Below the worst rapids the Pongo exhibits a swift succession of natural wonders. Fern-clad cliffs border it, a bush resembling the juniper reaches its dainty finger-like stems far out over the river, and the banks are heavily clad with mosses. The great woods, silent, impenetrable, mantle the high slopes and stretch up to the limits of vision. Cascades tumble from the cliff summits or go rippling down the long inclines of the slate beds set almost on edge. Finally appear the white pinnacles of limestone that hem in the narrow lower entrance or outlet of the Pongo. Beyond this passage one suddenly comes out upon the edge of a rolling forest-clad region, the rubber territory, the country of the great woods. Here the Andean realm ends and Amazonia begins.
From the summits of the white cliffs 4,000 feet above the river we were in a few days to have one of the most extensive views in South America. The break between the Andean Cordillera and the hill-dotted plains of the lower Urubamba valley is almost as sharp as a shoreline. The rolling plains are covered with leagues upon leagues of dense, shadowy, fever-haunted jungle. The great river winds through in a series of splendid meanders, and with so broad a channel as to make it visible almost to the horizon. Down river from our lookout one can reach ocean steamers at Iquitos with less than two weeks of travel. It is three weeks to the Pacific via Cuzco and more than a month if one takes the route across the high bleak lava-covered country which we were soon to cross on our way to the coast at Camaná.
CHAPTER III
THE RUBBER FORESTS
THE white limestone cliffs at Pongo de Mainique are a boundary between two great geographic provinces ([Fig. 17]). Down valley are the vast river plains, drained by broad meandering rivers; up valley are the rugged spurs of the eastern Andes and their encanyoned streams ([Fig. 18]). There are outliers of the Andes still farther toward the northeast where hangs the inevitable haze of the tropical horizon, but the country beyond them differs in no important respect from that immediately below the Pongo.
Fig. 17—Regional diagram of the Eastern Andes (here the Cordillera Vilcapampa) and the adjacent tropical plains. For an explanation of the method of construction and the symbolism of the diagram see [p. 51].
The foot-path to the summit of the cliffs is too narrow and steep for even the most agile mules. It is simply impassable for animals without hands. In places the packs are lowered by ropes over steep ledges and men must scramble down from one projecting root or swinging vine to another. In the breathless jungle it is a wearing task to pack in all supplies for the station below the Pongo and to carry out the season’s rubber. Recently however the ancient track has been replaced by a road that was cut with great labor, and by much blasting, across the mountain barrier, and at last mule transport has taken the place of the Indian.