Complete information on the location, profile, climate and natural vegetation of Africa

Africa stands second only to Asia in size. It occupies 22 per cent of the earth’s land area and straddles the equator on both the north and south. Most of Africa is an ancient plateau of what made up the Gondwanaland. The vast Sahara desert lies to the north. There are huge river basins, deep river valleys, spectacular waterfalls and rapids. The Great Rift Valley with its numerous lakes is a spectacular feature.

Till a new decades ago the continent was dominated by foreign colonists. Political and ethnic struggles have greatly hampered industrial and social development. Today all African nations have gained independence which brought with it democracy, education and a gradual development. Most of the continent is essentially rural and depends on foreign investment and aid even though it is rich in natural resources. It exports a huge part of its mineral wealth. All African nations are engaged in improving their agriculture and setting up industries. You will study about some African countries in detail. While the Democratic Republic of Congo (formerly Zaire) represents a typical Central Africa example, Nigeria in Western Africa is a fast developing country which lies partly in the equatorial forest and partly in the Savanna grassland.

South Africa in the far south of the continent is industrially very rich and has plenty of mineral resources. It is the most developed country of Africa. Two-thirds of its people are native Africans and only one-fifth are white Europeans. It was only recently that the non-white natives, got to enjoy their rights after a long struggle against the inhuman policy of racial segregation called ‘Apartheid’ – their struggle lasted over three decades.

The Arab Republic of Egypt is a part of the vast Sahara desert in North Africa. It owes its prosperity to the river Nile. It is a model of a densely populated river valley within a desert.

Exploration

A major part of Africa remained unknown to the outside world till the middle of the nineteenth century. The inhospitable climate, difficult terrain, dense impenetrable forests, the fear of dangerous wild animals and diseases were among the major causes for the isolation of this continent. As Africa remained unexplored and unknown for a long time, Europeans referred to it as the ‘Dark Continent’. It was only when explorers like Dr. David Livingstone penetrated in 1855 into the heart of the continent that the world came to know more about Africa. Today except for very remote deserts or forests, most areas in Africa have been explored, written about, filmed and studied.

Location

Africa is the world’s second largest continent. It has an area of nearly 30 million square kilometres. It lies to the south-west of Asia. Study the map 7.1 and note that the Red Sea separates it from Asia. Name the oceans that lie to the west, south and east of Africa. The Mediterranean Sea separates Africa from Europe. The continent touches Europe and Asia at three points : There is a strait in the north-west, a man-made canal in the north-east which cut the Isthmus of Suez and the straits of Bab-el-Mandab in the east. Locate all three joining points in the map and name the first two. The continent lies between the latitudes 37oN to 35oS. Other important latitudes that pass through Africa are the Equator, tropic of Cancer and t5ropic of Capricorn. Most of Africa lies within the tropics; its shape is such that it bulges in the north and narrows in the southern part so there is more land in the northern hemisphere than in the southern Longitudinally Africa stretches from 18oW to 52oE meridian. The prime meridian on 0o longitude passes through Western Africa.

Political Divisions

Africa seems to have the largest number of countries among all the continents of the world. Some of these are large while others are very small in size. Study the political map of Africa in and answer the following :

(a) Name the countries that face the Mediterranean Sea.

(b) Identify five land-locked counties (surrounded by land on all sides) located to the north of the equator.

(c) Which countries does the equator pass through ?

(d) List the countries that lie to the north of the Equator in the torrid zone.

(e) Which countries does the tropic of Capricorn pass through ?

Now arrange the names of all these countries in alphabetical order. Also make a note of the capital city of each country you have named.

Physical Profile

Study the map 7.2 and note that most of Africa is a large plateau ranging from 200 metres to 2000 metres above sea level. There is very little coastal plain around the plateau. The coastline is very regular (not jagged). The continent has the following physical divisions :

a) Plateaus and highlands

b) The Great Rift Valley

c) The deserts

The Plateau covers almost the entire continent. It is a part of the ancient Gondwanaland so it is made up of old hard rocks. It is higher in the south than it is to the north of the equator. The plateau surface is marked with hills and ridges. The Ahaggar Mountains and Tibesti Highlands are found in the centre of the Sahara Desert. The Ethiopian highlands in the north-east are small volcanic mountain ranges that radiate from a central knot. In the east there are number of volcanic peaks. Mt. Kilimanjaro in east Africa, is the highest of these peaks. Study the map 7.2 and find out its height. It is the cone of an extinct volcano and is snowcapped even though it is situated near the equator. Can you explain why ? Mt. Kenya, 5199 metres high, on the equator is another volcanic cone situated at the edge of the Rift Valley.

The Atlas Mountains in the north-west are a part of the young fold mountain system formed around only 50 million years ago when the Alps and Himalayas were formed. The Drakensberg in south-east Africa are very steep mountains. They are the uplifted edge of the plateau that covers peninsular Africa. Outpourings of volcanic rock have made them still higher.

The deserts are large sandy stretches. The Sahara Desert is the largest of its kind in the world. The Kalahari and Namib deserts lie to the south-west. Together the deserts cover one-third of the continent.

The Great Rift Valley is one of the special features of Africa. A rift valley is a long deep valley formed due to cracks or rifts in the land. Earth movements cause cracking, splitting and sinking of the earth’s surface. The low-lying area either fills up with water to form lakes or a river begins to flow through. The steep edges at the sides formed by the uplifted blocks are called block mountains or horsts. The Great Rift Valley of eastern Africa extents for a length of about 5000 kilometres from Lake Malawi northward through the lake Tanganykia and lake Rudolf to the Red Sea; then through the Gulf of Suez and Gulf of Aquaba to the Dead Sea. Other lakes that lie in the Rift Valley are lakes Kivu, Edward and Albert. Lake Victoria the largest lake in Africa, is outside the Rift Valley area.

Rivers

Nile is the longest river in the world. It has its source in lake Victoria. Find the names of the two tributary rivers that join river Nile. The river Zaire carries more water than the Nile because it rises in the central plateau and flows through the hot wet equatorial regions. In West Africa, the Niger is an important river. The famous Victoria Falls now known as Iguacu Falls are the highest in the world. They are on river Zambezi in Central Africa. They are also the most voluminous waterfall in the world. Rivers Orange and Limpopo drain the southern peninsula of Africa. Most of these, African rivers pass through high mountains and plateaus, so they make spectacular waterfalls before they flow into sea.

Climate and Natural vegetation

There are several factors that combine together to determine the climate of the African continent :

a) A tropical location ensures high temperatures all the year. In fact as a major portion of the land is within the tropics, Africa is said to be the most tropical of all the continents. The whole of North Africa is heated intensely; the Sahara desert has the highest temperatures in the would at this time. Al-Aziziah in Libya has recorded very high temperatures of 58o Celcius ! However it should be wrong to think that all Africa has a uniform climate.

b) The high altitude of the plateaus and highlands lowers the temperatures, so that they are much cooler than the lowlands.

c) The moderating influence of the oceans in the east, west and the Mediterranean Sea in the north is experienced by the narrow coastal strips. The oceanic influence cannot be carried far inland because of the high relief of the plateau.

d) The ocean currents such as the cold Benguela and Canary currents have a cooling influence on the north-western and south-western coast respectively. The warm Mozambique current raises the temperature of Africa’s south-eastern coast.

It must be remembered that north and south of Africa are in different hemispheres, so their seasons are different. Seasonal winds affect the distribution of rainfall. See Map 7.3 and note the various winds that are effecting the amount of rainfall. They are the North-east trade winds, westerly winds, the south-east trade winds and Monsoons. The Monsoons are seasonal winds that change their direction with a change in season.

On the basis of rainfall and temperature variations in Africa, five major climatic belts can be recognised. There is a close relationship between climate and natural vegetation in Africa (study maps of climatic belts and vegetation belt in Map 7.4 and 7.5 and note that similar climatic and vegetation belts are found on either side of the equator.

(a) Equatorial Climate is to be found in a belt 10oN to 10oS of the equator in the Congo basin and the coast of the Gulf of Guinea. In the plains, it is very hot and wet all year round. There is heavy convectional rainfall in this region. Intense heating of the land warms up the layers of air close to the ground. On heating, air expands and becomes lighter and rise upwards. These rising currents of air contain a lot of water vapour. In the process of rising they get cooled (temperature falls when we go up to higher altitudes). On cooling the water vapour in the air gets condensed and forms clouds. Towards evening, continuous condensation causes a heavy downpour accompanied usually by thunder and lightening. This is convectional rainfall. Tropical rain forests are found in such areas. Trees are tall and the forests are dense, varied and impenetrable. There are hardwoods like ebony and mahogany that provide timber. However, such forests are not fit to be exploited commercially. Can you explain why this is so ?

(b) The Sudan type of climate is found in a broad belt surrounding the zone of equatorial climate. Summers are warm and winters are mild. Most of the rain occurs in summer. There is a distinct dry period. Total rainfall is also lower than the equatorial regions. The region is covered with tall coarse grasses known as savanna. Apart from scattered acasia and tamarind, baobab is an important tree here. As rainfall is higher in the east coast it has forests instead of grasslands.

(c) Deserts are located to the north and south of the Sudan climatic belt. Which desert lies to the north ? Name the two deserts that lie in the south. These tropical deserts have very high temperatures all the year with almost no rainfall. The cold dry north-east trade winds bring no rain to the Sahara desert; the south-east trade winds also shed all their moisture before reaching the Kalahari desert and the adjoining Namib desert. It is very hot during the day and very cold at night. Summers are very hot while winters are bitterly cold. Vegetation is either wholly absent or some cact, scrub and thorny bushes grow. Date palms are found growing near isolated water points.

(d) Mediterranean Climate is experienced in the northern coast of Africa which lies facing the Mediterranean Sea and also at the southern tip of the continent. These areas are influenced by the westerly winds that bring mild rain in the winter season. Summers are hot and dry because in that season the north-east and south-east trade winds blow off-shore. Small evergreen shrubs and trees grow. Olives, figs and citrus trees like the lemon and oranges grow here. The vegetation is adapted to a summer drought.

(e) Warm Temperate Climate or China type of climate is found to the east of the Kalahari desert where the plateau is high and far from the sea. These are temperate grasslands called the ‘Veld’. The grass here is more luxuriant, short and juicy due to the cool moist climate. Warm temperate climate and the temperate grasses are also found in the Ethiopian Highlands. The area on the east-coast of Africa from Somalia to Mozambique has Monsoon Climate. Winds blow in from the sea to give more rain near the coast. The veld in south-east coastal areas of Africa has evergreen vegetation which gradually changes to temperate grass as we go west into the heart of South Africa.