FIRST: Showing the comparative length of the rivers; where and how they take their rise; where and how they empty; their chief branches and connected lakes; and the principal cities located on their banks.SECOND: Comparative height of mountains, arranged in groups by continents, showing the relative height of both mountains and continents. Seenext pagefor LOCATION and HEIGHT IN FEET of the various mountain peaks.
FIRST: Showing the comparative length of the rivers; where and how they take their rise; where and how they empty; their chief branches and connected lakes; and the principal cities located on their banks.
SECOND: Comparative height of mountains, arranged in groups by continents, showing the relative height of both mountains and continents. Seenext pagefor LOCATION and HEIGHT IN FEET of the various mountain peaks.
Large illustrations:Rivers (left-hand side)(480 kB)Rivers (right-hand side)(137 kB)Moutains (left-hand side)(187 kB)Moutains (right-hand side)(554 kB)
Most rivers are subject to an occasional, and in some instances to a periodical increase of volume. These seasons of flood are by no means regular, being partly dependent on the melting of the snows, and partly on occasional heavy falls of rain; and hence depend on the climatic variations of the country in which rivers originate.
FAMOUS MOUNTAIN AND OTHER ELEVATIONS OF THE WORLD
Note: The numbers refer back to the Picture Diagrams on thepreceding page.
Lakes are of different kinds. Some are mere tanks which receive the first outpourings of springs, others consist of basins or reservoirs which occur in the line of a river’s course; some consist of basins or cavities, into which rivers flow, but which, on account of their depression or their mountainous cincture have no outlets; lakes are also formed in the craters of extinct volcanoes; and some lakes are periodic, or subject to have their basins alternately empty and full of water.
Mountain Lakes, which are valleys or chasms filled by streams, are long and narrow, rarely of extensive area, but often of great depth. Examples of this class are found in Lakes Champlain and George, among the Appalachian Mountains; Lakes Constance and Geneva, on the northern side of the Alps; and Lake Maggiore and Lake Como, on the south side; all of which are renowned for the loveliness of their shores, or the grandeur of the surrounding mountain scenery.
Lake Maggiore, which is hardly three miles wide, is, according to Italian engineers, 2,623 feet deep—more than double the depth of Lake Superior—its basin reaching 1,936 feet below the sea level.
The forms of mountain lakes are very irregular, for the water often covers several contiguous and connected valleys. This is the case in Lake Como, which has two long arms; and Lakes Lucerneand Lugano, each of which fills four distinct valleys, meeting one another nearly at right angles.
Lakes in Plains.The lake basins in plains and plateaus are, usually, simple depressions in a comparatively uniform surface. The lakes are, therefore, often of great size, broad in proportion to their length, but of little depth compared with their area.
The largest lakes of the globe—the Caspian and Aral seas, and the great North American and African lakes—and the largest in Europe and South America, all belong to this class. Their vast expanse, together with the tameness of their shores, deprives them of the picturesque beauty of mountain lakes.
Characteristics of Salt Lakes.Numerous lakes in the interior of the continents, though receiving affluents, have no outlet. Their waters are chiefly lost by evaporation, though some portion may be absorbed by the sandy soil.
The surfaces of the continents having been the beds of the primeval oceans, the presence of salt in the soil is a natural consequence.
Famous Salt Lakes.The Great Salt Lake of Utah, in the Great American Basin, is one of the finest examples of its class. The Caspian and Aral seas, at the bottom of the vast depression between Europe and Asia, are the most extensive salt lakes. The former has about four times the area of Lake Superior; and the latter is a little larger than Lake Michigan.
The Caspian, though receiving the Volga, the largest river of Europe, evaporates so much water that its surface is about 83 feet lower than that of the Mediterranean, varying with the seasons. Many lakes in its neighborhood disappear entirely in the heat and drought of summer, leaving their beds covered with a crust of pure white crystalline salt.
The Remarkable Dead Sea, in Syria, is a lake in which the salt has accumulated until the water is converted into a heavy brine. It may be the remnant of an ancient sea of much greater extent, which has been gradually reduced in size by the excess of evaporation over the supply of water in its basin.
This celebrated body of water lies in the deepest part of a long chasm or valley, which is sunk not less than 4,000 feet below the level of the surrounding country. The surface of the lake is 1,286 feet, and its bottom 2,500 feet, below the level of the Mediterranean.
Its feeder, the river Jordan, flows almost throughout its entire course below the level of the sea, the only known instance of the kind. The beautiful lake of Tiberias, the scene of so many of the miracles of Jesus, which is but an expansion of the Jordan in its upper course, is about 650 feet below the surface of the Mediterranean.
Lakes are most numerous in the central and northern portions of Asia, Europe and North America. The southern continents, except Africa, have comparatively few.
Asiais pre-eminently the continent of salt lakes. They occur in countless numbers, both in the steppes north of the Caspian and Aral, and in all the interior plateaus. Lakes of fresh water are also found among the Altai Mountains and adjacent chains. Lake Baikal, one of these, is the largest mountain lake known, being nearly 500 miles long.
Europe.The most characteristic and celebrated lakes are those which adorn the Alps of Switzerland and Scandinavia, and the less lofty mountain chains of the British Isles. But the largest lakes are found in the low lands and slight swells which surround the Baltic Sea, in western Russia and Sweden. Lakes Ladoga and Onega in Russia, and Wener and Wetter in Sweden, are the largest in Europe.
North Americais peculiarly rich in great lakes. No continent presents a more remarkable series than that which stretches from northwest to southeast, through the central plains, along the line of contact of the oldest geological formations of the continent. This series includes Great Bear and Great Slave lakes, Athabasca and Winnipeg, and the five great lakes of the St. Lawrence, with many of less area.
Innumerable small lakes are scattered throughout the middle portions of the central plain, and the northern and less regular part of the Appalachian mountain region; but south of the parallel of Lake Erie there is an almost entire absence of lakes, whether large or small.