[CHAPTER VII.]
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]
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.
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.
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.