Название | A Book of the United States |
---|---|
Автор произведения | Various |
Жанр | Документальная литература |
Серия | |
Издательство | Документальная литература |
Год выпуска | 0 |
isbn | 4064066246792 |
GENERAL REMARKS ON RIVERS.
The beds of rivers are the lowest parts of great chasms, formed by the same revolutions which produced the mountains. Running waters unceasingly wear away their beds and banks in places where their declivity is very rapid; they hollow out and deepen their channels in mountains composed of rocks of moderate hardness; they draw along stones, and form accumulations of them in the lower part of their course; and thus their beds are often gradually elevated in the plains, while they are deepened and depressed in the mountains. But these changes, though continually going on for thousands of years, could only give form to the banks of rivers; they in no wise created the banks themselves. Many great rivers flow with an almost imperceptible declivity. The river of the Amazons has only ten feet and a half declivity upon two hundred leagues of its course, making one twenty-seventh of an inch for every thousand feet. When a river is obstructed in its course by a bank of solid rocks, and finds beneath them a stratum of softer materials, its waters wear away the softer substance, and thus open for themselves a subterraneous passage, more or less long. Such are the causes which have formed the magnificent Rock Bridge in Virginia, an astonishing vault uniting two mountains, separated by a ravine two hundred and seventy feet in depth, in which the Cedar Creek flows. In Louisiana, trees, or rather whole forests, have been observed to fall on a river, covering it nearly with vegetable earth; and thus giving rise to a natural bridge which for leagues has hid the course of the river.
Rivers in running into the sea present a great variety of interesting phenomena; many form sand-banks, as the Senegal and the Nile; others, like the Danube, run with such force into the sea, that one can for a certain space distinguish the waters of the river from those of the sea. The waters of the little river Syre in Norway are discernable for a considerable distance in the sea. It is only by a very large mouth, like that of the Loire, the Elbe, or the Plata, that a river can peacefully mingle with the sea. Rivers even of this nature, however, sometimes experience the superior influence of the sea, which repels the waters into their bed. Thus the Seine forms at its mouth a bar of considerable extent; and the Garonne, unable to discharge with sufficient rapidity the waters which it accumulates in a kind of gulf between Bordeaux and its mouth, exhibits this aquatic mountain, stopped by the flow of the tide rolling backwards, inundating the banks, and stopping vessels in their progress both up and down. This phenomenon, termed the Mascaret, is only the collision of two bodies of water moving in opposite directions. The most sublime phenomenon of this kind which presents itself is that of the giant of rivers Orellana, called the river of the Amazons. Twice a day it pours out its imprisoned waves into the bosom of the ocean. A liquid mountain is thus raised to the height of one hundred and eighty feet; it frequently meets the flowing tide of the sea, and the shock of these two bodies of water is so dreadful that it makes all the neighboring islands tremble; the fishermen and navigators fly from it in the utmost terror. The next day, or the second day after every new or full moon, the time when the tides are highest, the river also seems to redouble its power and energy; its waters and those of the ocean rush against each other like the onset of two armies. The banks are inundated with their foaming waves; the rocks drawn along like light vessels, dash against each other, almost upon the surface of the water which bears them on. Loud roarings echo from island to island. It has been said that the Genius of the River and the God of the Ocean contended in battle for the empire of the waves. The Indians call this phenomenon Pororoca.
COMPARATIVE VIEW OF THE RIVERS OF THE WORLD. | |
NORTH AMERICA. | |
---|---|
Names. | Length. |
Missouri | 4,400 |
Mississippi | 3,000 |
Arkansas | 2,100 |
St. Lawrence | 2,000 |
Mackenzie | 2,000 |
Del Norte | 2,000 |
Nelson | 1,500 |
Columbia | 1,500 |
Red River | 1,500 |
Platte | 1,500 |
Ohio | 1,350 |
Kansas | 1,200 |
White River | 1,200 |
Tennessee | 1,100 |
Alabama | 650 |
Savannah | 600 |
Potomac | 550 |
Connecticut | 410 |
Hudson | 324 |
Delaware | 300 |
SOUTH AMERICA. | |
Maranon | 4,500 |
La Plata | 3,000 |
Madeira | 2,500 |
Orinoco | 1,800 |
Tocantins | 1,800 |
Ucayale | 1,600 |
St. Francisco | 1,500 |
Paraguay | 1,400 |
Xingu | 1,400 |
Topajos | 1,300 |
EUROPE. | |
Volga | 2,040 |
Danube | 1,710 |
|