South America too has had its glacial periods, spreading from the south-polar regions and producing the same effects as in its north ern neighbor. The great heights of the Andes keeps them still existent up to and beyond the equator.
The Cordilleran System.— The two great axial chains which form the western base of the double continent, though (as said) of in dependent origin, have strong similarities and a like relation to the remainder of the surface, and may conveniently be treated together. For their detailed composition and characteristics, see ANDES and ROCKY MOUNTAINS. It should be noted that these are not mere dividing walls, but vast formative elements of the continental masses, and themselves of continental volume. With their foothills and spurs they amount in South America to at least 1,000,000 square miles in area, and in North America to some 2,500,000, or toward a third of the entire surface. They include almost every possible character of soil and climate and natural product, and suitability for every employment,— agriculture, manufac tures or mining. They make climates of their own, so that no inference can be drawn from that on one side to that on the other, and the two may have the difference of five degrees of latitude or 5,000 miles of distance: one side may be a sponge, the other a rainless desert, one a glacier, the other a garden. They make the difference between Puget Sound and Labra dor, and on the other hand between the Mexican plateau and the Nicaraguan plains, between Peru and Caracas. They enclose fertile proy inces and deserts of .rock and sand each large enough for an empire, and have great lakes and considerable rivers entirely their own.
As the development is better studied from the south, we shall begin with South America, whose cordilleras descend by steep short ter races to the seashore, or to a narrow belt of level land immediately adjoining it, form regu lar chains, display the loftiest masses of all America and send out only short branches to the eastern plains; whereas the North American cordilleras lean, in the west, on elevated pla teaus, so as to favor a large development of rivers, are less vertical in their structure and and send to the east more extensive ramifications. The name of particular groups of the Andes are taken from the countries to which they more especially appertain; thus, pro ceeding from south to north, we have the cordil leras of Chile, Bolivia, Peru, Ecuador and Co lombia. This, as a whole, is the highest moun
tain mass on the globe, and except the Hima layas has the highest peaks. Beginning among the rock islands of the Fuegian archipelago, it runs through Patagonia as a low single range with summits of perhaps 8,000 feet ; rises swiftly through Chile, growing at once higher and more multiplied, with .summits of 12,000 to 18,000 feet, till it culminates in the stupendous nevado of Aconcagua, from 23,000 to 24,000 feet high. the loftiest elevation on the western hemisphere. Beyond this it divides into two enormous paral lel arms with a high plateau between, and lower ranges to the east in Argentina increasing its complexity. Thence to the Isthmus it is not a ridge, but a rock continent 200 or 300 miles wide, with a great number of peaks from 19,000 to 21,000 and even 22,000 feet high, and the very over them 15,000 or 16,000 feet above the sea, terrific and nearly impassable gorges above the highest summits in Europe. Sometimes it contains three or four parallel ranges, with two and even three immense till able valleys on the same base. It attains its greatest breadth at about lat. S., in central Bolivia, where it is some 300 miles wide, with three main ranges; and at this point, in the northern part of the province of Tacna, it and the correspondent coast curve northwest as far as 5°, its course in this direction being exactly coincident with the limits of Peru. On these plateaus was situated the empire of the Just northeast of the turn it holds the great Lake Titicaca, some 1,800 miles in area, on a high plateau 12,645 feet above the sea, the sur face of the lake itself being nearly 12,500 feet above sea-level. This part is called the Royal Cordillera and contains several peaks above 20,000 feet. At the Gulf of Guayaquil it again turns north, with a gradual trend east to about lat. 4° N., when it curves north and west to meet the Isthmus, forming a large but nameless gulf. Near the equator, in Ecuador, are a number of very lofty volcanic summits, the two highest and most famous of which arc Chim borazo, 20,498 feet, and Cotopaxi, 19,613 feet. Thence to the Caribbean the height decreases, and in Colombia it divides into three, two running north and the third extending well into Venezuela, the true end of the Andean system.