Africa is the second largest continent on Earth. Together with the islands belonging to it, it occupies an area of ​​30,284 thousand km2, the area of ​​the mainland without islands is 29,200 thousand km2. The continent has a special geographical position: the equator crosses it almost in the middle, i.e. Africa is located almost symmetrically in the northern and southern hemispheres. For the most part The mainland is located in the eastern hemisphere, and the smaller one is in the western hemisphere.

Extreme points of the mainland:

1. Northern () - Cape Ras - Engela (37° 20′ N)
2. Yuzhnaya () – Cape Agulhas (34° 51′ S)
3. Zapadna () – Cape Almadi (17° 33′ W)
4. Eastern () – Cape Ras – Hafun (51° 24′ E)

The length of the continent from north to south is 8000 km, from west to east – 7500 km.

The continent is washed by the waters of two oceans: from the west - , from the east - . The western and southern coasts of the mainland, washed by the Atlantic Ocean, form the only large bay here - the Gulf of Guinea. In the extreme northeast, this gulf is divided into two independent gulfs - Biafra. Most of the bay has significant depths - up to 4 thousand m. And closer to the coast there are banks (banks are the shallow part of the bottom formed as a result of the death of benthic organisms and developed during internal parts shelves), as well as numerous volcanic islands: Annobon, Sao Tome and Fernando Po (Bioco). All these islands are of volcanic origin, they are mountainous in relief, and have very fertile soils - Andosols. Together with large volcano Cameroon on the continent they form the so-called lineage. All of these volcanic massifs are associated with the strike of transform faults that cut the Mid-Atlantic Ridge from west to east. All these islands are composed of young alkali-basaltic volcanics. In addition, there are islands of continental origin in the Gulf of Guinea. These are the Greater and Lesser Elobey, the island of Corisco, Horatio, Tinosa Pequena and Tinosa Grande.

As you move north, the length of the continent increases greatly, and as you move south, it decreases.
Off the northwestern coast of Africa in the Atlantic Ocean there are also islands of volcanic origin associated with the spread of MOR transform faults here. These are islands such as: Madeira, Canary Islands and Cape Verde Islands. The Cape Verde Islands are divided into two groups:

Leeward (Sotaventu) and Windward (Barlaventu). The Cape Verde Islands are very interesting and amazing. Most of Cape Verde Island is occupied by dry, gravelly highlands, called the “Moon Landscape”. It was here that the Americans filmed a film about how they conquered the moon.

There are a number of small volcanic islands far from the coastal zone. These are: Ascension, St. Helena, Tristan - yes - Cunha, Bouvet.

Cold currents pass in the northern and southern parts of the Atlantic Ocean off the coast of Africa. In the north there is the Canary Current, which brings water with a temperature of 15–16° to the shores of the mainland. The cold Bengal Current passes off the southwestern coast of Africa. The water temperature there is especially low (6 – 9° at the surface) due to the rise of cold deep waters - this process is called upwelling. Both cold currents have a significant impact on climatic conditions western edges of Africa in tropical latitudes. In the Atlantic Ocean, the coastal part of Africa is very unstable - the depths come very close to the coast. A not wide strip of continental shallows is limited by sharp ledges that immediately lead to depths of up to 2000 - 3000m. Only in the south at 20° S. The underwater Whale Ridge approaches the shores of the mainland.

The eastern and southern coasts of Africa are washed by the Indian Ocean. Here, not far from the coast, there are islands of coral origin - Mafia, Zanzibar and Pemba. Mainland ones include -, Seychelles and Socotra. The Comoros Islands are classified as volcanic. South of the equator, warm currents pass off the coast of Africa. Mozabique in the north and Cape Agulhas in the south. These two currents are formed from the South Trade Wind Current and cause winter temperatures off the coast of southeast Africa to rise to 20°C or more. The monsoon Somali Current penetrates to the north of the equator, bringing relatively cold waters from the southern hemisphere in the summer of the northern hemisphere, and in winter changing its direction to the south and carrying relatively warm waters from the north.

The northern shores of Africa were quite well known to the peoples of Ancient and Phenicia. Information about the nature and population of the continent accumulated and passed from the Egyptians and Phoenicians to the Greeks and Romans, from the Arabs to the Europeans.

For European Geography real African studies involve . At the beginning of the 15th century. who were looking for a sea route to, a path was laid along the western shores of the mainland and an exit to the Indian Ocean was found. In 1497-98, a caravan of ships led by Vasco da Gama, on their way to India, circumnavigated the continent and left the Atlantic Ocean into the Indian Ocean. Thus, the search for a sea route from Europe to India was completed. From the 16th century European traders began exporting slaves to America.

At the end of the 18th and early XIX V. They began to show increased interest in the exploration of Africa. Various goals led travelers on the road - not so much scientific as military-strategic and colonial. Among the explorers of Africa, the most famous are the British traveler D. Livingston (1813-1873), the Shatlander M. Park (1771-1806), the German G. Barth (1821-1865), the American G. Stanley (1841-1904), etc. They studied interior areas the continent, penetrating there along the rivers, they looked for their sources, described the lakes, the generous nature and population of the continent.

Africa is the largest of the three continents of the “southern group”. Separated from Europe by the Mediterranean Sea, it is connected in the northern eastern part by the Isthmus of Suez (which is crossed by the Suez Canal), 130 km wide. But, due to the fact that the Sinai Peninsula belongs politically, it is often classified as Africa. Africa stretches over 8,000 km from north to south, and 7,400 km from west to east. The length of the coastline is 26,000 km. Most big country Africa is Sudan, and the smallest is (an archipelago in the east of the mainland). The smallest mainland country is .

The structure of the continent's surface is quite uniform. Plains and plateaus with heights from 200 to 1000 m predominate; there are few lowlands. The most extensive plateaus are East African and South African. Elevated areas alternate with basins, the most extensive of which are the Kalahara basin, etc. The highest point is (5895 m), the lowest is Lake Asal (-150 m). The average height is 600 m above sea level.

The relief features are associated with the history of the development of the continent. At the heart of the continent lies the ancient African Arabian Plate - part of the fractured Gandwana. The platform was formed by archaea and praterazoa and over 2-3 billion years acquired greater stability. Only the Atlas Mountains in the north and the Cape in the south created by later movements earth's crust. The huge African hills experienced uplift and subsidence, while the northern part of the continent sank more often than it rose, and was flooded with seas. The crystalline foundation of the platform is covered by sedimentary rocks and only comes to the surface in the center of the Sahara and on the coast of the Gulf of Guinea. The relief of Eastern and Southern Africa was formed differently - the uplift of the earth's crust predominated, and giant faults, horsts and grabens were formed. Volcanic activity was actively developing. There are many lava plains here, grabens are occupied by lakes. Volcanic eruptions still occur today. The rift belt is home to volcanoes, including Mount Kilimanjaro.

Africa's mineral resources are rich. The location of deposits is closely related to geological history and tectonic structure. Eastern and Southern (“high”) Africa, where the surface is dominated by igneous crystalline and metamorphic rocks, known for ores of black and non-ferrous, noble and rare metals. Diamond deposits are confined to kimberlite volcanic pipes in the depths of the platform. In the strata of sedimentary rocks of the Northern and West Africa reserves of phosphorites, oil and natural gas(Saharan Plate region), table salt, coal(Nigeria). Oil and gas are produced not only on land, but also on the Atlantic shelf. IN South Africa significant reserves of coal, copper and uranium ores.

Africa is the hottest continent on the planet. In most of its part, the average temperature of any month is above +20 ° C, which is explained by the location of most of the continent between the tropics, where the sun stands high above the horizon throughout the year, and twice a year it is at its zenith. The seasons of the year differ more from each other in terms of the conditions of the holiday. Features are determined by circulation, on which the amount of precipitation and its pattern largely depend. A belt of low pressure is formed over the equatorial part of the continent, and in tropical latitudes - belts high pressure. These belts move following the zenital position of the sun and determine the movement of equatorial, tropical and temperate air masses over the continent. Almost the entire continent is under the influence of constant winds - trade winds. The northeast trade winds that come from land bring almost no moisture, while the southeast trade winds carry it from the Indian Ocean. In subtropical latitudes during the winter months, precipitation falls from moderate air masses dominated by westerly air transport from the Atlantic Ocean. Relief also influences the distribution of precipitation. The steep and high shores of the continent make it difficult for humid winds to penetrate from the ocean into the interior of the continent. More precipitation falls on the windward slopes of the mountains. On the slopes of Mount Cameroon, their number reaches 10,000 mm per year. The driest areas are located not only inside the mainland, but also in its Pryakian parts. Thus, the western coast of the mainland in tropical latitudes is washed by cold currents. The air above them becomes colder than in the upper layers, and its flow is difficult. Apart from dew and fog, there is almost no precipitation here. On the mainland there are equatorial, two subequatorial, two tropical and two subtropical. Within some of them there are differences that are determined by the amount of precipitation and its regime.

The coasts of Africa are washed by the waters of the Atlantic and Indian oceans. The Atlantic Ocean forms one large Gulf of Guinea off its coast. Along the poorly dissected western coast of Africa there is a narrow (up to 100 km) strip of continental shelf, the steep slope of which breaks off to the underwater plateaus and the depressions separating them. To the east of the Mid-Atlantic Ridge against Africa are the Canary, Cape Verde, Guinea, Angolan, Cape and Agulhas basins with depths from 3000 to 7200 m. Smooth surfaces The bottoms of the basins are in some places complicated by mountain uplifts, the volcanic peaks of which rise in the form of the Canary Islands, Cape Verde, etc. At 20° south. w. Between the Angola and Cape basins, the underwater Whale Ridge approaches the coast of Africa.

Off the coast of Africa in the Atlantic Ocean, trade wind circulation predominates, creating complex closed systems of currents in both hemispheres. In the north and south, cold currents - the Canary and Benguela - are directed from high latitudes towards the equator. They represent the eastern branches of the northern and southern gyres and carry relatively cold waters to the western coast of Africa. The Benguela Current is especially powerful, the influence of which manifests itself almost to the equator. It is analogous to the Peruvian Current Pacific Ocean off the coast South America. The southerly winds that constantly blow off the western coast of Africa drive away the surface layer of water, which causes the rise of cold deep waters, constantly moving towards the equator.

The southern part of the northern and northern part of the southern gyre form the Northern and Southern Trade Wind Currents. At their origin off the coast of Africa, they are a continuation of the Canary and Benguela currents, and their waters have relatively low temperature. These currents are stronger and more stable in the winter of the corresponding hemisphere. The vertical thickness of the flow does not exceed 300 m. From the coast of Africa, branches of trade wind currents are directed to the west. The Equatorial Countercurrent runs between them from west to east, the eastern part of which is called the Guinea Current. Currents have a significant impact on the temperature distribution of surface waters off the coast of Africa, making adjustments to general pattern temperature decreases from the equator to the north and south. Due to the high severity of cold currents and the rise of cold deep waters, the water temperature off the coast of Africa, especially south of the equator, is significantly lower than the average for these latitudes (by about 5-7 ° C). For example, at the sources of the Southern Trade Wind Current in August, the water temperature is + 22, + 25 ° C. The waters of the Guinea Current are heated to +28°C. The average annual water temperature off the northwestern coast of Africa is + 20°C, and on the southwestern coast + 15°C. In winter it can drop to + 12°C. The salinity of water in the Atlantic off the coast of Africa is close to normal oceanic. The exception is water areas located against trade wind deserts (especially the Sahara), where salinity rises to 37‰. This is the highest salinity in the open part of the World Ocean.

The northwestern Indian Ocean, which borders Africa to the east and south, was formed in the post-Cretaceous period as a result of the breakup of Gondwana. It is characterized by large bottom irregularities and sharp changes in depth. Its northwestern part is separated from the rest of the ocean by the underwater Arabian-Indian Ridge. Within its boundaries there are basins with depths exceeding 5000 m (Somali, Madagascar, Mozambique). The tops of the underwater ridges separating the basins form volcanic and coral islands (Mascarene, etc.). Some ridges have a continental type of crust and represent the remains of ancient Gondwanan structures.

The system of currents in the northern and northwestern parts The Indian Ocean is determined by the trade wind and monsoon circulation of the subequatorial and tropical zones. South of the equator, the warm Mozambique and Madagascar currents pass off the coast of Africa. Merging, they form the Cape Agulhas Current. The latter is one of the most stable and powerful currents in the World Ocean. These currents are formed from the South Trade Wind Current and cause an increase in water temperature in the winter of the southern hemisphere off the coast of Southeast Africa to + 20 ° C or more. North of the equator, the monsoon Somali Current operates, bringing relatively cold deep waters from the southern hemisphere in the summer of the northern hemisphere, and in winter carrying relatively warm waters from North. Overall in Indian Ocean north of 10° S. w. The temperature of waters to great depths is high throughout the year. They are warmest (+ 27, + 29°C) in May. The salinity of water off the coast of Africa is 35-36‰.

Straight and slightly dissected shores Africa They are predominantly of fault origin or represent ledges. The coastline corresponds to the main directions of the faults that fragmented the African platform; this is most clearly visible in the Northeast (the shores of the Red Sea and the Somali Peninsula). The general plan for the horizontal division of Africa was determined at the end of the Paleozoic and in the Mesozoic.

Africa's underwater base rises steeply from great ocean depths. An isobath of 1000 m passes almost everywhere near the coast; the continental shelf with depths of up to 200 m is poorly developed, reaching its greatest width of about 250 km only in the south (Cape Agulhas shoal).

Shores of Africa mostly abrasive, steep, especially in those places where the mountains come close to the coast - in the North-West along the Atlas Mountains, in the North-East along the Etbay ridges and in the South, where the Cape Mountains rise. Low-lying accumulative shores correspond to the largest coastal lowlands - in the East of Egypt (in the Nile Delta), along the shores of the Atlantic Ocean - in West Africa (in Senegal and Gambia), on the coast of the Gulf of Guinea, along the shores of the Indian Ocean - along the Mozambican lowland, in places on the Somali peninsula. In the warm tropical waters of the Red Sea and Indian Ocean off the coast of Africa, coral structures develop; In some places they are “soldered” to the coast in the form of raised coral reefs. The eastern shores of Africa, washed by the warm Mozambique Current, are framed between 25° and 3° south latitude mangrove vegetation. On the western coasts, exposed to the influence of cold currents (Canary and Benguela), the mangrove belt is developed only between 5° south latitude and 12° north latitude. Mangroves in combination with the steepness and straightness of the banks, open to action strong surf, increase the inaccessibility of the mainland coast. In the Mediterranean Sea, the coast generally decreases from West to East. A steep and mountainous coast with a series of abrasion terraces, weakly dissected by “kala” bays, along the Er Rif and Tel Atlas ridges (from Cape Espartel to Cape Et-Tib) gives way to low-lying flat shores along the coast of the gulfs of Gabes and Sidra. West of the Gulf of Sidra, the coast ends in a low ledge extending all the way to the Nile Delta.

The mountainous coast of the Red Sea is characterized by small bays of sharp outlines, cut into a narrow strip of raised coral reefs. The low abrasion coast of the Somali Peninsula along the Gulf of Aden in the Indian Ocean is dissected by small bays. The southeastern shores of the peninsula are straight, from Cape Guardafui to 5° north latitude - low rocky, then flat sandy, accompanied by dunes and spits that separate the lower reaches of the rivers from the ocean and close their mouths. In East Africa, between 3° and 15° south latitude, the coast is of fault origin with many small bays. The coastline is fringed in places by coral reefs, which form harbors with calm waters, but make approaches to the shore difficult. Between 15° and 30° south latitude the shores are accumulative flat, with alternating leveled and lagoonal areas. South of 30° south latitude the coast is predominantly steep and rocky, in the extreme south it is replete with capes and deep bays.

In the Atlantic Ocean, in the extreme North-West of the continent, the low-lying coast of Morocco is framed on the North and South by rocky ledges of the spurs of the Atlas Mountains. To the south, up to 19° north latitude (Cape Ndadibu), stretches the deserted low rocky coast of the Sahara with a few open bays. Between Cape Nda-dibu and Cape Verde the coast is lagoonal, with sand spits (the Barbary Spit at the mouth of the Senegal River, etc.). To the south of Cape Verde, the coasts of Africa become higher. Up to 8° south latitude, the bedrock abrasion coast is dissected by the estuaries of many rivers flowing from the Futa Djallon plateau. The headlands between the estuaries are smoothed by strong wave abrasion; The indented coastline is accompanied by small islands (Bizhagosh archipelago, etc.). The shores of the Gulf of Guinea and the Gulf of Biafra are predominantly low-lying lagoonal. Protrusions of bedrock form individual capes (Palm, Mesurado, Mount, etc.). Smooth ridges of sand spits along the coast separate chains of lagoons, creating convenient channels for coastal swimming. In the area from Accra to Cape Three Points, bedrock is exposed in a continuous strip, forming a low rocky coast. From the Gulf of Biafra to the mouth of the Kwanza River, a coastal plain stretches (no more than 50 m high), slowly sinking under water. The sandy deposits composing it are carried into the Atlantic Ocean by numerous rivers (the main ones are the Congo and Kwanza), and the Benguela Current passing along the coast fills the uneven coast with them. As a result, the southern section of the coast from Cape Lopez to the mouth of the river. Kwanzaa is a flat, slightly winding sandy shore. Behind a low sandy bank stretch lakes-lagoons, often not communicating with the ocean. Natural harbors are rare here. To the north, from Cape Lopez to the hall. Biafra, the coastline is indented by many protrusions framing the bays of Cameroon, Gabon, Corisco, etc. From the mouth of the river. Kwanzaa in the South, the indigenous rocky coast of Angola is dissected by small bays. The shores along the Namib Desert are mostly flat sandy, in the southern part they are rocky.

12. Geographical position Africa. Common features nature. Oceans off the coast and their influence on the nature of the continent.

Africa is the hottest continent on Earth. This is due to the fact that, located on both sides of the equator, it intersects it almost in the middle. Moreover, a significant part of it is located between the tropics. This location on the planet has led to the fact that the continent receives very a large number of solar heat. Africa covers an area of ​​30.3 million km². The length from north to south is 8 thousand km, from west to east in the northern part - 7.5 thousand km. The continent is located in equatorial, subequatorial, tropical And subtropical climatic zones. Africa is being washed Atlantic(Mediterranean Sea, Gulf of Guinea) and Indian(Red Sea, Gulf of Aden, Mozambique Strait) oceans. The mainland has a central position, connected to the Sinai Peninsula Eurasia.

The peculiarity of the nature of Africa is that there are no high and extensive mountain ranges (the highest point is Mount Kilimanjaro 5895 m). The relief is dominated by plains, plateaus and plateaus, with a few lowlands. The plains are usually surrounded by stepwise rising plateaus or plateaus and represent the bottoms of huge depressions (Kalahari Basin, Congo, Danakil, Chad Basin). The nature of Africa is incredibly rich. About 40 thousand species of plants are now known, many endemics, that is, plants that are found only in Africa. The world of African animals is rich and exotic, especially herbivores - giraffes, zebras, numerous antelopes, elephants, rhinoceroses, hippopotamuses. There are many predators: lions, cheetahs, hyenas, jackals.

The influence of ocean waters on the nature of continental Africa is limited and is felt mainly in coastal areas. This is explained, in particular, by the small dissected nature of the coastline. The only large bay is the Gulf of Guinea, it does not enter much land, there is only one significant island - Madagascar, separated from the mainland by the Mozambique Strait, one large peninsula Africa - Somalia, pushed into the Indian Ocean.

The nature of the continent is significantly influenced by sea currents. The northern and southern west of the continent are washed by the cold Canadian and Benguela currents, and the northeast by the Somali current. Under influence warm currents there is the Atlantic coast of the equatorial part of the Gulf of Guinea and the coast of the Mozambique Strait.

13. Tectonic structure of Africa. Patterns of placement of tectonic structures.

Almost all of Africa is part of the ancient continent of Gondwana, which formed in the Precambrian (Archean, Proterozoic). The modern basis - the foundation of the African continent - is the African Platform. It is composed mainly of hard crystalline, igneous and metamorphic rocks. In subsidence zones (troughs), the platform is covered by a cover of sedimentary deposits, which occupy 2/3 of the continent. In areas of uplifts, on shields and anticlises, the foundation of the platform comes to the surface. The largest shields and anticlises of the Archean-Proterozoic basement are the Ahaggar, Leono-Liberian, Nubian-Arabian, Central African, Madagascar, and other massifs. The most significant protrusions of the ancient foundation are located along the eastern edge of the continent (Ethiopian Highlands and East African Plateau). Here lies the world's largest system of East African faults - rifts, stretching 6,500 km from the lower reaches of the Zambezi River, through the East African Plateau and the Ethiopian Highlands to the Gulf of Aqaba in the Red Sea. Within the African Plate, geologists distinguish between the Saharan Plate (part of the larger Sahara-Arabian Plate) and the South African Shield. The border between them is drawn from the Cameroon massif to the Red Sea. The Saharan Plate and the South African Shield developed differently. Therefore, their modern relief is significantly different. In the northern part of the continent, on the Sahara Plate, they alternate deep depressions- syneclises (for example, Libyan-Egyptian), high stepped plains and plateaus, destroyed ancient highlands (Ahaggar and Tibesti). The northern part of the continent is called Low Africa, since the altitudes here do not exceed 1000 m. And individual depressions lie significantly below sea level: the Assal depression in Ethiopia (-153 m) and the Qattara depression in the Libyan desert (-133 m). The South African shield experienced predominantly uplift throughout the post-Proterozoic period. Therefore, its territory has predominant heights of more than 1000 m. This is already High Africa, where highlands and plateaus, horsts and grabens, high lava plateaus and volcanic massifs alternate. Within the East African Plateau, the Kilimanjaro volcanic massif, the highest point of the continent, rises to a height of 5895 m. In the extreme northwest and extreme south of the continent, mobile folded zones adjoin the African Platform - Atlas in the north and Cape in the south. Folding movements in the Cape Mountains ended during the Hercynian orogeny, and in the Atlas Mountains - during the Alpine. Currently, they are low and medium-altitude folded-block mountains, dissected by river valleys. In general, Africa is a fairly high continent. In terms of average altitude (750 m above sea level), it is second only to Antarctica and Eurasia. Mountain regions occupy slightly more than 20% of its area, lowlands - less than 10%; 70% of Africa's territory is covered by high stepped plains, plateaus, plateaus and highlands.