Africa

guincensis (oil-palm) and Raphia vinifera (bamboo-palm), not found,

generally speaking, in the savanna regions. The bombax or silk-cotton tree

attains gigantic proportions in the forests, which are the home of the

indiarubber-producing plants and of many valuable kinds of timber trees,

such as odum (Chlorophora excelsa), ebony, mahogany (Khaya senegalensis),

African teak or oak (Oldfieldia africana) and camwood (Baphia nitida.) The

climbing plants in the tropical forests are exceedingly luxuriant and the

undergrowth or ``bush'' is extremely dense. In the savannas the most

characteristic trees are the monkey bread tree or baobab (Adanisonia

digitata), doom palm (Hyphaene) and euphorbias. The coffee plant grows wild

in such widely separated places as Liberia and southern Abyssinia. The

higher mountains have a special flora showing close agreement over wide

intervals of space, as well as affinities with the mountain flora of the

eastern Mediterranean, the Himalayas and Indo-China (cf. A. Engler, Uber

die Hochgebirgsflora des tropischen Afrika, 1892).

In the swamp regions of north-east Africa the papyrus and associated

plants, including the soft-wooded ambach, flourish in immense quantities—-

and little else is found in the way of vegetation. South Africa is largely

destitute of forest save in the lower valleys and coast regions. Tropical

flora disappears, and in the semi-desert plains the fleshy, leafless,

contorted species of kapsias, mesembryanthemums, aloes and other succulent

plants make their appearance. There are, too, valuable timber trees, such

as the yellow pine (Podocarpus elongatus), stinkwood (Ocotea), sneezewood

or Cape ebony (Pteroxylon utile) and ironwood. Extensive miniature woods of

heaths are found in almost endless variety and covered throughout the

greater part of the year with innumerable blossoms in which red is very

prevalent. Of the grasses of Africa alfa is very abundant in the plateaus

of the Atlas range.

Fauna.—The fauna again shows the effect of the characteristics of the

vegetation. The open savannas are the home of large ungulates, especially

antelopes, the giraffe (peculiar to Africa), zebra, buffalo, wild ass and

four species of rhinoceros; and of carnivores, such as the lion, leopard,

hyaena, &c. The okapi (a genus restricted to Africa) is found only in the

dense forests of the Congo basin. Bears are confined to the Atlas region,

wolves and foxes to North Africa. The elephant (though its range has become

restricted through the attacks of hunters) is found both in the savannas

and forest regions, the latter being otherwise poor in large game, though

the special habitat of the chimpanzee and gorilla. Baboons and mandrills,

with few exceptions, are peculiar to Africa. The single-humped camel—as a

domestic animal—is especially characteristic of the northern deserts and

steppes.

The rivers in the tropical zone abound with hippopotami and crocodiles,

the former entirely confined to Africa. The vast herds of game, formerly so

characteristic of many parts of Africa, have much diminished with the

increase of intercourse with the interior. Game reserves have, however,

been established in South Africa, British Central Africa, British East

Africa, Somahland, &c., while measures for the protection of wild animals

were laid down in an international convention signed in May 1900.

The ornithology of northern Affica presents a close resemblance to that

of southern Europe, scarcely a species being found which does not also

occur in the other countries bordering the Mediterranean. Among the birds

most characteristic of Africa are the ostrich and the secretary-bird. The

ostrich is widely dispersed, but is found chiefly in the desert and steppe

regions. The secretary-bird is common in the south. The weaver birds and

their allies, including the long-tailed whydahs, are abundant, as are,

among game-birds, the francolin and guinea-fowl. Nany of the smaller birds,

such as the sun-birds, bee-eaters, the parrots and halcyons, as well as the

larger plantain-eaters, are noted for the brilliance of their plumage. Of

reptiles the lizard and chameleon are common, and there are a number of

venomous serpents, though these are not so numerous as in other tropical

countries. The scorpion is abundant. Of insects Africa has many thousand

different kinds; of these the locust is the proverbial scourge of the

continent, and the ravages of the termites or white ants are almost

incredible. The spread of malaria by means of mosquitoes has already been

mentioned. The tsetse fly, whose bite is fatal to all domestic animals, is

common in many districts of South and East Africa. Fortunately it is found

nowhere outside Africa. (E. HE.; F. R. C.)

1 With the islands, 11,498,000 sq. m.

2 Estimated.

3 See the calculations of Capt. T. T. Behrens, Geog. Journal, vol. xxix.

(1907).

4 The estimate of Capt. H. G. Lyons in 1905 was 1,107,227 sq. mi.

5 including waterless tracts naturally belonging to the river-basin.

II. GEOLOGY

In shape and general geological structure Africa bears a close

resemblance to India. Both possess a meridional extension with a broad east

and west folded region in the north. In both a successive series of

continental deposits, ranging from the Carboniferous to the Rhaetic, rests

on an older base of crystalline rocks. In the words of Professor Suess,

``India and Africa are true plateau countries.''

Of the primitive axes of Africa few traces remain. Both on the east and

west a broad zone of crystalline rochs extends parallel with the coast-line

to form the margin of the elevated plateau of the interior. Occasionally

the crystalline belt comes to the coast, but it is usually reached by two

steps known as the coastal belt and foot-plateau. On the flanks of the

primitive western axis certain ancient sedimentary strata are thrown into

folds which were completed before the commencement of the mesozoic period.

In the south, the later palaeozoic rocks are also thrown into acute folds

by a movement acting from the south, and which ceased towards the close of

the mesozoic period. In northern Africa the folded region of the Atlas

belongs to the comparatively recent date of the Alpine system. None of

these earth movements affected the interior, for here the continental

mesozoic deposits rest, undisturbed by folding, on the primary sedimentary

and crystalline rocks. The crystalline massif, therefore, presents a solid

block which has remained elevated since early palaeozoic times, and against

which earth waves of several geological periods have broken.

The formations older than the mesozoic are remarkably unfossiliferous, so

that the determination of their age is frequently a matter of speculation,

and in the following table the European equivalents of the pre-Karroo

formations in many regions must be regarded as subject to considerable

revision.

Rocks of Archean age cover wide areas in the interior, in West and East

Africa and across the Sahara. Along the coastal margins they underlie the

newer formations and appear in the deep valleys and kloofs wherever

denudation has laid them bare. The prevailing types are granites, gneisses

and schists. In the central regions the predominant strike of the fohae is

north and south. The rocks, for convenience classed as pre-Cambrian, occur

as several unconformable groups, chiefly developed in the south where alone

their stratigraphy has been determined. They are unfossiliferous, and in

the absence of undoubted Cambrian, Ordovician and Silurian strata in Africa

they may be regarded as of older date than any of these formations. The

general occurrence of jasper-bearing rocks is of interest, as these are

always present in the ancient pressure-altered sedimentary formations of

America and Europe. Some unfossiliferous conglomerates, sandstones and

dolomites in South Africa and on the west coast are considered to belong to

the Cambrian, Ordovician and Silurian formations, but merely from their

occurrence beneath strata yielding Devonian fossils. In Cape Colony the

Silurian age of the Table Mountain Sandstone is based on such evidence.

The Devonian and Carboniferous formations are well represented in the

north and south and in northern Angola.

Up to the close of the palaeozoic period the relative positions of the

ancient land masses and oceans remain unsolved; but the absence of marine

strata of early palaeozoic age from Central Africa points to there being

land in this direction. In late Carboniferous times Africa and India were

undoubtedly united to form a large continent, called by Suess Gondwana

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