MFUMBIRO or KIRUNGA, general names for a chain of volcanic mountains extending across the central African rif t valley immediately north of Lake Kivu. The range completely blocks the valley at this point, forming a divide between the rivers flowing north to the Nile and the waters of Lake Kivu, connected through Tanganyika with the Congo system. The chain consists of two groups of mountains, surrounded by a vast lava field. The lavas belong to a nephelinite suite with leucite and melilite as frequent minerals. The western group lies directly north of Lake Kivu, and contains two active volcanoes, Kirunga cha-gongo, the nearest to the lake (11,194 ft.), and Kirunga namlagira (9,711 ft.), so m. farther north. The eastern group contains several higher peaks, Karissimbi (14,683 ft.), Mikeno (14,385 ft.) and Muhavuru (13,562 ft.). The latter is the moun tain to which the names Mfumbiro and Kirunga were originally applied and its crater contains a lake. Some 6 m. W. of Muha vuru is Sabyino (Sabinjo), 11,881 ft. high. The eastern peaks are snowclad for a part of the year. North of these high moun tains is a district, extending towards Lake Albert, containing hundreds of low peaks and extinct volcanoes. It is to this region
that the name Umfumbira or Mfumbiro is said properly to belong.
Mfumbiro, i.e., Muhavuru, was first seen by a white man in 1861, J. H. Speke obtaining a distant view of the cone, which was also seen by H. M. Stanley in 1876. Its true position was first ascertained by Franz Stuhlmann in 1891. In 1894 Count von Gotzen travelled through the region which was subsequently explored by E. S. Grogan, Maj. St. Hill Gibbons, Capt. Herrmann, Dr. R. Kandt, Sir Alfred Sharp (1912) and others, the chief heights being determined in 1903. In 1907-08 the range was geologically and topographically examined by the duke of Meck lenberg's expedition. By the Anglo-German agreement of the 1st of July 1890 "Mount Mfumbiro" was included in the British sphere in East Africa.