Breadth and Area.—The area, on an estimate, necessarily rough and vague, has been computed to be triple that of the belt of comparativelyIevel land that borders on the Pacific. In other words, the average breadth of the chain is'•eekoned to be thrice that of the belt in question. In a rough way, the breadth may be estimated from the very shore of the Pacific, whence the w. slope commences, to the lowest pongos, or cataracts, on the eastward streams. But it is more correct to measure it from the foot of the .mountains, properly so called, on the one side to that on the other. The phraSeology of the country, which, on such a subject, ought to be conclusive, appears to support the latter mode of computation. In Lima and its neighborhood, where Ilerndon crossed the A., that officer speaks of "coast" and " sierra," as distinguished from each other even to the westward of the dividing ridge. The entire distance of the pass of Antarangra, as measured on the actual road, was 87 m.—the first 50 being coast and the remaining 37 sierra. Nor does the distinction seem to have been an arbitrary one. From Callao to Cocachera—a line of 44 in.—the rise above the sea-level, tolerably uniform the whole way, amounted to 4452 ft., or rather more than 101 ft. to the mile; hut the no.* 15 m., of which about a half still belonged to what was called coast, yielded an increase of 2850 ft., an average probably of 200 ft. for that part of the stage that fell under the definition of sierra. To give instances of extreme breadths of the A.—an average breadth being unattainable—the least breadth, and that in Patagonia. is believed to be 60 or TO m.; the greatest breadth, again, pretty nearly on the parallel of lake Titicaca, and right through the grand plateau of Bolivia, is said to be 400 m.; and to give an inter mediate ease, the breadth from Mendoza, in the basin of La Plata, to Santiago, in Chili, is given at 140 m.—the former city being 4486 ft. above the Atlantic, and the latter 2614 above the Pacific.
In drder, then, to have a definite idea of the breadth of the A., the chain must be viewed from one end to the other. In doing this there will be adopted the ordinary nomenclature, referring each division of the A. to the particular country through which it may pass.
Patagonian Andes.—Including the A. of the Fuegian archipelago, this part of the chain, extending from lat. 56" s. to lat. 42° s., a distance of more than 960 m. is the narrowest of all, or is, at all events, too irregular to have its breadth accurately esti mated. The Patagonian shore, strictly so called, is breasted, very much like the n.w. coast between Fuca's strait and mt. St. Elias, by a number of islands. On these, as already mentioned, the true A. are to be found, or rather, of these the true A. consist—the continent itself affording no footing to the chain till fully 300 m. to the northward of cape Horn. Even after the chain has laid hold of the mainland, it by no means can be said to abandon the islands; so that here, as farther to the n., the chain may be regarded as made up of parallel ranges—the main difference being that the inter vening valleys, which, to the n., are basins of fresh-water rivers, here present salt-water channels.
Ghilian Andes, stretching from lat. 42° s. to lat. 24° s., a distance of nearly 1250 miles. Throughout nearly the whole of this line, the A. consist of only one range, for the par allel ridges, which run along between the great water-shed and the Pacific, cannot claim to be any exception to this remark, inasmuch as their highest points do not exceed an elevation of 2500 ft. above the level of the sea. This part of the chain, however, presents several lateral ranges, if it does not present any parallel ones of importance.
These .spurs are to be seen on both sides, though of very different magnitudes. To the w. they are akin to the comparatively insignificant parallel ranges just noticed, being, if A. ut all, merely A. in miniature. But to the e. the spurs deserve more consideration. They are two in number, the one branching off between the 83d and 31st parallels, and the other between the 28th and 24th. The former, called the Sierra de Cordova, advances like a promontory into the plains of Rio de la Plata, or Pampas, as they are more generally denominated, as far as the 65th meridian; and the latter, called the Sierra de Salta, runs nearly as far to the e., and in a direction nearly parallel.
Peruvian Andes.—This part of the chain, stretching from lat. 24° s. to lat. 6° s.—a distance about the same as in the last paragraph—is perhaps the broadest of all the divi sions of the A. It certainly contains the largest of the plateaus, the plateau of Bolivia. Between the 20th and 19th parallels, not far from the city of Potosi, the chain separates into two ranges, known as the East and West Cordilleras of Bolivia; and it is the reunion of these ranges, between the 15th and 14th parallels, that incloses the landlocked plateau of Titicaca, containing, as is said, 30,000 sq.m., or an area equal to that of Ireland. Immediately above this table land, the united ranges in question constitute the moun tain-group of Cuzco, which, in point of superficial extent, is stated to be thrice as large as all Switzerland. About a degree further north, the chain again separates as before, reuniting also, as before, between the 11th and 10th parallels, so as to embrace the cities of Guanta and Guancavelica. Hardly have the two ranges reunited, when they mass themselves into the tableland of Pasco, not quite half the size of that of Titicaca. Fur ther to the n., the chain divides, not into two, but into three ranges, which unite again, on the frontiers of Ecuador, in the group of Loxa, about lat. 3° s.
Andes of Ecuador. —Immediately beyond the group of Loxa, between and 3° of s. the chain divides into two ranges, which, by again uniting in 2' 27', form the valley of Cuenca; and immediately beyond, this is the group of Assuay, with its table-land. Then another plateau of no great extent,and a short stretch of the undivided chain, lead to the vast table-land of Quito, which is said to be subdivided by low hills into five smaller plateaus, two to the east and three to the west. Towards the n. the table-land of Quito is succeeded by the group of Los Pastos, forming the extreme portion of the A. of Ecuador.
Andes of New Granada. —Beyond the city of Almaguer, the chain breaks off into two ranges, which never again join each other. The range on the w. side remains undi vide'd, till it disappears near the mouth of the Atrato, a little to the e. of the isthmus of Darien. But the range on the e., after massing itself into the group of Paramo de los Papas, breaks into two branches, which, as distinguished from the aforesaid on the w., are styled the Central and Eastern Cordilleras of New Granada. These two contain between them the upper waters of the Magdalena, the eastern separating them from the basin of the Orinoco, and the central dividing them from that of the Cauca. Between them also they contain several considerable table-lands, the principal one being that of Santa Fe de Bogota.
Height.—Under this head must he treated separately the plateaus, the most prominent mountains, and the passes—the altitudes of the lines of perpetual snow falling more natu rally under the head of climate. Here, as in the case of breadth, the chain will be fol lowed from south to north.