Chapter 31

Geological History of South America.--Rise of the Andes.--Creation of the Amazon.--Characteristic Features of the Continent.--Andean Chain.--The Equatorial Volcanoes.

Three cycles ago an island rose from the sea where now expands the vast continent of South America. It was the culminating point of the highlands of Guiana. For ages this granite peak was the solo representative of dry land in our hemisphere south of the Canada hills. In process of time, a cluster of islands rose above the thermal waters. They were the small beginnings of the future mountains of Brazil, holding in their laps the diamonds which now sparkle in the crown of Dom Pedro II. Long protracted eons elapsed without adding a page to the geology of South America. The Creator seems to have been busy elsewhere. Decorating the north with the gorgeous flora of the carboniferous period, till, in the language of Hugh Miller, "to distant planets our earth must have shone with a green and delicate ray," he rubbed the picture out, and ushered in the hideous reptilian age, when monstrous saurians, footed, paddled, and winged, were the lords of this lower world. All the great mountain chains were at this time slumbering beneath the ocean. The city of New York was sure of its site; but huge dinotheria wallowed in the mire where now stand the palaces of Paris, London, and Vienna.

At length the morning breaks upon the last day of creation, and the fiat goes forth that the proud waves of the Pacific, which have so long washed the table-lands of Guiana and Brazil, shall be stayed. Far away toward the setting sun the white surf beats in long lines of foam against a low, winding archipelago--the western outline of the coming continent. Fierce is the fight for the mastery between sea and land, between the denuding power of the waves and the volcanic forces underneath. But slowly--very slowly, yet surely--rises the long chain of islands by a double process; the submarine crust of the earth is cooling, and the rocks are folded up as it shrivels, while the molten material within, pressed out through the crevices, overflows and helps to build up the sea-defiant wall. A man's life would be too short to count even the centuries consumed in this operation. The coast of Peru has risen eighty feet since it felt the tread of Pizarro: supposing the Andes to have risen at this rate uniformly and without interruption, seventy thousand years must have elapsed before they reached their present altitude. But when we consider that, in fact, it was an intermittent movement--alternate upheaval and subsidence--we must add an unknown number of millennia.

Three times the Andes sank hundreds of feet beneath the ocean level, and again were slowly brought up to their present height. The suns of uncounted ages have risen and set upon these sculptured forms, though geologically recent, casting the same line of shadows century after century. A long succession of brute races roamed over the mountains and plains of South America, and died out ages ere man was created. In those pre-Adamite times, long before the Incas ruled, the mastodon and megatherium, the horse and the tapir, dwelt in the high valley of Quito; yet all these passed away before the arrival of the aborigines: the wild horses now feeding on the pampas of Buenos Ayres were imported from Europe three hundred and thirty-three years ago.[50]

[Footnote 50: At Paita, the most western point of South America, there is a raised beach three hundred feet high. The basal slate and sandstone rocks, dipping S. of E., are covered by conglomerate, sand, and a gypseous formation, containing shells of living species. Additional to those described by D'Orbigny we found here _Cerithium læviuscula_, _Ostrea gallus_, and _Ampullina Ortoni_, as determined by W.M. Gabb, Esq., of Philadelphia. Darwin found shells in Chile 1300 feet above the sea, covered with marine mud. President Loomis, of Lewisburg University, Pa., informs the writer, that in 1853, after nearly a day's ride from Iquique, he came to a former sea-beach. "It furnished abundant specimens of _Patellæ_ and other shells, still perfect, and identical with others that I had that morning obtained at Iquique with the living animal inhabiting them." This beach is elevated 2500 feet above the Pacific. The same observer says that near Potosi there is one uninterrupted mass of lava, having a columnar structure, not less than one hundred miles in length, fifty miles wide, and eight hundred feet thick. It overlies a bed of saliferous sandstone which has been worked for salt. Fifty feet within a mine, and in the undisturbed rock which forms its roof, the doctor found fragments of dicotyledonous trees with the bark on, undecomposed, uncharred, and fibrous.]

And now the Andes[51] stand complete in their present gigantic proportions, one of the grandest and most symmetrical mountain chains in the world. Starting from the Land of Fire, it stretches northward and mounts upward until it enters the Isthmus of Panama, where it bows gracefully to either ocean, but soon resumes, under another name, its former majesty, and loses its magnificence only where the trappers chase the fur-bearing animals over the Arctic plains. Nowhere else does Nature present such a continuous and lofty chain of mountains, unbroken for eight thousand miles, save where it is rent asunder by the Magellanic Straits, and proudly tossing up a thousand pinnacles into the region of eternal snow. Nowhere in the Old World do we see a single well-defined mountain chain, only a broad belt of mountainous country traversing the heart of the continent.

[Footnote 51: The name Andes is often derived from _anta_, an old Peruvian word signifying metal. But Humboldt says: "There are no means of interpreting it by connecting it with any signification or idea; if such connection exist, it is buried in the obscurity of the past." According to Col. Tod, the northern Hindoos apply the name Andes to the Himalayan Mountains.]

The moment the Andes arose, the great continental valley of the Amazon was sketched out and moulded in its lap. The tidal waves of the Atlantic were dashing against the Cordilleras, and a legion of rivulets were busily plowing up the sides into deep ravines; the sediment produced by this incessant wear and tear was carried eastward, and spread out stratum by stratum, till the shallow sea between the Andes and the islands of Guiana and Brazil was filled up with sand and clay. Huge glaciers (thinks Agassiz), afterward descending, moved over the inclined plane, and ground the loose rock to powder.[52] Eddies and currents, throwing up sand-banks as they do now, gradually defined the limits of the tributary streams, and directed them into one main trunk, which worked for itself a wide, deep bed, capable of containing its accumulated flood. Then and thus was created the Amazon.

[Footnote 52: On this point see Chapter XVII.]

In South America Nature has framed her works on a gigantic scale. Where else combined do we see such a series of towering mountains, such a volume of river-water, and such wide-spreading plains? We have no proper conception of Andine grandeur till we learn that the top of the tallest mountain in North America is nearly a mile beneath the untrodden dome of Chimborazo; nor any just view of the vast dimensions of the Amazonian Valley till we find that all the United States could be packed in it without touching its boundaries; nor any adequate idea of the Amazon itself till we ascertain that it drains a million square miles more than the Mississippi.

South America is a triangular continent, with its axis, the Andes, not central, as in Europe, but lying on its extreme western edge, and in harmony with the well-known law that the highest mountains and the grandest volcanoes face the broadest ocean. The highlands of Brazil and Guiana have neither volcanic nor snow-clad peaks.[53] Like all the dry land which first appeared, these primitive mountains on the Atlantic border trend east and west. The result of this position is a triple river system--the Orinoco, Amazon, and La Plata, draining three immense plains--the llanos of Venezuela, the sylvas of Brazil, and the pampas of the Argentine Republic. The continuity and extent of these vast depressions are more remarkable even than the height and length of the mountain chains.[54]

[Footnote 53: "The interior plateau of Brazil (says Dr. Lund) is composed of horizontal strata of the transition period, which are nowhere covered with the secondary or tertiary formations." The highest point in Brazil is 5755 feet. Darwin speaks of "some ancient submarine volcanic rocks (in the province of La Plata) worth mentioning, from their rarity on this eastern side of the continent." With the exception of the coast of Venezuela, the eastern system is little exposed to earthquakes.]

[Footnote 54: These three plains constitute four fifths of all South America east of the Andes. The west slope of the Ecuadorian Andes is about 275 feet per mile; on the east it is 125 feet.]

Such are the characteristic features of South America; they are not repeated in any other continent.[55] Not one feature could be changed without destroying those peculiarities of soil and climate which so remarkably distinguish South America. Its position on the equator places it in the path of the vapory trade winds, which continually sweep over it westward till they strike the Andes, which, like a great condenser, roll a thousand streams eastward again to feed the mighty Amazon. So effectual is that barrier, not a drop of moisture passes it, and the trade wind is not felt again on the Pacific till you are one hundred and fifty miles from the coast. Were the Andes on the Atlantic side, South America would be turned into a vast Sahara. As it is, the interest which attaches to this continent, save a few relics of the Incas, is exclusively that of pure nature. Nowhere does Nature affect us more deeply with the feeling of her grandeur; nowhere does she exhibit wilder freaks or more startling contrasts; nowhere do we find such a theatre for the free development of vegetable and animal life.

[Footnote 55: There is, however, a striking coincidence between the mountain and river systems of the northern and southern continents of this hemisphere. Thus,

The Andes represent the Rocky Mountains, " Highland of Guiana represent the Canadian Mountains. " " Brazil " Appalachian " " Amazon " Saskatchewan. " La Plata " Mississippi. " Orinoco " Mackenzie.

]

The long and lofty chain of the Andes is certainly one of the grandest results of the plications and uplifts of the earth's crust. While the waves of the Pacific, from Panama to Patagonia, submissively kiss the feet of the Andes, and the showers that swell the Amazon fall within sight of the mariner on that peaceful ocean, the Rocky Mountains are situated five hundred miles from the sea. The space west of the Andes does not contain 20,000 square leagues, while the country east of it equals 424,600. While the compact Andes have an average width of only sixty miles,[56] the straggling mountain system beyond the Mississippi has the breadth of the Empire State; but the mean elevation of the latter would scarcely reach the bottom of the Quito Valley. The mountains of Asia may surpass the Cordilleras in height, but, situated beyond the tropics, and destitute of volcanoes, they do not present that inexhaustible variety of phenomena which characterizes the latter. The outbursts of porphyry and trachytic domes, so characteristic of the high crests of the Cordilleras, impart a physiognomy quite distinct from that presented by the mountains of Europe. The Andes offer, in the least space, the greatest possible variety of impressions.[57] There is near Huanca, Peru, a coal-bed lifted up to the enormous height of 14,700 feet, and on the side of Chimborazo there is a salt spring 13,000 feet above the sea. Marine shells have not been found in Europe above the summit of the Pyrenees, or 11,700 feet; but the Andes can show some a thousand feet higher. A strange sight, to see shells once crawling on the bottom of the ocean now resting at an elevation twice the height of Mount Washington!

[Footnote 56: The width of the chain south of the equator varies with that of the continent.]

[Footnote 57: "No mountains which I have seen in Hungary, Saxony, or the Pyrenees are as irregular as the Andes, or broken into such alternate substances, manifesting such prodigious revolutions of nature."--_Helms_. "More sublime than the Alps by their _ensemble_, the Andes lack those curious and charming details of which Nature has been so lavish in the old continent."--_Holinski_.]

Beneath the Southern Cross, out of a sea perpetually swept by fearful gales, rise the rocky hills of Terra del Fuego. It is the starting-point of that granite chain which winds around the earth in a majestic curve, first northwesterly to the Arctic Sea, thence by the Aleutian and Japanese Isles to Asia, crossing the Old World southwesterly from China to South Africa.

Skirting the bleak shores of Patagonia in a single narrow sierra, the Andes enter Chile, rising higher and higher till they culminate in the gigantic porphyritic peak of Aconcagua. At the boundary-line of Bolivia, the chain, which has so far followed a precise meridional direction, turns to the northwest, and, at the same time, separates into two Cordilleras, inclosing the great table-land of Desaguadero. This wonderful valley, the Thibet of the New World, has four times the area of New York State, and five times the elevation of the Catskill Mountain House. At one end of the valley, perched above the clouds, is silvery Potosi, the highest city in the world; at the other stands the once golden capital of Cuzco. Between them is Lake Titicaca[58] (probably an ancient crater), within which is an island celebrated as the cradle of the strange empire of Peru, which, though crushed by Pizarro in its budding civilization, ranks as the most extraordinary and extensive empire in the annals of American history. The Cordillera, of which Sahama, Sorata, and Illimani are the pinnacles, so completely inclose this high valley that not a drop of water can escape except by evaporation. At the silver mines of Pasco the Andes throw off a third cordillera, and with this triple arrangement and a lower altitude, enter the republic of Ecuador. There they resume the double line, and surpass their former magnificence. Twenty volcanoes, presided over by the princely Chimborazo and Cotopaxi, rise out of a sublime congregation of mountains surrounding the famous valley of Quito. In New Granada there is a final and unique display of Andine grandeur: the Cordilleras combine just above the equator into one dizzy ridge, and then spread out like a fan, or, rather, like the graceful branches of the palm. One sierra bends to the east, holding in its lap the city of Bogota, and, rolling off a thousand streams to swell the Orinoco, terminates in the beautiful mountains of Caracas; the central range culminates in the volcanic Tolima,[59] but is soon lost in the Caribbean Sea; the western chain turns to the left, humbling itself as it threads the narrow isthmus, and expands into the level table-land of Mexico. You may cross Mexico from ocean to ocean in a carriage, but no wheeled vehicle ever crossed South America.

[Footnote 58: This lake is the largest fresh-water accumulation in South America. It has diminished within the historic period. Its surface is 12,795 feet above the Pacific, or higher than the highest peaks of the Pyrenees.]

[Footnote 59: This is the loftiest summit of the Andes in the northern hemisphere, being 18,200 feet. It is also remarkable for being situated farther from the sea (120 miles) than any other active volcano.]

We will now speak more particularly of the Andes of the equator. The mountain chain is built up of granite, gneissoid, and schistose rocks, often in vertical position, and capped with trachyte and porphyry.[60] Large masses of _solid_ rock are rarely seen; every thing is cracked, calcined, or triturated. While in Bolivia the Eastern Cordillera shows a succession of sharp, ragged peaks, in contrast with the conical summits of the Cordillera of the coast, there is no such distinction in the Andes of the equator.[61] The Eastern Cordillera has a greater mean height, and it displays more volcanic activity. Twenty volcanic mountains surround the valley, of which twelve are in the oriental chain. Three of the twenty are now active (Cotopaxi, Sangai, and Pichincha), and five others are known to have erupted since the Conquest (Chiles, Imbabura, Guamani, Tunguragua, and Quirotoa). The truncated cone of Cotopaxi, the jagged, Alpine crest of ruined Altar, and the dome of Chimborazo, are the representative forms of the volcanic summits. The extinct volcanoes usually have double domes or peaks, while the active peaks are slender cones. Antisana and Cayambi are fashioned after Chimborazo, though the latter is table-topped rather than convex; Caraguairazo, Quirotoa, Iliniza, Sincholagua, Rumiñagui, and Corazon, resemble Altar; Tunguragua, Sangai, Llanganati, Cotocachí, Chiles, and Imbabura, imitate Cotopaxi; Pichincha, Atacatzo, and Guamani are irregular. The Ecuadorian volcanoes have rarely ejected liquid lava, but chiefly water, mud, ashes, and fragments of trachyte and porphyry. Cotopaxi alone produces pure, foam-like pumice, and glossy, translucent obsidian.[62] The paucity of quartz, and the absence of basalt, are remarkable. Some of the porphyroids are conglomerate, but the majority are true porphyries, having a homogeneous base. Dr. T. Sterry Hunt calls them porphyroid trachytes. They have a black, rarely reddish, vitreous, or impalpable base, approaching obsidian, with a specific gravity of 2.59 in pure specimens, and holding crystals or crystalline grains of glassy feldspar, and sometimes of pyroxene and hematite. They differ from the Old World porphyries in containing no quartz, and seldom mica.[63] D'Orbigny considers the porphyries of the Andes to have been ejected at the close of the cretaceous period, and formed the first relief of the Cordillera. The prevalence of trachyte shows that the products have cooled under feeble pressure.

[Footnote 60: "As a general rule, whenever the mass of mountains rises much above the limit of perpetual snow, the primitive rocks disappear, and the summits are trachyte or trappean porphyry."--_Humboldt_. In general, "the great Cordilleras are formed of innumerable varieties of granites, gneiss, schists, hornblende, chloritic slates, porphyries, etc., and these rocks alternate with each other in meridional bands, which in the ridges frequently present the appearance of a radiated or fan-shaped structure, and under the plains are more or less vertical."--_Evan Hopkins, F.G.S_.]

[Footnote 61: Von Tschudi makes the incorrect statement that "throughout the whole extent of South America there is not a single instance of the Western Cordillera being intersected by a river." Witness the Esmeraldas.]

[Footnote 62: It is a singular fact that true trachyte, pumice, and obsidian are wanting in the volcanic Galápagos Islands, only 700 miles west of Pichincha.]

[Footnote 63: As many of the crystals are partly fused, or have round angles, the porphyries were probably formed by the melting of a crystalline rock, the base becoming fused into a homogeneous material, while the less fusible crystals remain imbedded.--_Dr. Hunt_.]

From the deluges of water lately thrown out have resulted deep furrows in the sides; and from the prevalence of the east wind, which is always met by the traveler on the crest of either Cordillera, there is a greater accumulation of ashes, and less snow on the west slope. Cotopaxi is a fine example of this. In Pichincha, Altar, and Rumiñagua, however, the western wall is lowest, apparently broken down.[64] There is no synchronism in the eruptions of Cotopaxi and Pichincha. These volcanoes must have independent reservoirs, for the former is 3000 feet higher than the latter, and only thirty miles distant. The reputed eruptions of Pichincha are dated 1534, 1539, 1566, 1575, 1588, and 1660; that of 1534 resting on the assertions of Checa, Garcilazo, and Herrera, indorsed by Humboldt. Excepting the traditional eruption in 1534, which probably is confounded with that of Pichincha, Cotopaxi did not open till 1742; then followed the eruptions of 1743, 1744, 1746, 1766, 1768, 1803, 1851, and 1855. We must mention, however, that, since the recent awakening of Pichincha, Cotopaxi has been unusually silent. There is also a remarkable coincidence (which may not be wholly accidental) in the renewed activity of Pichincha, and the great eruption of Mauna Loa, both occurring in March, 1868. It is generally believed by the natives that Cotopaxi and Tunguragua are sympathetic.

[Footnote 64: In the Galápagos volcanoes the south wall is lowest, while the craters in Mexico and Sandwich Islands are lowest on the northeast.]

There are fifty-one volcanoes in the Andean chain. Of these, twenty girdle the Valley of Quito, three active, five dormant, and twelve extinct.[65] Besides these are numerous mountain peaks not properly volcanic. Nowhere on the face of the earth is there such a grand assemblage of mountains. Twenty-two summits are covered with perpetual snow, and fifty are over ten thousand feet high.[66]

[Footnote 65: The altitudes of the most important Ecuadorian volcanoes are:

WESTERN CHAIN. _Chimborazo_, 21,420 feet (Humboldt). _Caraguairazo_, 19,183 feet (Humboldt). It is variously estimated from 15,673 feet to 19,720 feet; 18,000 feet is not far from the truth. _Iliniza_, 17,370 feet (Wisse); 16,300 (Hall). _Cotocachí_, 16,440 feet (Humboldt); 16,409 (Wisse). _Pichincha_, 15,922 feet (Humboldt); 15,827 (Orton).

EASTERN CHAIN. _Cayambi_, 19,648 feet (Humboldt); 19,358 (Wisse). _Antisana_, 19,148 feet (Humboldt); 19,279 (Wisse). _Cotopaxi_, 18,880 feet (Humboldt); 18,862 (Wisse). _Altar_, 17,400 feet. _Sangai_, 17,120 feet (Wisse). _Tunguragua_, 16,579 feet (Humboldt). _Sincholagua_, 16,434 feet (Humboldt).

]

[Footnote 66: The snow limit at the equator is 15,800 feet. No living creature, save the condor, passes this limit; naked rocks, fogs, and eternal snows mark the reign of uninterrupted solitude. The following is the approximate limit of perpetual snow in different latitudes:

0° 15,800 feet. 27° 18,800 " 33° 12,780 " 40° 8,300 feet. 54° 3,700 " 70° 3,300 "

The limit appears to descend more rapidly going south of the equator than in going north.]

All of these would be visible from a single stand-point--the summit of Cotopaxi. The lofty peaks shoot up with so much method as almost to provoke the theory that the Incas, in the zenith of their power, planted them as signal monuments along the royal road to Cuzco. The eastern series is called the _Cordillera real_, because along its flank are the remnants of the splendid highway which once connected Quito and the Peruvian capital.[67] It can also boast of such tremendous volcanoes as Cotopaxi and Sangai. The Western Cordillera contains but one active volcano; but then it can point to peerless Chimborazo and the deep crater of Pichincha. These twenty volcanic mountains rise within a space only two hundred miles long and thirty miles wide. It makes one tremble to think of the awful crevice over which they are placed.[68]

[Footnote 67: We traveled over a portion of this ancient road in going from Riobamba to Cajabamba. It is well paved with cut blocks of dark porphyry. It is not graded, but partakes of the irregularity of the country. Designed, not for carriages, but for troops and llamas, there are steps when the ascent is steep.]

[Footnote 68: Grand as the Andes are, how insignificant in a general view! How slightly they cause our globe to differ from a perfect sphere! Cotopaxi constitutes only 1/1100 of the earth's radius; and on a globe six feet in diameter, Chimborazo would be represented by a grain of sand less than 1/20 of an inch in thickness.]