VOLTA, the largest river of the coast of Upper Guinea, be tween the Gambia and the Niger, with a length of about goo m. Its mouth and the greater part of its course are in British territory. Its lower course had been known since the discoveries of the Portuguese, from whom it received (15th century) its name on account of the winding nature of its stream. It was not, however, until the last fifteen years of the 19th century that the extent of its basin—extending far north within the bend of the Niger— was made known.
There are two main upper branches, the Black and the White Volta. Their sources lie on the grassy plateaux north of the forest belt of the Guinea coast, the Black Volta rising (as the Baule) in about I I° N., 4° 5o' W. Its course is at first east and north east, to I 2° 25' N., at which point, after receiving a tributary from nearly 14° N.—the most northerly point of the basin—it turns sharply south. From the eleventh to the ninth parallel the river forms the boundary between the Northern Territories of the Gold Coast (British) and the French Ivory Coast colony. The southerly course of the stream ceases at 8° 15' N. where it is deflected east, and even north, by a mountain range composed of sandstone and granite, which it finally breaks through by a nar row pass, in which its width is only some 6o yards. Elsewhere
it has a general width of 150 to 200 yards. In 0° so' W. it re ceives the White Volta, which flows generally south from about 13° N. and likewise breaks through a narrow gap in the plateau es carpment. Both rivers shrink greatly in the dry season, reaching their lowest level at the end of January. Below the junction the Volta flows south-east and south, but turns east for 4o m. just north of 6°. In 7° 37' N. it receives on the left bank a large tributary, the Oti, coming from 12° N. In its lower course, through the forest belt, the river has often a width of over half a mile, with a depth in places of 4o to 5o f t. in the rains, but in 6° 18' N. it traverses a pass in which its width is narrowed to 3o yards. Its use as a water-way is limited by a number of rapids, the low est of which occur in 6° 7' N., above the trading port of Akuse. Its mouth is also obstructed during the greater part of the year by a bar. The river is usually navigable by small vessels from its mouth for about 6o miles.