the ocean of the other great ranges of Europe and Asia since the formation of the secondary strata.

The great mountains of this continent, also, the Appalachians and Andes, are now universally regarded as having been thrown up from the ocean since the period of the secondary formations. The Appalachians bear on their tops or sustain on their sides the main members of the great series from the Potsdam sandstone, the lowest of the fossiliferous rocks on this continent, up to the upper division of the carboniferous group. Deposits of equally late date are found also in the lofty ranges of the Andes.

"I will give a brief sketch of the geology of the several parallel lines forming the Cordilleras. Of these lines there are two considerably higher than the others; namely, on the Chilian side, the Peuquenes ridge, which, where the road. crosses it, is 13,210 feet above the sea; and the Portillo ridge on the Mendoza side, which is 14,305 feet. The lower beds of the Peuquenes ridge, and of the several great lines to the westward of it, are composed of a vast pile many thousand feet in thickness of porphyries, which have flowed as submarine lava, alternating with angular and rounded fragments of the same rocks, thrown out of the submarine craters. These alternating masses are covered in the central parts by a great thickness of red sandstone, conglomerate, and calcareous clay slate, associated with and passing into prodigious beds of gypsum. In these upper beds shells are tolerably frequent; and they belong to about the

period of the lower chalk of Europe. It is an old story, but not the less wonderful, to hear of shells which were once crawling in the bottom of the sea, now standing nearly 14,000 feet above its level. The lower beds in this great pile of strata have been dislocated, baked, crystallized, and almost blended together, through the agency of mountain masses of a peculiar white soda-granitic rock.

"The other main line, namely, that of the Portillo, is of a totally different formation; it consists chiefly of grand bare pinnacles of a red potash-granite, which low down on the western flank are covered by a sandstone, converted by the former heat into quartz-rock. On the quartz there rest beds of a conglomerate several thousand feet in thickness, which have been upheaved by the red granite, and dip at an angle of 45° towards the Peuquenes line. I was astonished to find that this conglomerate was partly composed of pebbles derived from the rocks, with their fossil shells of the Peuquenes range, and partly of red potash-granite, like that of Portillo. Hence we must conclude that both the Peuquenes and Portillo ranges were partially upheaved and exposed to wear and tear, when the conglomerate was forming..

...

"Looking at its earliest origin, the red granite seems to have been injected on an ancient pre-existing line of white granite and mica slate. In most parts, perhaps in all parts of the Cordilleras, it may be concluded that each line has been formed by repeated upheavals and injections; and that the several parallel lines are of different ages. Only thus can we gain time at all sufficient to explain the truly

astonishing amount of denudation which these great, though comparatively with most other ranges recent, mountains have suffered.

"The shells in the Peuquenes, or oldest ridge, prove, as before remarked, that it has been upraised 14,000 feet since a secondary period, which in Europe we are accustomed to consider as far from ancient; but since these shells lived in a moderately deep sea, it can be shown that the area now occupied by the Cordillera must have subsided several thousand feet-in northern Chili as much as 6,000 feet-so as to have allowed that amount of submarine strata to have been heaped up on the bed on which the shells lived."Darwin's Voyage of the Beagle, pp. 319–321.

"The Uspallata range is separated from the main Cordillera by a long narrow plain, or basin, like those so often mentioned in Chili, but higher, being six thousand feet above the sea. This range has nearly the same geographical position with respect to the Cordillera which the gigantic Portillo line has, but it is of a totally different origin; it consists of various kinds of submarine lava, alternating with volcanic sandstones and other remarkable sedimentary deposits; the whole having a very close resemblance to some of the tertiary beds on the shores of the Pacific. From this resemblance I expected to find silicified wood, which is generally characteristic of those formations. I was gratified in a very extraordinary manner. In the central part of the range, at an elevation of about 7,000 feet, I observed on a bare slope some snow-white projecting columns; these were petrified trees, eleven being silicified, and from thirty to

forty converted into coarsely-crystallized white calcareous spar. They were abruptly broken off, the upright stumps projecting a few feet above the ground. The trunks measured from three to five feet each in circumference. They stood a little way apart from each other, but the whole formed one group. Mr. R. Brown, who has examined the wood, says it belongs to the fir tribe, partaking of the character of the Araucanian family, but with some curious points of affinity with the yew. The volcanic sandstone in which the trees were imbedded, and from the lower part of which they must have sprung, had accumulated in successive thin layers around their trunks; and the stone yet retained the impression of the bark."-Darwin's Voyage of the Beagle, pp. 331, 332.

All the great ranges are thus of recent origin, and there are mountains-generally of inferior height, and consisting mainly of granite-that were elevated at an earlier period, yet none are known that can, with any probability, be regarded as having emerged from the ocean anterior to the formation of the lower groups of the strata.

"No truth is more certain or important in geological reasoning, than the formation of all our continents and islands by causes acting below the sea. As far as relates to the stratified rocks this is obvious; but it is not the less certain for the unstratified rocks, those having undoubtedly been uplifted to our view from beneath the strata. It is possible there may yet be found some granite rocks which were raised

above the general spherical surface before the production of any deposits from water, and which therefore may be presumed to form an exception to this general rule; but such truly primitive rocks have nowhere been seen, nor is there any ground of expectation that they will be discovered."Phillips's Geology, vol. ii., p. 248.

As the most ancient of our present mountains are thus of later date than the primary strata, and all the principal ranges-like the Alps, the Himalaya, and the Andes were elevated subsequently to the deposition of the secondary, and even portions of the tertiary formations, we have the most decisive evidence that they were not the sources of the materials from which the strata were formed. If their materials were derived from mountains and continents, it must have been from a different set, of which neither any traces remain, nor any indications of the positions which they occupied.

This consideration is thus again fatal to their theory. No condition can be more indispensable to its establishment, than that it should be shown that contemporaneously with the deposition of the strata, there were continents and mountains in existence that might have furnished materials for their formation; and in order to that, their position should be determined and their dimensions and elevation proved to be such as rendered them adequate to the office that