the continents next to it. In other words, in the lapse of the Palæozoic ages the nucleus of the earth had shrunk away from its coating of rocky layers, which again collapsed into great wrinkles.