coral; sand dunes; continental } Some volcanic islands;
dunes. Generally distributed } rift-valley volcanoes.
Pleistocene. Ancient alluviums and }
gravels; travertine. }
Generally distributed. } A long-continued
Pliocene. N. Africa; Madagascar. } succession in the
} central and northern
Miocene. N. Africa. } regions and among
} the island groups.
Oligocene. N. Africa. } Doubtfully represented
} south of the Zambezi.
Eocene. N. Africa, along east and }
west coasts; Madagascar. }
Cretaceous Extensively developed in } Diamond pipes of S.
N. Africa; along coast } Africa; Kaptian
and foot-plateaus in east } fissure eruptions;
and west; Madagascar. } Ashangi traps of
} Abyssinia
{Jurassic N. Africa; E. Africa;
K{ Madagascar; Stormberg } Chief volcanic period
a{ period (Rhaeric) in S. } in S. Africa
r{ Africa }
r{Trias. Beaufort Series in S. }
o{ Africa; Congo basin; }
o{ Central Africa; Algeria; }
{ Tunis. }
{Permian. Ecca Series in S. Africa. } Feebly, if anywhere
} developed.
Carboniferous. N. Africa; Sabaki Shales }
in E. Africa; Dwyka }
and Wittebery Series in }
South Africa }
Devonian. N. Africa; Angola; Bokkeveld } Not recorded.
Series in S. Africa }
Silurian. {Table Mountain Sandstone }
{ in S. Africa, Silurian(?). }
Ordovician. { Doubtfully represented } Klipriversberg and
{ in N. Africa, French } and Ventersdorp Series
Cambrian { Congo, Angola. and by } of the Transvaal (?).
{ Vaal River and Waterberg }
{ Series in S. Africa }
Pre-Cambrian. Quartzites, conglomerates }
phyllites, jasper-bearing } S. Africa and generally.
rocks and schists. }
Generally distributed. }
Archeaan. Gneisses and schists of the } Igneous complex of
continental platform. } sheared igneous
} rocks;granites.
and Australia. At the close of the Karroo period there was a remarkable manifestation of volcanic activity which again has its parallel in the Deccan traps of India.
How far the Karroo formation extended beyond its present confines has not been determined. To the east it reached India. In the south all that can be said is that it extended to the south of Worcester in Cape Colony. The Crystal Mountains of Angola may represent its western boundary; while the absence of mesozoic strata beneath the Cretaceous rocks of the mid-Sahara indicates that the system of Karroo lakeland had here reached its most northerly extension. Towards the close of the Karroo period, possibly about the middle, the southern rim of the great central depression became ridged up to form the folded regions of the Zwaarteberg, Cedarberg and Langeberg mountains in Cape Colony. This folded belt gives Africa its abrupt southern termination, and may be regarded as an embryonic indication of its present outline. The exact date of the maximum development of this folding is unknown, but it had done its work and some 10,000 ft. of strata had been removed before the commencement of the Cretaceous period. It appears to approximate in time to the similar earth movement and denudation at the close of the palaeozoic period in Europe. It was doubtless connected with the disruption of Gondwana Land, since it is known that this great alteration of geographical outline commenced in Jurassic times.
The breaking up of Gondwana Land is usually considered to have been caused by a series of blocks of country being let down by faulting with the consequent formation of the Indian Ocean. Other blocks, termed horsts, remained unmoved, the island of Madagascar affording a striking example. In the African portion Ruwenzori is regarded by some geologists to be a block mountain or horst.
In Jurassic times 1he sea gained access to East Africa north of Mozambique, but does not appear to have reached far beyond the foot-plateau except in Abyssinia.
The Cretaceous seas appear to have extended into the central Saharan regions, for fossils of this age have been discovered in the interior. On the west coast Cretaceous rocks extend continuously from Mogador to Cape Blanco. From here they are absent up to the Gabun river, where they commence to form a narrow fringe as far as the Kunene river, though often overlain by recent deposits. They are again absent up to the Sunday river in Cape Colony, where Lower Cretaceous rocks (for long considered to be of Oolitic age) of an inshore character are met with. Strata of Upper Cretaceous age occur in Pondoland and Natal, and are of exceptional interest since the fossils show an intermingling of Pacific types with other forms having European affinities. In Mozambique and in German East Africa, Cretaceous rocks extend from the coast to a distance inland of over 100 m.
Except in northern Africa, the Tertiary formations only occur in a few isolated patches on the east and west coasts. In northern Africa they are well developed and of much interest. They contain the well-known nummulitic limestone of Eocene age, which has been traced from Egypt across Asia to China. The Upper Eocene rocks of Egypt have also yielded primeval types of the Proboscidea and other mammalia. Evidences for the greater extension of the Eocene seas than was formerly considered to be the case have been discovered around Sokoto. During Miocene times Passarge considers that the region of the Zambezi underwent extreme desiccation.
The effect of the Glacial epoch in Europe is shown in northern Africa by the moraines of the higher Atlas, and the wider extension of the glaciers on Kilimanjaro, Kenya and Ruwenzori, and by the extensive accumulations of gravel over the Sahara.
The earliest signs of igneous activity in Africa are to be found in the granites, intrusive into the older rocks of the Cape peninsula, into those of the Transvaal, and into the gneisses and schists of Central Africa. The Ventersdorp boulder beds of the Transvaal may be of early palaeozoic age; but as a whole the palaeozoic period in Africa was remarkably free from volcanic and igneous disturbances. The close of the Stormberg period (Rhaetic) was one of great volcanic activity in South Africa. Whilst the later Secondary and Tertiary formations were being laid down in North Africa and around the margins of the rest of the continent, Africa received its last great accumulation of strata and at the same time underwent a consecutive series of earth-movements. The additional strata consist of the immense quantities of volcanic material on the plateau of East Africa, the basalt flows of West Africa and possibly those of the Zambezi basin. The exact period of the commencement of volcanic activity is unknown. In Abyssinia the Ashangi traps are certainly post-Oolitic. In East Africa the fissure eruptions are considered to belong to the Cretaceous. These early eruptions were followed by those of Kenya, Mawenzi, Elgon, Chibcharagnani, and these by the eruptions of Kibo, Longonot, Suswa and the Kyulu Mountains. The last phase of vulcanicity took place along the great meridional rifts of East Africa, and though feebly manifested has not entirely passed away. In northern Africa a continuous sequence of volcanic events has taken place from Eocene times to latest Tertiary; but in South Africa it is doubtful if there have been any intrusions later then Cretaceous.
During this long continuance of vulcanicity, earth-movements were in progress. In the north the chief movements gave rise to the system of latitudinal folding and faulting of the Moroccan and Algerian Atlas, the last stages being represented by the formation of the Algerian and Moroccan coast-outline and the sundering of Europe from Africa at the Straits of Gibraltar. Whilst northern Africa was being folded, the East African plateau was broken up by a series of longitudinal rifts extending from Nyasaland to Egypt. The depressed areas contain the long, narrow, precipitously walled lakes of East Africa. The Red Sea also occupies a meridional trough.
Lastly there are the recent elevations of the northern coastal regions, the Barbary coast and along the east coast. (W. G.*)
III. ETHNOLOGY In attempting a review of the races and tribes which inhabit Africa, their distribution, movements and culture, it is advisable that three points be borne in mind. The first of these is the comparative absence of natural barriers in the interior, owing to which intercommunication between tribes, the dissemination of culture and tribal migration have been considerably facilitated. Hence the student must be prepared to find that, for the most part, there are no sharp divisions to mark the extent of the various races composing the population, but that the number of what may be termed ``transitional'' peoples is unusually large. The second point is that Africa, with the exception of the lower Nile valley and what is known as Roman Africa (see AFRICA, ROMAN), is, so far as its native inhabitants are concerned, a continent practically without a history, and possessing no records from which such a history might be reconstructed. The early movements of tribes, the routes by which they reached their present abodes, and the origin of such forms of culture as may be distinguished in the general mass of customs, beliefs, &c., are largely matters of conjecture. The negro is essentially the child of the moment; and his memory, both tribal and individual, is very short. The third point is that many theories which have been formulated with respect to such matters are unsatisfactory owing to the small amount of information concerning many of the tribes in the interior.
The chief African races.
Excluding the Europeans who have found a home in various parts of Africa, and the Asiatics, Chinese and natives of India introduced by them (see section History below), the population of Africa consists of the following elements: —the Bushman, the Negro, the Eastern Hamite, the Libyan and the Semite, from the intermingling of which in various proportions a vast number of ``transitional'' tribes has arisen. The Bushmen (q.v.), a race of short yellowish-brown nomad hunters, inhabited, in the earliest times of which there is historic knowledge, the land adjoining the southern and eastern borders of the Kalahari desert, into which they were gradually being forced by the encroachment of the Hottentots and Bantu tribes. But signs of their former presence are not wanting as far north as Lake Tanganyika, and even, it is rumoured, still farther north. With them may be classed provisionally the Hottentots, a pastoral people of medium stature and yellowish-brown complexion. who in early times shared with the Bushmen the whole of what is now Cape Colony. Though the racial affinities of the Hottentots have been disputed, the most satisfactory view on the whole is that they represent a blend of Bushman, Negroid and Hamitic elements. Practically the rest of Africa, from the southern fringe of the Sahara and the upper valley of the Nile to the Cape, with the exception of Abyssinia and Galla and Somali-lands, is peopled by Negroes and the ``transitional'' tribes to which their admixture with Libyans on the north, and Semites (Arabs) and Hamites on the north-east and east, has given rise. A slight qualification of the last statement is necessary, in so far as, among the Fula in the western Sudan, and the Ba-Hima, &c., of the Victoria Nyanza, Libyan and Hamitic elements are respectively stronger than the Negroid. Of the tracts excepted, Abyssinia is inhabited mainly by Semito-Hamites (though a fairly strong negroid element can be found), and Somali and Galla-lands by Hamites. North of the Sahara in Algeria and Morocco are the Libyans (Berbers, q.v.), a distinctively white people, who have in certain respects (e.g. religion) fallen under Arab influence. In the north-east the brown-skinned Hamite and the Semite mingle in varied proportions. The Negroid peoples, which inhabit the vast tracts of forest and savanna between the areas held by Bushmen to the south and the Hamites, Semites and Libyans to the north, fall into two groups divided by a line running from the Cameroon (Rio del Rey) crossing the Ubangi river below the bend and passing between the Ituri and the Semliki rivers, to Lake Albert and thence with a slight southerly trend to the coast. North of this line are the Negroes proper, south are the Bantu. The division is primarily philological. Among the true Negroes the greatest linguistic confusion prevails; for instance, in certain parts of Nigeria it is possible to find half-a-dozen villages within a comparatively small area speaking, not different dialects, but different languages, a fact which adds greatly to the difficulty of political administration. To the south of the line the condition of affairs is entirely different; here the entire population speaks one or another dialect of the Bantu Languages (q.v..) As said before, the division is primarily linguistic and, especially upon the border line, does not always correspond with the variations of physical type. At the same time it is extremely convenient and to a certain extent justifiable on physical and psychological grounds; and it may be said roughly that while the linguistic uniformity of the Bantu is accompanied by great variation of physical type, the converse is in the main true of the Negro proper, especially where least affected by Libyan and Hamitic admixture, e.g. on the Guinea coast. The variation of type among the Bantu is due probably to a varying admixture of alien blood, which is more apparent as the east coast is approached. This foreign element cannot be identified with certainty, but since the Bantu seem to approach the Hamites in those points where they differ from the Negro proper, and since the physical characteristics of Hamites and Semites are very similar, it seems probable that the last two races have entered into the composition of the Bantu, though it is highly improbable that Semitic influence should have permeated any distance from the east coast. An extremely interesting section of the population not hitherto mentioned is constituted by the Pygmy tribes inhabiting the densely forested regions along the equator from Uganda to the Gabun and living the life of nomadic hunters. The affinities of this little people are undecided, owing to the small amount of knowledge concerning them. The theories which connected them with the Bushmen do not seem to be correct. It is more probable that they are to be classed among the Negroids, with whom they appear to have intermingled to a certain extent in the upper basin of the Ituri, and perhaps elsewhere. As far as is known they speak no language peculiar to themselves but adopt that of the nearest agricultural tribe. They are of a dark brown complexion, with very broad noses, lips but slightly everted, and small but usually sturdy physique, though often considerably emaciated owing to insufficiency of food. Another peculiar tribe, also of short stature, are the Vaalpens of the steppe region of the north Transvaal. Practically nothing is known of them except that they are said to be very dark in colour and live in holes in the ground, and under rock shelters.
Principal ethnological zones.
Having indicated the chief races of which in various degrees of purity and intermixture the population of Africa is formed, it remains to consider them in greater detail, particularly from the cultural standpoint. This is hardly possible without drawing attention to the main physical characters of the continent, as far as they affect the inhabitants. For ethnological purposes three principal zones may be distinguished; the first two are respectively a large region of steppes and desert in the north, and a smaller region of steppes and desert in the south. These two zones are connected by a vertical strip of grassy highland lying mainly to the east of the chain of great lakes. The third zone is a vast region of forest and rivers in the west centre, comprising the greater part of the basin of the Congo and the Guinea coast. The rainfall, which also has an important bearing upon the culture of peoples, will be found on the whole to be greatest in the third zone and also in the eastern highlands, and of course least in the desert, the steppes and savannas standing midway between the two. As might be expected these variations are accompanied by certain variations in culture. In the best-watered districts agriculture is naturally of the greatest importance, except where the density of the forest renders the work of clearing too arduous. The main portion therefore of the inhabitants of the forest zone are agriculturists, save only the nomad Pygmies, who live in the inmost recesses of the forest and support themselves by hunting the game with which it abounds. Agriculture, too, flourishes in the eastern highlands, and throughout the greater part of the steppe and savanna region of the northern and southern zones, especially the latter. In fact the only Bantu tribes who are not agriculturists are the Ova-Herero of German South-West Africa, whose purely pastoral habits are the natural outcome of the barren country they inhabit. But the wide open plains and slopes surrounding the forest area are eminently suited to cattle-breeding, and there are few tribes who do not take advantage of the fact. At the same time a natural check is imposed upon the desire for cattle, which is so characteristic of the Bantu peoples. This is constituted by the tsetse fly, which renders a pastoral life absolutely impossible throughout large tracts in central and southern Africa. In the northern zone this check is absent, and the number of more essentially pastoral peoples, such as the eastern Hamites, Masai, Dinka, Fula, &c., correspondingly greater. The desert regions yield support only to nomadic peoples, such as the Tuareg, Tibbu, Bedouins and Bushmen, though the presence of numerous oases in the north renders the condition of life easier for the inhabitants. Upon geographical conditions likewise depend to a large extent the political conditions prevailing among the various tribes. Thus among the wandering tribes of the desert and of the heart of the forests, where large communities are impossible, a patriarchal system prevails with the family as the unit. Where the forest is less dense and small agricultural communities begin to make their appearance, the unit expands to the village with its headman. Where the forest thins to the savanna and steppe, and communication is easier, are found the larger kingdoms and ``empires'' such as, in the north those established by the Songhai, Hausa, Fula, Bagirmi, Ba-Hima, &c., and in the south the states of Lunda, Kazembe, the Ba-Rotse, &c.