BASIN is a geographical term which is used in such expressions as the basin of a sea, the basin of a lake, the basin of a river ; and it includes all the countries drained by the waters that run into such sea, lake, or river.
If the basin of a sea runs far inland, and comprehends a great extent of country, it commonly contains large and fertile plains, maintains a numerous population, and at some period of history civilization has made considerable progress within its limits. Thus the basin of the Bay of Bengal comprehends countries not much less than half of Europe in extent. Accordingly we find, not only that it is, and ever has been, much frequented by vessels, but also that at a very early period civilization made considerable progress, and that at all times the arts of peace have been greatly cultivated within the limits of this basin.
On the other hand, if the basin of a sea is of small extent, the surrounding country is poor, its inhabitants backward in civilization, and its ports only occasionally resorted to by vessels. Such is the case with the Arabian Gulf, of which the basin commonly coincides with its shores, and in no place probably ex tends more than twenty miles inland.
The basins of lakes offer likewise several varieties. Those which are commonly called mountain-lakes, but with more propriety valley lakes, have in general a very narrow basin, being inclosed on all sides by mountains. Many of them receive a river at one extremity, in which case their basin runs up such river to its source. The lakes of plains have in general a much larger basin, as they receive the drainage of a more extensive country, as the lakes of North America, and those of Russia.
In its geological sense, a basin indicates a depression or concavity of strata. Thus, the tertiary basins of London, Hampshire, and Paris, resting on chalk ; the coal.basin of South Wales, resting on old red sandstone ; and, in a larger sense, the European basins between the Ural, the Scandinavian chains, and the Pyrenees, Alps, &c. Some of these basins are due to the original circumstances of deposition, others have acquired their con figuration from elevations and depressions of particular geographical areas.