whole is, for European races, the most unhealthy portion of the
world. This is especially the case in the lower and moister
regions, such as the west coast, where malarial fever is
very prevalent and deadly; the most unfavourable factors
being humidity with absence of climatic variation (daily or
seasonal). The higher plateaus, where not only is the average
temperature lower, but such variations are more extensive,
are more healthy; and in certain localities (e.g. Abyssinia
and parts of British East Africa) Europeans find the climate
suitable for permanent residence. On tablelands over 6500
ft. above the sea, frost is not uncommon at night, even in
places directly under the equator. The acclimatization of
white men in tropical Africa generally is dependent largely
on the successful treatment of tropical diseases. Districts
which had been notoriously deadly to Europeans were rendered
comparatively healthy after the discovery, in 1899, of the species
of mosquito which propagates malarial fever, and the measures
thereafter taken for its destruction and the filling up of
swamps. The rate of mortality among the natives from tropical
diseases is also high, one of the most fatal being that known
as sleeping sickness. (The ravages of this disease, which
also attacks Europeans, reached alarming proportions between
1893 and 1907, and in the last-named year an international
conference was held in London to consider measures to
combat it.) When removed to colder regions natives of the
equatorial districts suffer greatly from chest complaints.
Smallpox also makes great ravages among the negro population.
Flora.--The vegetation of Africa follows very closely
the distribution of heat and moisture. The northern and
southern temperate zones have a flora distinct from that
of the continent generally, which is tropical. In the
countries bordering the Mediterranean are groves of oranges
and olive trees, evergreen oaks, cork trees and pines,
intermixed with cypresses, myrtles, arbutus and fragrant
tree-heaths. South of the Atlas range the conditions
alter. The zones of minimum rainfall have a very scanty
flora, consisting of plants adapted to resist the great
dryness. Characteristic of the Sahara is the date-palm,
which flourishes where other vegetation can scarcely maintain
existence, while in the semidesert regions the acacia (whence
is obtained gum-arabic) is abundant. The more humid regions
have a richer vegetation --dense forest where the rainfall
is greatest and variations of temperature least, conditions
found chiefly on the tropical coasts, and in the west African
equatorial basin with its extension towards the upper Nile;
and savanna interspersed with trees on the greater part of the
plateaus, passing as the desert regions are approached into a
scrub vegetation consisting of thorny acacias, &c. Forests also
occur on the humid slopes of mountain ranges up to a certain
elevation. In the coast regions the typical tree is the
mangrove, which flourishes wherever the soil is of a swamp
character. The dense forests of West Africa contain, in
addition to a great variety of dicotyledonous trees, two
palms, the Elaeis 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
