Geology and geology of Africa is little known. Very ancient crystal line rocks are found rising into mountain ranges and sometimes spread over large areas. Most of the rocks that overlie them belong to the older formations, so that the continent as a whole is supposed to be of very ancient date. The sands which cover so large an area are be lieved to be mainly of nolian origin, and not to have been formed by the action of water. The porous clay found so abundantly in West Africa is of comparatively recent date. The region around Tanganyika is of Jurassic origin. Around the great lakes are abundant evidences of enormous volcanic activity at no very remote date; and, as already mentioned, active volcanoes are not unknown. Tanganyika, according to recent views, may at one period have been con nected with the sea. Salt is abundant, though often scarce from want of communication and working organization. Gold is found in abun dance in southern Africa from the Transvaal region to the Zambezi, and a number of very productive mines opened up industries in the Transvaal and Mashonaland. Diamonds have been found in large numbers, and in apparently inexhaustible supply, on the Vaal River and its tributaries, in Cape Colony and Orange River Colony. In the southern central district, par ticularly the country of Katanga, iron and cop per are found, and are worked in some dis tricts in the countries bordering on the Lualaba. Copper is also found in Loanda, iron in Angola, and lead, tin, iron and copper in Great Nama qualand; iron, copper and coal are found in Natal and Cape Colony.
The centre of Africa pos sesses, as already mentioned, an exuberant tropical vegetation. In the equatorial districts dense forests are found with trees of enormous size and luxuriant climbing plants. The open pastoral belt at the extremities of the tropics is distinguished by a rich and varied flora. A special characteristic of the vegetation of the southern extremity of Africa is the remarkable variety, size and beauty of the heaths, some of which grow to 12 or 15 feet and form minia ture forests. Cycadacem and bulbous and or chidaceous plants, aloes and other succulent plants also abound. The baobab or monkey bread tree, first discovered by Adanson in Sen egal, is found from the Sudan to Lake Ngami. Acercias, Euphorbias and palms of one variety or another are diffused over almost every part of Africa. The date palm is the special char acteristic of the desert, to which it is peculiarly adapted, and there it forms the principal means of subsistence. It is also cultivated as a garden plant in the northern coast regions. This dis trict as well as Egypt has an ancient celebrity for its fertility in grain. Wheat and maize are cultivated, fruit trees also abound, and groves of oranges and olives relieve the landscape. The castor oil plant, the fig tree, the dwarf palm and the lotus, formerly an important ar ticle of food, are here characteristic forms. The common oak, the cork oak and the pine form the staple, and the cypress, myrtle, ar butus and fragrant tree heaths the ornaments of the woods. The pastoral tropical belt pre sents a different order of vegetation. Besides the baobab, the cabbage palm, the oil palm, the wax palm, the Shea butter tree, the cotton tree, the African oak and the mangrove here pre vail; rice and maize are cultivated; the prin cipal fruits are the banana, papaw, custard apple, lemon, orange and tamarind. Many val uable timber trees and India-rubber plants are found in various forms, as trees and as climb ing plants, in abundance both in east and west tropical Africa. The prevalent plants of this district are also found in the fertile parts of Nubia. To the northeast of this region frankin cense, myrrh, cinnamon and cassia abound. The coffee plant is a native of the southern Abys sinian region, and also of western tropical Africa, where it forms thick woods. This plant is supposed to have been transported from Africa to Arabia. Abyssinia, though coffee and spices are native products, possesses generally, from its elevation, the vegetation of a perate region. The swamps of the tropical gion abound with papyrus. The cassava, yam, pigeon-pea and ground-nut are cultivated as bread plants.
Animals.— The fauna of Africa is extensive and varied, and numerous species of mammals are peculiar to the continent. According to a scientific view of the geographical distribution of animals, the northwest of Africa belongs to the Mediterranean sub-region, while the rest of the continent forms the Ethiopian region. Af rica possesses numerous species of the order Quadrumana (apes and monkeys), all of which are peculiar to it. They abound especially in the tropics. The most remarkable are the chim panzee and the gorilla. The lion is the typical carnivore of Africa. Latterly he has been driven from the coast settlements to the interior, where he still reigns king of the forest. There are three varieties, the Barbary, Senegal and Cape lions. The leopard and panther rank next to the lion among the carnivore. Hyenas of more than one species and jackals are found all over Africa. Elephants in large herds abound in the forests of the tropical regions, and their tusks form a leading article of commerce. These are larger and heavier than those of Asiatic ele phants. The elephant is not a domestic animal in Africa as it is in Asia. The rhinoceros is found, like the elephant, in middle and southern Africa. Hippopotami abound in many of the large rivers and the lakes. The zebra and quagga were numerous in central and southern Africa, but the latter is said to be now en tirely extinct. Of antelopes, the most numerous and characteristic of the ruminating animals of Africa, at least 50 species are considered pecu liar to this continent, of which 23 used to occur in Cape Colony. The giraffe is found in the interior and is exclusively an African animal. Several species of wild buffaloes roam in the interior, and the Asiatic buffalo has been nat uralized in the north. The camel, common in the north as a beast of burden, has no doubt been introduced from Asia. The horse and the ass are highly developed in the Barbary States. The cattle of Abyssinia and Bornu have horns of im mense size but extremely light. In Barbary and the Cape of Good Hope the sheep are broad tailed ; in Egypt and Nubia they are long-legged and short-tailed. Goats are in some parts more numerous than sheep, especially in the Sudan and in Abyssinia. Dogs are numerous, but cats rare, in Egypt and Barbary. The former in the northern towns serve as scavengers. Bears and foxes are found only in the north. The im mense herds of game which formerly abounded in many parts of Africa were diminishing so rapidly that in 1900 measures for their protec tion were laid down by an international conven tion, and game reserves have been established in British Africa, Somaliland and elsewhere. The birds of northern Africa are almost iden tical with those of the south of Europe and the Asiatic countries bordering on the Medi terranean. In the rest of Africa they show more resemblance to those of Australasia. Many of the African birds are famed for the brilliancy of their plumage, such as the sun birds, bee-eaters, rollers, plantain-eaters, par rots and kingfishers. The ostrich is found nearly all over Africa, but especially in the desert. A remarkable bird of southern Africa is the secretary-bird or serpent-eater, which renders great service to the inhabitants by kill ing serpents. Another peculiar bird of South Africa is the little honey-guide (q.v.), which points out the nests of bees. The whale-headed stork, remarkable for its enormous beak, may also be mentioned. Owls, falcons, eagles and vultures are numerous. Water-fowl are abun dant on the lakes and rivers, and there are many species of quails and partridges. One species of gallinaceous bird, the guinea-fowl, has been domesticated in other countries. Reptiles, owing to the dryness of the climate, are comparatively few. The largest is the crocodile, which abounds in the great rivers and tropical lakes. There are several species of venomous serpents, including the horned viper and the African cobra. The chameleon is common. The rivers and coasts abound with fish of numerous spe cies, and some of them of the most brilliant coloring. Insects are numerous. Among the more troublesome species are the locust, tsetse and white ant.