South America is distinguished by the highest height and contrast of the relief. On its territory are located the giant high mountain system of the Andes and the vast low-lying plains of the Amazonian, Laplatskaya, and others. The lowest continent is Australia (average height 210 meters). has a very high altitude (more than 2000 meters) due to the ice cover, the under-ice surface is raised by an average of 410 meters. Africa as a whole is a rather high continent (average height 650 meters), however, the hypsometric level of its surface does not differ in contrast: hills, plateaus and plateaus predominate in the relief. There are no large mountain systems and extensive lowlands on the mainland.

There are some similar features in the structure of the surface, which are associated, first of all, with the stages of their common geological history. Plains, plateaus and plateaus occupy the main areas of the territory of all the southern continents, and large mountainous countries are located on the outskirts - in the west of South America and Antarctica, in the east of Australia, in the north and south of Africa. A significant part of the territory of all four Southern continents is a fragment of ancient Gondwana. After the split of Gondwana and the separation of the continents, it turned out that Africa, which previously occupied the center of the supercontinent, is almost entirely a platform structure, bounded from the east and west by fault lines. Only in the extreme north and south, where the mainland once came out to the outskirts of Gondwana, are there now folded structures of the Hercynian and Alpine orogenies. The fold belts adjoin the Gondwanan platform structures of South America and Antarctica from the west, and Australia from the east.

The relief of the platform blocks of the earth's crust was created by neotectonic movements of an epeirogenic and fault character. The orographic structure of these parts of the continents is predetermined by ancient tectonic processes. Direct relief prevails on them: low-lying plains are located in large syneclises: the Amazonian, Orinokskaya, Laplatskaya lowlands in South America, the northeast of the Sahara in Africa, the Great Artesian Basin in Australia, the Bentley depression in Antarctica, and on the shields, elevated plains formed in most cases , plateaus and blocky mountains.

Sometimes the bottoms of basins formed in syneclises are at a rather high hypsometric level: the basins of North Africa have absolute heights of the bottoms from 250 meters to 400 meters, Congo - from 350 meters to 500 meters, Kalahari - from 950 meters to 1000 meters. But they are still lower than the surrounding plateaus and mountains. For a long time, the destruction products of the uplifts surrounding them accumulated in the basins.

On the southern continents there are also areas of inverted relief: high plateaus within the syneclises of Parana, Karoo, Kimberley, Canning. High plains also formed in the areas of foothill and marginal platform troughs along the Andes, the Atlas, Cape, and East Australian mountain systems.

Main types of endogenous relief (morphostructures)

Morphostructures of ancient platforms

The basis of the relief within the platform structures of the Southern continents is the socle plains and plateaus of the shields of the Precambrian platforms and the bedded and accumulative plains of plates of different hypsometric levels.

Socle plains and plateaus, created by denudation processes within ancient shield fold structures, occupy vast expanses on all four continents. They are found in the Guiana and Brazilian Highlands, Western Australia and East Antarctica. This type of relief is especially characteristic of High Africa and the areas of outcrop of crystalline rocks on the Leono-Liberian and Regibat shields. Accumulative plains have a limited distribution, being located mainly along the margins of the continents or in the central and axial parts of intraplatform syneclises. Layered lowlands, uplands, and plateaus are much more widespread on platform slabs.

The relief of blocky revived epiplatform mountains, widespread on the southern continents, was created by differentiated fault movements along faults within platform shields, and in some places even plates. Such mountains are common in the Guiana, Brazilian, East African Highlands, marginal ledges of South Africa, Western Australia, and East Antarctica.

Large areas on the Southern continents are occupied by morphostructures of lava plateaus on effusive covers, since the breakup of Gondwana and differentiated movements along faults throughout the history of the formation of the surface of the Southern continents were accompanied by volcanic processes. These plateaus, which, as a rule, have a stepped character, occupy vast areas within the Parana syneclise, on the Ethiopian highlands, and their smaller sections are found in almost all areas that have experienced differentiated movements in different eras. There are also volcanic massifs and mountain ranges on the ancient Gondwanan platforms. In the rift zones of Africa and Antarctica, active and extinct are not uncommon. The landforms associated with volcanism are typical for the Ahaggar and Tibesti highlands, the border of the Red Sea, for the East African Highlands. Large ones are known: Nyira-Gonga, individual craters of the Meru and Kilimanjaro massifs, Cameroon, etc. There are even more extinct volcanoes and volcanic formations: cones, shields, calderas, sometimes filled. There are large active volcanoes in Antarctica, such as Erebus. There is no modern volcanism in Australia, but there are sections of volcanic plateaus on the platform plains of the western part of the mainland, for example, in the east of the Kimberley plateau.

Morphostructures of mobile belts

The relief of the mobile belts adjacent to the Gondwana platforms is complex, but for all its diversity, some common features and regularities in the arrangement of morphostructures can be traced here. In all the mountain systems of the folded belts of the southern continents, young tectonic zones of the Alpine and Pacific orogenies border the continents from the side of the oceans.

Even the epipaleozoic East Australian belt has such a "young" border in the form of island arcs that accompany the Pacific coast of Australia. In the Andes, the Coastal Cordillera also stretches from the Pacific Ocean, in which, apparently, folding processes are still ongoing - the result of the incomplete subduction of oceanic plates. The coastal zone of the west of South America, like the island arcs along Eastern Australia, is accompanied by deep-water trenches. Low anticlinal or volcanic chains of mountains have a very large excess above the bottom of the trenches. In some places, for example, in the Central Andes region, the total amplitude of the heights of the relief is greater than the height of the Himalayas. In these mountain ranges, the processes of modern volcanism are developed, there are post-volcanic phenomena, and the degree of seismicity is high.

Volcanoes and geysers of New Zealand are well known, earthquakes, often catastrophic, in the discontinuous Coastal Cordillera of Chile and Peru, composed of Cenozoic rocks crumpled into folds or volcanic material.

The next orotectonic zone of the Andes, when moving into the Andean system, is the rejuvenated and revived blocky-folded and folded-blocky high and medium-altitude ranges of the Western Cordillera.

They stretch continuously from the very north of the Andean system from the Gulf of Darien to the Strait of Magellan in the south. From 28°S sh. this chain of ridges is called the Main, and from 42 ° S. sh. - Patagonian Cordillera. Folding here took place during the epoch of the Alpine orogeny. Alpine anticlinoria were raised by neotectonic movements along faults to a great height (4000-6000 meters). In the Main Cordillera is the highest point of the Andes - the city of Aconcagua (6960 meters). In this orotectonic zone, manifestations of Meso-Cenozoic volcanism are widespread in the form of granitoid intrusions, lava covers, extinct and active volcanoes of the Western Cordillera of the Central Andes, the Main and Patagonian Cordillera. Some of the volcanoes have a height exceeding 6000 meters, many are still active.

To the east (from the Guajira peninsula in the north to 38 ° S), the ridges of the Eastern Cordillera stretch. These are restored fold-block and block mountains, mainly on the Hercynian base.

The ridges reach great heights - 4000-5000 meters, some peaks over 6000 meters. In the north (about 3 ° N), the mountains branch out, forming the Central and Eastern Cordilleras of Colombia and Venezuela. Even to the east, where at the junction of the mobile belt and ancient platform structures, the edges of the platform were involved in active tectonic movements in places, between 20° and 37° S. sh. systems of revived blocky mountains rise on the Precambrian and Paleozoic folded base. These are the Pampinian (Pampian) Sierras and Precordillera. Relatively narrow blocky ridges are separated by valleys.

The orotectonic belts of the Andes are separated by zones of depressions. Between the Coastal and Western Cordillera is a strip of subsidence.

Within its boundaries, for example, the Atacama Basin is located, to the south - the Longitudinal (Central) Valley of Chile, to which a whole chain of volcanoes is confined along fault lines.

Between the Western and Eastern Cordillera north of 10° S. sh. narrow graben-like longitudinal depressions stretch, occupied by river valleys, the bottoms of which lie at a considerable height.

There are numerous volcanoes along the fault lines, including active ones - Cotopaxi, Sangai, etc.

The Western and Eastern Cordillera in the Central Andes frame the high-mountain plains - Puna, which formed within the middle massif, partially covered by lava covers.

The ancient block is located at a lower hypsometric level than the surrounding mountains (3000-4000 meters). In this depression, material is removed from the mountains, and weakly undulating accumulative plains and lava plateaus with separate remnant massifs and volcanoes are formed here. There used to be numerous lakes in the basins, which have now partially dried up.

The northern Andes are separated by a tectonic fault from the so-called Caribbean Andes. These are structures that complete the Caribbean-Antilles mobile zone from the south, which is believed to have formed in the western part of the Tethys Ocean. The zone is seismic, but there is no modern volcanism here.

The Andes in the extreme south through the system of islands of South Georgia, South Sandwich and South Orkney are connected to the mountain ranges of West Antarctica. The fold-block mountains of the Antarctic Peninsula, the western coast of the mainland and the so-called Antarctic Andes (Antarcandy) continue the tectonic zones of the Andean mobile belt (height - 3000-4000 meters, the highest point of the continent is located on Ellsworth Land - the Vinson massif, 5140 meters). This folded Meso-Cenozoic belt is separated from the Precambrian and Paleozoic structures of East Antarctica by a system of faults running from the Weddell Sea to the Ross Sea. Along them rise the horst ranges of the Transantarctic blocky mountains. The faults are associated with manifestations of volcanism on the mainland and islands.

The East Australian mountain system, bordering the Gondwana platforms from the east, is much simpler in orographic structure and lower in absolute heights than the Andean. It stretches for 4000 km along the east coast of Australia and is separated from the island arcs by marginal seas. Folded-block mountains prevail here, low and medium-altitude: as a rule, their height is 1000-1500 meters (the highest point of Kosciuszko is 2230 meters).

This mountainous country was created by differentiated neotectonic movements on the site of the post-Hercynian peneplain. The movements were accompanied by lava outpourings, but there is no modern volcanism here. The mountains of Eastern Australia are also characterized by low seismic activity, which indicates their relative tectonic stability at the present time. The ridges have steep eastern slopes, and gently undulating foothills descend to the inland plains, which are called down in Australia.

A mobile belt also adjoins the African platform from the north, within which the Atlas mountain system was formed. The same regularity is manifested here: on the outer side of the mainland along the coast of the Mediterranean Sea, there are ridges of young folded mountains - Er-Rif and Tel-Atlas. Most of the Atlas system is a revived fold-block mountains and intermountain plateaus on a Hercynian base. A high degree of tectonic activity remains in the northern ranges, and earthquakes often occur.

The mountains of the system are low - on average 2000-2500 meters. They reach the highest height in the High Atlas (Tubkal, 4165 meters - the highest point of the system). The young Alpine ridges of Rif and Tel Atlas barely reach 2500 meters.

The Cape mountain system, which occupies the extreme south of Africa, is a revived mountain with an inherited folded structure.

Folding movements took place here in the era of the Hercynian orogeny, when Gondwana was a single continent and the southern tip of the African continent was part of the mobile belt on its margin. Folding processes ended here in the Triassic period, and immediately after this, an intensive lowering of the territory began. Mountain structures, not yet smoothed out by denudation, were covered by a cover of Mesozoic marine sediments. Neotectonic uplifts, which covered the whole of South Africa in the Paleogene-Neogene time, led to the fact that the Hercynian anticline ridges were on the surface. Loose sedimentary rocks that overlay the folded structures were removed. The uplift was accompanied by increased deep erosion. As a result, the Cape Mountains are several parallel anticlinal ridges up to 1500 meters high, separated by longitudinal synclinal valleys. They are crossed by narrow deep river canyons, sometimes associated with tectonic fissures.

Features of exogenous relief (morphosculpture)

Of the exogenous factors that form the surface of the southern continents, the leading role belongs to the processes of weathering (hypergenesis), the work of surface and ground waters, in Africa and Australia - the work of the wind, in Antarctica and some regions of the Andes - glaciers.

The role of weathering processes

The activity of all exogenous factors in most of the southern tropical continents proceeds at high temperatures. Rocks of various genesis and composition undergo hypergenesis: crystalline, volcanogenic, sedimentary. Their upper layer over large areas is weathering crusts, which were formed over a long period of time (starting from the Mesozoic) under changing conditions.

This is a zone of hypergenesis of both ancient rocks of the Precambrian basement and Proterozoic syneclises, as well as younger sedimentary and effusive deposits. Thick, usually loose weathering crusts have a different structure and composition depending on the conditions of their formation and the lithology of the original rocks. Over vast areas, they were formed under conditions of increased moisture, if not year-round, then seasonal, and are a product of biochemical processing (mainly ferralitization) of surface rocks. These crusts consist of fine particles of clay minerals and hydroxides of iron, aluminum, and manganese. Depending on the formation conditions, dense ferruginous or ferruginous-aluminous lateritic layers are formed at different depths. The thickness of such cores can be from several to hundreds of meters. It depends on the duration of formation, and on the composition and structure of the original rocks, and on the modern processes of both their formation and destruction.

In the arid regions of the Southern Tropical Continents, there are areas of relic hydromorphic crusts - a legacy of the pluvial epochs. They are especially widespread on the plains and in the blocky mountains of Australia and North Africa. The ferruginous lateritic crusts, being destroyed under the influence of physical weathering, turn into placers of red-colored rubble, pebbles, and sand.

The processes of physical weathering, widely developed in areas of arid climate due to large temperature differences, destroy rocks. Sharp ridges and peaks, bizarrely shaped rocks with niches, arches, ledges are formed. Destruction products - large clastic material - fill up the lower parts of the slopes and the surrounding plains. These are rocky deserts - hamads (hamads). They are confined for the most part to tectonic uplifts, volcanic massifs, intrusive remnants, etc., and are widespread in all arid zones of the plains and mountains of the southern continents.

On the surface of hard rocks, processes of desquamation (peeling) develop, and the so-called "desert tan" is formed - rock ledges are covered with dark films. These processes operate not only in the hot arid regions of the southern tropical continents, but also in Antarctica, in its oases and mountainous regions, rising in places above the ice surface.

fluvial relief

The river network of constantly humid regions with equatorial, tropical and subtropical climates is characterized by a shallow erosional incision of the channels. On flat stratified and accumulative plains, water erodes weathering crusts, carries a mass of fine earth, and deposits fine silty material. The rivers constantly overflow, change their channels, wander along the wide bottoms of the valleys, branch into branches separated by low islands, and form meanders.

Alluvial plains - systems of floodplains, usually of several levels, and wide floodplain terraces - the main type of fluvial morphosculpture within tectonic depressions: the Amazonian, Orinokskaya, Laplatskaya, Pantanal - in South America, the basins of the Congo, Okavango, White Nile, middle Niger - in Africa, the Murray Basin in Australia. It is not for nothing that most of these plains bear the names of the rivers that drain them.

The channels of high-water African rivers flowing down from mountains and plateaus and crossing the raised margins of the mainland, such as, for example, the upper and lower reaches of the river, are not deeply incised. Congo (Zaire) or the lower reaches of the Zambezi, Orange, Kunene, etc.

These have a stepped longitudinal fall profile with rapids and waterfalls slowly receding upstream. This cannot be explained only by the youth of the valleys, since some of them, for example, the upper reaches of the river. Congo, developed in more or less stable tectonic conditions at least since the Mesozoic. According to the figurative expression of the French geographer Biro, rivers "jump over" the unevenness of the relief, and do not cut through them. This is apparently due to the fact that the waters of the rivers carry mainly fine earth. Large detrital material is rapidly decomposed by biochemical processes at high temperatures and high humidity, therefore, traction sediments do not have a strong eroding ability, especially since the bottoms of valleys are often composed of solid crystalline rocks. The channels are often armored with ferruginous crusts and films. In areas of variable humid climate of equatorial-tropical latitudes, lateritic shells lie at a shallow depth or even directly on the surface. When destroyed, they turn into hard pebbles, which have significant eroding capabilities. But at the same time, lateritic crusts armor the bottom of the channels, making it difficult to cut. As a result, both in constantly and in variable humid tropics, under more or less stable tectonic conditions, the erosion incision is shallow and the relief has soft outlines.

In the deserts of North and South Africa and Australia, relict erosional landforms have been preserved - the channels of former rivers and streams (the wadis or oueddas of Africa, similar to Arabian ones, and the cries of Australia).

These usually shallow and gently sloping hollows stretch for tens and hundreds of kilometers and end, as a rule, in the hollows of dry lakes. During periods of rare heavy rains, streams of water flow through them. This prevents the complete disappearance of channels, which deepen again after each such period. During the rains, the former lake basins are also filled for a short time, turning back into lakes, usually salty ones. Such depressions in the northeast of the Sahara and within the Atlas are called shotts or sebkhas.

Solifluction and landslide relief

With constant or seasonal waterlogging, slope runoff develops. Soaking loose soil literally flows between the roots and stems of plants, shifts down the slopes, even gentle ones. Solifluction forms appear. Landslide formation is widespread. The development of slope processes increases sharply if the vegetation cover disappears, which usually occurs as a result of human economic activity. Deforestation and burning of forests and shrubs, excessive grazing and other impacts on the vegetation cover, which binds the soil and hinders the flow and removal of material down the slopes, lead to the rapid development of solifluction and landslide processes. These processes are facilitated by the presence of dense water-resistant layers - lateritic shells, and in some places monolithic crystalline rocks lying close to the surface.

On more or less flat and gently sloping areas of the surface, suffosion also develops in loose weathering crusts, forming depressions.

The activity of surface and underground waters generally leads to the formation of a slightly undulating gently sloping relief with remnant mountains, ridges, and areas of table plateaus. Such leveling surfaces were developed during periods of stable tectonic regime throughout geological history.

Ascending neotectonic movements raised them to different heights, in the process of uplift they underwent intensive dissection, but nevertheless, fragments of peneplains and pediplains of various geological ages play a rather large role in the relief of the southern continents. On all continents, the remains of several alignment surfaces can be traced.

The remnant table plateaus 1000-1500 meters high, and in some places even 2000-3000 meters high, are fragments of a dissected "Gondwanan" surface, which was created by denudation in the Jurassic period. They are found within the highlands of Africa and South America. Later surfaces are widespread, created by denudation cycles of the Late Cretaceous - Oligocene, Neogene and, finally, the Pleistocene cycle, which continues to the present. As a result, table heights and plateaus, flat-topped mountains and slightly undulating plains, complicated by remnant massifs or low ridges at outcrops of denser bedrocks, on intrusive massifs, are often found on the southern continents. Peneplanated plains with remnants are very characteristic of Western and Central Australia. Table forms are often associated with the presence of armoring layers, for example, hard sandstones and quartzites: the chappadas of the Brazilian, tepuys of the Guiana Highlands, and the mesas of South Africa.

Aeolian landform

Forms of aeolian accumulation: various types of dunes, sandy ridges are common in those areas of arid regions that are composed of sands from the surface (usually ancient river or sea alluvium). The dune relief is typical for the coastal deserts of the west of South America and South Africa. The vast sandy expanses of the deserts of Australia are mainly ridges, elongated in the direction of the prevailing winds. In the African sandy deserts (in the ergs of the Sahara, in the Namibe) one can find almost all types of aeolian accumulative relief. In the Sahara there are separate dunes, reaching hundreds of meters in height.

In the arid regions of the southern continents, forms associated with deflation (blowing) and corrosion are also widespread. Rocky ledges turn into stone mushrooms, often found in the Brazilian Highlands, in the arid mountainous regions of all the southern continents. There are areas on the dry plateaus of South Africa where granite rocks have been turned by the combined work of weathering and wind into giant balls and pyramids of almost geometrically regular shape.

Karst relief

Unlike the Northern continents, it has a limited distribution on the Southern continents. Its formation requires a combination of outcrops of karst rocks with a sufficient amount of precipitation. There are few such areas within the southern continents.

Karst is most widespread in Australia, where limestone strata come to the surface on the Barkley Plateau within the subequatorial climate zone with summer precipitation, in the East Australian Mountains, where precipitation falls all year round, on the Nullarbor Plain, in a subtropical climate with winter precipitation. In the basin of the Darling and Murray rivers, limestones occur under a layer of alluvial sediments, and covered karst is developed.

Karst forms of different regions differ depending on local conditions. In the north and northeast of Australia, mainly tropical tower karst with conical limestone outcrops is formed. On the plains and plateaus of the subtropical zone, the most diverse forms of bare and covered karst are common. There are numerous caves, grottoes and niches in the mountains and on the abrasion ledges. At the foot of the limestone ledge, by which the Nullarbor Plain breaks off to the Great Australian Bight, the sea seems to boil from the outlets of underwater karst sources. The coastal cliff has a scalloped shape, since sea water intensively dissolves the rock along the cracks perpendicular to the coast line. Narrow bays deeply protruding into the land are formed, which are separated by rounded ledges of the coastal ledge.

In Africa and South America, karst forms are found in small areas in the Andes, in the Brazilian Highlands (there are also caves), in East and South Africa. Significant areas are occupied by karst landforms in the Atlas mountain system, on the Somali peninsula and in the northern Sahara (for example, in the Tasilli ridges bordering the Akhagarr highlands). In these arid regions, the formation of karst is associated with the pluvial epochs of the Pleistocene (such a relief has a relict character). In the karst caves of Tasilli and other ridges, wall paintings of primitive people who inhabited the Sahara when it was not yet a waterless desert were found.

Coast relief

The types of coasts of the southern continents are very diverse. Among them there are both primary-even, and dissected, and created by abrasion and accumulative activity of the sea, non-wave and wave processes. The coasts formed by fault movements are very widespread, since most of the margins are passive margins of the continents. They are, as a rule, bordered by narrow strips of accumulative lowlands at the foot of high steep cliffs, usually treated by abrasion. Widely developed lagoon shores, often accompanied by mangroves. The mangrove type of coasts is typical for low coastal areas in the equatorial-tropical regions of the southern continents.

The eastern outskirts of Australia are interesting, where the coastline is accompanied by numerous coral buildings.

There is a unique formation here - the Great Barrier Reef.

This is a discontinuous ridge of coral reefs and islands, stretching along the northeastern coast of the mainland for 2300 km and separated from the coast by a wide lagoon. Despite the rather large distance from the coast of the mainland in some places, the reef has a significant impact on the nature and economy of the coast. The oceans break on the Great Barrier Reef, it rebuilds the currents approaching the mainland, creates special conditions for the life of organisms in the calm and warm waters of the lagoon. The destruction of reef structures, occurring under the influence of both natural and anthropogenic processes, can have significant consequences for natural complexes and the population of the Australian coast. Coral reefs accompany the northern coast of Australia and South America and are practically absent from the steep coastline of the passive margins of the African continent.

glacial relief

Glacial, including relict landforms, so characteristic of Eurasia and North America, are very limited in the Southern Tropical continents. Glacial relief, both exarative and accumulative, exists on the plains of the Patagonian plateau, in the mountains of Eastern Australia (mountain relic forms) and in the Andes. The Andean highlands and almost the entire region of the South Andes, where there is a whole complex of forms associated with mountain glaciation, including troughs, glacial lake basins and fjord coasts, were subjected to glacial processing in the past and are now being subjected to.

Glaciation is the leading exogenous factor in the formation of the relief of Antarctica. For almost the entire territory of the mainland, one has to speak of the subglacial relief of the stone bed of a giant ice sheet. Only 0.2-0.3% of the continent's area is free of ice. The influence of other external relief-forming processes is experienced by mountains protruding above the ice surface, small areas of the so-called Antarctic oases that are not covered with ice, and rocky cliffs that occupy 8% of the length of the sea coast. But even here, mountain-glacial exaration and accumulative landforms predominate, and in oases, water-glacial landforms also prevail.

Glacial landforms in the mountains of the mainland are apparently of ancient age and have been preserved since the times when the climate was warmer, since at very low temperatures prevailing in Antarctica, cirque and valley glaciers lose their mobility. The processes of physical weathering are in the nature of desquamation of rocks, giving their surface a cellular structure. Some chemical reactions also take place, as a result of which red-brown crusts are formed - “desert tan”, or white efflorescences of gypsum and calcite. A significant role in the sculptural processing of the surface belongs to the wind. The products of physical weathering are carried by the wind. Due to the high force of the wind flow, fragments rolling over the surface can be up to 10-20 cm in diameter. They have considerable corroding capabilities: hard material grinds and grinds rocky surfaces. Aeolian accumulation processes are also taking place in oases: sand dunes and ridges have been found there along with fluvioglacial relief - mainly glacier melt water runoff troughs.

Of interest is the relief of the snow-ice surface of the ice sheet with numerous and varied irregularities: snow hills, sastrugi, glacial cracks, winding "valleys" of streams flowing along the ice plain during periods of melting, etc. This very mobile, rapidly changing relief is formed under the influence of a large number of interacting factors: the movement of ice on an uneven stone bed, the processes of melting and freezing, the work of wind, melt water and many others.

The coast of Antarctica for thousands of kilometers is a high ice barrier, which has no analogues anywhere on Earth. Icebergs are constantly breaking off from it. Rocky shores (about 8% of the coastline) are usually high steep cliffs, in the niches of which lie glaciers and snowfields.

Thus, for South America, the fluvial relief is most characteristic, in Africa, mainly fluvial and eolian morphosculpture is developed, in Australia, over most of the territory, the leading role belongs to eolian processes, in Antarctica, the main surface forms are created by the work of glaciers and wind. At the same time, the fluvial and eolian relief of the Southern Tropical Continents has many common features. This is due to the fact that within their limits there are similar climatic conditions: climates of equatorial-tropical latitudes prevail.

The relief of the country is dominated by plains with heights of 200-500 m above sea level.
In the northwest there is the Air massif - a system of plateaus of different heights, stretching for 400 km from north to south and for 250 km from west to east.
The highest point, Mount Bagezan, reaches 1900 m.
The plateau slopes to the west, densely indented by wadi - dry riverbeds, filled in the rainy season. The eastern part of Air abruptly breaks off to the vast sandy desert of Tenere with an area of ​​about 400 thousand km2. In the northern (Tenere-Tafazaset) and central part of Tenere, between the Air and Jado plateaus, there are mobile sand dunes.
In the center of Tenere is located Kavar - a steep area with many oases.
In the southern part of Tenere, sparse grass and shrubs hold back the sands and create fixed dunes. To the west of the Air plateau is the Talak plain - a desert with moving dunes with an area of ​​2-3 thousand km2. The part of the plain adjoining Air is composed of clay and irrigated from the wadi during the rainy season, which makes it a good pasture for nomads.

In the northeast are the sandstone plateaus of Jado and Mangeni. To the east, on the border with Chad, are the Afafi and Chigai plateaus. These plateaus have steep slopes, are indented by canyons and are difficult to access for humans. In the southeast is the semi-desert Manga - the Dried Basin of Lake Chad. The south of the country is occupied by plains with separate outcrops of crystalline rocks.

The main mineral deposits are located in the outcrops of crystalline rocks on the Air and Liptako plateaus, as well as in sedimentary rocks in the center and east of the country.

The country's main wealth is uranium ore, in terms of reserves of which Niger is in ninth place in the world (sixth in terms of production). Explored reserves of uranium ore (uranium oxide) are estimated at 200 thousand tons. The main deposits of uranium are located in the west of the Air plateau. Mining is carried out in the cities of Arlit and Akuta. Exploration for uranium is also being carried out on the Jado Plateau, large reserves have been found in the Kawara oases, and there is an assumption that the distribution of uranium in Niger is much more extensive.

In addition to uranium, the country is also rich in other minerals.
To the north of the city of Agadez is the Anu-Araren coal deposit, whose reserves are about 6 million tons. The low quality of the coal is compensated by the low depth of occurrence (about 40 m).
In the east of Niger, in the sedimentary rocks of the Manga Basin and Lake Chad, there are oil-bearing layers. The iron ore deposit near the city of Sai contains 600-700 million tons of raw materials. There is a large deposit of phosphorites (500 million tons) near the city of Tapoa.
In the vicinity of the villages of Timia and Elmeki, cassiterite containing tungsten and tantalum is mined, deposits have also been discovered near the city of Zinder.
Near the city of Malbaza there are large reserves of limestone and gypsum.
Salt deposits have been developed in the oases of Bilma, Fashi and Tegiddan-Tesum. Minor gold placers were found in the sediments of the Sirba River.

Copper, niobium, lithium, manganese, cobalt, nickel and other minerals found

First, the Niger River.
Niger, a river in West Africa (3rd in length after the Nile and the Congo) length 4160 km basin area 2092 thousand km2 average water flow 9300 m3 / s, flows into the Gulf of Guinea. The largest river of such states as Niger (Republic of Niger) and Nigeria (Federal Republic of Nigeria)
Nigeria is a country in West Africa on the Gulf of Guinea. It borders Benin to the west, Niger to the north, Chad to the northeast, and Cameroon to the east and southeast. In the south it is washed by the waters of the Atlantic Ocean. territory: 923,768 km2, population: 140 million people (2006). capital: Abuja. The relief is dominated by plains and plateaus (the highest height is 2042m, Vogel peak. Oil, tin, columbite production.

Everyone remembers that Africa is the hottest continent on the planet. But few people know that Africa is also the "highest" of the continents, since it has the highest average height above sea level. The relief of Africa is very diverse and complex: there are mountain systems, plateaus, large plains, active and long-extinct volcanoes.

The relief of any region, as is known, is closely connected with the tectonic and geological structure of the territory. The relief of Africa and the minerals of this continent are also associated with the tectonics of the mainland. Let's consider this question in more detail.

Plan for describing the relief of the territory of Africa

The relief of any continent is characterized according to a specific plan. The relief of Africa is described according to the following algorithm:

1. characteristics of the mainland.
2. Analysis of the history of the development of the earth's crust.
3. Characterization of external and internal (exogenous and endogenous) factors of relief formation.
4. Description of the general features of the relief of the continent.
5. Highlighting the maximum and minimum height.
6. Minerals and their distribution on the territory of the mainland.

Low and High Africa

The description of the relief of Africa should begin with the fact that the mainland, from an orographic point of view, is divided into two parts: High and Low Africa.

Low Africa occupies more than 60% of the entire area of ​​​​the continent (geographically, these are the northern, western and central parts of Africa). Heights up to 1000 meters prevail here. High Africa covers the southern and eastern parts of the mainland, where the average heights are 1000-1500 meters above sea level. Here are the highest points - Kilimanjaro (5895 meters), Rwenzori and Kenya.

General characteristics of the African relief

Now consider the main features of the relief of Africa.

The main feature is that the relief of the mainland is mostly flat. Mountain ranges border the mainland only in the south and northwest. In East Africa, the relief is predominantly flat.

Such landforms of Africa predominate: plateaus, plains, highlands, plateaus, remnant peaks and volcanic massifs. At the same time, they are located on the territory of the mainland very unevenly: inside it there are mostly leveled surfaces - plains and plateaus, and along the edges - hills and mountain ranges. This feature is associated with the tectonic structure of Africa, most of which lies on the ancient platform of the Precambrian age, and along its edges there are areas of folding.

Of all the mountain systems in Africa, only the Atlas is young. In the east of the mainland, the huge East African Rift Valley stretches for more than 6,000 kilometers in length. Grandiose volcanoes formed in the places of its faults, and very deep lakes formed in the depressions.

It is worth listing the largest landforms in Africa. These include the Atlas, Draconian and Ethiopian highlands, the Tibesti and Ahaggar highlands, the East African plateau.

atlas mountains

The mountainous landforms of Africa are, as already mentioned, only in the south and northwest of the mainland. One of the African mountain systems is the Atlas.

The Atlas Mountains arose 300 million years ago as a result of the collision of the Eurasian and African plates. Later, they were raised to considerable heights due to neotectonic movements that took place at the end of the Paleogene. It is worth noting that earthquakes occur in this area even now.

The Atlas is composed mainly of marls, limestones, and also ancient volcanic rocks. The bowels are rich in metal ores, as well as phosphorites and oil.

This is the largest mountain system in Africa, which includes several almost parallel mountain ranges:

• High Atlas.
• Rif.
• Tel Atlas.
• Middle Atlas.
• Sahara Atlas.
• Antiatlas.

The total length of the mountain range is about 2400 kilometers. The maximum heights are located on the territory of the state of Morocco (Mount Toubkal, 4165 meters). The average heights of the ridges range from 2000-2500 meters.

dragon mountains

This mountain system in the south of the mainland is located on the territory of three states - Lesotho, South Africa and Swaziland. The highest point of the Dragon Mountains is Mount Thabana-Ntlenyana with a height of 3482 meters. The mountains formed 360 million years ago, during the Hercynian era. They got such a formidable name due to their inaccessibility and wild appearance.

The territory is rich in minerals: platinum, gold, tin and coal. The organic world of the Dragon Mountains is also unique, with several endemic species. The main part of the mountain range (Drakensberg Park) is a UNESCO site.

The Drakensberg Mountains are the watershed boundary between the Indian Ocean basin and the upper reaches of the Orange River. They have a unique shape: their tops are flat, table-like, separated by erosion processes into separate plateaus.

Ethiopian highlands

The relief of Africa is strikingly diverse. Here you can find high mountain ranges of the Alpine type, hilly plateaus, vast plains and deep depressions. One of the most famous mainland is the Ethiopian Highlands, within which not only Ethiopia is located, but also 6 other African states.

This is a real mountain system with average heights of 2-3 kilometers and the highest point of 4550 meters (Mount Ras Dashen). Due to the specific features of the relief of the highlands, it is often called the "roof of Africa". In addition, this "roof" often shakes, seismicity remains high here.

The highlands formed only 75 million years ago. It consists of crystalline schists and gneisses overlain from above by volcanic rocks. Quite picturesque are the western slopes of the Ethiopian Highlands, indented by the canyons of the Blue Nile River.

Within the highlands there are rich deposits of gold, sulfur, platinum, copper and in addition, it is also an important agricultural region. It is considered the birthplace of coffee, as well as some varieties of wheat.

Mount Kilimanjaro

This volcano is not only the highest point of the mainland (5895 meters), but also a kind of symbol of all of Africa. The volcano is located on the border of two states - Kenya and Tanzania. From the Swahili language, the name of the volcano is translated as "sparkling mountain".

Kilimanjaro rises above the Masai plateau at a height of 900 meters, so visually it seems that the volcano is unrealistically high. Scientists do not predict the activity of the volcano in the near future (other than possible gas emissions), although it was recently found that the lava is located 400 meters from the Kibo crater.

According to local legends, the volcano erupted about two centuries ago. Although there is no documentary evidence for this. The highest point of Kilimanjaro - Uhuru Peak - was first conquered in 1889 by Hans Meyer. Today, the speedy conquest of Kilimanjaro is practiced. In 2010, the Spaniard Kilian Burgada set a kind of world record by climbing to the top of the volcano in 5 hours and 23 minutes.

Relief of Africa and minerals

Africa is a continent with huge economic potential, which is characterized by huge reserves of various minerals. In addition, a more or less even, slightly dissected topography of the territory contributes to the development of industry and the construction of roads and other means of communication.

Africa is rich in minerals, on the basis of which metallurgy and petrochemistry can develop. Thus, the continent holds the absolute leadership in the world in terms of total reserves of phosphorites, chromites and tantalum. Africa also has large deposits of manganese, copper and uranium ore, bauxite, gold and even diamonds. On the mainland, they even distinguish the so-called "copper belt" - a belt of high mineral and raw material potential, stretching from Katanga to (DRC). In addition to copper itself, gold, cobalt, tin, uranium and oil are also mined here.

In addition, such regions of Africa as North Africa and West Africa (its Guinean part) are also considered very rich in the presence of minerals.

So you got acquainted with the features of the relief of the hottest continent on Earth. The relief of Africa is unique and diverse, here you can find all its forms - mountain ranges, plateaus and plateaus, highlands, hills and depressions.

Relief - a set of irregularities of the earth's surface. There are two main landforms: plains and mountains. Plains are a form of relief with small (up to 200 m) differences in relative heights. Mountains are a form of relief with large (more than 200 m) differences in relative heights. Relative altitude is the elevation of one point on the earth's surface above another, while absolute altitude is the height of a place above sea level.

Most of Russia is occupied by plains. The mountains are located mainly in the south and east of our country, which leads to a general slope of the territory of Russia to the north.

Relief formation is influenced by internal and external forces. First of all, the main landforms depend on the tectonic structure of the territory. Platform areas - the ancient Russian and Siberian platforms or the young West Siberian plate - are characterized by plains: , and plain, respectively. On the territory of ancient platforms, all types can be found: lowlands, uplands and plateaus, and lowlands predominate on the territory of young platforms.

Lowland is a type of plains with absolute heights up to 200 m (Caspian lowland, West Siberian plain, North Siberian,).

Elevation is a type of plains with absolute heights from 200 to 500 m (Central Russian, Smolepsko-Moscow, Valdai, Volga, Stavropol).

The plateau is a type of plains with absolute heights of more than 500 m (Central Siberian Plateau).

If the crystalline foundation of ancient platforms comes to the surface (shields), then elevated landforms arise - hills (on the Voronezh massif), plateaus (on the Anabar shield - the Anabar plateau) or even platform mountains (on the shield and on the Aldan shield).

The largest plains of Russia are the East European (Russian), West Siberian Plain and the Central Siberian Plateau.

Folded areas (geosynclines) correspond to .

By absolute height, low, medium and high mountains are distinguished.
Low mountains are mountains with absolute heights below 2000 m (Khibiny, mountains, Byrranga).

The middle mountains are mountains with absolute heights from 2000 to 5000 m (, Aldan and highlands, Chersky ridge, Sikhote-Alin).

High mountains are mountains with absolute heights of more than 5000 m (Big).

For ancient mountains (Baikal, Caledonian and Hercynian folding), as a rule, low mountains (Urals) are characteristic, medium-altitude mountains correspond to areas of medium (Mesozoic) folding (Verkhoyansky ridge, Chersky ridge, uplands, Sikhote-Alin), and for young mountains ( Cenozoic, or folding) are characterized by high mountains (Caucasus). The areas of young folding are characterized by active manifestations and (and islands), where all the active ones are located - Klyuchevskaya Sopka, Koryakskaya Sopka, Tolbachik, Shiveluch, Tyatya and others.

A special group is formed by renewed (or revived) mountains: these mountains are of ancient age, but in their history they have experienced additional uplifts and reach quite large absolute heights: - Altai, Sayans, and others.

The highest mountains in Russia are the Greater Caucasus, the highest point of which is the extinct Elbrus - 5642 m. In Kamchatka there is the highest active volcano in the world in terms of cone height - Klyuchevskaya Sopka (4688 m).

The lowest point of Russia - level