East Africa is a subcontinent located in the east of the continent, uniting two physical and geographical countries: the Ethiopian Highlands and the Somali Peninsula and the East African Highlands (plateau). The region is elongated in the submeridional direction (between 18° north and south latitude). It begins in the north at the southeastern edge of the Sahara, in the west it has fairly clear orographically determined boundaries with the regions of North and Central Africa, in the south it is separated by a system of faults from similar structures in South Africa, reaching the tectonic valley of the lower reaches of the river. Zambezi. In the east, the subcontinent faces the Indian Ocean and its seas.
The subcontinent is located in the most tectonically active part of the African platform in the zone of development of a grandiose, complex system of continental rifts, unparalleled both in length and in amplitudes of vertical movements.
The East African rift zones occupy a special place in shaping the nature of the region. They are associated with relief features, mainly mountainous and plateau, widespread development of volcanism, including modern ones, and increased seismicity. Rifts are expressed as grabens, the bottoms of which are often occupied by lakes.
The region is within the equatorial monsoon zone of both hemispheres. A characteristic feature of its climate is the extreme differentiation of moisture conditions not only across seasons, but also within the territory. To a large extent, this depends on the fragmentation of the relief and configuration coastline.
- East Africa is distinguished by a great variety of soil and vegetation cover - from evergreen tropical rainforests on the windward mountain slopes to the desert landscapes of the Afar depression.
- Large areas are occupied by savannas of various types. Altitudinal zones are expressed in the mountains.
- East Africa is the main watershed of the continent. This is where the rivers of the basins originate Indian Ocean, Mediterranean Sea and the Congo river system leading to the Atlantic.
- The fauna of the subcontinent is very rich and diverse: all the main representatives of the fauna of the African savannas live here.
- East Africa is an area of fairly dense settlement and long-standing agricultural land use.
- The subcontinent has large mineral reserves. Due to human activities, the nature of the subcontinent has been significantly changed.
- East Africa is considered to be the ancestral homeland of man. Perhaps this is where the species Homo sapiens arose as a result of the evolution of ancient primates.
Ethiopian Highlands and Somali Plateau
This physiographic country includes the Ethiopian Highlands, the Afar Depression, the plateau and the coastal lowlands of the Somali Peninsula. In the west, the region borders on the White Nile Basin, in the south on the East African Highlands, in the north and east it faces the Red Sea, the Gulf of Aden and directly to the Indian Ocean. Its territory includes Ethiopia, Somalia and Djibouti; in 1993, Eritrea separated from Ethiopia.
As a result of active tectonic movements, a very diverse and even contrasting relief in height and shape was formed here. The main part of the region is occupied by the Ethiopian Highlands, which is a highly elevated block of the African Platform within the Eritrean Anteclise (Nubian-Arabian Arch), bounded by faults on almost all sides.
The height reaches 3000-4000 meters, the highest point is Ras Dashan (4623 meters). The steep stepped slopes of the highland make it difficult to access, which is why it is often called a bastion massif. Fissure eruptions of trachyte and basalt lavas occurred along fault lines. Covers were formed, with a thickness of up to 2000 meters in places. Stepped lava plateaus - ambas - are characteristic of the highland topography. Cut through in all directions by deep erosion-tectonic valleys-canyons, the ambas have the appearance of flat-topped remnants with individual volcanoes. Some of them were active in historical times. Faults define the shorelines of the Red Sea and Gulf of Aden, limit the zone of subsidence - the Afar depression. Its bottom, covered with lavas, consists of low plateaus with isolated volcanic cones. Some basins lie below sea level. Lake Assal is the lowest place on the African continent (-153 meters). The Ethiopian graben in the south separates the highlands from the plateau of the Somali peninsula; they descend in steps to the southeast to the Indian Ocean. The bottom stage is a wide, low-lying coastal plain. The eastern edge of the peninsula is also limited by a fault along which the ocean floor subsided.
In general, the climate of the country is subequatorial, variablely humid, but the fragmentation of the relief determines the diversity and contrast climatic conditions region. Local factors of climate formation play no less a role here than general patterns.
Precipitation is mainly associated with the summer equatorial monsoon in the southwest direction. Most of the moisture (1000 mm per year or more) is received by the windward southwestern and western slopes of the Ethiopian Highlands. The northern slopes are influenced by tropical air. They are dry. Most of the Somali Peninsula receives little precipitation (250-500 mm per year). Even along the Indian Ocean coast, the climate is arid as the southwest monsoon flows along the coastline. The driest areas are the Ethiopian Graben, the coasts of the Red Sea and Gulf of Aden, and especially the Afar Depression. The entire region, except for mountainous areas, is characterized by high air temperatures: average monthly - not lower than 20°C, maximum - up to 40-50°C. The Afar Depression is one of the hottest places: the average January there is 24°C, the average July is 36°C. The Ethiopian Highlands are much cooler. The altitudinal climatic zone can be traced here:
- colla belt (hot) - up to an altitude of 1500-1800 meters; average monthly temperatures - 20°C and above, precipitation on windward slopes - 1000-1500 mm per year;
- war-dega belt (moderate) - up to an altitude of 2400-2500 meters; slight seasonal temperature fluctuations: in December - no lower than 13°C, in April (the warmest month) - no higher than 16-18°C; precipitation - 1500-2000 mm per year;
- degas belt (cold) - on high mountain ranges; average monthly temperatures do not exceed 16°C, in winter there are severe frosts and snow falls; however, there are no glaciers.
Thus, the region combines dry and hot climates of the low plains, wet and cool climates of the highlands and plateaus, humid and hot climates of the Kolla mountain belt and the adjacent lowland areas.
The river network is well developed in the Ethiopian Highlands. Here originate one of the sources of the Nile - the Blue Nile, the right tributaries of the White Nile - Sobat and the Nile - Atbara, Omo. The Blue Nile carries twice as much water into the main river as the White Nile. Its flow is regulated by Lake Tana. There are small lakes at the bottom of the Ethiopian graben. On the Somali Peninsula, the river network is poorly developed, most rivers dry up, and in the Afar Depression there is practically no surface flow, there are only a few small salt lakes. The river flows into one of them. Awash flowing down from the highlands.
The complex structure of the relief and contrasts in climatic conditions determine the diversity of vegetation cover in the Ethiopian-Somali region. In the Ethiopian Highlands, altitudinal zonation is extremely pronounced.
On the humid western slopes in the colla belt and in deep valleys with good moisture, dense evergreen tropical forests grow, similar in species composition and structure to equatorial ones. The watershed plateaus are occupied by savannas. Thickets of thorny bushes and xerophytic woodlands dominate on dry leeward slopes. The war-dega belt was once dominated by forests of cedars and yews, which have been largely cut down. The thickets of tree-like juniper and open forests of deciduous trees - wild olive and fig tree - are better preserved. The main part of the belt is currently occupied by mountain savanna with candelabra-shaped milkweeds, umbrella acacias, giant sycamores and a rich grass cover of cereals. In the lower part of the degas belt, coniferous forests of junipers, podocarpus, etc. grow. Above, mountain meadows predominate - grasslands with groves of cousso trees and individual tree-like junipers. Even higher, thickets of giant St. John's worts, tree-like heathers, and communities of xerophytic bush grasses appear. The uppermost parts of the mountains are covered with rocky areas, which are covered with snow in winter. Semi-desert and desert vegetation is developed in the Afar Depression and on the coasts of the Red Sea, Gulf of Aden and Indian Ocean. The interior plateaus of the Somali Peninsula are dominated by desert savannah landscapes.
The fauna is common in savannas and tropical forests of Africa, including mountain ones.
In the war-dega belt there are monkeys that cannot tolerate constant heat - hamadryas, gverets, geladas. The fauna of the region has a relatively high degree of preservation even outside protected areas. Thus, elephants live in the forests of the lower mountain belt, and this is one of the few places where they do not live in reserves.
The Ethiopian Highlands have significant agroclimatic and land resources. Its territory as a whole receives sufficient rainfall for agriculture. Conditions for growing valuable crops and for the life of people are especially favorable in the war-degas belt with its relatively cool, constantly humid climate and fertile dark red and chernozem-like soils.
Most of the Ethiopian population lives here. This is one of the ancient centers of agriculture. They grow grain crops, tobacco, oilseeds, citrus fruits, and grapes. The name of the belt, translated from the language of local peoples, means “grape zone”. This belt is considered the birthplace of the coffee tree. In the south and southwest, coffee plantations rise to 2000 meters. Some grains also come from here - durum wheat, rye, barley, etc. Only some flat valleys are waterlogged, swampy and unfavorable for life. In the Kolla belt, with a hot, humid climate, the population is sparse, but in some places there are plantations of coffee, cotton, and sugar cane. Cattle breeding is developed in dry areas. Residents of the dega, a cold zone, also breed livestock (zebu, sheep, goats), and only in its lower part up to an altitude of 2800 meters do they grow the local cereal teff. At the lower border of this belt at an altitude of 2440 m is the capital of Ethiopia - Addis Ababa.
The arid areas of the Somali Peninsula are not suitable for agriculture. The population is concentrated in river valleys and oases, where tropical cash crops are grown on irrigated lands: bananas, sugar cane, cotton, date palm, and grains and legumes for their own consumption. The majority of the population is engaged in cattle breeding. In many places in the Afar, desert coasts, and interior parts of the Somali plateau, even the water in wells is brackish. There is practically no settled population there. In the arid areas of this region, well-preserved bone remains of animals have been found, including ancient primates, which are considered the ancestors of humans.
Large reserves of ore minerals are concentrated in the depths of the region. There is gold, platinum, ores of copper, nickel, manganese, iron, niobium, uranium and thorium. There are also deposits of piezoquartz, potassium and table salts, native sulfur, mica, and gypsum. But only a small part of this wealth is used.
The main problem in the region is the lack of water in many parts of it. There are severe droughts that cause famine. Drought in the 70s XX century in Somalia led to a huge decline in livestock and the death of large numbers of people. The fight against drought is one of the most pressing problems in the region. Despite the fairly good preservation of the fauna, many animal species have been severely exterminated and are even on the verge of destruction. Several have been created to protect them. national parks and reserves in Ethiopia and reserves in Somalia. They protect not only animals, but also typical and interesting landscapes, for example, in the Awash Park, where there are manifestations of volcanic activity. Palm forests around hot springs and riverine gallery forests are subject to protection.
East African Highlands
Most of this physical-geographical country is located in the Southern Hemisphere. In the north, the East African Highlands borders the Ethiopian along faults in the area of Lake Rudolf, and to the south it extends to the valley of the river. Zambezi. The western border with the Congo Basin follows the watershed between the rivers of the Congo and Great African Lakes basins. In the east the region faces the Indian Ocean. Within its borders are Kenya, Uganda, Rwanda, Burundi, Malawi, Tanzania and northern Mozambique. In many natural features, this physical and geographical country is similar to the Ethiopian Highlands. Tectonic mobility, fragmented relief, manifestations of ancient and modern volcanism, subequatorial climate with sharp internal differences, diversity of landscapes with the dominance of savanna formations determine the similarity of these regions. The rift zones of the East African Highlands are genetically related to the Ethiopian graben, which, in fact, is their continuation to the north. However, the region has a number natural features, distinguishing it from the Ethiopian-Somali country.
With no less tectonic mobility than in the Ethiopian Highlands, the areas of lava covers are not so large in the East African Highlands. There are volcanic massifs, often of considerable height: Kilimanjaro (peak Kibo - 5895 meters, the highest point of the mainland), Kenya (5199 meters), Meru (4567 meters), Karisimbi (4507 meters), Elgon (4322 meters), etc. Among the large ones and there are many active small volcanoes.
The highlands are located within the anteclise of the ancient African platform with outcrops of crystalline rocks, in places overlain by continental sediments and lava covers. In the Cenozoic, the rising arch of the anteclise was broken by rift faults. There are three branches of continental rifts. The Western Rift runs along the entire western edge of the highlands. Within its boundaries, a system of grabens has been formed - from the graben occupied by the river valley. Albert Nile, in the north, to the tectonic valley of the lower reaches of the river. Zambezi. Most of them are a chain of narrow, long and deep lake basins (the bottom of Lake Tanganyika lies more than 600 meters below sea level). Between them and along the sides of the grabens there are horst and arch rises with an average height of 1000-3000 meters. As a rule, active volcanoes are confined to them. Between lakes Albert and Lake Edward rises the Rwenzori (Mountains of the Moon) massif, reaching 5109 meters at its highest point - Peak Margherita. The entire zone is characterized by high seismicity. The central rift begins in the north with the basin of Lake Rudolf and in the south in the basin of Lake Nyasa it joins the western branch. Here a flat-bottomed valley formed in the graben ( Great Valley, or Rift Valley) with steep slopes (“rift shoulders”). At its bottom there are many small salt lakes. Within this zone, lavas erupted, and then the central type was formed, which, including the highest massifs of the highlands, rise along tectonic cracks. Calderas are also characteristic of this zone, including the famous Ngorongoro crater with a diameter of 22 km. The eastern fault zone descends in fault steps towards the Indian Ocean and determines the rectilinear contours of the coastline. The spaces between the rift zones are dominated by plateau relief, more or less leveled, with remnant mountains and hills.
The subequatorial climate of the highlands has its own characteristics.
In the southern part, winds with an eastern component dominate throughout the year, since the northeastern winter monsoon of the Northern Hemisphere does not change direction when passing through the equator, being drawn into the South African baric minimum. In the north, the southwest monsoon dominates in summer. Winter precipitation is orographic, so only the windward slopes of the mountains are irrigated. The humidity of different areas within the highlands is not the same. Highlands receive the greatest amount of precipitation (up to 2000-3000 mm per year). mountain ranges. In the northwest and southwest of the country and on the mountainous coast south of 5° south. w. 1000-1500 mm falls. In the rest of the highlands, annual precipitation is 700-1000 mm, and in closed depressions and in the extreme northeast - no more than 500 mm. Due to the general high hypsometric level of the East African Highlands, air temperatures in most of its territory are relatively low (monthly averages are not higher than 19-20°C). Only at low altitudes, mainly on the coast, they rise to 23-28°C. Annual amplitudes average monthly temperatures- up to 5-6°C. In the mountains above 2000 meters there are frosts, at an altitude of 3500 meters snow falls, the highest peaks (Kilimanjaro, Kenya, Rwenzori) have ice caps.
The East African Highlands - the “roof of Africa” - is the highest region of the continent and the main watershed of the Indian, Atlantic Oceans and Mediterranean Seas. The river begins here. Nile, from here numerous tributaries of the river flow. Congo (Lualaba), r. Zambezi, a large number of rivers flowing into the Indian Ocean. The Highlands are distinguished by one of the largest concentrations of lakes on Earth. The Great African Lakes, which occupy grabens in the Western Rift Zone, have an elongated shape and great depths (Tanganyika - up to 1435 meters). They are usually flowing and fresh. In a vast tectonic basin outside the rift zones lies the second largest freshwater body of water in the world - Lake Victoria. Large bodies of water from large lakes have a significant impact on local climates. At the bottoms of grabens in the Central Rift there are many salt lakes - Natron, Nakuru, etc.
Most of the highlands are occupied by typical savannas and woodlands.
In the driest northeastern regions, the same plant groups as on the Somali Peninsula (desert savannas) are common. The drainless basins of salt lakes are surrounded by salt marshes with halophytic vegetation. In the western regions with a humid climate, the lower slopes of the mountains and lake shores were occupied by hylaea, which are now replaced over large areas by mixed forests with an admixture of deciduous species and tall grass savannas. Altitudinal zones are expressed in the mountains. Among the belts, the “belt of fogs” with mountain hylea (2300-2500 meters) and the belt of mountain meadows with giant lobelias and tree-like groundsels stand out. The nival belt begins at an altitude of 4,800 meters.
Nowhere in the world is there such a diversity of large animals, especially the inhabitants of the savannas.
Antelope, buffalo, zebra, giraffe and other herbivores once densely populated the highlands. They were hunted by large predators (lions, leopards, cheetahs, etc.). There were many elephants, rhinoceroses, hippos, and various monkeys. Long-term extermination has caused a strong decrease in the number of animals, some of the species are on the verge of extinction. Countries in the region have created numerous National parks and reserves in which the number of animals is regulated. Among the world famous parks are Virunga, Kagera, Mount Kenya, Kilimanjaro, Serengeti, Ngorongoro (a natural “aviary” limited by the slopes of the caldera), Nakuru, where 370 species of birds live near the lake, including giant colonies of flamingos. Mountain gorillas live in the southern protected part of Kivu Park.
Scientific research is conducted in protected areas. The countries of the region receive substantial income from foreign tourists, who are attracted here by exotic fauna and flora, unusual landscapes, and the possibility of sport hunting under licenses
In addition to land, agroclimatic and biological resources, the East African Highlands has unique freshwater reserves concentrated in the African Great Lakes, which are used both for water supply and as transport routes, and as a source of fish. The subsoil of the region is rich: there is gold, diamonds, various ores, and salts are mined, including sodium carbonate - natron.
The region is populated quite densely, but unevenly. Most people live on the shores of fresh lakes. Maasai pastoralists roam the savannas of Kenya and Tanzania. Almost all landscapes of the East African Highlands have undergone anthropogenic changes.
That is why mountain-building processes on the continent are very poorly developed - young mountains grow only in the north of the continent.
More than 4/5 of Africa is occupied by plateaus. There are virtually no lowlands on the mainland. On the African-Arabian platform is located not only the mainland, but also Madagascar, Seychelles and the Arabian Peninsula.
The African highlands are located in the southeastern part of the continent. Average altitudes here exceed 1000 m above sea level. In this region, the African-Arabian plate rises somewhat.
The Ethiopian Highlands is located in southeast Africa. This part of the continent is called High Africa, it is here that the highest peak of the continent is located - Mount Kilimanjaro.
These areas are characterized by frequent earthquakes, which provoke eruptions of the Karisimbi and Cameroon volcanoes. Highlands are also found in the Sahara Desert, the highest of which are the Tibesti and Ahaggar highlands.
African mountains
On the coast of the Indian Ocean are the Cape and Drakensberg Mountains - their height decreases towards the center of the mainland. The Cape Mountains were formed during the Upper Paleozoic era.
The Cape Mountains region has a Mediterranean type of climate. The Cape Mountains are a striking example of regenerated mountains, which were formed on ancient destroyed mountain systems and inherited from them the folded structure that can be seen in the modern topography.
The highest peak of the Cape Mountains is Mount Kompasberg, whose height reaches 2500 m. In the north of the continent, as a result of the displacement of lithospheric plates, the young Atlas Mountains were formed.
These mountains are a continuation of the young mountains of Europe, which are located in the Gibraltar region. The length of the Atlas Mountains mountain ranges is 2500 km: they originate in the north of Morocco and stretch to Tunisia.
The highest peak of the Atlas Mountains is Mount Toubkal (4100m). Due to tectonic faults, earthquakes often occur in the Atlas Mountains region.
Lowlands of Africa
The lowlands of Africa occupy only 9% of its territory. The lowest point on the continent is salt Lake Assal, which is located on the territory of the state of Djibouti (Red Sea coast). Lowlands are also common in some countries of Central Africa.
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Africa is part of the world. Geography of African countries
Mining regions of Africa
Over the past decades, Africa has become one of the most largest producers of mineral raw materials.
Its share in the world mining industry is approximately 1/7, but in the production of diamonds, gold, cobalt, manganese ores, chromites, uranium concentrates, and phosphorites it is much larger. A lot of copper and iron ore, bauxite, oil and natural gas are also mined.
Let us add that Africa dominates the market for such “20th century metals” as vanadium, lithium, beryllium, tantalum, niobium, and germanium. Almost all extracted raw materials and fuel are exported from Africa to economically developed countries, which makes its economy very dependent on the world market.
This especially applies to countries such as Algeria, Libya, Guinea, Zambia, Botswana, where the mining industry provides more than 9/10 of all exports.
Africa has very favorable conditions for the development of the mining industry. natural prerequisites.
Its mineral resources are genetically associated, firstly, with the outcrops of the folded basement of the African platform, secondly, with sedimentary deposits of the cover of this platform, thirdly, with areas of Paleozoic, Mesozoic and Cenozoic (Alpine) folding, fourthly, with sedimentary sediments of foothill and intermountain troughs, fifthly, with lateritic weathering crusts and, finally, sixthly, with intrusions of igneous rocks.
In this case, for example, deposits of iron and copper ores can be found both in outcrops of the crystalline basement and in the cover of sedimentary deposits, and iron ore can also be found in the lateritic weathering crust.
It must also be borne in mind that the subsoil of Africa has not yet been sufficiently studied. In recent decades, prospecting and exploration have expanded and led to a significant increase in reserves of most minerals.
But nevertheless, many, especially deep, horizons in this sense remain “terra incognita”, which opens up prospects for new great geological discoveries - just as happened in the 1950-1960s. with African oil.
In total in Africa we can distinguish seven main mining regions.
Three of them are in North Africa and four in sub-Saharan Africa (Fig. 149).
Two of North Africa's mining regions predate World War II and have undergone further development in recent decades.
This is the region of the Atlas Mountains, where quite large deposits of iron, manganese, and polymetallic ores are associated with the mineralization processes that occurred during the Hercynian folding period.
But the main wealth of this area is the world's largest phosphorite-bearing belt, stretching along the southern slopes of the Atlas through the territory of Morocco, Algeria and Tunisia. The thickness of the phosphorite suite here reaches 80-100 m, and the total reserves of phosphorites (in terms of P205) amount to 22 billion tons, of which 21 billion are in Morocco. In terms of phosphorite production, this country is second only to the USA and China, and in terms of their exports it ranks first in the world.
The second mining region of North Africa is located in Egypt. Here, deposits of oil and natural gas, iron, titanium and other ores, phosphorites, rock salt and other fossil raw materials are associated with the sedimentary cover of the Nubian-Arabian massif and the rift basins of the Red Sea .
Rice. 149.
Mining areas in Africa
But, of course, the main mining region of North Africa is the youngest of them, located within the Algerian and Libyan parts of the Sahara Desert.
The territorial combination of mineral resources in it is much more limited and is represented in fact only by oil and natural gas, but in terms of the size of their reserves, production and the general role of the region in the world economy, it is far ahead.
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Physiographic characteristics of South Africa.
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High Africa. South Africa occupies the high part of the continent south of the watershed plateaus between the Congo and Zambezi river basins. The relief is dominated by plateaus and plateaus. The country is distinguished by a wide variety of landscapes due to sharp contrasts in humidity and topography of individual areas.
The main part is occupied by the South African Plateau, which is adjacent to the Cape Mountains to the south. The island of Madagascar forms a special natural area.
South African plateau lies within the Precambrian African Platform, occupying the Kalahari and Karoo syneclises. The Precambrian basement in the Kalahari syneclise lies shallow and in some places comes to the surface, forming protrusions and uplifts; The sedimentary cover is represented by horizontally lying continental deposits of the Upper Cretaceous and Cenozoic, mainly sandstones and sands (Kalahari formation).
The Karoo syneclise is a platform foredeep that arose in connection with the formation of the Cape mountain system; within its boundaries, the crystalline basement is deeply depressed and hidden under a thick layer of lagoonal sediments of Permian-Triassic age, mainly sandstones and shales (Karru formation); In some places these rocks are intruded by lavas.
Deposits of the Karoo Formation make up the southern and southeastern plateaus.
In terms of surface structure, the South African Plateau has much in common with the Congo Basin, but is located much higher. The central part of the plateau is occupied by plains Kalahari basins, lying at an altitude of 900-1000 m; Here on the surface there are red and white sands, hilly into low dunes.
The Kalahari Basin is surrounded on all sides by marginal plateaus and hills with numerous island outliers and mountains.
They gradually rise towards the outskirts to 1200-2500 m or more. The greatest width of the plateau is reached in the east and south of the region.
To the east are the Matabele and Weld plateaus, and to the south the Upper Karoo plateau.
Matabele Plateau lies between the Zambezi and Limpopo rivers. The plateau is composed of crystalline rocks; its surface is slightly hilly, there are separate island mountains. The marginal parts of the plateau are strongly dissected by river erosion and stand out sharply above the neighboring plains.
South of the Limpopo River is located Veld plateau. It consists of a series of stepped plateaus (High, Middle, Shrub and Low Veldt) descending towards the Kalahari Basin and the Limpopo River valley.
The plateau is composed of sandstones, shales and conglomerates of the Karoo formation, in some places intrusive and volcanic rocks.
Upper Karoo, located south of the Orange River, it closes the Kalahari Basin in the south, descending to it in several steps.
The plateau is composed of horizontally lying sandstones and shales, penetrated by numerous intrusions, forming remnant hills, sometimes sharp peaks.
In the west of the plateau, the strip of marginal plateaus narrows. The plateaus are composed of crystalline rocks and continental sediments. They are crowned by island mountains and remnant massifs, reaching their greatest heights in the Comas Plateau, where dislocated shales and quartzites are exposed.
The marginal plateaus of the South African plateau in the west, east and south drop steeply to the coastal plains and depression Great Karoo by the Great Escarpment, the outer slopes of which are deeply dissected by river erosion.
The Ledge reaches its greatest height in the east, in the Drakensberg Mountains. South part mountains - the Basuto Highlands, which has basaltic lavas, is the highest massif of the Kalahari ring frame. Its peak Thabana Ntlenyana (3482 m) is the highest in South Africa.
Adjacent to the marginal plateaus in the east is a vast Mozambican lowland.
It is composed of Cretaceous and Tertiary deposits and is broken up by tectonic fractures in the northern part. In the west of the plateau, the marginal plateaus break off to the coastal plain. Its section between the Kunene and Orange rivers is the Namib Desert. The desert stretches from north to south for more than 1,500 km, occupying a narrow strip of ancient crystalline peneplain, fragmented by faults.
The plateau lies in the subequatorial, tropical and subtropical climate zones.
However, tropical climate types predominate. In the summer of the Southern Hemisphere, a local pressure depression forms over the Kalahari.
The north of the region (up to the middle reaches of the Zambezi) is irrigated by the summer equatorial monsoon. The entire eastern part is influenced by the southeast trade wind, bringing humid tropical air from the Indian Ocean, heated over the warm Mozambique Current.
Heavy rainfall occurs on the Mozambican lowlands, the slopes of the Great Escarpment and the eastern marginal plateaus. To the west of the Great Escarpment and the marginal plateaus, marine tropical air quickly transforms into continental air and the amount of precipitation decreases.
The West Coast is under the influence of the South Atlantic Anticyclone, strengthened by the powerful cold Benguela Current. Atlantic air warms up over the surface of the continent and produces almost no precipitation.
On the western marginal plateaus there is a front between maritime Atlantic and continental tropical air; here the amount of precipitation increases slightly.
In the winter of the Southern Hemisphere, a local anticyclone forms over the plateau, connecting with the South Atlantic and South Indian baric maxima. Downward air currents cause the dry season; there is no precipitation.
The South African plateau is an area of relatively high temperatures, with significant daily and annual fluctuations. But on the plateau, temperatures are moderated by significant altitude. Above for the most part plateau summer temperatures are + 20-* + 25°C, not rising above +40°C; winter temperatures are +10 - + 16°C.
The Upper Karoo Plateau experiences frosts in winter, while the Basotho Highlands experience snowfall.
The plateau is an area of predominantly scanty precipitation, distributed very unevenly across its territory. Their number decreases when moving from the east and north to the west and south. In the north of the region, up to 1500 mm of moisture falls per year; here the rainy season, brought by the equatorial monsoons, lasts up to 7 months. A lot of precipitation falls on the east coast, where the barrier role of the Great Escarpment is especially pronounced.
Precipitation is brought here by the southeastern summer trade wind (more than 1000 mm per year, and on the slopes of the Basuto Highlands - over 2000 mm). The most frequent and heaviest rainfall occurs from November to April. On the eastern marginal plateaus, rainfall decreases on the Veld plateau (750-500) and Matabele (750-1000 mm). The summer maximum precipitation remains in the interior regions, but the annual amounts decrease.
On the central Kalahari plains, the rainy season is reduced to 5-6 months, and the annual precipitation does not exceed 500 mm. To the southwest, precipitation decreases to 125 mm per year. The driest part of the area is the coastal Namib Desert (less than 100 mm of precipitation per year). Little precipitation will fall on the western marginal plateaus (up to 300 mm per year).
The river network on the plateau is poorly developed.
Most of the channels of the Kalahari, western and southern marginal plateaus do not have permanent watercourses. The largest river is the Zambezi.
The region's large rivers, the Orange and Limpopo, collect their waters from the Matabele Plateau and High Veldt. The Okovango River is the main internal drainage system of the Kalahari Basin. During the rainy season, the Okovango Basin sometimes overflows with water, the excess flowing from Okovango to the Zambezi and the Makarikari Salt Flat.
The large size of the South African plateau, differences in relief and climate create a variety of landscapes.
South Africa has almost all the continent's landscapes.
Along with zonal differences, sectoral differences also appear.
The region has well-defined eastern humid oceanic, mid-continental and western relatively cool desert oceanic sectors. In the eastern sector, where there is a lot of precipitation, zones of seasonally wet forests alternate from north to south: subequatorial (up to 20° S), tropical (20-30° S) and subtropical monsoon.
On the slopes of the Drakensberg Mountains, the altitudinal zone of the forest-meadow type is well defined. Seasonally wet forests occupy the windward slopes up to an altitude of 800-1000 m. Above that, shrubs and mountain-valley, predominantly coniferous forests, meadows, and rocky areas appear; similar vegetation is characteristic of the Basuto Highlands (bush thickets, isolated trees, meadows and rocky areas).
In the middle continental sector (Kalahari Basin and marginal plateaus) natural zones of savannas, woodlands and shrubs of the subequatorial and tropical zones, tropical and subtropical semi-deserts, and subtropical mountain steppes are developed.
However, semi-desert landscapes dominate.
Lowlands, plains, plateaus
Rare vegetation consists of xerophytic grasses, shrubs and individual acacias, euphorbias, and aloe. The Kalahari are characterized by wild watermelons, the stems of which cover large areas.
In the western oceanic sector is the tropical desert Nami b. In its southern part, along the valleys of dry riverbeds and in places of shallow groundwater, quite dense vegetation of succulent shrubs and subshrubs, low-growing acacias and tough grasses is developed.
The most interesting plant in the northern part of the desert is the ancient relict of Welwitschia.
The South African plateau, with its wide variety of landscapes, has a rich and varied fauna.
But the number of wild animals has now significantly decreased, and many of their species are disappearing. The number of herbivorous animals - antelopes, zebras, giraffes - has especially decreased; predators have also been severely exterminated. Lions, leopards, and wild cats have almost completely disappeared; hyenas and jackals are more common. The largest reserve in the region is national park Kruger in South Africa. Almost all African animals are collected here.
Cape Mountains located in the extreme southwest and south of the mainland, between the mouth of the Olifants River in the west and the city of Port Elizabeth in the east.
They stretch along the coast for 800 km, their average height is 1500 m. They are separated from the Great Escarpment of the South African Plateau by the Great Karoo depression.
Folding processes here occurred from the second half of the Carboniferous to the second half of the Triassic, to which their main phases belong.
Therefore, the Cape Mountains are somewhat younger in age than typical Hercynian structures. They were subsequently destroyed and smoothed, and then rejuvenated by later uplifts.
The Cape Mountains consist of several anticlinal ridges that are blocky in nature. The ridges are separated by wide longitudinal synclinal valleys and narrow transverse gorges.
The main part of the Cape Mountains is the southern system of latitudinal ranges.
Here are the highest (up to 2324 m) and longest mountains of Zwartberg (Small and Large) and Langeberg, between which lies the intermountain Little Karoo plateau. To the east, the ridges decline and end in rocky headlands into the sea. In the extreme south they break up into small isolated ridges and massifs rising among the coastal plain. Another system of ridges stretches along Atlantic Ocean in a north-northwest direction.
In the southwest and south, the mountains approach the coast at an angle, indented by convenient bays.
The climate of the Cape Mountains is subtropical. In the southwest it is of the Mediterranean type, with rainy, warm winters and dry, hot summers. Temperatures are moderated by altitude and sea. In Cape Town, the average temperature in January is + 21 ° C, in July + 12 ° C. The rains begin in April, are heavy from June to September, and then stop as humid westerly winds give way to winds from subtropical anticyclones.
In winter, snow falls on the mountain tops. In the western part of the mountains, on their windward slopes, the greatest amount of precipitation falls (up to 1800 mm per year). To the east their number decreases to 800 mm. East of 22°E. In the precipitation regime, the typical features of the Mediterranean climate disappear, and the summer maximum begins to predominate due to the penetration of humid oceanic monsoons onto the mainland.
On the coastal plain there is little precipitation (in Cape Town - 650 mm per year). The climate of the inner parts of the mountains is subtropical continental.
The Cape Mountains are covered mainly by Mediterranean type vegetation with a predominance of evergreen hard-leaved shrubs and herbaceous perennials.
The landscapes here have much in common with the Atlas Mountains. They are also characterized by brown (typical and leached) and mountain-forest brown soils.
However, the floristic composition of the vegetation is different, specific to the Cape flora. Very characteristic times
personal heathers, proteas, pelargoniums, mesembryanthemums, aloe, cactus-like euphorbias, fatworts, etc. Interesting are the Cape nightshade with yellow poisonous fruits, the silver tree with silvery fluffy leaves, the Cape water lily with red flowers, wild watermelon, etc.
There are few trees among the Cape flora. The predominant species are evergreen shrubs and perennial grasses.
Thickets of evergreen hard-leaved shrubs form the fynbos formation (an analogue of the Mediterranean maquis), which arose on the site of cleared forests that previously covered the mountain slopes.
Fynbos includes members of the Proteaceae (including silverwood), Ericaceae, Legumes, Campanaceae and Rutaceae families.
Forests have survived only on inaccessible, well-watered mountain slopes.
In the west, in deep and inaccessible valleys, you can find a few groves of southern conifers (podocarpus, etc.), in the east, on the slopes of the mountains, there are dense monsoon mixed forests, consisting of coniferous and evergreen deciduous trees (laurel olive, cape beech, etc. .) trees. Palm groves grow in the coastal lowlands.
Vast areas in the Cape Mountains are covered with grasses with a predominance of bulbous, tuberous and rhizomatous forms from the family Amaryllis, Iris, Orchids and Lamiaceae.
Characteristic are immortelle, cineraria and other Compositae. On especially dry and hot leeward slopes and in depressions, semi-desert landscapes with succulent shrubs and subshrubs are developed. In the Little Karoo depression, thickets of acacias and aloe are common along the rivers; in other parts the vegetation is represented by rare shrubs
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These are humid forests with a dense network of deep rivers. The eastern part stands out as sublime, the southern part as endless.
North Africa- the most extensive part of the continent. It is based on the plate of the African-Arabian ancient platform. The prevailing relief is plateaus and hills 300-400 m high. Between them rise the rocky highlands of Ahaggar, Tibesti, Darfur, Jos, formed on the crystalline shields of the ancient platform. In the northwest, the folded Atlas Mountains adjoin the platform.
Atlas Mountains- a mountainous country consisting of a system of mountain ranges, intermountain plateaus and depressions. Here, on the coastal plains and windward slopes of the mountains, there are dry, hot summers and mild, wet winters, while on the intermountain plateaus and internal slopes of the ridges it is arid and harsh due to the high altitude. The nature of Atlas has been greatly changed by man.
The world's largest tropical desert, its length is 6,000 km from west to east and 2,000 km from north to south. It owes its existence to a continental tropical climate with precipitation less than 50 mm per year and high temperatures.
Due to the different composition of rocks, different types of deserts are formed here: rocky-gravelly, pebble, sandy, clayey. Sandy deserts with dune topography occupy only about 20% of the Sahara.
There is almost no surface water in the Sahara. The only large one crossing receives food outside its borders.
Sudanese plains lie south of the Sahara. They are located in the subequatorial climate zone. The duration of the rainy season decreases from south to north from 10 to 2 months. There are many rivers in the western and eastern parts of the Sudanese plains. The largest of them are the White Nile. The central part of the plains is an area of lake, which changes its size and shape depending on precipitation.
The natural conditions of the Sudanese plains are the most favorable for human life. The population has long been engaged in cattle breeding here.
Central Africa covers the Gulf of Guinea coast and basin. The equatorial climate prevails here and there is a dense network of deep rivers.
The northern coast of the Gulf of Guinea is formed by hills and plateaus, descending in steps to the coastal lowlands. In the east of the area there is an active volcano (4100 m). On its slopes facing the bay, a record amount of precipitation falls for Africa - 9000 mm per year. The largest river, the Niger, forms a large delta when it flows into the Gulf of Guinea. Nature has been greatly altered by humans, since the area has a long history of development and high population density.
The central part of the Congo Basin is occupied by humid equatorial forests. They consist of hundreds of species of trees, vines, shrubs and grasses. Diverse and animal world: okapi dwarf giraffes, water deer, elephants, hippos, various monkeys, birds. Along the coast of the Gulf of Guinea, forest areas have been greatly reduced due to logging and burning, giving way to open forests and savannas or plantations of tropical crops.
South Africa located south of the watershed of the Congo and Zambezi rivers. divided into three natural regions.
The South African Plateau is a system of plateaus formed by the outcroppings of the platform's basement. The plateau rises towards the outskirts of the continent, and in the internal parts there are depressions. Among them, the largest is. In the southeast, the Drakensberg Mountains adjoin the plateau. The plateau is located in, but the temperatures here, due to the significant altitude, are not as high as in North Africa. Natural areas in accordance with the decrease in precipitation, they change from east to west. In the east, tall grass savannas are common. These are beautiful pastures and fertile plains. Acacias, aloe, euphorbia, and herbs with powerful rhizomes grow here, blooming brightly during the rainy season. To the west, desert savannas predominate, occupying most of the Kalahari. In the Kalahari there are barren rocky areas. On the coast washed by cold currents is the Namib Desert.
There are few rivers with permanent water flow, only navigable. The majestic one is located on it. On South African plateau rich fauna. In many areas, hunting is the main occupation of the population.
Cape Mountains- These are low and medium-height ridges, approaching the coast indented with convenient bays in the southwest of the mainland. Subtropical and shrubland with a large number of endemic species grew here in the past. From here, a variety of ornamental plants spread throughout the world. However, almost no natural vegetation has been preserved.
Madagascar- an island region, the relief and climate of which have much in common with the relief and climate of neighboring areas of the mainland. The organic world is characterized by great originality due to its long development in isolation. Among wild animals there are almost no ungulates and predators, poisonous snakes,
East Africa- the highest part of the continent, called the “roof of Africa”. There are two natural areas here -
East Africa is a densely populated area, and land has been used for agriculture for a long time. In the Ethiopian Highlands, the belt of mountain savannas up to an altitude of 2.5 km is most favorable for human life. This belt is considered the birthplace of the coffee tree, durum wheat, rye, barley and some other cultivated plants.
Nowhere in the world is there such a diversity of large animals as in East Africa. However, long-term extermination has caused a decrease in their numbers, so national parks have been created in many countries. Kagera, Mnunt-Kenya, Serengeti, and Kivu are world famous. The exotic nature and the possibility of sport hunting attract a large number of foreign tourists to the parks, which brings income to the countries of the area.
Geographical position
Note 1
The East African Plateau is a territory located on both sides of the equator, between the Somali Peninsula, the Ethiopian Highlands, Eastern Sudan in the north and the lower Zambezi in the south and between the Indian Ocean in the east and the Congo Basin in the west. The plateau lies from 5° N. w. to 17° south w.
The East African Plateau is a tectonically active, mobile part of the African Plate. This is where they are highest points continent of Africa and the largest rift system. The platform consists of Precambrian crystalline rocks, mainly granite. The foundation is covered by Mesozoic and Paleozoic continental sediments.
Figure 1. East African plateau. Author24 - online exchange of student works
The plateau has been elevated for a long time. Rifts and tectonic faults arose in the Cenozoic. They are a continuation of the Ethiopian Highlands, the Red Sea grabens, to the south of Lake Rudolph they branch and form three fault systems: central, western and eastern.
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Rifts are narrow depressions with steep stepped slopes. Along their periphery there are high mountain systems: Rwenzori massif, volcanoes Kenya, Kilimanjaro, Elgon, etc. Currently, volcanic activity continues along the faults.
Areas not affected by faults have the appearance of a peneplain with island mountains.
On the East African Plateau there are vast basins, one of which contains Lake Victoria.
Fault systems of the East African Plateau
The following fault systems are distinguished in the East African Plateau:
- The western fault system stretches along the western regions of the plateau. It consisted of deep grabens occupied by lakes Edward, Albert (Mobutu-Sese-Seko), Tanganyika, Kivu, and the Albert Nile River valley. From Tanganyika, this fault system stretched through the tectonic basin of the island. Nyasa, the depression with Lake Rukwa, the valley of the Shire River, the lower reaches of the Zambezi. This territory is one of the most seismically active zones of the continent. The grabens of lakes Edward and Albert separate the Rwenzori massif. The massif includes crystalline schists, gneisses, and intrusions of basic rocks. Rwenzori has glacial forms of Quaternary and modern glaciation (circles, cirques, terminal moraines, trough valleys). Between the grabens of lakes Kivu and Edward is the Virunga volcanic region, which is home to seven volcanoes. Currently, new volcanic cones continue to form. Between the depressions of lakes Tanganyika and Kivu there is a tectonic trough covered with ancient lavas. At the bottom of lakes Nyasa and Kivu, constant volcanic eruptions occur. Between lakes Victoria, Albert, Edward and the White Nile basin there is the Lake Plateau (1000-1500 m), composed mainly of crystalline rocks. In the central part of the plateau is Lake Kyoga and a swampy valley.
- The central fault system is an extension of the Ethiopian Graben, which runs north to south from Lake Rudolph to Lake Nyasa, where it joins the western fault system. In the northern regions within the boundaries of the Kenyan volcanic plateau, volcanic relief is clearly visible. The extinct volcanoes Elgon, Kenya, Kilimanjaro, and a group of giant craters (Ngorongoro volcano) rise along tectonic cracks covered with tuffs and basalts.
- The eastern fault system is characterized mainly by unilateral faults, which limit the narrow coastal lowland to the west with scarps. The lowland is composed mainly of limestones and tertiary sandstones.
Between the central and western fault systems, between lakes Nyasa and Victoria, the Unyamwezi plateau is located. The plateau is heavily swamped and composed of granites. To the east are the Masai and Nyasa plateaus.
Climatic conditions
The climate of the East African Plateau is subequatorial. It is variablely humid, hot, with clearly defined zonality on high mountain ranges. On the Lake Plateau and in the vicinity of Lake Victoria, the climate is close to equatorial, which is proved by the precipitation regime, its quantity, and the even temperature variation.
The plateau is dominated by equatorial monsoons and trade winds. In winter (in the Northern Hemisphere), the northeast trade wind blows, which over the Kalahari is drawn into a pressure depression. Passing from South-East Asia to Africa over the ocean, it releases small amounts of precipitation. In summer, the southeast wind intensifies, the south trade wind, which passes through the equator, takes on the character of a southwest monsoon.
High temperatures are observed along the Indian Ocean coast and at low altitudes. The average temperature in January (the warmest month) is +28 °C, in August (the coldest month) - +23 °C. Temperatures decrease with altitude, but annual rates remain uniform. At an altitude of more than 2000 m, temperatures can drop below 0 ° C, and above 3500 m snow falls. There are small glaciers on the highest mountain ranges - Kilimanjaro, Kenya and Rwenzori.
Precipitation on the territory of the East African Plateau falls unevenly:
- 2000-3000 mm - high mountain areas;
- from 1000 to 1500 mm - the coast of the Indian Ocean, northwest and southwest of the plateau;
- 750-1000 mm – central areas plateaus;
- 500 mm and less – closed depressions and the territory of the extreme northeast.
The driest region of the East African Plateau is Kenya. Here periods without precipitation can last up to 7-9 months.
The equatorial precipitation regime can be observed between 5°N. w. and 5° S. w. For these territories, there are two rainy seasons (November-December, March-May) and two periods of decreased precipitation. IN southern regions There is one rainy season, lasting from October to April, followed by long, dry weather.
The East African Plateau separates the basins of the Mediterranean Sea and the Indian and Atlantic oceans.
In the north-west of the plateau, the Nile River originates, the system of which includes lakes Kyoga, Victoria, Edward and Albert. Lakes Kivu and Tanganyika belong to the Congo system, and Lake Nyasa drains into the Zambezi. In the central part there are many endorheic lakes: Rukwa, Rudolph, Baringo, etc. In terms of their size, depth, influence on the climate and flow of the lakes, the plateaus can be compared with the Great Lakes of North America.
The diversity and diversity of landscapes is determined by: the diversity of relief, tectonic fragmentation, and the diversity of climatic conditions. In the interior there are many typical savannas, with large tracts of shrubs and woodlands that shed their leaves in the dry season. The vegetation is represented by cereals, mimosas, acacias, tamarisks, baobabs, etc.
The East African Plateau is located on both sides of the equator, between the Congo Basin in the west and the Indian Ocean in the east, Eastern Sudan, the Ethiopian Highlands, the Somali Peninsula in the north and the lower reaches of the Zambezi in the south and covers the area from 5° N. w. to 17° south w.
The plateau is a mobile, tectonically active part of the African Plate. The greatest rift system and highest altitudes mainland. It is composed of Precambrian crystalline rocks, among which granites are widespread. The ancient foundation is covered in places by Paleozoic and Mesozoic, mainly continental sediments.
The plateau remained an elevated area for a long time. In the Cenozoic, enormous tectonic faults and rifts arose. They continue the grabens of the Red Sea and the Ethiopian Highlands and branch south of Lake Rudolf, forming the western, central and eastern fault systems. Rifts are expressed in relief as narrow depressions with steep stepped slopes; along their edges rise high mountain ranges (Rwenzori massif, volcanoes Kilimanjaro, Kenya, Elgon, etc.). Volcanic activity along the faults has not ended to this day. Areas not affected by faults have the appearance of a typical peneplain with island mountains. The plateau also contains extensive basins (Lake Victoria).
Western fault system runs along the western edge of the plateau and includes deep grabens,
occupied by the Albert Nile River valley, lakes Albert (Mobutu-Sese-Seko), Edward, Kivu, Tanganyika. From Lake Tanganyika it stretches through the depression with the endorheic Lake Rukwa, the tectonic basin of Lake Nyasa, the Shire River valley and the lower reaches of the Zambezi. Fault tectonics is especially evident here. This is one of the most seismic zones of the continent and an arena of modern volcanism.
The grabens of lakes Albert and Edward are separated by the Rwenzori horst massif, the most high peak Africa (5119 m) after Kilimanjaro (5895 m) and Kenya (5199 m). The massif is composed of gneisses, crystalline schists and intrusions of basic rocks, has glacial forms of Quaternary and modern glaciation (kars, cirques, trough valleys, terminal moraines), giving an alpine character to the relief of its peaks.
Located between the grabens of lakes Eduard and Kivu Virunga volcanic region(seven volcanoes). Here besides active volcanoes New volcanic cones are also formed. Ancient lavas cover the tectonic trough between the depressions of lakes Kivu and Tanganyika.
Underwater volcanic eruptions occur at the bottom of lakes Kivu and Nyasa
Adjacent to the northern segment of the western fault system from the east is Lake Plateau(Uganda plateau), located between lakes Edward, Albert, Victoria and the White Nile basin. The plateau has an undulating surface, is composed mainly of crystalline rocks and reaches a height of 1000 to 1500 m. The central part of the plateau is swampy
186 Africa. Regional overview
plain with Lake Kyoga. The plateau ends with stepped slopes towards the East Sudanese Basin, and in the east it joins the volcanic plateau of Kenya.
Central fault system serves as a continuation of the Ethiopian graben, running in a meridional direction from Lake Rudolf in the north to Lake Nyasa in the south, where it meets the western fault system.
In the northern part of the central faults, within the volcanic plateau of Kenya, the volcanic relief is especially pronounced. The extinct volcanoes Kilimanjaro, Kenya, Elgon and a group of giant craters rise along tectonic cracks, the edges of which are covered with basalts and tuffs. Among the group of giant craters stands out the Ngorongoro volcano with a huge caldera.
Between the western and central fault systems, on the one hand, and lakes Victoria and Nyasa, on the other, there is Unyamwezi plateau. It is composed of granites and is very swampy. To the east are the Nyasa and Masai plateaus. These are peneplains on a granite base, broken by faults and crowned with rounded crystalline outlier peaks.
Eastern fault system is represented predominantly by one-sided faults. They limit with ledges from the west a narrow coastal lowland, composed mainly of permeable Tertiary sandstones and limestones.
The climate of the East African Plateau is subequatorial, hot, variable-humid, with a clearly defined climatic zone on high mountain ranges. Only in the vicinity of Lake Victoria, on the Lake Plateau, does it approach the equatorial
rial both in terms of the amount and regime of precipitation, and in the even course of temperatures, which, however, due to the high altitude of the area, are 3-5 ° C lower than the average monthly temperatures of the equatorial strip in the Congo Basin.
Within the plateau, trade winds and equatorial monsoons dominate. During the winter months of the Northern Hemisphere, the northeast trade wind, without changing its direction, is drawn into a pressure depression over the Kalahari. Passing over the ocean from Southeast Asia to Africa, it is moistened and produces a small amount of precipitation, mainly orographic. In the summer of the Northern Hemisphere, the south trade wind (southeast wind) intensifies; crossing the equator, it takes on the character of a southwest monsoon. The main wet period is also associated with them; most precipitation falls on the windward slopes of the mountains.
High temperatures are observed only at low altitudes, especially along the Indian Ocean coast. In Dar es Salaam, for example, the average temperature of the warmest month (January) is +28 °C, the coldest month (August) is +23 °C. It becomes cooler with height, although the annual cycle remains uniform. In the mountains at an altitude of more than 2000 m, the temperature is below 0 ° C, snow falls above 3500 m, and on the highest massifs - Rwenzori, Kilimanjaro and Kenya - there are small glaciers.
The moisture content of different parts of the East African Plateau varies. High mountain ranges receive the greatest amount of precipitation (up to 2000-3000 mm or more). From 1000 mm to 1500 mm of precipitation falls in the north-west and south-west of the country, as well as on the Indian coast
East African plateau 187
ocean south of 4° S. sh., where the mountainous meridional coast delays moist winds from the Indian Ocean. In the rest of the plateau, 750-1000 mm of precipitation falls per year, decreasing in the extreme northeast and in closed depressions to 500 mm or less. Kenya is the driest region of the plateau, with a long rainless period of 7 to 9 months.
For territories located between 5° N. w. and 5° S. sh., is characterized by an equatorial precipitation regime, with two rainy seasons (March-May and November-December), separated by two periods of relative decrease. To the south they merge into one rainy season (from October-November to March-April), followed by a dry period.
The East African Plateau occupies a watershed - a position between the basins of the Atlantic, Indian Oceans and the Mediterranean Sea. In the north-west of the region, the Nile originates, the system of which includes lakes Victoria, Kyoga, Albert and Edward. Lakes Tanganyika and Kivu belong to the Congo river system; Lake Nyasa drains into the Zambezi. In the central part of the plateau there are endorheic lakes (Rudolph, Ruk-va, Baringo, etc.). In terms of size, depth, influence on flow and climate, the lakes of the plateau are comparable to the Great Lakes of North America.
The tectonic fragmentation of the plateau, the diversity of relief and climatic conditions determine the diversity and variety of landscapes. Inland areas are dominated by typical savannas with fairly large tracts of woodlands and shrubs that shed their leaves during the dry season. The vegetation consists of cereals, acacias, mimosas, baobabs, tama-
risks, milkweed, etc. Red-brown soils are developed under typical savannas and open forests on the plains, black tropical soils are developed in poorly drained relief depressions, and young brown tropical soils are found on basic volcanic rocks.
In the arid northeastern regions (Kenya plateau, north of 2°-3° N latitude), desert savannas and thickets of thorny shrubs of xerophytic acacias, leafless for most of the year, are developed on red-brown soils, sometimes turning into semi-desert. Similar and drier landscapes characterize deep depressions the central system of faults, where drainless lakes are half-filled with sand, covered with a crust of salts, and surrounded by salt marshes with halophytic vegetation.
The northern part of the coastal lowland off the coast of the Indian Ocean also has sparse, semi-desert vegetation. In the southern part of the lowlands, semi-deserts give way to savannas, red-brown soils give way to red ones; Mixed deciduous-evergreen forests appear along rivers and on the windward slopes of mountains. There are mangroves along the coast.
In heavily moist areas
widespread humid equatorial
forests on red-yellow soils and
mixed deciduous-evergreen-
new ones - on red soils. They are mostly cut down and replaced by secondary formations - wet tall grass savannas. Evergreen and mixed forests are found mainly in the west (Lacustrine Plateau), where they meet the hylaea of the Congo Basin, as well as on the windward moist slopes of the high mountain ranges.
188 Africa. Regional overview
