RUDOLF (otherwise known as Basso Norok and Gallop), a large lake of E. equatorial Africa, forming the centre of an inland drainage system, occupying the S. of the Abyssinian highlands and a portion of the great equatorial plateau. The lake itself lies towards the N. of the great East African rift valley, between the parallels of 2° 26′ and 5° N., while the meridian of 36° E. is slightly W. of the centre of the northern wider part, the narrower southern portion bending to 3612° E. The length along the curved axis is 185 m., the maximum width 37, and the area roughly 3500 sq. m. Its altitude is 1250 ft. Towards the S. it seems to be deep, but it is comparatively shallow in the N. Its water is brackish, but drinkable. The country bordering the lake on almost every side is sterile and forbidding. The S. end, for some 50 m. on the W. and for a longer distance on the E., is shut in by high cliffs—the escarpments of a rugged lava-strewn country, which shows abundant signs of volcanic activity, great changes having been reported since 1889. In particular, the great volcano of Lubburua (Teleki’s volcano) at the S. end of the lake is said to have been destroyed between 1889 and 1897 by a sudden explosion. The highest point of the S.E. side of the lake is Mount Kulal, 7812 ft., while the culminating height within the basin of the lake is Mount Sil, 9280 ft., which lies about 20 m. S. of Lubburua. Further N., on the W. side, sandy plains alternate with lines of low hills, the immediate shores (on which the water appears to have encroached in very modern times) being marked by spits of sand, which in places cut off lagoons from the main body of the lake. These are the haunt of great numbers of water-birds. In 3° 8′ N. the dry bed of the Turkwell—in its upper course a large river descending the slopes of Mount Elgon—approaches the lake. Near the N. end mountains again approach the shores, the most prominent being Mount Lubbur (5200 ft.), an extinct Volcano with a well-preserved crater. At the extreme N.W. corner a bay some 35 m, long (Sanderson Gulf) is almost separated from the rest of the lake by two long points of land. On the E. side, open arid plains, with few trees, occupy most of the N. country. One hill, in 3° 20′ N., has a height of 3470 ft., and at the N.E. end, separating the lake from Lake Stefanie, is a hilly country, the highest point between the lakes being 3524 ft. Immediately N. of these hills rises the Hummurr Range, with one peak exceeding 7000 ft. Near the S. end is the volcanic island of Elmolo, 10 m. long, and there are a few small islets. Just N. of 4° N. is a small volcanic island with highest point 2100 ft. At the N. end of the lake a level swampy plain is traversed by various arms of the lake and by the Nianam river. This river has been shown to be identical with the Omo, the course of which »was long one of the most debated questions of African geography. Its northernmost feeders rise on the high plateau S. of the Blue Nile, in 9° 10′ N., and being swollen by other streams from the E. and W., soon form a large river. During its lower course it makes two considerable bends to the W. before finally entering the lake as a deep stream a quarter of a mile wide. Lake Rudolf (previously known on the east coast by report) was discovered in 1888 by Count Samuel Teleki and Lieutenant Ludwig von Hohnel. It was subsequently visited by Dr Donaldson Smith, Vittorio Bottego, H. S. H. Cavendish, H. H. Austin, and others, and by 1905 its shores and the neighbouring country had become fairly well known. In 1907, by an agreement between the powers concerned, the N.E. end of the lake, into which the Omo debouches, was assigned to Abyssinia, the rest of the lake to Great Britain.
Authorities.—Geographical Journal (September 1896, April 1898, August 1899, May 1904; the last-named issue contains a map by Captain P. Maud, R.E.); Ludwig von Höhnel, Discovery of Lakes Rudolf and Stefanie (London, 139); A. Donaldson Smith, Through Unknown African Countries (London, 1897); A. H. Neumann, Elephant-Hunting in East Equatorial Africa (London, 1898); L. Vannutelli and C. Citerni, L’Omo (Milan, 1899); M. S. Wellby, ’Twixt Sirdar and Menelik (London, 1901); H. H. Austin, Among Swamps and Giants in Equatorial Africa (1902); C. H. Stigand, To Abyssinia through an Unknown Land (1910). (E. He.)