N. of the equator, the other cordillera separates into two chains, of which the easternmost, Suma Paz, runs by hake Maracaibo and terminates near Caracas on the Caribbean sea. The central chain of Quindiu divides the Cauca and Magdalena, and culminates in the volcanic Tolima, 18,270 feet, the highest peak in the new world N. of the line, and situated further from the sea (120 m.) than any other active volcano. - In general, the Andes present a steep slope toward the Pacific, and descend gradually into the vast plains of the east. In Ecuador, the western slope (according to Prof. Orton) is 225 feet per mile, and the eastern 125 feet. In Chili, says Darwin, the descent on the E. side of the cordillera is much shorter or steeper than on the Pacific side. Besides the longitudinal valleys between the cordilleras already mentioned, there are innumerable valleys of erosion on the sides of the Andes in keeping with their colossal size. The gigantic mountain chain, throughout its entire length, forms a great barrier to the interchange of life and commerce between the eastern and western sides of the continent. No river crosses it, and even the separate cordilleras are broken at few points. The passes are wild paths, narrow, steep, rugged, and often running along the edge of precipices.

Man has done little to improve them, except in the elevated plains of Peru, where the incas laid out four grand roads from their favorite capital, Cuzco, which rival the similar works of the old Romans. The least elevation of these passes is rarely less than twice the height of Mount Washington. If it does not reach above the extreme limits of vegetation, it is a favorable pass. Frequently they lead through the regions of perpetual snow, and during the winter months are entirely closed. In Chili there are eight of these passes, S. of lat. 32° S., of which the chief are the Uspallata and Portillo, leading from Valparaiso to Mendoza, and reaching the altitude of 12,450 feet. There are six passes in Bolivia, of which the best is by Cochabamba leading to the Mamore; its highest point is 15,000 feet. Peru may be crossed by three paths: from Lima to Mayro, via Cerro Pasco and Huanuco; from Lima to Tingo Maria, via Huanuco; and fromTruxillo to Moyobamba, via Chachapoyas. One leading from Lima to Tarma and Pasco is 15,700 feet high, the highest pass in the Andes. Ecuador is generally crossed via the A renal on Chimborazo, 14,250 feet, and Papallacta. The maritime chain in New Granada, though low, has but few and difficult passes.

Prom Truxillo to Popayan a great commercial road for mules runs longitudinally along the Andes. The finest carriage ways in western South America are in the Quito valley. - There is a marked difference between the vegetation, the quadrupeds, and to some degree the birds and insects on the eastern side of the Andes and those on the western. This fact accords with geological history; for these mountains, says Darwin, have existed as a great barrier since the present races of animals have appeared; and therefore, unless we suppose the same species to have been created in two different places, we ought not to expect any closer similarity between the organic beings on the opposite sides of the Andes than on the opposite shores of the ocean. The characteristic forms of animal life on the Andes are llamas, vicunas, alpacas, condors, and humming-birds; nearly all the domesticated animals are importations. The puma, jaguar, peccary, deer, opossum, monkey, squirrel, weasel, and a small black bear abound in the lower altitudes. The population of the Pacific states, consisting of Indians (Aymard in the southern and Quichua in the northern half) and Spanish Americans, is mainly gathered in the high valleys.

Near Ocu-ruro in Peru is the little post hut of Rumi-huasi, on a wild, forbidding height 420 feet higher than the summit of Mont Blanc - the loftiest habitation in the world. - Ascending the equatorial Andes, we find every variety of climate arranged in zones according to the altitude, and characterized by floral life. From the bananas and palms on the steaming lowlands, we pass in succession tree ferns, cinchona, polylepis (the last of the trees), heaths, gentians and geraniums, paja (the long wiry grass of the paramos), and lichens. The most prominent flowers in the Quito valley belong to the composiae, labiatae legaminosae, and gentianaceae. The Andes pass from the hot climates of the equatorial regions through the southern temperate zone nearly to its extreme verge. At their termination, in lat. 56° S., the climate is indeed more boisterous and wintry than that just over the limit of the frigid zone in the northern hemisphere. In the summer season, at Tierra del Fuego, the warmth is insufficient to lift the line of perpetual snow higher than 3,500 or 4,000 feet above the level of the sea, while in Norway for such a climate one must go from 11 to 14 degrees further from the equator.

As the Andes toward the north spread out into broader masses, and stretch upward to higher elevations, they carrv with them through the tropics the cold temperature of their southern termination. But the mountains are not only the regulators of the climate, they are also the great condensers, lifted up into the higher regions of the atmosphere to catch the abundant moisture distilled by the trade winds, and to shed it in copious streams from the eastern slopes on which it is precipitated, eastward toward the Atlantic, feeding: the great livers of the continent, and spreading fertility along their paths. - Glaciers are rare, being found only in the narrow ravines of the southern section. The volcanoes of the Andes, 51 in number, are remarkable for their continuity, in scattered groups, from the western coast of Patagonia, in lat. 43° 28' S., to the northern limits of the Andes a few degrees from the equator; and even into Central America the continuation of this volcanic belt may be traced in the cordilleras of Costa Rica, Nicaragua, Honduras, and Mexico. The most southern group extends from Yanteles, opposite the island of Chiloe, to Coquimbo, in lat. 30°. There is then a space of more than eight degrees of latitude with no volcano known to have been in action, to which succeeds the range of volcanoes of Bolivia and Peru, the extent of which is from lat. 21° to 15° S. Thence to the volcanoes of Quito is a district of fourteen degrees of latitude, little known and thinly populated.