Inland by a line of cliffs, the Susu Hills, which form the first step in the terrace-like formation of the interior, culminating in the massif of Futa Jallon, composed chiefly of Archean and granite rocks.
Gum-producing and kola trees are abundant, and there are many fruit trees, the orange and citron growing well in the Susu and Futa Jallon districts.
Fish are abundant, one large-headed species, in the Susu tongue called khokon, is so numerous as to have given its name to a province, Kokunia.
The other tribes named are but sparsely represented in French Guinea, the coast region south of the Nunez and all the interior up to Futa Jallon being occupied by the Susu, a tribe belonging to the great Mandingan race, which forced its way seaward about the beginning of the 18th century and pressed back the Timni into Sierra Leone.
The Mandingo, the Fula and the Susu are Mahommedans, though the Susu retain many of their ancient rites and beliefs - those associated with spirit worship and fetish, still the religion of the Baga and other tribes.
Sierra Leone is inhabited by various ethnic groups, the chief being the Timni, the Sulima, the Susu and the Mendi.
Beside these there is another group of largely freshwater species, constituting the family Platanistidae, and typified by the susu (Platanista gangetica), extensively distributed throughout nearly the whole of the river-systems of the Ganges, Brahmaputra and Indus, ascending as high as there is water enough to swim in, but never passing out to sea.
The susu (Platanista) is, for instance, extensively distributed throughout nearly the whole of the river systems of the Ganges, Brahmaputra and Indus, ascending as high as there is water enough to swim in, but apparently never passing out to sea.