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 Lucerne and 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.