The central and equatorial land, 34° deep, including and bordering upon the zone of almost constant rain, is distinguished by the oppressive exuberance of its vegetation and by the consequent insalubrity of its climate. The drainage of the interior, pouring with discoloured efflux to the ocean, in large and often navigable channels, subject to violent freshes, taints the water-lines with deadly malaria. The false coasts of coralline or of alluvial deposits—a modern formation, and still forming— fringed with green-capped islets, and broken by sandy bays and by projecting capes, are exposed to swells and rollers, to surf and surge, to numbing torrents and chilling tornadoes, whilst muddy backwaters and stagnant islets disclose lagoon-valves or vistas through tangled morass, jungle, and hardly penetrable mangrove-swamp. This maremma, the home of fever, is also the seat of trade, but the tribes which occupy it soon die out. The true coast has already risen high enough above the waters to maintain its level; and the vegetation—calabashes, palms, and tamarinds— offers a contrast to the swampy growth below. Inland of the raised seaboard are high and jungly mountains and coast-range or ghaut, in many parts yet unvisited by Europeans. Beyond these sierras begins the basin- shaped plateau of Central Equatorial Africa. The inhabitants are mostly inland tribes, ever gravitating towards the coast. They occupy stockaded and barricaded clumps of pent-houses or circular tents, smothered by thicket and veiled, especially after the heavy annual rains, with the ‘smokes,’ a dense white vapour, moisture made visible by the earth being cooler than the saturated air.[26] I have elsewhere remarked (The Lake Regions of Central Intertropical Africa; Abeokuta and the Camaroons Mountains, &c.) the striking geological contrast between the two equatorial coasts, eastern and western. The former, south of the Guardafui granites, offers to one proceeding inland from the ocean a succession of corallines, of sandstone and of calcaires, which appear to be an offset from the section of that great zone forming the Somali country. The western coasts, after quitting the basalts and lavas of the Camaroons, are composed chiefly of the granites and syenites with their degradations of schiste, gneiss, and sandstone. Similarly, in the great Austro-American continent, one shore, that of the Brazil, is granitic, whilst the other, Chili, mainly consists of the various porphyries.