Africa by Élisée Reclus/Volume 1/Chapter 1
THE EARTH AND ITS INHABITANTS.
NORTH-EAST AFRICA.
CHAPTER I.
GENERAL SURVEY.
As now surveyed around its entire seaboard, Africa stands out as the best-defined division of the Old World — a vast island, attached only by a narrow isthmus, 90 miles broad, to the Asiatic mainland. Even this isthmus itself is an old marine and fluvial basin — Mediterranean alluvium in the north, a deposit of the Red Sea in the south; between these two marine zones an ancient Nilotic delta, which, to judge from the allied faunas, probably at one time communicated with the Jordan. But although the Isthmus of Suez had no existence in Tertiary times, there were other stretches of land connecting Egypt with Cyprus and Syria; for nowhere else in the periphery of the globe are there found contiguous marine inlets presenting such differences in their fauna as do those of Suez and Gaza.
But if the waters of the Indian Ocean have remained completely distinct from those of the Mediterranean since the Eocene epoch, with the exception perhaps of a shallow channel flooded in Quaternary times, the intervening barrier has at last been removed by the hand of man. Thanks to his industry, the two seas henceforth mingle their waters in the inland basin of Lake Timsah, and the circumnavigation of Africa is open to the largest vessels afloat. Compared with this southern continent, whose contour is so clearly defined, the two other divisions of the Old World seem to merge in one continental mass. Certainly the depression skirting the Ural range from the Gulf of Ob to the Caspian, and the Manich isthmus between the Caspian and Euxine, cannot be regarded as such sharp geographical parting lines as the marine channel now flowing between Suez and Port Said.
But however clearly severed at present from the rest of the Eastern hemisphere, Africa is not so entirely distinct from Europe and Asia as might at first sight be supposed. Parts of its seaboard were even formerly connected directly with the regions beyond the Mediterranean, and there was a time when the Atlas Mountains effected a junction across the present Strait of Gibraltar with the parallel Sierra Nevada range. Even down to the close of the Pliocene epoch, Tunisia was still united with Sicily and Italy through a broad zone, of which the only surviving fragments are the little Maltese group of islets. Greece also merged southwards in boundless plains watered by streams whose banks were frequented by the elephant and hippopotamus.[1]
Although now detached from Spain and Italy, North-west Africa is still in its geology, natural history, and climate essentially a Mediterranean land, forming with the opposite European seaboard a distinct physical region. Along both coasts the same fossils occur on the old rocks, while similar floras and faunas are now in possession of the soil. The Mauritanian coastlands differ far more from Nigretia, from which they are separated by the Sahara, than they do from Provence, and as already remarked by Sallust, North Africa is physically a part of Europe. Eastwards also the Ethiopian shore of the Red Sea belongs to the same formations as the opposite coast of Arabia, and a general resemblance characterises the climate, natural productions, and inhabitants on either side of Bab-el-Mandeb.
In its massive outlines Africa presents the same monotonous appearance as the two other southern divisions of the globe — South America and Australia. It is even less indented than the corresponding section of the New World; nor is it supplemented, like Australia, by a vast region of archipelagoes and islands, scattered over the northern and eastern seas. Its very size, estimated at nearly 12,000,000 square miles, or over three times that of Europe and four times that of Australia, contributes to its heavy uniform aspect. Notwithstanding its greater bulk, its coastline is considerably less than that of Europe. Exclusive of a thousand smaller inlets, such as the Scandinavian fjords and the firths of Scotland, the latter has a periphery of about 19,000 miles, the former not more than 15,000, much of which is unbroken by a single creek or bay. Its general form is that of an ellipsoid, disposed in the direction from north to south, and bulging out westwards in a still less varied semi-elliptical mass between Cape Bon and the Gulf of Guinea. The prevailing uniformity is modified on the east side chiefly by the sharp peninsula terminating at Cape Gardafui, on the west by the retreating curve of the coastline, by which the Atlantic basin is suddenly doubled in width. The eastern projection, which is separated by the Gulf of Aden from Hadramaut, follows the direction of the south-eastern extremity of Arabia, a region which in its climate and other respects forms a land of transition between the two continents.
Mountains.
From its regular contour, Africa might seem to be built on a generally uniform and simple plan. But such is not the case. Europe, notwithstanding its countless indentations, may be compared to an organism furnished with a backbone and members; Asia also groups its boundless plains and peninsulas around a culminating nucleus, the Great Pamir, or "Roof of the World;" while both Americas have their western Cordilleras, and in the east vast alluvial plains and river basins separated one from the other by scarcely perceptible parting lines. But Africa is comparatively speaking an almost shapeless mass, with a rudimentary organisation destitute alike of central uplands and regular watersheds. Nevertheless the eastern coast ranges, running parallel with the Indian Ocean, may in some respects be regarded as forming, if not a backbone, at least the border chain of one great continental highland system. Spite of the broad gaps pierced by the Limpopo, Zambezi, and Juba rivers, the broken fragments of a vast Cordillera may be recognised in the uplands stretching interruptedly from the Cape northwards to the Abyssinian highlands. In this zone of border ranges occur the culminating points of the continent, the extinct Kilima-njaro and Kenia volcanoes, perhaps the summits known to the ancients as the "Mountains of the Moon." West of these peaks the plateau is intersected by a parallel chain of other volcanoes, some of which are said still to emit smoke; while beyond Victoria Nyanza a third range, dominated by Mfumbiro and Gambaragara, would seem to form a western border system or water-parting between the Upper Nile and Congo basins. Here the plateau expands to a breadth of 550 miles, terminating northwards in the Abyssinian highlands, a rocky citadel whose base exceeds those of all the other continental orographic systems. These Ethiopian heights stand over against those of Yemen, and like them are a remnant of the border range sweeping round the Indian and Pacific Oceans from the Cape of Good Hope to Cape Horn, and forming a vast semicircle of 24,000 miles, equal to the circumference of the globe.
Although not yet thoroughly explored, Africa is already sufficiently known at least in the main features of its general relief. More compact and less indented than the other divisions of the globe, it also remains less accessible through the
Fig. 1. — Highlands and Plateaux of Central Africa.
Scale 1: 20,000,000.
work of erosion. Its mean elevation exceeds that of Europe and Asia, although there are scarcely any mountains equal to the Alps and Caucasus, none comparable to the Himalayas. Considered as a solid mass with vertical scarps and horizontal surface, its altitude, according to Chevanne, is at least 1,900, possibly 2,200, feet. An oblique line drawn from Loanda on the Atlantic to a point on the Red Sea between Suakin and Massawah marks off a region which forms an almost continuous tableland, intersected by mountain ranges resting on foundations of from 3,000 to 4,500 feet. The Congo and Nile basins confine on the north and west this region of plateaux, which comprises about a third of the whole continent. On the other sides the border ranges are considerably less elevated and much more divided than those of South and East Africa. They are nowhere continuous, but rise in scattered fragments between the Congo and Niger, between the Nile and Lake Tsad, in the heart of the Sahara, which is broken by the two isolated masses of Tibesti and Ahaggar, in the extreme west, where the scarps of the plateaux run parallel with the coasts of Upper Guinea and Senegambia; lastly in Mauritania, where the Atlas range constitutes a distinct orographic system, formerly connected with those of South Europe. South
Fig. 2. — Hydrography of Africa according to Mediaval Geographers.
of this system the continent may be roughly described as a vast plane inclined in a north-westerly direction.:
Rivers.
The rudimentary character of its general relief is also reflected in its hydrographic system. The African rivers, still to a great part entangled in the intricacies of the plateau, have a somewhat irregular and unfinished course, often forcing their way through narrow rocky gorges, and obstructed by numerous falls and rapids. Even the more copious streams are relatively less accessible to navigation than those of the other contents. In this respect the contrast is specially striking between Africa and South America, the two divisions of the globe which are more frequently compared with each other. The "Dark Continent" is entirely destitute of the great estuaries and broad arteries giving access in the New World from the Atlantic seaboard almost to the foot of the Andes. The comparative absence of navigable waters, of islands and good harbours, combined with the great extent of desert wastes, has mainly contributed to exclude Africa from the general life of the commercial world.
All the great rivers — Nile, Congo, and Niger — are interrupted by cataracts and rapids, which cut off from outward intercourse populous regions whose fluvial systems ramify over many hundred millions of acres. The Nile and Congo rising amid the higher plateaux, where the slope is still undecided, traverse in their upper courses many great lakes, which according to a vague tradition once constituted a single lacustrine basin of enormous extent. In the sixteenth century the Portuguese explorers had some idea of this hydrographic system. But in tracing the outlines of the great equatorial lakes they seem to have rather copied older maps than relied on positive information. But, however this be, they appear to have believed in the existence of a single source for the Nile, Congo, and even the Zambesi. But the streams were also supposed to traverse extensive underground regions, and an Italian map engraved in the middle of the fifteenth century represents a Nile with three heads, separated by a vast space from the emissaries of the chief fountain. This Nile is moreover made to flow in the direction from north to south, a small Egyptian delta corresponding to a much larger delta in South Africa.
The first modern explorers of the same region were also influenced by these traditional ideas. Even Speke traced the course of four rivers issuing from various parts of Lake Nyanza to form the Nile, while Stanley made Tanganyka the source of two effluents, one flowing northwards to the Nile, the other westwards to the Congo. But although these great arteries do not rise in a common source, the water-parting between them is in some places so low and undecided that a slight disturbance of the surface would suffice to change the direction of many affluents. It is even possible that on the dividing line of some basins there may exist lakes or swamps draining in both directions.
The unfinished aspect of the central rivers, the cataracts interrupting their course, the lacustrine reservoirs scattered over the plateaux, produce a certain resemblance between equatorial Africa and the Scandinavian peninsula. But in the northern region, still under ice within a comparatively recent geological epoch, the rivers have scarcely commenced their work of erosion. The climatic conditions are of course entirely different, and although the existence of an old glacial period may be suspected even in the torrid zone, the long ages that have elapsed since that remote epoch must have effaced nearly all trace of glaciers and moraines. Hence the rudimentary character of these fluvial basins is probably due to a different cause. The climate, which was formerly much more humid in the Sahara, may possibly have been correspondingly drier in the south-eastern region of the Nyanza plateau. In the absence of a copious rainfall the rocks would remain uneroded, and the now flooded cavities unfilled by the alluvia of running waters. During its long geological life the earth has witnessed many shif tings of the climatic zones. If the rains are more abundant in some places than formerly, in others they are more rare, and the Igharghar basin, for instance, in North-west Africa, belongs to one of these dried-up regions.
East of the Nile and of the great lakes there is no space between the plateaux and the coast for the development of large streams. From the Egyptian uplands the Red Sea receives nothing but intermittent wadies, and along a seaboard of about 2,400 miles southwards to Mozambique the Indian Ocean is fed only by such
Fig. 3. — Outflow of Lake Nyanza, according to Speke.
Scale 1 : 1,000,000.
the gorges of its upper course. The Kunene and Koanza, which follow from south to north, although more copious, have still but a slight volume compared with their respective areas of drainage. The same may be said of the Ogowé, which rises in the peninsular tract formed by the great bend of the Congo east of equatorial Guinea.
The Niger, or "Nile of the Blacks," forms with the Nile, Congo, and Zambezi, one of the four great arteries of Africa. Even down to the beginning of this century many geographers still supposed that the Nile and the Niger mingled their waters across the continent. Some old maps represent the latter as rising in the same lake as the eastern Nile, whereas its main source lies, not in the centre of Africa, but at Mount Loma, on the slope of the Rokelle Mountains, in the vicinity of the west coast. A space of at least 2,700 miles thus intervenes between the farthest headstreams of both rivers, while the nearest affluents are still separated by a distance of some 720 miles. The Niger in fact belongs to a region wholly different from that of the Nile in the form and disposition of its plateaux. On the other side of the hills where it takes its rise, the Congo, Rio Grande, Gambia, and several other streams flow to independent estuaries on the west coast, while farther north the Senegal, rising on the same slope as the Niger, sweeps round the hills, forcing its way to the Atlantic through a series of rocky gorges and rapids.
North of the Senegal no large river reaches the coast, and for a space of 4,800 miles from the bar of Saint Louis to the Nile delta nothing is met except a few wadies or small streams, such as the Draa, in the south of Morocco, the Moluya, Shelif, Mejerda, flowing to the Mediterranean. The Congo alone probably discharges as much water as all the other African rivers together. Next to it rank the Niger and Zambezi, the Nile in this respect taking only the fourth place.
Of the inland basins either constantly or intermittently closed, the most important are Lakes Tsad in the north, and Makarakara-Ngami in the south, both lying at nearly equal distance from the middle Congo, and thus presenting a symmetrical disposition on either side of the equator. Tsad, much the largest of the two, is also situated in the northern or largest section of the continent, the extent of both thus corresponding with that of the surrounding regions draining to the oceans. But here all further analogy ceases, at least if it be true that Tsad has always been a closed basin; for the Ngami reservoirs certainly communicated at some former geological epoch with the Limpopo and Zambezi.
Besides these central depressions, each section of the continent has its deserts, strewn with secondary basins and oases, whose waters lose themselves in the surrounding sands. Altogether the area of inland drainage is estimated by Chavanne at nearly 3,000,000 square miles, of which 560,000, or less than a fifth, lie south of the equator.[2]
Amongst the northern tracts without any outflow there are some depressions which at present lie below sea-level. These are probably the remains of straits and inlets formerly belonging to the Mediterranean and Red Sea. The largest are those which seem to form a continuation of the Tunisian Gulf of Cabes (Syrtis Minor), south of Algeria, which formerly received the discharge of the now dried up Igharghar, a river 780 miles long, and consequently longer than the Limpopo. Other cavities below sea-level follow in succession between the Great Syrtia and the Nile south of the plateau of Cyrenaica. At the foot of the Abyssinian highlands on the Red Sea coast are also found deep troughs, the surface waters of which have sunk to a level fur below that of the neighbouring inlets. In the southern section of the continent such maritime depressions do not occur.
Islands.
Africa is as poorly furnished with a complement of islands as it is with large inlets and orographic systems. In their submarine relief those in the Mediterranean belong rather to Europe than to this continent. Crete is connected with Asia Minor and with Greece; Sicily, Corsica, and Sardinia with Italy; the Balearic group by a submarine bank with the coast of Valcntia; Jerba alone and a few islets in the Gulf of Cabes and along the Mauritanian shores form parts of the northern seaboard. On the Atlantic side little occurs beyond some rocks and low-lying banks, such as the Bissagos or Bishlas Archipelago, which a slight alluvial deposit or upheaval of the land would suffice to connect with the continent. The more distant groups of Madeira and Porto Santo, the Canaries and Cape Verde Islands, are of volcanic origin, and separated from the mainland by abysses over 3,000 feet in depth. Of igneous formation are also the islets in the Gulf of Guinea, Annabom, Saint Thomas, Prince, Femando-Po, which form a chain of volcanoes all more recent than the neighbouring mainland.
The small groups in the Red Sea are mere coral reefs dominated here and there by a few volcanic peaks. Even in the Indian Ocean the only real African island is Socotra, the "spear-head" of the peninsula at present terminating at Cape Gardafui, and farther south Pemba, Zanzibar, and Mafia, disposed parallel with the coast. The Comoro Group is of volcanic origin, and Madagascar too far removed from Mozambique to be regarded as a dependency of the continent. Its nearest headland is 180 miles distant, and even this space is doubled for ordinary craft by the velocity of the intervening marine currents. Its flora and fauna also show that this great island belongs to a distinct geological domain. Geoffrey de Saint-Hilaire looked on it as a world apart, and most subsequent zoologists have regarded it as a fragment of "Lemuria," a vanished continent, which also embraced the granite groups of the Seychelles and Rodriguez as well as Ceylon and the Maldives, and may have even reached as far as Celebes in the Eastern Archipelago.
Climate.
Above all the great divisions of the globe, Africa is distinguished by the general regularity of its climatic phenomena, a circumstance due to its massive form and to its equatorial position. In the region approaching nearest to the northern or southern lines of the equinoxes, rain falls throughout the year, thanks to the opposing trade winds, which by neutralising each other often preserve the stillness of the atmosphere, and enable the local vapours to condense and precipitate themselves on the spot. In the northern hemisphere a zone of two wet seasons stretches from the equator to the fifteenth degree of latitude. In summer, copious rains are caused by the moisture-bearing south-west winds; in winter, those blowing from the north-west become in their turn the bearers of heavy rain-charged clouds to the southern hemisphere. But on both sides of the torrid zone, which comprises about seven-tenths of the whole continent, the difference in the disposition of the winds
Fig. 4. — Isothermal Lines of Africa.
Scale 1: 75.00,000.
causes a corresponding a in the rainfall. Here the trade winds maintain their normal direction constantly, or with but slight temporary deviations; blowing from the north-east in the northern, from the south-east in the southern hemisphere, they divert to the equator most of the vapours crossing their path, leaving elsewhere clear skies and arid lands. Thus it happens that Africa has two almost completely barren zones of rocks, gravels, marls, clay and sand — the Sahara and Libyan desert in the north, Kalahari and other wastes in the south. This symmetrical disposition of the climates is completed by the regular alternation of winds and rains in the zones of Mauritania and the Cape of Good Hope, both belonging to the region of sub-tropical rains, which fall in the respective winters of each hemisphere. Africa is thus disposed from north to south in successive grey and more or less intensely green belts, presenting to the inhabitants of the other
Fig. 5.—Disribution of the Rainfall in Africa.
Scale 1 : 7,500,000.
planets an aspect perhaps analogous to that offered to our gaze by the parallel cloudy zones round about Jupiter.
These different zones of moisture, whose limits coincide in several places with the isothermal lines, are developed across the continent with sufficient regularity to enable M. Chavanne to map them out. Africa is more sharply distributed in distinct regions by its deserts than it could have been by broad arms of the sea, and the distribution of its inhabitants has also been determined almost exclusively by the climatic conditions, depending everywhere on the abundance of rain and vegetation.
Flora and Fauna.
In its flora and fauna, as well as its climate and geology, North Africa belongs to the zone of transition between Europe and Asia. The apparent unity imparted to the continent by its compact form is not realised when we examine in detail the phenomena of life. Cyrenaica and the whole Mauritanian seaboard on the slope of the Atlas range belong to the vegetable domain of the Mediterranean, in which are also comprised Spain, Provence, Italy, the Balkan peninsula, the shores of Asia Minor, and Syria. The zone of the Sahara, which stretches under the Tropic of Cancer across the continent, is continued in Arabia to the Persian Gulf, and even through some of their rarer species embraces the Baluchistan coast, Thar, the Rann, and the Kathyawar peninsula in India. Lastly, the floras of Yemen and Hadraraaut resemble those of Sudan, the narrow Red Sea having been easily traversed by African species.
For the whole continent, the characteristic vegetable zone is that of Sudan and the equatorial regions, which stretches from sea to sea, and from desert to desert, between the Atlantic and Indian Oceans, between the Sahara and Kalahari. Speaking broadly, it is much poorer in distinct species than the other tropical regions, such as India and the Sunda Islands, and even than some sub-tropical lands, such as Asia Minor. Nevertheless certain central districts in Africa possess a remarkable variety of plants, as for instance, the territory watered by the Diur, not far from the dividing line between the Nile and Congo basins. Here Schweinfurth collected in five months nearly seven hundred flowering species, which it would be impossible to do in the richest European lands.
Most of the African tropical domain is exposed to the periodical rains, with long intervening periods of dryness. Hence arborescent vegetation nowhere displays greater exuberance and vigour than on the plains between the Congo and Nile, where the streams often disappear amid dense masses of foliage, and in the neighbourhood of the Bight of Benin, which enjoys far more humidity than the interior. A large extent of the zone of the Sudan is occupied by prairies, although some tracts are so overgrown with graminaceous and other herbs that animals refuse to penetrate into them. In the Nile marsh lands, certain andropogonous varieties have non-woody stalks over twenty feet high, affording to the giraffe cover from the hunter. The various graminaceous plants of Central Africa are not intermingled like those of the European fields, and tracts several hundred square miles in extent are sometimes occupied by a single species.
Thorny plants are relatively very abundant in the forests of the Sudan, and after clearances the trees appear not to spring up so rapidly in this zone as in South America. Varieties of the palm family are ten times more numerous in Asia and America than in Africa, which has consequently a wider range for its prevailing species. The equatorial regions of other continents have scarcely any cocoa-nut
- ↑ Ramsay; Zittal; Neumayr.
- ↑ Closed hydrographic basins o£ the African continent: —
North Africa. Sq. Miles. Basin of the Tsad, including the Fedé 730,000 „„Igharghar 330.000 Other basins and waterless spaces 1,345,000 South Africa. Basin of Lake Ngami 314,000 Other basins and waterless spaces 257,000