South America: geographical location and climate. Features of the relief of South America

In the orography of South America, there is some similarity with North America. On the east, off the coast of the Atlantic Ocean there are vast highlands: Brazilian, Guiana and Patagonian. In the extreme west and north of the mainland, repeating the outlines of its coasts, the longest mountain system in the world, the Andes, or the South American Cordillera, stretches for 9 thousand km. Between the highlands and the Andes there are vast low-lying plains, occupying approximately 45% of the territory of the mainland: the Amazonian, Orinoco and Paraguayan-Parana. They are irrigated by the largest rivers of America and all are connected with each other, forming a continuous strip of plains in the middle part of the mainland.

The large, eastern part of the mainland is a platform. In the north and west, it is bordered by a zone of structures.

The foundation of the South American platform for the most part Precambrian age, and in the south - Hercynian. On this basis, on modern tectonic maps of the South, the Guiano-Brazilian (South American) platform is distinguished on the Archean-Proterozoic folded basement and the Patagonian - on the Hercynian base. The development of platform structures in South America obviously took place in close connection with the platforms of other continents of the southern hemisphere - Africa, Australia, Antarctica and South Asia. The structure of the platform is characterized by the presence of protrusions of the ancient base and depressions in which the ancient folded base is hidden under the layers of younger sedimentary deposits. The protrusions in the relief usually correspond to the highlands of the eastern part of the mainland, and the depressions correspond to the lowlands. However, there is no complete coincidence of structure and relief.

Precambrian orogenic cycles covered a significant part of South America. Maybe, what in the Precambrian there was a connection between all the continents of the southern hemisphere. At the same time, extensive geosynclinal basins were laid, one of which was the Andean basin. geosynclines, continuing on the north of the Cordillera geosyncline of North America.

In the Cambrian, a significant trough occurred at the site of the Amazonian lowland, which then spread into the Paraguay basin. The sea occupied large areas on the platform in the Devonian, and in the Carboniferous period its area was again reduced. Obviously, in the southern part of the mainland, approximately south of 37 ° S. sh., from the beginning of the Paleozoic there was a deflection of the geosynclinal type, in which mountain building occurred during the Hercynian cycle, what led to the creation of the Patagonian platform. These folded structures (Gondwanids) joined from the south To Precambrian platform, forming a single whole with it. The Precambrian base of the platform during the Hercynian cycle was subjected to splits, which in the southern part of the Brazilian ledge were accompanied by powerful outpourings of magma. Manifestation Hercynian orogeny was also v within the Andean geosyncline, and mountain building captured its eastern margin, adjacent to the platform.

Throughout the Paleozoic, the huge mainland of the southern hemisphere - Gondwana continued to exist as a whole. At the end of the Carboniferous and in the Permian, in connection with the completion of the Hercynian folding and the general uplift of the land, there was continental glaciation in Gondwana. Findings of ancient moraine in the southern part of the Brazilian Highlands, as well as in Africa and Australia.

In the Triassic, a trough formed at the site of the South Atlantic Ocean, and Gondwana began to break up.

On the platform during the Mesozoic, the previously formed mountains were destroyed and large masses of continental sediments accumulated, which gradually filled the areas of troughs, turning them into land.

In the Lower Cretaceous, orogeny began within the Andean geosyncline, which first covered its western regions and was accompanied by intense volcanic processes. In the Tertiary period, mountain building spread to the eastern parts of the geosynclinal region, and in the Pliocene the Coastal Cordilleras were formed and the final connection between the two American continents took place. The outskirts of the platform were also captured by mountain building processes, as a result of which strongly modified sections of Precambrian and Upper Paleozoic structures were attached to the Andean system.

At the end of the Tertiary and at the beginning of the Quaternary period, the entire Andean system was covered by differentiated vertical movements, faults and volcanism.

Descents at the end of the tertiary period caused the subsidence of a significant part of the western margin of the Andes. The modern Andes represent only the eastern marginal part of the fold zone, while its main part is submerged under the waters of the Pacific Ocean. Vertical movements, expressed in the uplift of the rest of the Andes, led to increased denudation and the formation of a number of leveling surfaces and a system of steps, which are distinctive feature relief of the Andes. Volcanism and seismic as evidence of unfinished processes mountain building, are characteristic of the Andes and at the present time. The final phases of the orogenic cycle also affected the entire platform part of South America. They manifested themselves in the formation of faults, accompanied by lava outpourings, uplift and subsidence of individual sections and the associated With this revival of the processes of erosion and denudation.

In the Quaternary period, the Andes underwent mountain glaciation. In some places, the glaciers went beyond the mountainous country, as evidenced by the accumulation of loess-like deposits in the neighboring plains between the 30th and 40th parallels.

The following large structural and morphological regions are distinguished on the territory of South America:

Brazilian Highlands - the most extensive uplift v within the platform. It extends in the eastern part of the mainland from 4 to 30 ° S. sh. Most of the upland corresponds to a protrusion on the surface of the folded base of the platform, welded together from Archean and Proterozoic folds. But in the center of the highlands, the crystalline basement is deeply lowered and overlain by horizontally occurring, but highly elevated Mesozoic deposits. Thus, the inner part of the upland is a depression in the folded base of the platform.

The eastern and southeastern margins of the massif, facing directly to the Atlantic Ocean, are uplifted by normal faults and strongly dissected. They break up into a series of ridges, reaching more than 2000 m in height. These ridges rising high above ocean or over a narrow coastal plain, gradually descend towards the center of the highlands, turning into a wavy peneplanized surface with an average height of 600- 800 m. The southeastern edge of the highlands comes close to the coast in the Rio de Janeiro region, where a heavily dissected coast, accompanied by small islands, indicates recent land subsidence. To the north and south of this area, the Brazilian Highlands recedes from the ocean, separated from it by a young sandy plain with a lagoonal coast.

The inner part of the highlands, composed of sedimentary rocks, consists of a series of table plateaus with steep slopes. To the northwest and north, the highlands noticeably decrease towards the adjacent lowland plains.

The edges of the highlands in these places, and the presence of crystalline rocks noted numerous rapids and waterfalls, which abound in the tributaries of the Amazon flowing from the Brazilian Highlands.

In the north of the mainland, a vast ledge of the folded base of the South American Platform corresponds in the relief of the Guiana Highlands.

The highest and most dissected is the central part of the highlands, between the valleys of the upper Orinoco and Essequibo rivers. Separate ridges crowned with layers of dense sandstones reach 1000-1500 m, and the highest massif exceeds 2500 m. The eastern part of the highlands is a hilly crystalline plateau with an elevated southern margin.

The western part of the Guiana ledge is orographically not connected with the rest of the highlands, but is separated from it by the Orinoco lowland. This is the Pardaos massif adjacent to the Andes, within whom crystalline rocks covered thicknesses Cretaceous and Tertiary deposits and are opened only in the deepest valleys.

In the extreme southeast of the mainland, on the Patagonian Plateau, the base of the platform is formed by structures of Hercynian age. In the northern part they protrude to the surface, and to the south they are covered with Cretaceous sedimentary deposits and volcanic rocks. The surface of the plateau is small dismembered, because due to the dryness of the climate there nearly there are no streams. The plateau, reaching 1500 m in height, rises to the very shore of the Atlantic Ocean and breaks off to it with hundred-meter steps.

On either side of 30° S. sh. there is a section of the platform that was subjected to Late Tertiary uplifts due to mountain building within the Andean geosynclines. At present, meridional blocky ridges are rising there, composed of crystalline rocks and reaching heights from 2000 to 6000 m. Depressions filled with continental deposits lie between the ridges. The ranges called the Pampina Sierras and Precordillera are partly part of the Andes system.

The largest lowland in South America Amazonian- one of the largest on the globe, was formed on the site of an ancient extensive deflection within the platform. It is located between the Andes, the Brazilian and Guiana highlands. The folded foundation is submerged to a depth of many thousands of meters. In the western part of the lowland surface is almost perfect flat. To the east, i.e., downstream of the Amazon, the Guiana and Brazilian highlands converge and the alluvial lowland remains only in the form of a wide strip along the Amazon. To the south and north of the valley, the crystalline basement of the platform lies close to surfaces and is opened by deep valleys of the tributaries of the Amazon.

In the trough between the Guiana Highlands and the Andes, there is the Orinok Lowland, filled with Tertiary marine sediments and continental sediments carried down from neighboring mountains. Its western part is lower and flatter, the eastern part is elevated and dissected by deep river valleys on a plateau 200-300 m high. traces recent sinkings.

In the basin of the Parana, Paraguay and Uruguay rivers, in the zone of the platform trough between the Brazilian Highlands and the Andes, the Gran Chaco plain and the La Plata lowland are located.

In the northwestern part, in the Gran Chaco, heights reach 600-800 m, and the dissected surface folded continental tertiary deposits. To the south the surface is lowered. It is covered by strata of Quaternary alluvial, fluvioglacial and loess-like deposits, under which older continental strata are hidden, reaching great thickness. South of La Plata, within that part of the lowlands called the Pampas, isolated highlands rise. They are outcroppings of Precambrian and Paleozoic platform structures and are called the Sierras of Buenos Aires.

The north and west of the mainland is occupied by a complex system of the Andes, diverse both in tectonic and morphological terms. In the structure of the mountain system, a number of parallel orographic zones are distinguished, replacing each other from the Pacific Ocean deep into the mainland: low plateau-like ridges of the Coastal Cordillera stretch along the coast of the Pacific Ocean and along the islands. For more parts the coasts of the mountain abruptly break off to the ocean, forming an undivided longitudinally tectonic coast.

Coastal Cordilleras do not form a continuous strip. They appear at the end northern section of the coast as a continuation of the mountains of Central America, then break off and continue again only to 20 ° S. sh. In the extreme south due to With By recent subsidence, the marginal zone of the Andes has experienced fragmentation and turned into islands located in close proximity to the mainland.

The main part of the mountain system consists of structures of the Mesozoic-Tertiary age. An important role in the structure of mountains is played by volcanic rocks, extinct and active volcanoes. The most important areas of modern and recent volcanism are located in the Andes on both sides of the equator in the territory of Ecuador, south of 30 ° S. sh. within Chile and in the central part of the mainland between 13 and 29 ° S. sh.

The ridges of the Andes, called the Cordillera, stretch in parallel chains or fan out. In the middle part of the mountain system between the Cordilleras, there are vast flat areas cluttered with detrital material and products of volcanic eruptions. They're called Andean plateaus or Poons. Their heights are 3500-4500 m, while in the Cordillera individual peaks rise to 6000 and even 7000 m. The high Andes Cordillera are distinguished by a typical alpine relief, with mountain-glacial forms and with modern glaciers.

In the southeast of the mainland near the parallel 40 ° S. w. the Andes are joined in the form of blocky ridges by the Mesozoic uplifts of the Hercynian structures of the Natagonian platform, the so-called "patagonides".

The mineral resources of South America have been explored very unevenly. But even what is already known testifies to the enormous wealth of the mainland in various minerals. The deposits of various metal ores associated with how with the oldest crystalline rocks of the platform basement, and with the processes of volcanism that took place in the Andean geosynclinal region. But there are also large reserves of minerals on the mainland. sedimentary origin.

The richest reserves of metal ores are concentrated in the Andes, mainly in their central part. These ore deposits were formed during the formation of the Andes in connections with processes of volcanism and contact metamorphism. Bolivia has deposits of tin, tungsten, antimony, lead, zinc and silver. In Peru, polymetallic ores containing copper, lead, zinc and gold are common in the territory Colombia- reserves of gold and platinum. Chile is rich in copper and contains one of the largest copper deposits in the world. the globe, formed in connection with the processes of tertiary volcanism. In addition, on average Chile there are large deposits of radioactive elements. With processes volcanism in the Andes connected sulfur deposits.

On the Brazilian and Guiana Highlands, in the Algonquian slates and conglomerates, there are deposits of iron ores (the largest of them are in the southeast of the Brazilian Highlands and on the northern slope of the Guiana Highlands). Approximately in the same areas, manganese ores occur, formed as a result of the weathering of ancient crystalline rocks.

Numerous gold deposits are associated with ancient intrusions and metamorphic processes, occurring on the southeastern margin of the Brazilian Highlands and in the northeast of the Guiana Highlands. The destruction products of ancient pegmatite veins contain radioactive elements and diamonds.

In the Guiana and partly in the Brazilian Highlands, there are large deposits of bauxite, formed as a result of lateritic weathering of acidic and alkaline rocks of an ancient crystalline basement.

The entire territory between the Andes and the Brazilian Highlands, the intermountain basins and the coastal zone of the Andes are rich in oil. Especially large its reserves are concentrated in Venezuela around the Maracaibo lagoon and in the Caribbean Andes, as well as in Colombia, in the valley of the Magdalena and Cauca rivers. Relatively recently, oil was also discovered within the platform - in Patagonia, on the Amazonian lowland and on the Brazilian Highlands.

On the coast of the Pacific ocean, in the Atacama Desert and offshore islands are the world's only deposits of natural saltpeter. It is a product of the decomposition of organic remains accumulated in dry and hot climates during previous geological periods.

The process of formation of valuable organic matter(guano), used as a fertilizer, occurs on the coastal islands of the Pacific Ocean and at present. The material for this is organic remains accumulated by birds nesting there.

Features of the geological structure of South America

An ancient supercontinent existed millions of years ago gondwana . It broke up into three large blocks of the lithosphere, which formed the basis of four modern continents: Africa, Australia, Antarctica and South America . The latter will be discussed in this article.

In the geological structure of South America, there is a clear difference between the eastern and central parts and the western part of the continent. The east and center of the mainland are located on the old Precambrian South American platform . In the north and east of the platform, there are extensive areas where the ancient crystalline foundation of the platform comes to the surface - Guianan and Brazilian shields . The western part of the mainland is represented folded area , formed as a result of the collision of the continental platform and the oceanic lithospheric plate.

The oceanic plate sags and goes under the continental, forming a deep Peruvian trough (trough) along the entire west coast.

The edge of the continental plate is crumpled into folds. Mountains rose along the entire western edge of the mainland. This is a young area Cenozoic folding . This is evidenced by volcanic eruptions and frequent earthquakes. There is an active process of mountain building. The west coast of South America is part of "Pacific Ring of Fire" – areas of active seismic activity.

The platform part of the mainland in the past experienced repeated subsidence and uplift. This is evidenced by deposits of sedimentary rocks, including marine sediments.

At present, erosion processes, intensified by human economic activity, predominate on the platform part of the continent.

Features of the relief of South America

The folded region in the west of South America forms one of the largest mountain systems on the planet - andes mountains . In Indian language it means "copper mountains" .

The Andes Mountains stretch along the Pacific coast in three parallel mountain ranges. Many peaks rise above $6000$ m above sea level.

Highest point in South America Aconcagua ($6960$ m).

At the same time, it is the highest point of the entire Western Hemisphere.

There are also many active volcanoes here. The most famous of them are Cotopaxi, Ruiz, San Pedro . In the middle part of the mountain system there are internal plateaus, the heights of which reach $3500-4000$ m. The platform areas of South America are represented by plains - lowlands and plateaus.

Definition 1

Lowland - This is a section of the plain with absolute heights up to $200$ m.

Definition 2

Plateau - this is a section of the plain with absolute heights - more than $ 500 $ m.

The lowlands of South America are Orinoc, Amazon and La Plata . The elevation difference here is negligible. These are almost flat plains.

Remark 1

Amazonian lowland - the largest lowland in the world.

Thanks to marine deposits, the northern parts of the plains are rich in oil. On the crystal shields formed Brazilian and Guiana Plateaus . As a result of ancient tectonic activity, the lowering and raising of the platform were accompanied by breaks in the earth's crust, lava outcrops. In some places, the relief of the plateaus has the appearance of table mountains. They are replaced by landscapes of hilly plains, low massifs cut by gorges.

Minerals

The distribution of minerals is also associated with the geological structure.

Deposits are located on ancient shields iron, manganese, uranium ores, bauxite, diamond.
The Andes, justifying their name, are famous copper ores, deposits gold.
Large deposits discovered in the north of the mainland oil.
On the desert west coast, due to the peculiarities of the climate, deposits were formed sodium nitrate.

The center of the mainland (Amazon lowland) is still poorly studied and developed.

Features of the geological structure of South America

The oceanic plate sags and goes under the continental, forming a deep Peruvian trough (trough) along the entire west coast.

The platform part of the mainland in the past experienced repeated subsidence and uplift. This is evidenced by deposits of sedimentary rocks, including marine sediments.

At present, erosion processes, intensified by human economic activity, predominate on the platform part of the continent.

Features of the relief of South America

The folded region in the west of South America forms one of the largest mountain systems on the planet - andes mountains . In Indian language it means "copper mountains" .

The Andes Mountains stretch along the Pacific coast in three parallel mountain ranges. Many peaks rise above $6000$ m above sea level.

Highest point in South America Aconcagua ($6960$ m).

At the same time, it is the highest point of the entire Western Hemisphere.

Definition 1

Lowland - This is a section of the plain with absolute heights up to $200$ m.

Definition 2

Plateau - this is a section of the plain with absolute heights - more than $ 500 $ m.

The lowlands of South America are Orinoc, Amazon and La Plata . The elevation difference here is negligible. These are almost flat plains.

Remark 1

Amazonian lowland - the largest lowland in the world.

Thanks to marine deposits, the northern parts of the plains are rich in oil. Formed on crystalline shields Brazilian and Guiana Plateaus . As a result of ancient tectonic activity, the lowering and raising of the platform were accompanied by breaks in the earth's crust, lava outcrops. In some places, the relief of the plateaus has the appearance of table mountains. They are replaced by landscapes of hilly plains, low massifs cut by gorges.

Minerals

The distribution of minerals is also associated with the geological structure.

Deposits are located on ancient shields iron, manganese, uranium ores, bauxites, diamonds.
The Andes, justifying their name, are famous copper ores, deposits gold.
Large deposits discovered in the north of the mainland oil.
On the desert west coast, due to the peculiarities of the climate, deposits were formed sodium nitrate.

The center of the mainland (Amazon lowland) is still poorly studied and developed.

The relief of South America is varied and contrasting. According to the nature of the structure of the surface on the mainland, two parts are distinguished. Most of the eastern part is dominated by low, elevated plains and plateaus, in the west by the longest mountain ranges of the Andes.

The low-lying plains (Amazon, Orinoc, La Plata) have a flat relief and are composed of marine and lake-river deposits. The relief of the western part of the mainland is the result of the interaction of several lithospheric plates, on the border of which mountain building movements occur.

The formation of the Andes began in the Paleozoic and has not ended so far. The Andes continue to rise, volcanoes erupt, strong earthquakes occur.

South America is rich in mineral deposits. The richest deposits of iron, manganese, nickel ores, uranium, bauxite deposits containing aluminum are confined to the ancient shields of the platform. Oil was found in the depressions and deflections of the platform, natural gas, coal. In the Andes, a deposit of non-ferrous and rare metals was found. For example, the famous "tin belt" of Bolivia stretches from north to south for 940 km. The Andes contain the world's largest deposits of copper ores, as well as ores of molybdenum, silver, tungsten, lead and zinc. Sulfur, boron, iodine, saltpeter are mined from non-metallic minerals on the Pacific coast and in the foothills of the Andes. There is oil in the intermountain basins.

South America is made up of two main geological elements: the Andes - a folded mountain belt in the east and the South American mountain platform. Throughout its existence, the platform has been lowered and raised several times. Sedimentary rocks accumulated in the subsided areas, and crystalline rocks accumulated in the uplifted areas. Due to the different uplift rates, the earth's crust cracked and lava splashed onto the surface.

The mainland, due to the peculiarities of the internal structure, can be divided into two parts:

1. Vast lowlands.

Landforms of South America

La Plata, Orinokska and Amazonian lowlands, located in the troughs of the South American platform, occupy almost half of the mainland area.

2. Plateaus. in the east Guiana and the Brazilian Plateau are formed by outcroppings of the basement. In some places their height reaches 3000 m. The plateaus on the mainland are dotted with numerous river valleys, which can be seen if you view video in english.

central part Guiana The plateau is notable for its huge flat-topped massifs, the walls of which are almost vertical. It is cut by abysses and deep canyons, but from a great height it seems that the surface is absolutely flat.

The Andes mountain system stretches along the Pacific coast, the average heights of which range from 3000 to 5000 m. The highest point is Mount Aconcagua (6960 m). These are young mountains, strong earthquakes and volcanisms are happening here and now, as a result of which the San Pedro volcanoes and Cotopaxi.

Gold, uranium, aluminum, manganese, and iron ore are mined on the Guiana and Brazilian plateaus. In the Andes there are deposits of precious stones, zinc, lead and copper ores.

Due to the arid climate in the west of the South American continent, deposits of Chilean sulfur were formed in dry reservoirs, which is a raw material for nitrogen fertilizer and iodine.

Volcanic phenomena in Andes contributed to the formation of deposits building materials and sulfur. In the foothills and troughs of the platform in sedimentary deposits there are deposits of gas, oil, hard coal. The largest oil fields are concentrated on the coast of the Caspian Sea and in the foothills of the Andes.

South America. PHYSICAL AND GHEGRAPHICAL POSITION.

The area of the mainland is 17.8 million square kilometers without islands and 18.3 million square kilometers with islands. The length from north to south is -70 gr. h.d. exceeds 7500 km, from west to east (in the widest part) more than 4500 km. South America is crossed by the equator in the northern part. The extreme northern point is Cape Gallinhas, 13 gr. n.l.; extreme southern mainland point Cape Frouerd, 54 gr. S, insular Cape Horn, 56 gr. S The mainland lies entirely in the western hemisphere. The extreme western point of Cape Parinhas, 81 gr. h.d.; extreme eastern point Cape Cabo Branco, 34 gr. h.d.

South America lies in the equatorial, two subequatorial, two tropical climatic zones; the southern part is located in the subtropics and in the temperate zone.

The mainland is connected to North America by the Isthmus of Panama and separated from it by the Panama Canal, and separated from Antarctica by the Drake Passage.

Geological structure and main landforms of South America

It is washed in the west by the Pacific Ocean, in the south by the Drake Irrigation, in the east by the Atlantic Ocean, in the north by the Caribbean Sea of the Atlantic Ocean. In the north is the warm North Trade Wind Current, in the northeast is the warm Guiana Current, in the east is the warm Brazil Current, in the southeast is the cold Falkland Current, in the south is the cold West Winds Current, in the west is the cold Peruvian Current, in the north in the west - the warm current of El Niño. The coastline is slightly indented. Small bays are located at the mouths of rivers (La Plata, Maracaibo). Adjacent islands: in the north - Lesser Antilles, in the southeast - Falkland (Malvinas), in the south - Tierra del Fuego, in the southwest - the Chilean archipelago. The geographical position of the mainland, mainly in low latitudes, determines the predominance of tropical types of landscapes - the "kingdom of tropical nature."

TECTONIC STRUCTURE, RELIEF, MINERALS.

The relief of South America is asymmetrical. Most of the mainland is occupied by vast plains different heights. In the west is one of the highest mountain systems in the world - the South American Cordillera (Andes). The average height of the mainland is 580 m, the highest point is Mount Aconcagua 6960 m, the lowest is the Valdes Peninsula -40 m. The relief features are determined by the tectonic structure. At the base of South America lies the ancient South American Platform with a basement of Precambrian age. Within the platform there are large shields in the north and east, which correspond to the Guiana and Brazilian plateaus. Powerful block processes took place within the Guiana Plateau, so the plateau has a highly dissected relief. The highest point is Mount Roraima 2771 m, average heights are from 500 to 1000 m.

The Brazilian plateau corresponds to three shields: South Amazonian, East Brazilian, West Brazilian. This plateau gently rises from the north and northwest to the southeast. The highest point is Mount Bandeira 2890 m. Active magmatism took place within this territory, traps and volcanic plateaus are found here. This area is finished

its formation. Peneplens (leveling surfaces, denudation plains) are formed here.

Between the shields there are syneclises (troughs) of the platform foundation, which are filled with thick strata of sedimentary rocks. They correspond to the vast low-lying plains of South America: Amazonian, La Platskaya, Orinokskaya.

In the west, the platform adjoins an area of Alpine folding, which was formed in the Cenozoic as a result of the subduction of the Nazca Plate and the South American lithospheric plate. This region of folding corresponds to the Andes, which belong to the high and highest mountains. The highest point is Mount Aconcagua 6960 m. The processes of mountain building have not yet been completed here and are accompanied by earthquakes and volcanism (volcanoes of Cotopaxi, Chimborazo). Tectonic processes are strong in the Caribbean, Northern and Southern Andes, calm in the Central and Patagonian Andes. The Andes are made up of parallel ranges. Approaching, they form mountain knots, and where the ridges diverge, lie the Central Andean highlands and plateaus 3500-4000m high.

South America has a huge mineral resource base. The ore deposits are confined to the outcrops of the crystalline basement to the surface and to the Andean folded belt. Non-metallic - to the cover of sedimentary rocks of the platform. In ancient igneous and metamorphic rocks and weathering crusts, significant deposits of iron (Minas Geiras - Brazil), manganese, bauxite, titanium and uranium ores were formed. The reserves of beryllium, niobium, zirconium, tantalum are concentrated here. The vein deposits of gold and diamonds in Brazil play a significant role. On the Guiana Plateau there are large deposits of iron ore, bauxite and gold, in Peru and Chile large reserves of copper are concentrated in the Andean belt, in Bolivia there is a tin belt. Emeralds are mined in Colombia. In the sedimentary cover of the Orinoc, Amazonian and La Plata lowlands there are oil deposits, especially in Venezuela. Atacama contains 99% of the world's saltpeter reserves.

South America is the wettest continent on Earth, but not as hot as Africa, since the southern part lies in the temperate zone. Within the mainland, an equatorial, two subequatorial, two tropical climatic zones are formed; the southern part lies in the subtropics and in the temperate zone.

In general, the climate of South America is more varied than that of Africa and Australia. The average annual temperatures in most of the mainland are from +20 to +28, and only in the south are these figures lower (from +8 in winter to +16 in summer). The maximum recorded temperature is +46 (Cordoba), the minimum is -33 (Sariento). Antarctica has a huge impact on the climate of South America, from which the cold pampero wind breaks into the temperate and even subtropical zone. In Patagonia, the temperature can drop to 0 in summer, to -30 in winter; in the subtropics in the south of the Brazilian Plateau in summer up to +15, in winter up to +8.

The distribution of precipitation is extremely uneven, but the thickness of the precipitation layer is enormous - on average 1700 mm. The runoff layer into the hydrographic network is 700 mm. These values are twice the average. Maximum

the amount of precipitation falls in the western part of the Amazonian lowland (3000-4000 mm), on the western slopes of the equatorial Andes (up to 7000 mm) and on the western slopes of the Patagonian Andes (up to 4000-5000 mm). The minimum amount of precipitation is the inland regions of the tropical belt, the south of the La Plata lowland, the zone of the barrier rain shadow, in Patagonia. In general, the climate of South America, which is characterized by an abundance of heat and light in most of the territory, creates favorable conditions for year-round vegetation of plants.

INLAND WATERS.

Since South America is the wettest continent on Earth, one of the largest hydrographic networks in the world has formed here. South America occupies 12% of the land area, but it accounts for 36% of the world's flow to the ocean, of which 15% belongs to the Amazon. The pattern of the hydrographic network is extremely asymmetric, which is determined by the features of the relief. The main watershed runs along the peaks of the Andes near the Pacific Ocean, so all major rivers belong to the Atlantic Ocean basin (Amazon, Parana, Orinoco, Sao Francisco). Most of the rivers are rain fed, and only the rivers of Patagonia and the Patagonian Andes are snow and glacial. The regime of rivers is determined by their position in climatic zones. For example, the rivers of the Amazon Basin, which are rain-fed, are full-flowing throughout the year with two maxima in spring and autumn during the zenithal rains. Rivers of the subequatorial type are also fed by rain. These are major tributaries of the Amazon, the Orinoco River and the Paraguay. They have a maximum flow in late summer, early autumn and winter low water. The rivers of the tropical zone in the inland regions are shallow, and in the southeast of the Brazilian Plateau, they are full-flowing throughout the year. Most of the rivers in the upper reaches have a mountainous character, as they begin in the Andes and on the plateaus. There is an abundance of rapids and waterfalls. The Guiana Plateau is home to the highest Angel Falls in the world (1054 m). On the Iguazu River (Brazilian Plateau) - the world's longest Iguazu Falls (about 3000 m long, includes more than 270 cascades).

There are few large lakes. In the southern part of the Andes there are glacial lakes, in the north there is the Maracaibo lagoon lake of tectonic origin, in the Central Andes at an altitude of 3800 m lies the largest high-altitude lake Titicaca with depths up to 300 m.

Modern glaciation is relatively weakly distributed due to the high position of the snow line. Maximum glaciation in the Patagonian Andes and Tierra del Fuego.

NATURAL ZONES.

Due to the large extent from north to south, natural zonality is clearly represented on the mainland from equatorial forests in the center to semi-deserts and deserts of the temperate zone in the south. Due to the predominance of a hot, humid climate on the mainland, forests are widespread here and there are relatively few deserts and semi-deserts.

1) The zone of humid equatorial forests (selva) is located on both sides of the equator in the Amazon basin, on the slopes of the Andes and in the north of the Pacific coast. The zone is formed within the equatorial and subequatorial climatic zones. Due to the processes of chemical weathering, fertile red-yellow ferralitic soils are formed in the selva. Various types of palm trees, cocoa, hevea, many orchids, lianas, melon tree, ceiba grow here. Many animals are adapted to life in trees: chain-tailed monkeys, sloths, tree porcupines; tapirs, anteaters, jaguars also live here;

many species of parrots, hummingbirds; the world of insects is very rich; snakes are common, including anacondas. Forests have up to 12 tiers.

2) The zone of variable-moist equatorial forests is located north and south of the selva, in the west of the Atlantic coast. It is formed within subequatorial climatic zones. Red soils and yellow soils are formed here. The flora and fauna are the same as in

3) The savannah zone occupies the Orinok lowland and most of the Guiana and Brazilian plateaus. It is located in the subequatorial climate zone. Red ferralitic and red-brown soils are formed here. Savannahs of the Northern and Southern Hemispheres within the Southern

Americas are different. In the northern savannahs (llanos), palm trees and acacias, mimosas, spurges, and bottle trees grow among the grasses. In the southern savannahs (campos), the vegetation is poorer due to less rainfall: there are low-growing woodlands of quebracho with very hard

wood. Among the animals in the savannahs are small deer, wild peccary pigs, armadillos, anteaters, jaguars, cougars, and rhea ostriches.

4) The zone of tropical deserts occupies a small coastal strip on the west coast. Here, not far from the ocean, lies one of the most waterless deserts in the world - Atacama. On stony, barren soils, cacti and thorny cushion-like shrubs grow here and there. Onshore

rocks are bird colonies.

5) The steppe zone (pampa) is located south of the savannas. In a hot tropical climate, fertile red ferralitic soils have formed here. The main vegetation is grasses, among which feather grass, wild millet and other cereals predominate. In the southwest, where there is less

rainfall, there are thickets of thorny grasses and shrubs. Fast-running animals are typical for pampas: pampas deer, pampas cat, several types of llamas. There are many rodents (nutria, viscacha), as well as armadillos and birds.

6) The zone of semi-deserts and deserts of the temperate zone was formed in Patagonia under conditions temperate climate with low rainfall. The soils are poor brown and gray-brown. The vegetation is represented by dry grasses and cushion shrubs. Animal world similar to pampas, inhabited by rodents and burrowing animals. Among them are nutria, small armadillos.

7) Altitudinal zonation.

In the equatorial belt: up to 1000 m - humid equatorial forests.

Up to 3000 m - mountain and alpine forests, where bamboo and tree ferns, cinchona are found.

Up to 4000 m - low trees and shrubs, light forests appear. There are heather and myrtle thickets, undersized bamboos.

Above 4000 m - alpine meadows (paramos). The vegetation consists of rare grain cereals, cushion-shaped shrubs. Moss swamps are located on flat areas, and stony barren deserts are characteristic of large slopes.

Above 4500 m - bare rocks, a belt of eternal ice.

In the subtropics at the foot there are deserts, turning into a belt of hard-leaved forests, extending to a height of 2000 m on the western slopes and up to 1800 m on the eastern ones. Here you can find plane trees, glanders, and in the undergrowth - thickets of flowering geraniums. Hard-leaved forests are replaced by deciduous beech forests, and above 2500 m there are mountain meadows.

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Tectonic map

At the base of the mainland lies the South American Platform, so most of the relief is plains. In the west there is an area of new folding, where the relief is mountainous. The central and eastern part is occupied by plains (lowlands, uplands and plateaus), and in the west by the Andes mountains.

The Andes is the longest (9000 km) and one of the highest (Mount Aconcagua, 6962 m) mountain systems of the Earth, bordering all of South America from the north and west; southern part of the Cordillera. In some places, the Andes reach a width of over 500 km (the greatest width - up to 750 km - in the Central Andes, between 18 ° and 20 ° S). The average height is about 4000 m.

The relief of the eastern part was formed on the ancient South American platform. The rise of its foundation in the relief corresponds to plateaus, and low plains have formed in the troughs. The strongest tectonic movements took place on the shields, they are broken by cracks, there are faults. Erosion processes, weathering, tectonic processes have created a wide variety of landforms on the Guiana and Brazilian plateaus.

The low-lying plains (Amazon, Orinoc, La Plata) have a flat relief and are composed of marine and lake-river deposits.

Features of the landforms of South America

The relief of the western part of the mainland is the result of the interaction of several lithospheric plates, on the border of which mountain building movements occur. The formation of the Andes began in the Paleozoic and has not ended so far. The Andes continue to rise, volcanoes erupt, strong earthquakes occur.

Physical and geographical characteristics of the Inner Plains of South America.

The internal plains are located between the Brazilian Plateau and the Andes in the central part of the mainland and are confined to three zones - subequatorial, tropical and subtropical. The Internal Plains include five natural areas: Mamore, Pantanal, Gran Chaco, the interfluve of Parana and Uruguay, Pampa.

Mamore Plains— flat alluvial plains . In summer, equatorial air masses bring heavy rainfall here, up to 2000 mm per year. In winter, there is less rain, but the dry season is weakly expressed, so the composition of woody vegetation is closer to the hylaea of the Amazon.

H variability Pantanal , dry in winter and flooded by rainwater in summer. It is composed of a thick layer of sedimentary rocks. On the plains of the Pantanal, tall grasses dominate, in some places trees and shrubs. Moisture-loving forests grow along the rivers.

Plains of the Gran Chaco. This is the hottest place in South America, the average temperature in January is + 28, + 29 ° C, the absolute maximum is + 47 ° C. The change of winter dry and summer rainy seasons is well pronounced in the region. Precipitation is predominantly torrential in nature. On the western, more elevated part of the region, there are forests of prickly acacias, cacti, agaves; to the east, patches of steppes and forests appear. Wax palm grows in wetter places. In the north of the region there are vast wetlands.

Interfluve of Parana and Uruguay It is a plain up to 100 m high. The climate here is subtropical, humid, with a uniform distribution of precipitation over the seasons, during the year they fall over 1000 mm. The northern part is swampy; the center and south of the interfluve is a well-drained, slightly hilly plain, composed of sandstones covered with marls. The black-colored soils of the subtropical savannas are well developed; forests of mimosas and acacias grow here. There are areas of subtropical steppes.

The southern part of the Inner Plains is pampas - grassy plains. The climate of Pampa is subtropical. average temperature January + 22 - + 24 ° С, July + 7 - + 9 ° С; precipitation falls 1000-1200 mm per year, they are distributed evenly over the seasons.

In the flora of the Pampas, there are up to a thousand species of various cereals. There are areas devoid of grass. On the clay soils of the Pampas, silver guinea grass is represented. The fauna of the Pampas is not rich and monotonous. Often there is a viscacha - a large rodent. Rare predators (puma). Of the birds, the ibis, ipikaha, tinamou are characteristic, resembling a partridge in size and appearance.

44. Precordillera and Pampina Sierras (physical and geographical characteristics).

Precordillera - Har-ny large contrasts of relief, climate, soil and vegetation cover. Against the backdrop of elevated plains, steep mountain ranges 2500-4000 m high often rise here. They are composed of Precambrian and Paleozoic rocks, subjected to long-term destruction and leveling. Between the mountain ranges, wide valleys formed - bolsons and depressions (Salinas Grande).

Precordillera is characterized by a continental arid climate. Precipitation falls unevenly. The amount of precipitation decreases from east to west, and the eastern slopes of the mountain ranges receive more precipitation than the western ones. The river network is poorly developed. A large area is occupied by solonchaks.

The vegetation has a xerophytic appearance, the monte-type shrub formation is widespread. At an altitude of 500-1000 m, the remains of subtropical forests with hard-leaved evergreen trees and shrubs have been preserved. Above 2500 m the mountain cereal steppe begins.

To the south, the forests become rarer. In the South-West large territories occupy semi-deserts with serozems and solonchaks.

The southeastern part of Predkordil-er is occupied by Patagonia. The surface of this natural area is a stepped plateau composed of Meso-Cenozoic deposits. Lowlands are only in the northeast and southeast. The position of Patagonia in temperate latitudes in the zone of western transport, between two oceans, should have led to a mild climate and good development hydraulic networks. The main reason for the aridity of Patagonia lies in the fact that the westerly winds prevailing in these latitudes carry the moist sea air of the Pacific Ocean and run into the mountainous barrier of the Andes. The annual amount of precipitation in Patagonia is 120 - 200 mm. The vegetation cover is dominated by cushion-shaped and creeping forms of shrubs with pronounced xeromorphism; few trees. Among the grasses, thorny nondescript bushes of harili, dense pillows of bolax and azorella are plentiful; there are southern types of cacti.

Among the endemic representatives of the fauna of Patagonia, it is necessary to note the skunk-sa sorrillo, the fox-like Magellanic dog, the Darwin ostrich (the southern species of rhea). Rodents are also characteristic (mara, tuko-tuko, etc.), there are pampas cats, armadillos.

46. Northern Andes (physical and geographical characteristics).

The mountain ranges of the Northern Andes, dissected by river valleys, extend from the coast caribbean up to 5°S sh. The North Andes include the Caribbean Andes along the Caribbean coast, the Northwest Andes (Andes of Colombia and Venezuela), and the Andes of Ecuador.

Caribbean Andes unlike other parts of the mountain system, they have a latitudinal strike. These are the northernmost and youngest ranges, they are more arid than the nearby plains. The mountains are almost devoid of forest cover. The main fold formations in the Caribbean Andes occurred in the Pliocene, when two main anticlines arose - the Coastal and Inner Cordillera. They are separated by a longitudinal depression now occupied by lacustrine alluvial deposits. The Caribbean Andes have a distinct winter dry season. The lower belt of mountains is represented by summer-green woodlands or thorny shrubs (chaparro) that develop on red-brown soils. Higher, with decreasing temperatures, precipitation becomes more, so the forests are denser, and at an altitude of 1500-1600 m evergreens appear.

North of the Caribbean Andes are located Caribbean lowlands, composed of alluvium. Lake Maracaibo once occupied the entire lowland, now its area is shrinking due to filling with alluvial sediments. At the same time, coastal regions are experiencing gradual subsidence.

The second tectonic trough is occupied by the lowlands of the Magdalena and Cauca rivers, composed of alluvium and coarse clastic material carried down from the Andean mountain ranges. Northwestern Andes- the most branched and complexly built part of the Andean mountain system. They are located mainly in Colombia. Three main ridges are well expressed here - Western, Central and Eastern Cordillera with a height of more than 5000 m. Among the mountain peaks there are many extinct and active volcanoes. The Central Cordillera reaches the highest average height (Huila volcano, 5750 m, peak Ruiz, 5400 m). Western and Eastern Cordillera below; the latter is divided in the north into two ranges (Sierra de Merida and Sierra de Perija), covering the lowland of Maracaibo. Between the Eastern and Central Cordillera is the valley of the Magdalena River - a graben filled with a thick layer of Cretaceous and Cenozoic deposits. To the north-west along the coast of the Pacific Ocean stretches the low Sierra de Baudo, composed of Cretaceous and Tertiary tuffaceous strata.

The northwestern Andes are located in a subequatorial and equatorial climate. In the direction from north to south, the duration of the dry period gradually decreases, which is practically absent south of Bogotá. Mountain ranges as a whole are abundantly moistened, and on the Pacific coast, due to local circulation and orographic conditions, the amount of precipitation reaches 8000 m (the largest amount in South America). Inland areas are less humidified, but aridity is not pronounced. Climatic features are also reflected in the zonality of the soil and vegetation cover. In the west, on the Pacific coast and the slopes of the Sierra de Baudo, a dense mountain hylaea is formed. To the east, the amount of precipitation decreases, therefore, the lower parts of the slopes are covered with summer-green light forests and shrubs, higher - with mixed, deciduous-evergreen forests, and only at an altitude of 1000 m does wet mountain hylaia begin. There are toquilla palm, balsa wood with very light wood, a number of tree species typical of the Amazon. The avifauna is richly represented - up to 1500 species. Parrots, hummingbirds, as well as a sunbird are characteristic.

Higher, as the temperature decreases, belts of light forests and crooked forests appear, at an altitude of 2500-3500 m mountain meadows paramos stretch.

Geological structure, relief, minerals of South America

Even higher are peculiar associations of highlands of herbaceous vegetation with individual shrubs and cacti. The inner slopes of the northwestern Andes are drier. Hard-leaved or summer-green forests grow here.

Andes of Ecuador(from 2 ° N to 5 ° S) - the narrowest part of the Andes, high-mountainous and tectonically active. Two parallel chains are well expressed in them - the Eastern Cordillera and the Western Cordillera, separated by a number of intermountain basins. Overall Width mountain system here is about 90 km. The ridges consist of separate mountain ranges, separated by saddles, weakly expressed in the relief. The main peaks are, as a rule, active and extinct volcanoes, including the highest of them, the Chimborazo volcano (6267 m). The active volcanoes of Cotopaxi, Antisana, Sangai are known. Intermountain basins are located at an altitude of 2500-2800 m, they are filled with a layer of volcanic ash, tuffs and alluvium. The epicenters of earthquakes are most often located in the region of the intermountain valley that separates these chains of the Cordilleras.

To the west of the Andes mountain range, there is a strip of the Costa coastal plain, with a hot and humid climate. Here there is a rapid decrease in precipitation from 1200-1500 mm in the northern part (with high relative humidity) to 400 mm in the south. These changes are also reflected in the vegetation cover. Savannahs with patches of moist equatorial forests occupying the northern part of the Costa are gradually replaced to the south by dry steppe vegetation. In the mountainous part, vertical zonality is well expressed. Up to 800-1000 m, the change in climate and vegetation cover is still weakly felt, then the amount of precipitation noticeably increases, the amplitude of temperatures decreases with their general decrease. Cinchona, balsa, and ceiba appear in this belt. From a height of 1500-1800 m, palm trees disappear, and tree-like ferns become more numerous. Above 3000 m, vegetation of the paramos type dominates on mountain meadow and mountain steppe soils. Eternal snows begin from a height of 4200-4500 m. The mountain climate is more favorable for human life than the climate of the Costa and Gilei.

Relief. In the relief of South America, a plain-flat-mountain platform extra-Andean East and a mountainous Andean West, corresponding to a mobile orogenic belt, are clearly distinguished. The uplifts of the South American platform are represented by the Guiana, Brazilian and Patagonian plateaus, the troughs are represented by the lowlands and plains of the Llanos-Orinoco, Amazonian, Beni-Mamore, Gran Chaco, Mesopotamia (Parana and Uruguay rivers) and Pampa; from the east. plateaus are framed by narrow intermittent strips of coastal plains.

The Guiana Plateau rises towards the center (the city of Neblina, 3014 m), the Brazilian - from the northwest. to the south-east (Bandeira, 2890 m), Patagonian - from east to west (up to 2200 m). The relief of the Guiana and Brazilian plateaus is dominated by socle gently undulating plains (up to 1500-1700 m high), within which remnant cone-shaped peaks and ridges (for example, Serra do Espinhaso) or table, mostly sandstone, uplands - the so-called chapadas (Auyan-Tepui and Roraima, etc.). The eastern edge of the Brazilian plateau is divided into separate massifs (Serra da Mantiqueira and others), which have the characteristic forms of "sugar loaves" (for example, Pan di Azucar in Rio de Janeiro). The troughs and troughs of the Brazilian Plateau are expressed in relief as monocline-stratal plains with raised cuesta edges, accumulative plains (the depression of the San Francisco River, etc.), or a lava plateau (in the middle reaches of the Parana). The relief of Patagonia is dominated by layered, including volcanic, stepped plateaus, covered by ancient moraine and water-glacial deposits; the plateaus are cut by deep canyons of rivers originating in the Andes; arid forms of denudation are characteristic.

The Andean ridge system extends for 9,000 km to the north and west of the mainland. In the north and northeast, in Venezuela, there are two chains of the Caribbean Andes, deeply dissected by faults and river erosion. The main, meridional system of the Andes, or Andean Cordillera (Cordillera de los Andes), reaching 6960 m (Aconcagua), rises in the west of Yu.A. and is subdivided into Northern, Central and Southern Andes. The northern Andes (up to 5° S) are distinguished by the alternation of high fold-block ridges and deep depressions. In Ecuador, they consist of the Eastern and Western Cordilleras, the depression between which is filled with the products of the activity of the volcanoes Chimborazo, Cotopaxi, and others. Magdalena and Kauka. Volcanoes (Huila, Ruiz, Puras, and others) are concentrated mainly in the Central and South Western Cordilleras; for the central part of the Eastern Cordillera, ancient lake plateaus are typical, with a height of 2-3 thousand meters. In the north and west lie the largest lowlands in the Andean west - the Caribbean and the Pacific.

The Central Andes (up to 27-28 ° S. latitude) are much wider and more monolithic than the Northern ones. They are characterized by internal plateaus raised up to 3.8-4.8 thousand m, bordered by marginal ridges; the highest mountains carry considerable glaciation. The southern part - the Central Andean Highlands - the widest (up to 750 km) segment of the Andes; its main element is the Puna plateau with the ancient lake Altiplano plateau in the southwest and a number of blocky ridges in the east and south. In the east, Pune is framed by the Cordillera Real, with the west by the volcanic Western Cordillera (the second volcanic region of the Andes with the volcanoes of Misti, Lullaillaco, Sahama, and others), a longitudinal tectonic depression (with the Atacama Desert), and the Coastal Cordillera.

In the southern Andes in the north (up to 41 ° 30 "S), the relief is expressed: the double Main Cordillera (the city of Aconcagua in the east, or Front), to which the Precordillera massifs are attached to the east; the Longitudinal Valley of Chile and the Coastal Cordillera. Between 33-52° S there is another Andean volcanic region with large quantity active volcanoes to the west of the Main Cordillera and extinct volcanoes to the east of it. In the southernmost segment of the Andes - the Patagonian Andes - the Coastal Cordillera turns into an archipelago of islands, the Longitudinal Valley - into a system of straits, and the flooded troughs of the sharply declining Patagonian Cordillera - into fjords. Glacial forms dominate. Modern glaciation in Yu.A. occupies an area of 25 thousand km 2, of which over 21 thousand km 2 falls on the Southern Andes. There are also glaciers in the Western Cordillera, between 9 and 11 ° S. sh. and on the islands of Tierra del Fuego.