Elevation des of BOOK as so many separate summits. Pichincha, Cayambe, CotoLXXXVI. paxi, all these volcanic peaks, which are designated by particular names, although, for more than one half of their total height, they consist of only one single mass, appear to the inhabitants of Quito as if they were distinct mountains, rising from the middle of a plain destitute of woods. The deception becomes more complete, in consequence of the rugged points of this double crest of the Cordilleras rising to the level of the lofty inhabited plains. Accordingly, the Andes only present the appearance of a chain when viewed at a distance, either from the shores of the great ocean, or from the savannas that extend to the base of their eastern declivity. The Andes of Quito compose the most elevated portion of of the An- the whole system, particularly between the equator and 1° 45' of south latitude. It is only on this limited space of the globe that mountains of above 19,000 feet in height, have been measured with exactness; and even in this respect, there are only three peaks to which this remark can be applied; namely, Chimborazo, which would exceed the height of Mount Etna, placed on the summit of Canigou, or that of St. Gothard piled on the top of the Peak of Teneriffe; the other two are Cayambe and Antisana. (a) From the traditions of the Indians of Lican, we learn, with some degree of certainty, that the Mountain of the Altar, called by the natives Capa Urcu, had once a greater elevation than Chimborazo, but that, after a continual eruption of eight years, this volcano became extinguished. In proof of this fact, the top of the mountain presents, on its oblique peaks, nothing but the traces of destruction. Quito. Structure and geo logical The geological structure of this part of the Andes does not essentially differ from that of the great mountainous composi- chains of Europe. Granite constitutes the base, upon which the less ancient formations repose. It comes into view at the foot of the Andes, on the shores of the Pacific Ocean, as well as on those of the Atlantic, near the mouths tion. (a) [The height of the Peak of Misté, or Volcano of Arequipa, near the city of Arequipa, according to the barometrical measurement of Mr. Curson, made in 1811, is 20,328 feet.] AM. ED. of the Oronoko. Sometimes in masses, at others in strata, BOOK regularly inclined and parallel, and containing round mass- LXXXVI. es, in which mica alone prevails, the granite of Peru rcsembles that of the higher Alps and of Madagascar. Upon this rock, and occasionally alternating with it, is found gneiss or foliated granite, which passes into mica-slate, and this again into primitive clay slate. The granular limestone, primitive trap, and chlorite slate, form subordinate beds in the gneiss and mica-slate; while this latter extensively diffused through the Andes, often encloses beds of graphite, and serves as a base to formations of serpentine. which sometimes alternate with syenite. The crest of the Andes is every where covered with various forms of porphyries, basalts, clink stone and green stone. These rocks, divided into columns, present, at a distance, the appearance of an immense assemblage of dilapidated towers. The thickness and extent of the schistose and porphyritic rocks is the only great phenomenon by which the Andes differ from the mountains of Europe. The porphyries of Chimborazo are 11,400 feet in thickness, without a mixture of any other rock; the pure quartz, to the west of Caxamarca, is 9000, and the sandstone of the environs of Cuença 4800. These porphyritic rocks form the whole of the central elevation of the Andes, while, in Europe, granite or primitive limestone constitutes the summit of the chain. Volcanoes have penetrated these immense beds, and have covered their sides with porous obsidian and amygdaloid. The lowest volcanoes sometimes throw out lava; but Volcanoes. those of the Cordillera, properly so called, only propel water or scorified rocks, and most frequently clay, intermixed with sulphur and carbon.* As we penetrate into the interior of Peru, we see the mountain ranges of the Andes become more numerous, and increase in breadth, but, at the same time, diminish in clevation. A. de Humboldt's Description of the Equatorial Regions, p. 122-130. VOL. V. 47 Cordillera of Peru. BOOK Chimborazo, like Mont Blanc, forms the extremity of a LXXXVI. colossal group. From Chimborazo, as far as 120 leagues to the south, no mountain peak attains the limit of perpetual snow. The general ridge of the Andes has only from 3360 to 3800 yards of elevation. From the eighth degree of north latitude. or the province of Guamachuco, the snowy peaks become more numerous, especially near Cuzco and la Paz, where the Ilimani and the Cururana shoot up their summits to the clouds. Everywhere in this region, the Andes, properly so called, are bordered to the east by several inferior chains. The missionaries who have examined the mountains of Chachapoya, those that skirt the Pampa del Sacramento, those that form the Sierra de San Carlos, or the Grand Pajonal, and the Andes de Cuzco, represent them as being covered with large trees and luxuriant meadows, and consequently, as being considerably lower than the true Cordillera. With regard to the latter, M. Helm, director of the mines of Spain, has afforded us some knowledge of the central portion, where the division into two parallel ridges, which Bouguer had observed farther to the north, is very manifestly visible. According to this writer, the eastern side of the Andes sometimes presents both red and green granite, and gneiss, amongst other places, towards Cordova and Tucuman; but the great chain principally consists of argillaceous schistus, or different species of thick clay slate, of a bluish, dark red, grey, or yellow colour. From time to time beds of limestone, and large masses of ferruginous sandstone are met with. A beautiful mass of porphyry crowns the mountain of Potosi. From that town to Lima, the argillaceous schistus seems to this observer to predominate; the granite sometimes appeared in long beds or in round masses; the base of the clay slate was often covered with beds of marl, gypsum, limestone, sand, fragments of porphyry, and even of rock salt. The accidental observations of M. Helm do not furnish us with a complete geological view; but yet they coincide with the above description of the Andes of Quito, which we have taken from M. de Humboldt. BOOK LXXXVI. Cordillera The Andes of Chili do not seem to yield in height to those of Peru; but their nature is less perfectly known. of Chili. Volcanoes appear to be here more numerous. The lateral chain disappears, and the Cordillera itself presents only a single ridge. More to the south, in New Chili, latitude 44 S. the Cordillera approaches so close to the ocean that the precipitous islets of the archipelago of Huayatecas may be regarded as a fragment detached from the chain of the Andes. They are so many Chimborazos and Cotopaxis, but plunged two-thirds of their height into the abyss of the ocean. On the continent the snowy cone of Cuptana is elevated nearly 3142 yards; but more to the south, near Cape Pilar, the granitic mountains sink to about 433 yards, and even still lower. According to the accounts of navigators, there is reason to consider the principal part of the southern extremity of the Andes, at the Straits of Magellan, as composed of masses of basalt, which rise in the form of columns. mines. The metallic riches of the chain of the Andes appear to surpass those of the Mexican Cordillera; but placed at a greater elevation in the snowy region, and far from forests Situation and cultivated land, the mines, hitherto discovered, have not of the been equally productive. At the same time, this remark, important as it is in a political point of view, is any thing but conclusive with regard to physical geography. For even supposing that mines are not discovered in the Andes at a lower level, still, nevertheless, they may exist, and be concealed from the view, and from all approach, merely by some formations of rocks placed upon the metalliferous schistus in a greater mass than in Mexico. majus. The Andes, by no means abounding in calcareous rocks, Fossil recontain very few petrifactions. The belemnites and ammonites, so common in Europe, seem to be unknown. In the chain of coasts of the Caraccas, M. de Humboldt found a great quantity of petrified shells, which resemble those of the neighbouring sea. In the plain of the Oronoko, trees BOOK are found petrified, and converted into a very hard brecLXXXVI. cia. Climates rature. Petrified shells are also found at Micuipampa and at Huancavelica, 12,000 and 13,200 feet in height. Other remains of a former world are discovered at an inferior level. There has been found near Santa Fe, in the Campo de Giguante, at an elevation of 10,220 feet, an immense quantity of the fossil bones of elephants, both of the African kind and of the carnivorous species, discovered near the Ohio. Some have also been seen to the south of Quito, and in Chili; so that we can now prove the existence and the destruction of these gigantic elephants from the Ohio to Patagonia. The temperature, determined as much by the level as by and tempe- the latitude, here presents contrasts similar to those which we have observed in Mexico. The inferior limit of perpetual snow under the equator is at the height of 14,760 feet; this boundary, invariable and strongly defined, must strike the most careless observer. The other divisions of climate are still more intermingled; notwithstanding which, they may be enumerated with greater precision than they have hitherto been. Three zones. Hot zone. The three zones of temperature which originate in America from the enormous difference of level between the various regions, cannot by any means be compared with the zones which result from a difference of latitude. The agreeable, the salutary vicissitudes of the seasons are wanting in those regions that are here distinguished by the denominations of frigid, temperate, hot or torrid. In the frigid zone it is not the intensity but the continuance of the cold, the absence of all vivid heat, the constant humidity of a foggy atmosphere, that arrest the growth of the great vegetable productions, and, in man, perpetuate those diseases that arise from checked perspiration. The hot zone of these places does not experience excessive heat; but it is a continuance of the heat, together with exhalations from a marshy soil, and the miasmata of an immense mass of vegetable putrefaction, added to the effects of an extreme hu |