but there are no mountain systems like the Rockies and Andes in the two Americas, no wide fertile valleys like that of the Mississippi, no region like that of the Alps, where for scores of thousands of square miles mountain is piled on mountain. In general, Africa is a great tableland or plateau which in some places runs abruptly to the very coast, but in others leaves a narrow coastal plain. The average height of this plateau is 2,130 feet, but while in the southern part of the continent land less than 2,000 feet above the sea is unusual, except in the coastal plains, in the northern part land above that elevation is the exception. The line dividing the higher plateau regions from the lower extends roughly from Suakin on the Red Sea to the head of the Gulf of Guinea.

North Africa. It is in the lower northern part that there occurs the highest mountain range, the Atlas. This runs parallel to the Mediterranean coast and attains in its western half a considerable height, some of its peaks exceeding 14,000 feet. The coastward slope of these mountains is gentle, and plains occur at their base, but to the south they drop abruptly and at one point are bordered by a depression which is below sea level. The other outstanding highlands of North Africa are three: a north-and-south elevation along the shore of the Red Sea; a long ridge which runs from northwest to southeast across the center of the regions, and a comparatively low range at the head of the Gulf of Guinea. The one outstanding feature of the continent, more or less familiar to every child, is the great Sahara Desert, stretching from coast to coast excepting a narrow strip along the Nile River. This great barrier between the north and south is described in its proper place in these volumes.

South Africa. Though South Africa has not the largest mountain range, it has many high peaks, for Kenia and Kilimanjaro rise to heights over 18,000 and 19,000 feet. These are close to the equator and are old volcanic craters, but the Ruwenzori, which is a range rather than a peak and rises to a height of 16,800 feet, is of the folded variety of mountains that is, it is due to a lifting and bending of the earth's crust, and not to a heaping up of lava.

The most important highland of the whole continent is the so-called plateau of Abyssinia, which begins in the country from which it takes its name and extends far to the south until it ends in the Drakenburg Mountains. In this

great plateau there occur sharp furrows, or rift valley cracks left by some disturbance of the earth's surface in past geologic ages; and in these basins are found the great lakes.

Rivers and Lakes. Africa has five large rivers in the order of their length the Nile, the Congo, the Niger, the Zambezi and the Orange; and of these the Congo is second only to the Amazon among the rivers of the world in the volume of water it carries to the sea (see article on each river named). But these rivers, except the first named, have had no such effect on the history and commerce of the countries they traverse as have the Mississippi and the Saint Lawrence; for in common with other African rivers they have one great fault as waterways. Rising in the high plateaus, they drop down the successive terraces toward the coast in a series of waterfalls which make for picturesqueness and beauty but not for navigation. As the development of the continent goes on, however, under the guidance of Europeans, this difficulty is being surmounted in many places by the building of railroads about the falls.

The Zambezi is the only one of the great river systems which discharges its waters into the Indian Ocean, for the drainage of Africa, like that of most of the other continents, is into the Atlantic. However, about one-third of the vast territory sends no waters into the sea, and in this proportion of its interior drainage Africa surpasses all other continents except Asia. Much of this inward-flowing water finds its way into Lake Chad, in the Sudan-a large, shallow body of water which remains fresh despite the fact that, except in times of flood, it has no outlet.

This second largest of the continents, which boasts next to the largest river in the world, also possesses the largest fresh-water lake but one, for Victoria Nyanza is surpassed only by Lake Superior. It lies in the eastern part of the continent, and its northern boundary touches the equator. To the west of this great lake stretches a chain of smaller bodies of water which occupy one of the rift valleys and lie at a greater height above sea level than most other lakes of the world. These are Tanganyika, the longest lake in the world, and one of the deepest; Kivu Albert Edward Nyanza and Albert Nyanza. Other noteworthy African lakes are Tsana, in Abyssinia, Mweru, and Bangweolo, the last-named of which is little more than a morass except in the rainy

season.

Climate. North America stretches from well within the tropics to the Arctic Circle, and in consequence has a climate which runs through all degrees from torrid to frigid. Africa, on the other hand, lies almost wholly within the tropics, and has therefore a much more even temperature. And that temperature is almost uniformly high, for cooling sea breezes are shut out by the steep edges of the plateaus which everywhere border the coast. The variation in temperature throughout the year is not more than 20°, while North America has in many places a range three times that great. The extreme southern part of the continent is the only region which has not a tropical climate, though there are places farther north where unusual elevation assures pleasant climatic conditions.

Africa is deficient in rainfall, except in the regions bordering the equator. Here there are two seasons of especially heavy rainfall, though there is considerable rain every month in the year. Northward and southward from this belt it diminishes rapidly, and over portions of the Sahara no rain ever falls. In the south, too, there is a stretch of desert land, the Kalahari, but this is not so dry as the Sahara, having enough moisture to make it a profitable grazing

RAINFALL CHART

country. To the north of the Sahara and south of the Kalahari there is one rainy season during the year, and agriculture may be successfully practised. The surface structure of the continent has as much to do with its lack of rainfall as with its temperature, for moisture-bearing winds do not reach the interior. Indeed, so dry and hot are the winds which blow over parts of the continent that they absorb the moisture from the lands over which they pass and make them yet more arid.

The highest parts of the plateaus of Africa, as well as the more temperate northern and southern portions, are healthful for Europeans as well as for the natives; but the damp equatorial regions abound in fevers and are considered the most unhealthful places in the world. Even the natives in these parts are short-lived, for the fevers attack them as well

as the newcomers. In a few places improved sanitation has been introduced since the coming of the Europeans, and the result has been a markedly lower death rate.

Vegetable Life. The above account of the climate and rainfall tells the story of the vegetation as well. North of the Atlas Mountains conditions are much like those of Southern Europe, and the oak, olive, semi tropical fruits, and grains flourish. In Algeria and Tunis wheat is successfully raised, and Morocco has a region which offers like possibilities. In the time of the Roman

occupation, AFRICAN PHYSICAL MAP before the Chris

Showing vegetation zones.

tian era, this northern belt was the granary of the world.

South of the Atlas the slope is abrupt to the Sahara Desert, where the sandy, salty soil affords life to little except a few thorny shrubs. In the oasis, however, where buried springs come to the surface, there is a pleasing contrast, for grass, date palms and grain clothe the surface with green (see OASIS). To the south of the Sahara, as well as in the more southerly parts of the continent where there is one rainy season a year, lie the great savannas, or prairies, where grass grows luxuriantly and the baobab tree flourishes. It is on these savannas that the farms, whether for cattle and sheep or for ostriches, have been established. The temperate region of the south has many trees and flowers which grow nowhere else, for the Sahara Desert, stretching from sea to sea, is a barrier that cannot be crossed by plant forms.

Throughout most of the equatorial region, where rainfall is plentiful, there is a dense tropical forest. No other forests except those of the Amazon equal in size, in density, and in variety of trees that which extends almost across Central Africa. The vines and underbrush are so luxuriant that throughout much of this vast extent the sun seldom if ever penetrates to the ground. No one can even begin to estimate the wealth in timber, vegetable oils and other plant products hidden in this forest of giant trees.

Animal Life. As the climate and rainfall govern the vegetation, so the latter determines the distribution of animal life. It may be said in general, however, that Africa is the home of the largest members of the animal kingdom, some of which live there exclusively; and that, for the most part, all regions south of the Sahara, whatever their latitude, have about the same forms of animal life if their plant life is similar.

Northern Africa has much the same animals as Southern Europe, but south of the Sahara distinctive characters appear. Over the grassy savannas, which with their scattered forest areas afford shelter for such animals as feed upon the grass of the prairies, range the buffalo, the rhinoceros, the gnu, the zebra, almost 100 kinds of antelope, and the giraffe, which is peculiar to Africa. Where these grass-eating animals are to be found, there also are the flesh-eating animals which prey upon them— the lion, the panther, the leopard, the hyena and the jackal. Bears, foxes and wolves are found nowhere in Africa. Formerly elephants were very common in all parts of the continent, but they have been so persistently hunted for the ivory of their tusks that there is danger of their complete extinction. In the swamp and river regions are to be found crocodiles in large numbers, as well as the hippopotami, which live nowhere but in Africa.

It might seem that the great forests near the equator would furnish just the sort of homes that animals might desire, but one of the outstanding features of the life of the continent is the scarcity of life in these regions. Even the largest animals find the plant growth too dense, so these great tracts are given almost exclusively to reptiles, insects and the great monkeys, the chimpanzee and the gorilla, which are peculiar to Africa. Numerous other species of monkeys live in the less dense forests farther south, and on the southern savannas dwells the ostrich, which is to be found native nowhere outside of Africa. The reptile and bird life is abundant, many of the birds being characterized by their brilliant feathers. Song birds are not as common as they are in North America, and most of the gorgeous birds have but indifferent voices.

With the exception of the great journeys of exploration, discussed below under the subhead History, the most famous of African expeditions was that undertaken by Theodore Roosevelt in 1909-1910. It was purely scientific in its object and sent back to the Smithsonian

Institution (which see) a larger number of big game specimens than were ever before secured by any other single expedition.

More destructive by far than the great animals of Africa and far more important as a cause of the backwardness of the continent are the insects, which swarm everywhere. The white ants ruin frame buildings by hollowing out the timbers; the locusts make farmers poor by devouring the crops, and the tsetse fly has a bite which is fatal to dogs, horses and cattle, and which in some instances is believed to transmit sleeping sickness (see TSETSE FLY; SLEEPING SICKNESS). But perhaps the greatest pest of all is the mosquito, which spreads by its bite the tropical fever, and so makes large parts of the continent uninhabitable.

Mineral Wealth. When the mineral resources of Africa are referred to, diamonds and gold are at once brought to mind, and these are indeed the most valuable. The center of production for both lies within the Union of South Africa, the Transvaal ranking next to Australia and the United States in the production of gold, and Kimberley exporting nine-tenths of the world's supply of diamonds. See DIAMOND; GOLD; KIMBERLEY; SOUTH AFRICA, UNION OF; TRANSVAAL.

South Africa also bids fair to produce a large amount of coal when its resources are further developed; great deposits of tin have been discovered in Nigeria, and the Belgian Congo has opened copper mines which seem practically inexhaustible. Thus it may be predicted that when the "Dark Continent" is more thoroughly known it will prove to be one of the world's richest treasure houses of minerals.

The People. Broadly speaking, Africa's population, estimated at about 140,000,000, is made up of two races, the white and the black. It is not, therefore, strictly correct to use the term African as meaning the same as negro, as is so often done. But to eyes accustomed to looking upon the Caucasians of Europe and North America, the white men of Africa would not look white, for they have been burned by century after century of tropic sun. Indeed, the division between the two races is made according to the shape of head and features, and language, rather than according to color. North and east of the Sahara the white race is to be found; south of that barrier the black; and, as is natural, on the borderland between the two is a mixed race.

Just south of the white man's country, in a broad strip called the Sudan, are the most