African plains. African relief and minerals. Landforms of Africa

", "mineral resources". They are considered in the physical and geographical characteristics of a region.

Definition 1

Geological structure - this is the structure of the site earth's crust, features of the occurrence of rock layers, their mineralogical composition, origin.

When studying the geological structure of continents, the concepts “platform” and “folded area” are encountered.

Definition 2

Platform is a large, relatively stationary section of the earth's crust.

The platform underlies every continent. In relief, the platforms correspond to plains.

Definition 3

folded area - a moving section of the earth’s crust where active mountain-building processes take place (earthquakes, volcanic eruptions).

In relief, folded areas are represented by mountain systems.

Definition 4

Relief is a collection of irregularities on the earth's surface.

Definition 5

Minerals - these are the riches of the earth's interior that can be used by man to satisfy his needs.

Features of the geological structure of Africa

About $180$ million years ago, the territory of Africa was integral part ancient supercontinent Gondwana. When Gondwana broke apart, the African lithospheric plate separated. At the core modern territory Africa lies part of this plate, namely the ancient (Precambrian) African-Arabian platform .

In most of the territory, active mountain formation ceased $1000–$500 million years ago. Later, the rigid skeleton of the continent did not experience folding processes.

The lower part of the platform, that is, its foundation, consists of crystalline rocks - basalts and granites , having igneous and metamorphic origin. They are very ancient in age. Continental sediments accumulated on the foundation due to weathering, and marine sediments accumulated in depressions. Over millions of years, they formed a thick sedimentary cover on the platform. It should be noted that the sedimentary cover unevenly covers the foundation, because over a long period of time the platform experienced several slow uplifts and subsidences. In those areas where a long process of uplift took place, ancient crystalline basement rocks ended up on the surface, forming shields.

Definition 6

The shield is where the crystalline foundation of the platform emerges to the surface.

In other areas of the platform, processes of subsidence and flooding by the waters of ancient seas occurred. In these places, the foundation was covered by a huge thickness of marine sediments, and slabs formed in such areas of the platform. Millions of years later, the platform in its northwestern and southern parts was “completed” with parts of the ocean floor, while the thickness of its sedimentary rocks crumpled into folds and formed folded areas (region Atlas and Cape Mountains ). More than $60 million years ago, the African-Arabian Plate began to rise intensively. This rise was accompanied by giant faults in the earth's crust. During these faults, the largest system on land was formed East African faults (rifts) . It stretches for $4000$ km from the Isthmus of Suez along the bottom of the Red Sea and overland to the Zambezi River. The width of the rifts in some places reaches up to $120$ km. The above faults, like a knife, cut through the African-Arabian platform. Along them there are earthquakes and manifestations of volcanism.

Relief of Africa

The topography of Africa is dominated by flat areas. This is due to the fact that almost the entire continent is based on a platform. A feature of the African plains is the predominance of high plains:

hills,
plateau,
plateaus.

This can be explained by the general uplift of the entire territory of Africa in the Cenozoic. The lowlands extend only in narrow strips, mainly along the sea coasts.

The largest plains are located in the northern and western parts of the mainland. Their surface is very heterogeneous. At the same time, characteristic of Africa is the alternation of highlands with lowlands and plateaus. In places where crystalline basement rocks reach the surface, they rise Ahaggar and Tibesti highlands , with a height of more than $3000$ m. Among the high plateaus (up to $1000$ m) lies the swampy depression of the Congo. The Kalahari Depression is also surrounded on all sides by plateaus and plateaus.

A relatively small area in Africa is occupied by mountains. Has the highest marks East African plateau . It contains extinct volcanoes Kenya ($5199 m) and Kilimanjaro ($5895 m) – the highest point in Africa.

These volcanic mountains are confined to the East African Rift Zone. Ethiopian Highlands with numerous extinct volcanoes, it is elevated by $2000-$3000 m. It drops steeply in the east and declines with ledges in the west. In the northwestern part of the continent rise Atlas mountains (or Atlas Mountains), formed at the junction of two lithospheric plates, in a place where the earth’s crust was folded. In the south of the continent rise low and flat-topped Cape Mountains . They look like cups turned upside down (hence the name). Drakensberg Mountains - higher, from the coast in giant ledges they descend to the interior of the continent.

Minerals

The subsoil of Africa is rich in a variety of minerals, their distribution is closely related to geological structure mainland. Deposits of ore minerals are confined to the ancient foundation of the platform. In particular, this applies to gold and ores such as:

iron,
copper,
zinc,
tin,
chrome.

The largest deposits are concentrated in the south and east of Africa, in places where the foundation is shallow. In particular, there are significant deposits there gold and copper , in terms of the number of their reserves, Africa ranks first and second in the world, respectively. The bowels of the continent are rich and uranium ores . Africa is famous for its deposits diamonds – valuable precious stones.

Note 1

They are used not only for the manufacture of expensive and exquisite jewelry, but also as materials unsurpassed in their hardness. Half of the world's diamonds are mined in Africa.

Their deposits were found on the southwestern coast and in the center of the mainland. Deposits of non-metallic minerals occur in sedimentary rocks that cover the low areas of the platform with a thick cover. These breeds in Africa include:

coal,
natural gas,
oil,
phosphorites and others.

There are huge deposits in the northern Sahara and on the shelf of the Gulf of Guinea. Developed deposits of phosphorites, widely used in the production of fertilizers, are located in the north of the continent. In sedimentary strata there are also ore minerals that were formed as a result of weathering processes of igneous and metamorphic rocks. For example, in the southern and western regions of Africa there are known deposits iron, copper, manganese ores and gold of sedimentary origin.

Africa is the second largest continent on Earth after Eurasia. Its area is 30.3 million km2. Among other continents, Africa occupies a special geographical position. Almost in the middle it is crossed by the equator and is located mainly between the Northern and Southern tropics. In the west lies the prime meridian. Thus, Africa is located, on the one hand, in the Northern and Southern Hemispheres, on the other, in the Western and Eastern Hemispheres. This gigantic land area belongs to the group of so-called southern continents, which have many common features. From north to south, Africa stretches for 8000 km. The widest part of the continent is in the Northern Hemisphere.

The coasts of Africa are washed by the waters of the Atlantic and Indian oceans. On the west coast, the Atlantic Ocean forms the large Gulf of Guinea. A narrow (up to 100 km) continental shelf stretches along the western coast.

To the east, Somalia's only large peninsula juts out into the Indian Ocean. Islands off the coast of Africa are few in number. The largest of them, Madagascar, is separated from the continent in the east by the Mozambique Strait. In tropical latitudes, the western coast of the continent is washed by the cold Canary and Benguela currents, and the eastern coast by the warm Mozambique current. The African continent is closely connected with Eurasia. They are separated by the Straits of Gibraltar and Bab el-Mandeb, the Mediterranean and Red Seas, and the Suez Canal. Africa and Eurasia are a single land mass in the Eastern Hemisphere, separated from other continents by vast oceanic expanses.

The geographic location of Africa determines high air temperatures in most of its territory and contributes to the clear manifestation of geographic zonality on its territory.

Geographical studies of Africa

(Using the thematic map of the atlas, determine which areas of Africa were most explored in the 19th century.) Exploration of Africa was uneven. The southern regions of Africa, compared to the northern ones, became known to Europeans much later. Research in Africa was associated with the search for a sea route to India, and from the 15th century. - with the development of the slave trade. In search of a route to India, B. Dias was the first to circumnavigate Africa from the south. Later (1497-1499), Vasco da Gama, having rounded the Cape of Good Hope and explored the eastern coast of Africa, reached the shores of India. To expand their possessions, England and France organize a number of expeditions. The vast interior regions became known to Europeans only from the middle of the 19th century.

In the 19th century. The English naturalist David Livingstone made a great contribution to the research of South and Central Africa. He studied animals and vegetable world, natural features travel areas. D. Livingston was the first to describe the geology and topography of South Africa, explored the Kalahari Desert, a number of lakes, including Nyasa, and the Zambezi River. Having lived in Africa for thirty years, D. Livingston established himself as a humane and noble researcher, and single-handedly fought the slave trade.

The Anglo-American expedition of Henry Stanley explored Lakes Victoria and Tanganyika and established their outlines, discovered the Rwenzori mountain range, and recognized the Kagera River as the main tributary of Lake Victoria. G. Stanley corrected the mistake of D. Livingston, who had previously accepted the source of the river. Congo at the source of the river. Nila.

Among Russian researchers, V.V. Junker occupies a special place, who collected interesting information about the nature of Central and Eastern Africa in late XIX c.. Doctor by training and geographer by vocation, V.V. Junker for own funds traveled across the continent for ten years. He described plant and animal world tropical forests and savannas, carried out meteorological observations, and for the first time compiled a map of the watershed area of the great African rivers - the Nile, Congo and Niger. N. I. Vavilov, studying centers of origin cultivated plants, in the 20s. XX century organized scientific expeditions to study the vegetation of the Mediterranean (Algeria, Tunisia, Morocco, Ethiopia). In the second half of the 16th century. Nikolai Radziwill (Orphan) visited Africa.

The structure of the earth's crust and the relief of Africa

At the base of most of the continent lies the ancient African-Arabian Plate. Under the influence of tectonic movements and external processes over a long geological time, the surface of the continent was leveled: sections of the platform rose and fell, elevated areas were destroyed, depressions were filled with sediments. This is what determined the modern forms and features of the relief, the presence of mineral resources on the continent. The relief of Africa is represented mainly by elevated plains, and the eastern part is represented by plateaus and highlands.

The sedimentary cover on top of the platform foundation is more developed in North Africa (Saharan Plate). Deflections of the crystalline basement lie at the base of the Congo, Kalahari, and Karoo basins. The Ahaggar, Tibesti, North Guinea and South Guinea uplifts, and the East African Plateau are confined to the uplifts and outcrops of the crystalline foundation - the shields.

A significant part of the continent's area is occupied by the East African Plateau and the Ethiopian Highlands. They were formed under the influence of internal processes (lifting and sliding), which contributed to the fact that individual parts of the platform rose. The movements were accompanied by fractures of the earth's crust with the formation of horsts and grabens, and volcanic eruptions. This is how large lava sheets formed on the Ethiopian Highlands. As a result of tectonic processes in the eastern part of the continent, linearly elongated tectonic structures- rifts that stretch along the Red Sea through the Ethiopian Highlands to the river. Zambezi. Individual cracks gradually expanded and filled with water, forming deep and elongated lakes: Tanganyika, Nyasa, Rudolph, Edward, Albert. This area is called the East African Rift Zone.

Here is the highest peak in Africa - the Kilimanjaro volcano (5895 m) and the lowest place on the mainland - Lake Assal (157 m below sea level).

In the north and south of the continent, the African-Arabian Platform is adjacent to folded areas formed in different geological periods. These are mountainous regions: in the north there are the young folded Atlas Mountains, part of the Alpine-Himalayan folded belt, and in the south there are the more ancient dilapidated Cape Mountains. During the era of the last mountain building, the marginal parts of the continent were uplifted, as a result of which the blocky, flat-topped Drakensberg Mountains were formed. Along the coasts of Africa and in river valleys there are lowlands (Senegal, Mozambique, etc.).

Minerals of Africa

Africa is rich in a variety of mineral resources. Their placement is determined by the structure of the earth's crust and the geological history of its development. The sedimentary cover of the Sahara Plate and the coastal lowlands of the Gulf of Guinea are rich in oil reserves (Algeria, Libya, Egypt, Nigeria). Rich ore deposits have been discovered on crystalline shields. The famous African copper belt stretches to the west from the East African Plateau. Iron ore deposits have been explored in northern Africa, and manganese ore deposits have been explored in the Congo and Orange river basins.

Gold reserves are located in the south of the continent - in South Africa. TO ancient foundation continent, within Eastern and Southern Africa, the largest deposits of iron ores, chromites, gold, diamonds and uranium ores. In places of ancient volcanism in Southern and Eastern Africa, diamond deposits (kimberlite pipes) were formed. In South Africa, sedimentary strata contain large reserves of coal. Oil and phosphorite deposits have been discovered in the Atlas folded region.

Africa is crossed almost in the middle by the equator and most of it is located between the tropics. This explains her hot climate. A notable contribution to the study of Africa was made by Russian researchers - V.V. Junker (meteorological observations and study of flora and fauna), N.I. Vavilov (study of vegetation).

10 Features of the relief of Africa

1.Features of physical geographical location.

2. Main stages of geological history.

Mediterranean region

Gondwana region

3. Characteristics of morphological areas.

1. Africa is the second largest continent, area = 29.2 million km (with islands 30.3 million km) or 1/5 of the land area of the globe. The most important thing for the formation of the nature of the continent is its symmetrical position relative to the equator. 2/3 of the continent's territory is located in the northern hemisphere and 1/3 in the southern hemisphere. Therefore, it is correct to say that the extreme northern and southern points are equidistant from the equator.

Northern Cape El Abyad (Ben Sekka) -37 20N.

Southern Cape Agulhas –34 52 S.

Africa is washed by Indian and atlantic oceans(Mediterranean and Red Seas).

Important feature Africa's geographical location is its proximity to the Eurasian continent. The narrow (120 km) Isthmus of Suez connects it with Asia. Africa is separated from Europe by the Strait of Gibraltar, up to 14 km wide.

The shores of the mainland are slightly indented, usually without well-protected natural bays. The slight horizontal division of Africa is due to the fact that about 22% of its territory is more than 100 km away from the sea.

There are islands off the coast of Africa: in the east - Madagascar, Comoros, Mascarene, Amirante, Seychelles, Pemba, Mafia, Zanzibar, Socotra; in the west - Madeira, Canaries, Cape Verde, Sao Tome, Principe, Fernando Po, and at a great distance Ascension, St. Helena, Tristan da Cunha.

2. At the base of most of the continent lies the ancient African platform, composed of crystalline, metamorphosed and igneous Precambrian rocks, the age of which in some areas reaches 3 billion years. The basement rocks are covered by a sedimentary cover that occupies 2/3 of the continent. During the Paleozoic and during most of the Mesozoic, the platform apparently formed part of the hypothetical continent of Gondwana. From the northwest and south, the Precambrian foundation of the continent is framed by Hercynian folded structures. In the south they make up the Cape Mountains, in the northwest internal zones Atlas Mountains The northern ranges of these mountains (Er Rif, Tell Atlas) are the only alpine folded structures on the mainland.

S-ancient platform 96%

S-Paleozoic folded zones 3%

S- Cenozoic-Mesozoic zones 1%

The African platform is complicated by syneclises and anteclises. The largest syneclises are the Karoo, Kalahari, Congo, Chad (Mali-Nigerian), Aravan-Taudeni, and Libyan-Egyptian. The largest shields and uplifts of the Archean-Proterozoic basement are the Ahaggar, Regibat, Leon-Liberian, Nubian-Arabian, Central African, and Madagascar massifs. The most significant protrusions of the ancient foundation are located along the eastern edge of the continent. The world's largest system of East African Rifts is also located here, stretching 6,500 km from the Gulf of Aqaba through the Red Sea, the Ethiopian Highlands, the East African Plateau and the lower reaches of the Zambezi River.

Taking into account the features and differences in the geological history of the continent, two regions are distinguished - the northern Mediterranean and southern Gondwana. The border between them runs from the Gulf of Guinea to the Gulf of Aden.

In the Paleozoic and Meso-Cenozoic, the Mediterranean region occupied a predominantly low hypsometric position and repeatedly experienced transgression. In the east, in the deep regions of the Sahara and Sudan, a predominantly continental regime remained in the Paleozoic and Mesozoic. During this period, Nubian sandstones accumulate. The Hercynian tectonic movements, which manifested themselves mainly in the Atlas sector, were followed by a general uplift of the region and the accumulation of continental Triassic strata. In the Jurassic, the sea covered only the territory of Egypt and Sudan. Starting from the Cretaceous, large blocks of the platform began to subside in the Gulf of Guinea region. The sea floods its coast and along the ancient grabens of the Niger and Benue rivers penetrates into Sudan to the southern slopes of the Ahaggar massif. In the Upper Cretaceous most of The Mediterranean region represents the sea basin. Since the beginning of the Cenozoic era, the Mediterranean region has experienced a general uplift, the sea has retreated, and in the Holocene the region's territory is under continental conditions. Under the influence of folding movements in the Tethys geosyncline, the Regibat and Tuareg shields, as well as the Nubian-Arabian, were uplifted, which led to the junction of the Saharan and Arabian parts of the platform.

At the same time, the modern outlines of large syneclises took shape—Senegal, Chad, White Nile and Aravan-Taudenni, filled with Neogene-Quaternary continental sediments.

The Gondwanan platform region has been an uplifted area since the Paleozoic. Sedimentary strata accumulated here only in inland syneclises - the Karoo, Kalahari and Congo depressions and on the coasts, under conditions of marginal transgressions. At first Paleozoic era along the southern edge of the platform there is a geosyncline, in the shallow zone of which formations of the Cape system were deposited, folded in the Early Triassic

(Hercynian orogeny). When the Cape Mountains rose, a foredeep was formed in front of them, which subsequently developed into the Karoo syneclise.

Since the end of the Paleozoic era, the uplift of the Gondwana region has intensified. In the Permian, rifts occurred along the eastern margin of the region, along which the Madagascar block separated, and the Mozambique Strait graben was founded. In the Triassic, the sea entered the eastern coast of Africa and, by the Cretaceous, spread north to the Somali Peninsula, and in the south, transgression covered the destroyed Cape Mountains. The amplitudes were especially sharp in the southeastern sector due to which basaltic lava outpoured along deep faults in the Drakensberg Mountains in the Jurassic.

The Paleogene–Neogene and Quaternary tectonics of the Gondwana region manifested itself in several phases of strong uplifts of the marginal zones of the platform, including the Cape Mountains, which led to the rejuvenation of the mountains. However, the main tectonic events are associated with the formation of the fault system of the Ethiopian Plateau and East Africa. Along fault lines, sections of the earth's crust were lowered to great depths, resulting in complex systems grabens.

The system of faults in its modern form began to form in the Oligocene, simultaneously with the growth of large uplifts and mountain building in the eastern part of Africa and Arabia. Movements along the faults led to a powerful outbreak of volcanic activity, which reached its maximum in the Neogene and continues today; all active volcanoes in Africa are located in this zone.

3. Africa is a high continent. The average height of the continent is 750m (second only to Antarctica and Eurasia).

The highest altitude belongs to Kilimanjaro (5895m). Africa is the only continent where the main peaks do not belong to zones of folded structures. The “lowest” place on the mainland is the Assal depression (-150m) and Qattara (-133m).

The predominance of leveled relief on the mainland is due to its platform structure. Based on the prevailing altitudes, Africa is divided into 2 subcontinents: Low and High Africa. Low Africa occupies about 2/3 of the continent, covering its northern and western parts: here the altitudes are predominantly below 1000m. High Africa occupies the southern and eastern parts of the continent, where altitudes over 1000m predominate.

Features of morphosculptures. The relief of the continent in the modern period changes under the influence of exogenous processes, different in climatic zones. In tropical latitudes, physical weathering dominates, chemically unaltered coarse detrital rubble material is formed, debris is demolished under the influence of gravity, sand is transported by wind, and aeolian accumulation occurs. Weathering crust of insignificant thickness. Its composition retains many weakly altered primary minerals, even such unstable ones as mica and feldspars. Subequatorial latitudes are characterized by alternating processes of erosion (during wet seasons) and physical weathering (during dry seasons). During wet seasons, most of the carbonates and sulfates are carried out of the soil, forming calcareous and gypsum nodules; Mass hydrolysis of silicates and aluminosilicates occurs with the formation of clay minerals and iron hydroxides. The latter lose water in dry seasons and turn into water-poor hydrohematites or hematites. Deeply decomposed lateritic weathering crusts, or laterites, appear.

In equatorial latitudes, the weathering crust is intensively washed by precipitation and all soluble weathering products are carried away by water. Primary silicates and aluminosilicates are transformed into minerals of the kaolinite group, which do not contain alkali and alkaline earth metals. A thick (up to 50-100) kaolin weathering crust is formed. In many areas of Africa, where ferruginous or saline crusts are exposed or shallowly buried, the surface resists destruction.

Cryogenic -----

Glacial ------

Fluvial 57.6%

Arid 42.4%

In accordance with the morphotectonic history of the African continent, the most important morphotectonic differences have formed in its relief, on the basis of which several structural and morphological regions are distinguished on the territory of Africa.

Atlas mountainous country. The northern coastal part of this country consists of alpine folded structures. In the structure of the southern part of the mountainous country, a significant role is played by Paleozoic formations (Moroccan Meseta), which experienced intense Hercynian tectogenesis. To the east (zone of the High Plateaus, including the Oran Meseta) lie weakly deformed shallow marine sediments of the Cretaceous and Paleogene. In the zone of the High and Saharan Atlas, the thickness of the Mesozoic increases. In the south, the Atlas is separated by a large fault (South Atlas) from the African platform. Another fault runs along the coast Mediterranean Sea. The Atlas mountainous country is distinguished by a variety of morphosculptures:

Traces of ancient glaciation (karas, troughs, moraines, etc.)

The interior areas are occupied by denudation and accumulative plains, cuesta ridges, and remnant plateaus.

In areas where calcareous rocks are widespread, karst is widely developed.

In relief Saharan mesa Plains below 500m predominate. Large uplifts only in the Central Sahara, the Ahaggar highlands (Takhat mountain, 3003m) and Tibesti (Emi-Kusi mountain, 3415m) bearing traces of active Neogene and anthropogenic volcanism (lava fields, geyser deposits), are dissected by deep canyons and dry riverbeds of ancient and modern watercourses. Adjacent to Ahaggar and Tibesti from the south are the plateaus of Iforas (up to 728m), Air (up to 1900m), Ennedi (up to 1310m). This area is characterized by numerous drainless depressions: Shott-Melgir (-26m), Siva, Qattara (-133m), etc.

The region of the plains and low table plateaus of Sudan. The predominant heights are 200-500m, above the flat surface of which mountain outcrops rise, indicating the level of denudation of this territory. A typical table plateau is Kordofan. Important elements of the relief are river valleys, beds of temporary watercourses, and lake basins. In the modern era, the formation of relief occurs due to the processes of weathering and erosion.

Upper Guinean uplifts. It includes the Sierra Leonean Highlands, the Cameroon Plateau with the Cameroon Volcano (4070m), which are confined to the anteclise of the African Platform and represent low mountain uplifts (1000-1500m).

5.Congo Trench occupies a huge syneclise of the same name, composed mainly of continental deposits. On all sides it is surrounded by protrusions of a crystalline foundation (Lunda-Katanga plateau, Azande), which drop in steps to the Congo syneclise.

6.Abyssinian Highlands. The northern part is peneplain on crystalline rocks with island mountains, the southern part is a stepped plateau, divided by deep canyon-like valleys into separate massifs. Greatest height reach Mount Symen (Ras Dashan, 4623m). In the southeast, the highlands drop off in steep steps to a deep fault depression separating the Somali Plateau. Transverse lava thresholds divide the depression into several basins, at the bottom of which there are traces of active tectonic activity: fumaroles, hot springs.

7. East African Highlands. It is characterized by a complex combination of various relief forms that are closely related genetically. The heavily terraced coastal lowlands experienced uplift at the beginning of the Quaternary. East Africa is characterized by massive blocky uplifts (Rwenzori massif, Livingston Mountains). On the western outskirts there is a chain of deep lakes lying in graben-like depressions. To the east of Lake Victoria rise the most significant elevations of East Africa - the Kenya volcano (5199m), Kilimanjaro (5895m), Meru (4565m). In addition, the relief of the highlands is characterized by the presence of giant craters (Ngorongoro up to 20 m in diameter).

8.South African region occupies the Kalahari and Karoo syneclises. The area is elevated to a considerable height and is distinguished by the simplicity of its relief structure. Above the sandy plains of the Kalahari depression, the marginal plateaus and mountains rise in steps (the Matabele plateau, the Veld, the Drakensberg Mountains, etc.). The Nama and Dammar rises stand out. To the south they continue into the denudation of the Great Escarpment, which separates the Upper Karoo plateau from the Cape Mountains.

Cape Mountains belong to a rare type of restored mountains with an inherited folded structure, clearly expressed in the modern relief. The Cape Mountains consist of several parallel ridges. Wed. height 1500m, highest -2326m. The mountains are low, flat-topped, formed during the Hercynian orogeny. They were subjected to long-term leveling, and at the end of the Neogene they were uplifted.

Drakensberg Mountains composed of light-colored sandstones of the Karoo system, overlain by dark-colored basalts, causing the flat peaks of the Drakensberg Mountains.

Africa is predominantly a flat continent. Mountain systems occupy only the northwestern (Atlas Mountains) and southern (Cape Mountains) outskirts of the continent. The eastern part of Africa (High Africa) is occupied by the East African Plateau, which is highly uplifted and fragmented by shifts in the earth's crust. Here are the highest peaks of the continent - the giant extinct and active volcanoes Kilimanjaro, Kenya, etc.

The peculiarities of the development of Africa determined the main features of the structure of its surface. Most of the continent is characterized by flat terrain with a wide development of planation surfaces from Permo-Carboniferous and Triassic to Neogene and even Quaternary with blocky and volcanic mountains protruding separately among them.

The main modern structural elements of the continent are inherited from the beginning of the Paleozoic. They are similar to the corresponding structures of the East South America, with which Africa maintained unity until the end of the Mesozoic. The northern Sahara-Arabian part is characterized by the distribution of plates and syneclises with a Paleozoic and Phanerozoic cover (Saharan Plate, Taoudenny, Mali-Nigerian, Chad syneclises, etc.), between which are located elevated areas of the Archean-Proterozoic basement (Ahaggar, Regibatsky, Leono massifs -Liberian, etc.).

The part of the continent southeast of the Cameroon - northern tip of the Red Sea line experienced a tendency to rise and was subject to strong tectonic activity, especially in the east. Syneclises occupy only the inner parts of the southern subcontinent, their axis runs along the 20th meridian. The northernmost and largest equatorial basin of the Congo is replaced in the south by less extensive ones - the Okavango and others. Large uplifts in the east and south are the Nubian-Arabian shield, dissected by the Red Sea rift, the Mozambique Proterozoic fold belt, etc.

In the north and south, Africa is surrounded by folded zones. In the south is the Paleozoic Cape region, in the north is the Atlas folded zone, which is part of the Mediterranean belt.

Among the main types of flat relief within Africa there are: basement plains and plateaus on the Archean and Proterozoic foundation. Their heights in northern Africa usually do not exceed 500 m and very rarely reach 1000 m. Among the gently undulating crystalline surfaces stand remnant mountains and ridges composed of the most stable rocks. This type of relief is common on weakly activated massifs separating ancient syneclises; stratified plains and hills, horizontal or inclined and stepped, characteristic of areas of sedimentary cover along the periphery of ancient syneclises (for example, the Congo or Kalahari syneclises) and on the outskirts of the continent, which experienced subsidence in the Mesozoic and the first half of the Cenozoic. This type of relief is also found on basement ledges covered by sedimentary deposits or in ancient syneclises within large uplifts. Stratified plains and hills are young, with weak erosional dissection, and ancient, with deep and varied dissection; accumulative plains formed from the surface by Neogene and anthropogenic marine or continental sediments. They occupy the central parts of ancient syneclises and the bottoms of rift zones, and are also located along the outskirts of the continent, which were subject to young transgressions.

Approximately 20% of Africa's surface is characterized by mountainous terrain. Revived mountains and highlands, formed as a result of Meso-Cenozoic and neotectonic uplifts, accompanied by faults and volcanism, are characteristic mainly of the eastern edge of Africa, along the rift zones crossing it. But individual sections of mountainous terrain are also located among flat-platform areas, being associated with massifs that have experienced tectonic activation (Ahaggar, Tibesti, Drakensberg Mountains, etc.). Among the main types of morphostructure of the revived mountains there are: basement block mountains and highlands formed in areas where the foundation emerges; mesas formed in areas of sedimentary rocks and volcanic nappes; volcanic mountains and volcanic plateaus confined to fault systems.

The Cape Mountains belong to a very rare type of restored mountain with an inherited folded structure clearly expressed in the modern topography.

The Atlas region includes Paleozoic structures, reworked by Meso-Cenozoic movements to such an extent that they are considered part of the Mediterranean mountain belt. These older structures occupy the middle and southern parts of the Atlas region, while its northern chains represent formations created mainly in the late Miocene - early Pliocene.

The African continent has a complex of various mineral resources. The oldest core of the platform, within East and Southern Africa, contains the largest reserves of iron ores, chromites, gold and uranium ores. Upper Proterozoic structures, especially in the Democratic Republic of the Congo, contain deposits of ores of copper, tin, lead and other non-ferrous metals. In kimberlite pipes of Mesozoic age, which penetrated the crystalline basement in different areas, primary diamond deposits were formed. Diamonds from Southern and Eastern Africa are especially famous. Deposits of rare metals were formed along the boundaries of intrusive granite bodies of the same age.

No less significant are the minerals of sedimentary origin, formed during the weathering of ancient crystalline rocks or deposited in the rocks of the sedimentary cover. The first include bauxites from West and East Africa; to the second - large deposits oil and gas within the Sahara Plate, in Algeria, Libya, Egypt and Nigeria.

The lagoonal-continental Karoo formation in South Africa contains large reserves of coal. In the synclinal zones of the Atlas folded region there are deposits of oil and phosphorites.

The modern relief of the continent is characterized by monotony: most of it is a vast table plateau, which is characterized by insignificant hypsometric dissection.

The main features of hypsometry of the African continent:

According to the characteristics of vertical division, the continent is divided into two parts: the northern flat-undulating Low Africa (with average altitudes of about 500 m) and the southern, more elevated High Africa (with average altitudes slightly more than 1000 m). The difference between these parts of the continent lies not only in the altitude characteristics , but also in the greater dissection of the surface of High Africa. The border between them is the line from Benguela in western Angola to Massawa on the Red Sea coast, running through the watershed plateau of the Congo and Zambezi basins, along the western foothills of the mountain ranges along the line of the Great African Rift and encircling the Ethiopian Plateau from the west and north.
The African continent is characterized by the presence of internal basins. The orography of South Africa is made up of the Kalahari Basin located in the center, bounded on the Indian Ocean side by the uplifts of the Drakensberg Mountains, in the south by the parallel chains of the Cape Mountains, and in the west by the Great Escarpment massifs (Kaoko, Dammara, etc.). All the marginal elevations of Africa have an asymmetrical profile: they descend steeply to the seashore and gently descend into the interior of the continent. Their formation is associated with the “emergence” of the continent, especially its marginal parts, as a result of a deeper “immersion” of the oceanic crust of the Atlantic, Indian and Southern Oceans into the asthenosphere, i.e. with the processes of isostasis equalization of gravity on the lower planes of lithospheric plates. This process began at the end of the Mesozoic and continues to this day. In Low (Northern) Africa, internal basins are also expressed: Chad, Upper Nile, Middle Congo, etc.
Inland basins are very often areas of internal drainage and sedimentation (ie, the accumulation of modern sedimentary rocks).

Active uplift processes do not allow rivers to form an equilibrium profile, which causes the presence of rapids and waterfalls on almost all rivers.
Particularly contrasting hypsometric indicators are characteristic of East Africa. The elevation differences on the East African Plateau exceed 1000 m; the flatness of the plateau is broken by isolated uplifts: volcano. Kenya, Rwenzori massif, volcano. Karisibi, vol. Mary, Elgon and others (with altitudes over 4000 m). It is here that the highest point of the continent is located - volcano. Kilimanjaro (5895 m). These are blocky and volcanic formations, the formation of which took place as a result of the development of the rift zone in East Africa - the Great African Rift.
The uniqueness of Africa's topography also lies in the fact that, in contrast to Eurasia, there are almost no extensive coastal lowlands.
There are only two mountainous regions with a folded structure on the mainland: the Atlas and Cape.
The Cape Mountains are a mountain system in the south of the mainland, consisting of a series of parallel mid-altitude ranges, between which are the plains of the Little Karoo. The highest peak is (2326 m).

Atlas Mountains- a mountain system in the north-west of the continent, consisting of 3 mountain belts: Mediterranean (Er-Rif, Tell Atlas ranges); Atlas (High Atlas, Saharan Atlas); sub-Saharan (Anti-Atlas ridge). The highest peak - the city of Toubkal (4100 m) is located in the ridge. High Atlas. Between the Mediterranean and Atlas mountain belts are the High Plateaus of the Chotts (Algerian and Moroccan Messetas). Shotty (seibkh) - drainless lakes filled with water in winter period when it rains and the water flows through the ueds into the lakes. Mountain belts differ in height, degree of erosion and tectonic dissection, composition of rocks and age of folded structures. The youngest mountains of the Alpine orogeny are the ridge. Er-Rif and Tell Atlas are composed of Mesozoic limestones, which, along with good moisture on their slopes, contributes to their active erosional dissection. Average heights are 2450 m (Er-Rif ridge) and 2000 m (Tell Atlas ridge).

The Atlas belt of ridges is higher: The mountains are composed of metamorphic and igneous rocks of the Paleozoic, formed in the Hercynian fold. Consist of a series of parallel ridges. The leeward slopes are characterized by desert weathering forms. The Anti-Atlas Ridge (sub-Saharan belt) is a blocky uplift of the edge of the African Platform, in fact it is a structural-denudation ridge on folded sedimentary rocks of the Upper Proterozoic - Lower Paleozoic. Characterized by deeply dissected relief in dry subtropical conditions.