The coast rivers flowing into the Atlantic cross four terraces. On the higher portion of the plateau their course is over bare sand; on the second terrace, from 1200 to 2000 ft. high, it is over wide grassy tracts; then, for some 100 m., the rivers pass through virgin forest, and, lastly, they cross the shore region, which is about 10 m. broad. The rivers which fall directly into the Atlantic are generally unnavigable. The most important, the Ogowé (q.v.), is, however, navigable from its mouth to N’Jole, a distance of 235 m. Rivers to the south of the Ogowé are the Nyanga, 120 m. long, and the Kwilu. The latter, 320 m. in length, is formed by the Kiasi and the Luété; it has a very winding course, flowing by turns from north to south, from east to west, from south to north-west and from north to south-west. It is encumbered with rocks and eddies, and is navigable only over 38 m., and for five months in the year. The mouth is 1100 ft. wide. The Muni river, the northernmost in the colony, is obstructed by cataracts in its passage through the escarpment to the coast.
Nearly all the upper basin of the Shari (q.v.) as well as the right bank of the lower river is within French Congo. The greater part of the country belongs, however, to the drainage area of the Congo river. In addition to the northern banks of the Mbomu and Ubangi, 330 m. of the north shore of the Congo itself are in the French protectorate as well as numerous subsidiary streams. For some 100 m. however, the right bank of the Sanga, the most important of these subsidiary streams, is in German territory (see [Congo]).
Geology.—Three main divisions are recognized in the French Congo:—(1) the littoral zone, covered with alluvium and superficial deposits and underlain by Tertiary and Cretaceous rocks; (2) the mountain zone of the Crystal Mountains, composed of granite, metamorphic and ancient sediments; (3) the plateau of the northern portion of the Congo basin, occupied by Karroo sandstones. The core of the Crystal Mountains consists of granite and schists. Infolded with them, and on the flanks, are three rock systems ascribed to the Silurian, Devonian and Carboniferous. These are unfossiliferous, but fossils of Devonian age occur on the Congo (see [Congo Free State]). Granite covers wide areas north-west of the Crystal Mountains. The plateau sandstones lie horizontally and consist of a lower red sandstone group and an upper white sandstone group. They have not yielded fossils. Limestones of Lower Cretaceous age, with Schloenbachia inflata, occur north of the Gabun and in the Ogowé basin. Marls and limestones with fossils of an Eocene facies overlie the Cretaceous rocks on the Gabun. A superficial iron-cemented sand, erroneously termed laterite, covers large areas in the littoral zone, on the flanks of the mountains and on the high plateau.
Climate.—The whole of the country being in the equatorial region, the climate is everywhere very hot and dangerous for Europeans. On the coast four seasons are distinguished: the dry season (15th of May to 15th of September), the rainy season (15th of September to 15th of January), then a second dry season (15th of January to 1st of March), and a second rainy season (1st of March to 15th of May). The rainfall at Libreville is about 96 in. a year.
Flora and Fauna.—The elephant, the hippopotamus, the crocodile and several kinds of apes—including the chimpanzee and the rare gorilla—are the most noteworthy larger animals; the birds are various and beautiful—grey parrots, shrikes, fly-catchers, rhinoceros birds, weaver birds (often in large colonies on the palm-trees), ice-birds, from the Cecyle Sharpii to the dwarfish Alcedo cristata, butterfly finches, and helmet-birds (Turacus giganteus), as well as more familiar types. Snakes are extremely common. The curious climbing-fish, which frequents the mangroves, the Protopterus or lung-fish, which lies in the mud in a state of lethargy during the dry season, the strange and poisonous Tetrodon guttifer, and the herring-like Pellona africana, often caught in great shoals—are the more remarkable of the fishes. Oysters are got in abundance from the lagoons, and the huge Cardisoma armatum or heart-crab is fattened for table. Fireflies, mosquitoes and sandflies are among the most familiar forms of insect life. A kind of ant builds very striking bent-house or umbrella-shaped nests rising on the tree trunks one above the other.
Among the more characteristic forms of vegetation are baobabs, silk-cotton trees, screw-pines and palms—especially Hyphaene guineensis (a fan-palm), Raphia (the wine-palm), and Elaeis guineensis (the oil-palm). Anonaceous plants (notably Anona senegalensis), and the pallabanda, an olive-myrtle-like tree, are common in the prairies; the papyrus shoots up to a height of 20 ft. along the rivers; the banks are fringed by the cottony Hibiscus tiliaceus, ipomaeas and fragrant jasmines; and the thickets are bound together in one inextricable mass by lianas of many kinds. In the upper Shari region, and that of the Kotto tributary of the Ubangi, are species of the coffee tree, one species attaining a height of over 60 ft. Its bean resembles that of Abyssinian coffee of medium quality. Among the fruit trees are the mango and the papaw, the orange and the lemon. Negro-pepper (a variety of capsicum) and ginger grow wild.
Inhabitants and Chief Towns.—A census, necessarily imperfect, taken in 1906 showed a total population, exclusive of Wadai, of 3,652,000, divided in districts as follows:—Gabun, 376,000; Middle Congo, 259,000; Ubangi-Shari, 2,130,000; Chad, 885,000. The country is peopled by diverse negro races, and, in the regions bordering Lake Chad and in Wadai, by Fula, Hausa, Arabs and semi-Arab tribes. Among the best-known tribes living in French Congo are the Fang (Fans), the Bakalai, the Batekes and the Zandeh or Niam-Niam. Several of the tribes are cannibals and among many of them the fetish worship characteristic of the West African negroes prevails. Their civilization is of a low order. In the northern regions the majority of the inhabitants are Mahommedans, and it is only in those districts that organized and powerful states exist. Elsewhere the authority of a chief or “king” extends, ordinarily, little beyond the village in which he lives. (An account of the chief tribes is given under their names.) The European inhabitants are chiefly of French nationality, and are for the most part traders, officials and missionaries.
The chief towns are Libreville (capital of the Gabun colony) with 3000 inhabitants; Brazzaville, on the Congo on the north side of Stanley Pool (opposite the Belgian capital of Leopoldville), the seat of the governor-general; Franceville, on the upper Ogowé; Loango, an important seaport in 4° 39′ S.; N’Jole, a busy trading centre on the lower Ogowé; Chekna, capital of Bagirmi, which forms part of the Chad territory; Abeshr, the capital of Wadai, Bangi on the Ubangi river, the administrative capital of the Ubangi-Shari-Chad colony. Kunde, Lame and Binder are native trading centres near the Cameroon frontier.
Communications.—The rivers are the chief means of internal communication. Access to the greater part of the colony is obtained by ocean steamers to Matadi on the lower Congo, and thence round the falls by the Congo railway to Stanley Pool. From Brazzaville on Stanley Pool there is 680 m. of uninterrupted steam navigation N.E. into the heart of Africa, 330 m. being on the Congo and 350 m. on the Ubangi. The farthest point reached is Zongo, where rapids block the river, but beyond that port there are several navigable stretches of the Ubangi, and for small vessels access to the Nile is possible by means of the Bahr-el-Ghazal tributaries. The Sanga, which joins the Congo, 270 m. above Brazzaville, can be navigated by steamers for 350 m., i.e. up to and beyond the S.E. frontier of the German colony of Cameroon. The Shari is also navigable for a considerable distance and by means of its affluent, the Logone, connects with the Benue and Niger, affording a waterway between the Gulf of Guinea and Lake Chad. Stores for government posts in the Chad territory are forwarded by this route. There is, however, no connecting link between the coast rivers—Gabun, Ogowé and Kwilu and the Congo system. A railway, about 500 m. long, from the Gabun to the Sanga is projected and the surveys for the purpose made. Another route surveyed for a railway is that from Loango to Brazzaville. A narrow-gauge line, 75 m. long, from Brazzaville to Mindule in the cataracts region was begun in November 1908, the first railway to be built in French Congo. The district served by the line is rich in copper and other minerals. From Wadai a caravan route across the Sahara leads to Bengazi on the shores of the Mediterranean. Telegraph lines connect Loango with Brazzaville and Libreville, there is telegraphic communication with Europe by submarine cable, and steamship communication between Loango and Libreville and Marseilles, Bordeaux, Liverpool and Hamburg.