volcanic upland in west-central Africa. Though the plateau is chiefly in north-central Cameroon, the part of it known as the Gotel Mountains is in southeastern Nigeria. The plateau is the source of the Benue River. Its highest elevations are more than 8,700 feet (2,650 metres) above sea level. Many craters and small lakes attest to the region's volcanic origin. Vegetation is chiefly savanna, with some tropical woodlands. The economy is based on pastoralism with subsistence agriculture, and there are also some cattle ranches. Some tin deposits are exploited. Exploitation of bauxite deposits began in 1976–77. The region is named for Modibbo Adama (died 1847/48), the founder of a Fulani emirate, which was an offshoot of the Sokoto caliphate in Nigeria (see Sokoto).