In order to understand the features of the relief, it is necessary to know the geological history of its formation. Scientists, studying the layers of rocks, found out that all of them have come a long way of formation and have a different age. You will learn about this in this lesson, taking a fascinating journey through the history of development. earth's crust. And also, learn to read the geochronological table and get acquainted with the geological map.
Topic: Geological structure, relief and minerals
Lesson: Features of the relief as a result of the geological history of the formation of the territory
To understand the pattern of formation of mountains and plains, it is necessary to get acquainted with the history of the geological formation of the territory. The history of the geological development of any territory is learned by studying the age, composition and occurrence of rocks. It is from these data that one can find out what happened to the territory in distant geological epochs, whether the territory was covered by the sea or volcanoes erupted, whether there were deserts or glaciers here.
Some parts of the earth's surface are composed of ancient metamorphic rocks, others are young volcanic, and still others are sedimentary. Rocks can lie horizontally or form folds. All rocks have an absolute or relative age. . Relative age is defined by the concepts of "old" and "younger". Sedimentary and volcanic rocks accumulate in horizontal layers and it is therefore natural to assume that the older ones are deeper and the younger ones are closer to the surface. (see fig. 1)
Rice. 1. Occurrence of layers of sedimentary rocks
help determine relative age and ancient fossils. (see fig. 2)
Rice. 2. Trilobite. Age about 380 million years
Powerful strata of sedimentary rocks are formed at the bottom of the oceans. The ocean once covered the vast territories of our planet and various animals lived in it, which died and settled to the bottom, were covered with sand, silt, soft tissues decomposed, and hard tissues became fossils.
The more complex the organism is, the younger the rock; the simpler, the older. Absolute age breeds is the number of years that have passed since the formation of these breeds.
The study of rocks, extinct remains of animals and plants, made it possible to identify several stages in the formation of the geological history of our planet. These stages are reflected in the geochronological table ("geo" - earth, "chronos" - time, "logos" - doctrine). The geochronological table is a geological record of events taking place on our planet. The table shows the sequence and duration of the change of various geological stages, and the table can also present various geological events in different periods, typical animals, as well as minerals that were formed in different eras. The geochronological table is built on the principle: from ancient to modern, so you need to read it from bottom to top. (see fig. 3)
Rice. 3. Geological table ()
According to the most significant changes that have occurred on our planet in the geological past, all geological time is divided into two large geological segments - eons: Cryptozoic- time of hidden life, Phanerozoic- explicit life time. The aeons include era: Cryptozoic - Archean and Proterozoic, Phanerozoic - Paleozoic, Mesozoic and Cenozoic. (see fig. 4)
Rice. 4. Division of geological time into eons and eras
The last three eras: Paleozoic, Mesozoic, Cenozoic are divided into periods, due to the fact that the geological world was very complicated at that time. The names of the periods were given according to where rocks of a given age were first discovered, or according to those rocks that make up a particular area, for example: Permian and Devonian by the name of the area, and Carboniferous, or Cretaceous by rocks. We live in the Cainozoan era, the modern one, which continues to this day. It began about 1.7 million years ago. (see fig. 3)
Let's consider some characteristics of geological eras. archaeus And Proterozoic considered the time of hidden life (Cryptose). It is believed that the organic life forms that existed at that time did not have hard skeletons, so they did not leave any traces in the sediments of these eras. (see fig. 5)
Rice. 5. Cryptozoic (Archaean and Proterozoic) ()
The time of domination of invertebrates, crustaceans, insects, mollusks. In the late Paleozoic, the first vertebrates appeared - amphibians, fish. The plant kingdom was dominated by algae and pselophytes . Later, horsetails and club mosses appear. (see fig. 6)
Rice. 6. Paleozoic ()
In the Mesozoic, large reptiles dominate, and in flora gymnosperms .(see fig. 7)
In the Cenozoic - the dominance of angiosperms flowering plants, the appearance of mammals and, finally, humans. (see fig. 8)
Rice. 8. Cenozoic ()
In each of the geological epochs and periods, the accumulation of the chemical and mechanical composition of rocks took place. In order to find out what rocks this or that territory of our country is composed of, we can use the geological map of Russia. (see fig.9)
Rice. 9. Geological map of Russia ()
Geological map contains information about the age of rocks, about minerals. Information on the map is shown in different colors. If you look at the geological map, you will see that the most ancient rocks form the territory of Transbaikalia and the Kola Peninsula.
Different periods are shown in different colors, for example, the Carboniferous rocks are shown in grey, while the Mesozoic rocks are shown in green. Analyzing the geological map, one can pay attention to the fact that the East European Plain is composed of rocks of the Paleozoic era, and only in the Far North-West we see outcrops of rocks of the Archean and Proterozoic period. The West Siberian lowland is composed of young deposits of the Paleogene and Neogene.
Using geological maps, you can get information about minerals, as well as predict their search.
The geological age of our planet is approximately 4.7 billion years. It was during this period that the core, the mantle, were formed as a result of the differentiation of matter. (see fig. 10)
Rice. 10. The internal structure of the Earth
The earth's crust is broken into blocks - lithospheric plates. Moving through the mantle, lithospheric plates changed the outlines of continents and oceans. (see fig. 11)
Rice. 11. Lithospheric plates
There were periods when the lithospheric plates descended, and then the land area decreased, and the area of the World Ocean increased. Such eras, more peaceful in geological terms, were called epochs of the seas. They alternated with geologically more turbulent and shorter periods, which were called epochs of land. These epochs were accompanied by active volcanism and mountain building.
Homework
- Using the geochronological table, determine which periods are older: Devonian or Permian, Ordovician or Cretaceous, Jurassic or Neogene?
- Which of the eras is more ancient: Proterozoic or Mesozoic, Cenozoic or Paleozoic?
- What era and period are we living in?
- Geography of Russia. Nature. Population. 1 hour Grade 8 / auth. V.P. Dronov, I.I. Barinova, V.Ya Rom, A.A. Lobzhanidze
- Geography of Russia. population and economy. Grade 9 / author V.P. Dronov, V.Ya. Rum
- Atlas. Geography of Russia. Population and economy / publishing house "Drofa" 2012
- TMC (educational kit) "SPHERES". Textbook "Russia: nature, population, economy. Grade 8 "author. V.P. Dronov, L.E. Savelyeva. Atlas.
Other tutorials on this topic
- The structure of the earth's crust (lithosphere) in Russia ().
- relief of Russia, geological structure and minerals ().
Find out more on the topic
- Relief, geological structure and minerals ().
- The history of life on Earth ().
- Interactive geological atlas of Russia ().
- Site of the Mineralogical Museum named after A.E. Fersman ().
- Website of the State Geological Museum named after V.I. Vernadsky ().
The entire "smooth" territory of Russia is represented by plains - Russian and West Siberian, separated from each other by the Ural ridges. On physical map the difference in forms is visible, but what underlies the differences? This is what I want to talk about.
Characteristics of the Russian Plain
The structure is located in the European part of Russia. From the north and south it is bounded by the Barents, Black and Caspian seas, and from the east by the Baltic. From the west it is supported by the Ural Mountains. It is based on the ancient platform of the same name, which is composed of layers of sedimentary rocks of different ages. The oldest - Precambrian - 4 billion years. Paleozoic rocks predominate - 541.0–251.902 Ma.
The average height of the forms is 171 m. The highest point is 479 m, and the lowest point is located below sea level - -27 m. The plain got its appearance known to us due to glaciation and tectonic processes. So, in the north, basins of many lakes and lowlands were formed. Hills are the results of faults.
Of the natural phenomena, you can only observe floods and tornadoes. I think many people remember how in 1984 a tornado raged in the Ivanovo and Kostroma regions.
Characteristics of the West Siberian Plain
She spread out on the other side of the Urals. The frames are created: in the north - the Kara Sea, in the east - the Central Siberian Plateau, and in the south - the Turgai Plateau and the Kazakh Upland. In this case, the foundation is a platform, but a young one is the West Siberian one. It consists of Mesozoic and Cenozoic rocks (252.2–23 Ma).
Differences in height on the plain are not particularly observed. The average value is 142 m, the maximum is 254 m, and the minimum is 50 m. The smoothness of the relief was ensured by periodic flooding of the territory by seas, between which glaciations (the result - Siberian Ridges) and tectonic processes (uplands) influenced.
I would classify swampiness as a natural phenomenon of the plain, which became possible due to a number of reasons:
The development of permafrost thermokarst led to failure phenomena in the soil.
Relief features
The relief is a set of forms of the earth's surface, different in shape, size, origin, age and history of development. The relief influences the formation of the climate, the nature and direction of the flow of rivers depend on it, the features of the distribution of flora and fauna are associated with it. The relief also affects the way of life of a person and his economic activity. Large landforms of Russia. The relief of our country is very diverse: high mountains adjoin vast plains. The highest point of the country (and Europe) - Mount Elbrus in the Caucasus reaches a height of 5642 m above sea level, and the Caspian lowland is located 28 m below this level. Territories with flat relief prevail, occupying more than half of the country's area. Among the plains of Russia - one of the largest plains of the globe (East European) Russian and the vast West Siberian. They are separated by the low Ural Mountains. The south of the European part of Russia is occupied by the young Caucasus Mountains, the east by vast mountainous countries. They are separated from the West Siberian Plain by the Central Siberian Plateau with a dense network of river valleys. To the east of the Lena are the mountain systems of North-Eastern Siberia: the Verkhoyansk Range and the Chersky Range. In the south of the Asian part of Russia there are Altai, Sayan Mountains, the Salair Ridge, the Kuznetsk Alatau and the ridges of the Baikal and Transbaikalia, as well as the Stanovoy Range, the Vitim Plateau, the Stanovoye, Patom and Aldan Highlands. Along the Pacific coast from south to north, the medium-altitude ridges of Sikhote-Alin, Bureinsky, Dzhugdzhur stretch, and in the north they are replaced by high uplands: Kolyma, Chukotsky, Koryaksky. High mountain ranges with volcanic peaks are located in Kamchatka.
Thus, the following conclusions can be drawn:
1) the relief of Russia is very diverse: vast plains, plateaus, high and medium-altitude mountains are represented;
2) flat territories prevail;
3) the territory, especially in the Asian part of the country, has a general depression to the north, as evidenced by the direction of flow of most major rivers;
4) mountain structures frame vast plains, with the main part of the mountains concentrated in the south of Siberia, the northeast and east of the country.
The structure of the earth's crust.
The largest features of the country's relief are determined by the peculiarities of the geological structure and tectonic structures. The territory of Russia, like the whole of Eurasia, was formed as a result of the gradual convergence and collision of individual large lithospheric plates. The structure of lithospheric plates is heterogeneous. Within their limits there are relatively stable areas - platforms and mobile folded belts. The location of the largest forms of land relief - plains and mountains - depends on the structure of lithospheric plates. Areas with a flat relief are confined to platforms - stable areas of the earth's crust, where folding processes have long ended. The most ancient of the platforms are East European and Siberian. At the base of the platforms lies a rigid foundation composed of igneous and highly metamorphosed rocks of the Precambrian age (granites, gneisses, quartzites, crystalline schists). The foundation is usually covered with a cover of horizontal sedimentary rocks, and only on the Siberian Platform (Central Siberian Plateau) are significant areas occupied by volcanic rocks - Siberian traps. The outcrops of the foundation, composed of crystalline rocks, to the surface are called shields.
In our country, the Baltic Shield on the Russian Platform and the Aldan Shield on the Siberian Platform are known. Mountainous regions are distinguished by a more complex geological structure. Mountains are formed in the most mobile parts of the earth's crust, where, as a result of tectonic processes, rocks are crushed into folds, broken by faults and faults. These tectonic structures arose at different times - in the eras of Paleozoic, Mesozoic and Cenozoic folding - in the marginal parts of the lithospheric plates during their collision with each other. Sometimes folded belts are located in the inner parts of the lithospheric plate (Ural Range). This indicates that once there was a boundary between two plates, which later turned into a single, more large slab. The youngest mountains of our country are located in the Far East (Kuril Islands and Kamchatka). They are part of the vast Pacific volcanic belt, or the Pacific Ring of Fire, as it is called. They are characterized by significant seismicity, frequent strong earthquakes presence of active volcanoes.
Geological structure
The diversity of modern relief is the result of a long geological development and the impact of modern relief-forming factors, including (including) human activity. Geology deals with the study of the structure and history of the development of the Earth. The geological history of the Earth begins with the formation of the earth's crust. The oldest rocks indicate that the age of the lithosphere is more than 3.5 billion years. The period of time corresponding to the largest stage in the development of the earth's crust and the organic world is commonly called the geological era. The entire history of the Earth is divided into 5 eras: Archean (ancient), Proterozoic (era of early life), Paleozoic (era of ancient life), Mesozoic (era of middle life), Cenozoic (era of new life). Eras are subdivided into geological periods, most often named after the areas where the corresponding deposits were first found. Geological reckoning, or geochronology, is a branch of geology that studies the age, duration and sequence of formation of rocks that make up the earth's crust. It is possible to determine the time of their formation by the nature and sequence of the occurrence of rocks. If the occurrence of rocks is not disturbed by crushing, folds, ruptures, then each layer is younger than the one on which it lies, and the uppermost layer was formed later than all those lying below.
In addition, the relative age of rocks can be determined from the remains of extinct organisms that lived in a particular geological period. It was only in the 20th century that they learned to determine the absolute age of rocks with sufficient accuracy. For these purposes, the process of decay of radioactive elements contained in the rock is used. The geochronological table contains information about the successive change of eras and periods in the development of the Earth and their duration. Sometimes the most important geological events, stages in the development of life, as well as the most typical minerals for a given period, etc. are indicated in the table. The principle of constructing the table is from the most ancient stages of the Earth's development to the modern one, so you need to study geochronology from the bottom up. Using the table, you can get information about the duration and geological events in different eras and periods of the Earth's development. Geological maps contain detailed information about what rocks are found in certain regions of the globe, what minerals lie in their depths, etc.
Development of landforms
Like all other components of nature, the relief is constantly changing. Modern relief-forming processes can be divided into two groups: internal (endogenous), caused by movements of the earth's crust (they are called neotectonic, or recent), and external (exogenous). The latest tectonic movements of the earth's crust can manifest themselves both in mountains and on flat platform areas. The latest uplifts occur in the Caucasus, the amplitude of movements reaches several centimeters per year. Exogenous processes are associated primarily with the activity of flowing waters, primarily rivers and glaciers, as well as with the features climatic conditions. Such, for example, is the relief created by permafrost processes.
Ancient glaciation in Russia. In the Quaternary period, due to changes in climatic conditions, several ice sheets arose in many regions of the Earth. The largest of them was the Dnieper. The centers of glaciation in Eurasia were the mountains of Scandinavia, the Polar Urals, the Putorana Plateau in the north of the Central Siberian Plateau, and the Vyrranga Mountains on the Taimyr Peninsula. From here, the glacier spread to the adjacent territories.
As the glacier moved southward, the Earth's surface changed dramatically. Stones (boulders) and loose deposits (sand, clay, crushed stone) moved along with the ice. The glacier smoothed the rocks, leaving deep scratches on them. In the southern regions with a warmer climate, the glacier melted, depositing the material brought with it. Loose clay-boulder glacial deposits are called moraine. The moraine hilly-ridge relief prevails on the Valdai and Smolensk-Moscow uplands of the Russian Plain. During the melting of the glacier, huge masses of water were formed, which carried and deposited sandy material. The surface gradually leveled off. So along the outskirts of the glacier, water-glacial plains were created. In the northern regions, melted glacial waters filled depressions deepened by the glacier in hard crystalline rocks. Numerous lakes arose, especially in the northwest of the Russian Plain.
Activity of flowing waters.
The surface of the land is constantly exposed to flowing water - rivers, groundwater, temporary streams associated with precipitation. The activity of flowing waters is especially enhanced in areas with significant slopes and high rainfall. Therefore, water-erosion relief prevails in many mountainous regions. Flowing waters not only dissect the surface, creating gorges, ravines, hollows, but also deposit destruction products in river valleys, in foothill areas and on gentle mountain slopes.
wind activity.
Where there is a small amount of precipitation, the wind plays a leading role in changing the relief. The relief of the regions of the Caspian lowland is a vivid evidence of this.
Human activity.
Even Academician V. I. Vernadsky noted that mining has turned a person into a serious relief-forming factor. So, with an open method of mining, quarries and pits are formed. People build canals, dams, railway tunnels, while moving huge masses of soil. All this leads to an acceleration of relief-forming processes, often accompanied by landslides and landslides, flooding of large areas of fertile land, etc.
Natural natural phenomena occurring in the lithosphere and bringing great disasters to people are earthquakes and volcanic eruptions, as well as landslides, landslides, avalanches, mudflows and mudflows.
Mineral resources
The bowels of our country are rich in various minerals. Minerals are mineral formations of the earth's crust that can be effectively used in the field of material production. Accumulations of minerals form deposits, and with large areas of distribution - provinces, basins.
The thick loose deposits of the sedimentary cover of ancient platforms contain almost all deposits of fossil fuels. They were formed from deposits of organic matter that accumulated for a long time at the bottom of shallow sea bays, in lakes or swamps. Among them, oil and natural gas from the north of Western Siberia, the Volga-Ural basin, are of the greatest importance. The deposits of the plains of the North Caucasus and Sakhalin Island are less rich.
The Paleozoic and Mesozoic deposits of the platform areas contain deposits of black and brown coal. Coal deposits in the European part of Russia are located in the Vorkuta region, in the eastern part of the Donets Basin. Brown coal is mined in the Moscow Region basin. In Siberia, the coal deposits of the Kuznetsk basin (Kuzbass) have long been developed. They are mined by open and underground methods. But the coal reserves of the Tunguska, Lena, Kansk-Achinsk and other basins located in the sparsely populated regions of Russia are especially large. The country has very significant reserves of peat and oil shale.
Deposits of ore minerals are often associated with those areas of platforms where the basement or younger inclusions of crystalline rocks come close to the surface. Among them are the deposits of iron ores of the Kursk magnetic anomaly, the Kola Peninsula, the Aldan Shield, the Angara-Pitsky and Angara-Ilimsky regions, as well as the nickel ores of the Kola Peninsula and polymetallic ores in the vicinity of Norilsk.
But the mountainous regions are especially rich in ores of non-ferrous and rare metals: copper (Urals, Transbaikalia), lead and zinc (Altai, Primorsky Territory, North Caucasus), tin (Eastern Siberia and the Far East), raw materials for aluminum production - bauxites and nephelines (Northern Ural, Krasnoyarsk Territory). Gold deposits are located in Eastern Siberia, Yakutia, in the north of the Far East. The largest deposit of platinum is located in the Urals.
Of the non-metallic minerals, diamond deposits in the volcanic rocks of western Yakutia, apatites on the Kola Peninsula, potassium salts in the Volga region, the Kirov region, and on the western slope of the Urals are of great importance. The subsoil of Russia has deposits of graphite (Urals, Eastern Siberia, Far East), rock salt (Urals), table salt (Volga region), mica (Eastern Siberia), as well as a variety of raw materials for the production of mineral building materials - granites, dolomites, limestones, gravel , high quality clays, etc.
All these minerals constitute the mineral resource base of our country. The country's mineral resources are characterized by the following features:
1) the size of stocks;
2) extreme uneven placement;
3) differences in operating conditions;
4) the possibility of partial compensation for depleted mineral deposits through exploration and development of new deposits.
However, it must be remembered that the minerals accumulated over the entire history of the Earth's development are non-renewable when they are exhausted. The extraction of huge masses of substances from the bowels of the earth does not pass without a trace. As a result of human activity, anthropogenic landforms are formed - quarries, waste heaps, vast voids in the earth's crust, etc. The extraction of building materials such as sand, gravel, limestone also leads to the formation of quarries that disfigure the landscape and disrupt the natural course of natural processes. Restoration of lands disturbed mining, is carried out in the following areas: the use of soils cut during overburden work, leveling the surface by backfilling ravines, reclamation of dumps; creation of forest sanitary protection zones.
Date of: 30.11.2019
Relief
At the heart of the mainland lies the ancient African-Arabian platform, which forms the predominantly flat relief of the continent. The relief of Africa is dominated by plains, plateaus and plateaus, located at an altitude of 200-500 m above sea level (39% of the area) and 500-1000 m above sea level (28.1% of the area). Lowlands occupy only 9.8% of the area and are located mainly along the coastal margins. In terms of average height above sea level (750 m), Africa is second only to Antarctica and Eurasia.
Almost all of Africa north of the equator is occupied by the plains and plateaus of the Sahara and Sudan, among which the Akhaggar and Tibesti highlands rise in the center of the Sahara (Mt. Ami-Kussi, height 3415 m), in Sudan - the Darfur plateau (Mr. Marra, 3088 m) . In the northwest, the Atlas Mountains (Tubkal, 4165 m) rise above the plains of the Sahara; in the east, along the Red Sea, the Etbai Range (Oda, 2259 m) stretches. The plains of Sudan from the south are framed by the North Guinean Upland (Bintimani, 1948 m) and the Azande Plateau; from the east, the Ethiopian highlands rise above them (the city of Ras-Dashen; 4620). It abruptly breaks off to the Afar depression, where the deepest depression in Africa is located (Lake Assal, 150 m).
The Congo Depression is bounded from the west by the South Guinean Upland, from the south by the Lunda-Katanga Plateau, from the east by the East African Plateau, on which rise the highest peaks of Africa - Mount Kilimanjaro (5895 m), Rwenzori (5109 m).
South Africa is occupied by the high plains of the Kalahari, framed from the west by the plateaus of Namaqualand, Damaraland, Kaoko, from the east by the Dragon Mountains (Tabana-Ntlenyana, 3482 m). Along the southern edge of the mainland stretch the medium-altitude Cape Mountains. The predominance of the leveled relief is due to the platform structure of the mainland.
In the northwestern part of Africa, with a deep basement and a wide development of the sedimentary cover, heights of less than 1000 m predominate ( Low Africa); southwest Africa is characterized by heights of more than 1000 m ( High Africa). Troughs and protrusions of the African platform correspond to large depressions (Kalahari, Congo, Chadian, etc.).
The eastern margin of Africa is more elevated and fragmented within the activated area of the platform - the Ethiopian Highlands, the East African Plateau, where a complex system of East African faults extends. In the uplifted regions of High Africa, the largest area is occupied by basement plains and basement blocky mountains, framing the depressions of East Africa (including Rwenzori) and Katanga. In Low Africa, basement ridges and massifs, stretching along the coast of the Gulf of Guinea, protrude into the Sahara (in the Ahaggar, Tibesti, Etbai ranges). Lava plateaus and cones, common in the Ethiopian Highlands and East Africa (Kilimanjaro, Kenya, etc.), crown the peaks of Ahaggar and Tibesti, are in Sudan (Marra), Cameroon (Cameroon Volcano, Adamawa Mountains), cover the Dragon Mountains in Lesotho.
The processes of volcanism are associated with faults in the earth's crust, which are the cause of the formation of high uplands and volcanic peaks. The mountains of Africa are of different ages: the old ones are located in the south (Dragon and Cape), the young ones (Atlas) are in the north.
Geological structure and minerals
Almost all of Africa, except for the Atlas Mountains in the northwest and the Cape Mountains in the extreme south, is an ancient platform, which also included the Arabian Peninsula and about. Madagascar with the Seychelles.
At the heart of the mainland lies the old African-Arabian platform with significantly destroyed folded formations. In the south and east of the mainland, the crystalline basement comes to the surface. Here is a zone of deep faults in the earth's crust: handfuls (uplift) - the Ethiopian Highlands, the East African Plateau, the Dragon Mountains, grabens (lowering) - the Nyasa and Tanganyika basins. Mobile folded zones adjoin the platform: in the north - the Atlas, in the south - the Cape Mountains.
The foundation of the African-Arabian platform, composed of Precambrian rocks, mostly folded and metamorphosed, protrudes in many parts of Africa - from the Anti-Atlas and Western Arabia to the Transvaal. The basement includes rocks of all age subdivisions of the Precambrian, from the Lower Archean (more than 3 Ga) to the upper Proterozoic. The consolidation of most of Africa was completed by the middle of the Proterozoic (1.9-1.7 billion years ago); in the late Proterozoic, only peripheral (Mauritano-Senegalese, Arabian) and some internal (Western Congolese) geosynclinal systems developed, and by the beginning of the Paleozoic, the entire area of \u200b\u200bthe modern platform was stabilized.
The rocks of the early Precambrian basement are represented by various crystalline schists, gneisses, metamorphosed volcanic formations, and are replaced by granites over large areas. They are characterized by deposits of iron ores, gold (in connection with granites), chromites. Large accumulations of gold and uranium ores are known in the clastic rocks of the base of the sedimentary cover in southern Africa.
Younger, weakly metamorphosed rocks of the Upper Proterozoic contain deposits of tin, tungsten (in or near granites), copper, lead, zinc, and uranium ores. Powerful volcanic eruptions and eruptions of the main (basaltic) magma belong to the beginning of the Jurassic, most common in South Africa, but also found in western North Africa. By the same time (the end of the Jurassic) is the formation of the modern contours of Africa, associated with the subsidence along the ruptures of the bottom of the Indian and Atlantic oceans and the formation of a system of perioceanic troughs containing significant deposits of oil and gas (Nigeria, Gibon, Angola, etc.).
Madagascar separated from the continent at the end of the Paleozoic. At the same time, the modern coast of Tunisia and Libya was intensively submerged by the formation of oil deposits in the Cretaceous and Eocene deposits. In the middle and end of the Cretaceous, a significant transgression of the sea engulfed the Sahara Plate: sea straits arose that connected the Mediterranean Sea and the Gulf of Guinea and existed until the middle of the Eocene.
Africa has large deposits of iron ores (total reserves are estimated at about 16-23 billion tons), manganese ores (about 400 million tons), chromites (500-700 million tons), bauxite (3.3 billion tons), copper (reliable and probable reserves of about 48 million tons), cobalt (0.5 million tons), phosphorites (26 billion tons), antimony, lithium, uranium, asbestos, gold (Africa provides about 80% of the world's total production), platinum and platinoids (about 60 % of production), diamonds (98% of production). After the Second World War, large deposits of oil (total reserves are estimated at 5.6 billion tons) and natural gas were discovered in Africa (mainly in Algeria, Libya and Nigeria).
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FGP, research historyClimatic conditions
see also
Africa. Physical and geographical position. History of research and development
The relief of Russia is characterized by three main features: - it is diverse, that is, there are both high mountains and vast plains; - 2/3 of the territory is occupied by plains; - The mountains are located mainly on the southern and eastern outskirts of the country. These features are explained by the large size of the territory, its diverse tectonic structure, and the location of the main tectonic structures. Plains are located on platforms, mountains have arisen within folded areas.
In the western part of the country is the East European (Russian) plain, it is located on the ancient Russian platform. The relief of the plain is diverse - it is characterized by an alternation of lowlands (Upper Volga, Meshcherskaya) and uplands (Valdai, Central Russian, Smolensk-Moscow). In its southern part, there is the Caspian lowland located below sea level. Here is the lowest (-28 m) point of the country. The average height of the Russian Plain is about 200 m. The Ural Mountains are located along its eastern outskirts. These low (max. height 1894 m - Mount Narodnaya) mountains stretched from north to south - from the Arctic Ocean to the steppes of Kazakhstan.
To the east of the Urals lies the vast West Siberian Plain. Half of it has a height of less than 100 m, and only at the edges of a height of 150-200 m. To the east of it, between the Lena and the Yenisei, lies the Central Siberian Plateau, located on the ancient Siberian platform. Its average height is 500-700 m, the maximum is 1701 m.
To the south of the Russian Plain are the highest (Elbrus 5642 m) mountains of Russia - the Caucasus.
In the upper reaches of the Ob and Yenisei are the Altai (Belukha Mountain, 4506 m) and Sayan (8) ranges. From the east, the mountains of the Baikal and Transbaikalia adjoin the Sayans: the Stanovoye Upland, the Stanovoy Range. To the east of the Central Siberian Plateau lie the Verkhoyansky and Chersky ranges. In the Far East along the coast Pacific Ocean the Sikhote-Alin ridge stretches. There are high mountains on the Kamchatka Peninsula (Klyuchevskaya Sopka volcano, 4750 m).
Minerals. Russia has large reserves of many minerals; in terms of natural gas reserves, it ranks first in the world.
Iron ores are confined to the foundations of ancient platforms. Especially large are the deposits of the Kursk Magnetic Anomaly (KMA), in the Central Chernozem region, where high-quality ore is mined in quarries.
The Olenegorskoye and Kovdorskoye deposits in the Murmansk region are confined to the Baltic Shield. and Kostomuksha in Karelia.
The Urals remains one of the important iron ore regions of Russia, although its reserves have already been greatly depleted.
90% of iron ore reserves are concentrated in the European part of the country, but Siberia and the Far East are also rich in iron ore. In Western Siberia, these are the deposits of Gornaya Shoria in the Kemerovo region, in Eastern Siberia - the Abakanskoye in Khakassia and the Rudnogorskoye and Korshunovskoye deposits in the Irkutsk region, as well as deposits in the Neryungri region in the south of Yakutia; in the Far East - deposits in the Zeya River basin.
Deposits of copper ores are concentrated mainly in the Urals (Krasnoturinskoye, Krasnouralskoye, Gayskoye, etc.) and on the Kola Peninsula (Monchegorskoye deposit of copper-nickel ores in the Murmansk region), as well as in the mountains of Southern Siberia (Udokan) in the north of Eastern Siberia - the Talnakh deposit near Norilsk.
The largest deposits of aluminum ores (bauxites) are located in the Urals, in the North-Western region - Tikhvinskoe (bauxites) and Khibinskoe (nephelines); in Eastern Siberia - in the south of the Irkutsk region and the Krasnoyarsk Territory.
The largest oil and gas province in Russia, the West Siberian province, is located on the territory of the West Siberian region. Volga-Ural - within the Volga and Ural regions. Timan-Pechersk occupies the eastern part of the territory of the Northern region and the waters of the Barents and Kara Seas. Significant gas reserves are located on the territory of the Astrakhan region, oil - on the territory of the North Caucasus.
Of the total geological coal reserves in the country, 95% are in the eastern regions, including 60% in Siberia. The bulk of the reserves are concentrated in several major basins: Tunguska (2299 billion tons), Lena (1647 billion tons), Kansk-Achinsk (638 billion tons) and Kuznetsk (2299 billion tons). The Pechora basin, the largest in terms of reserves in the European part, accounts for only 3.5% of the reserves.
CLIMATE
The territory of Russia is characterized by a wide variety of climates: in the south of the Caspian lowland in summer it can reach +40 ° C, and on the coast of the Arctic Ocean it is only slightly warmer than zero degrees. The average January temperature in Sochi is about 0 °C, and in the Oymyakon area frosts reach -71 °C. Up to 3000 mm of precipitation falls on the Black Sea coast of the North Caucasus. And in the Astrakhan region - less than 200 mm. This diversity is explained by the great length of the country from north to south, diverse relief, and different distances from the oceans.
On the Arctic islands of the Arctic Ocean, the climate is arctic. It has low temperatures throughout the year. Winter temperatures here range from -24 °С to -30 °С. Summer temperatures are close to zero, and at the southern borders of the belt they rise to +5 °С. There is little precipitation (200-300 mm). They fall mainly in the form of snow, which persists for most of the year.
On the northern coast of the country there is a cold subarctic climate. Winters here are long, their severity increases from west to east. Summer is cold (from +4 °С in the north to +14 °С in the south). Precipitation is frequent, but in small amounts. Their maximum is in the summer. The annual amount of precipitation is 200-400 mm, but at low temperatures and low evaporation, excessive wetting of the surface is created and waterlogging occurs.
In the south, in the Sochi region, it is subtropical, but temperate climates prevail in most of the country. There are four subtypes of climates in the temperate zone.
The temperate continental climate of the temperate zone is formed in the European part of the country under the influence of air from the Atlantic. In connection with its arrival, the European part is better moistened than the eastern regions. Winter is less severe here. January temperatures vary from -4 °C to -20 °C. Summer is warm (from +12 °С to +24 °С). The greatest amount of precipitation falls in the western regions (800 mm), but due to frequent thaws, the thickness of the snow cover here is small. In the area of temperate continental climate dominance, there is a change in moisture from excessive to insufficient, which causes a change in natural zones from taiga to steppe.
The continental climate of the temperate zone is common in Western Siberia. Here, the annual amount of precipitation in the north does not reach 600 mm, and in the south - 100 mm. Winters are more severe than in the west. Summers are hot in the south and quite warm in the north.
The sharply continental climate of the temperate zone is characterized by extremely low winter temperatures (from -24 °С to -40 °С) and significant warming in summer (up to +16, +20 °С). It is distributed in Eastern Siberia. The annual rainfall here is less than 400 mm. The moisture coefficient is close to unity.
The monsoon climate of the temperate zone is characteristic of the Far East. Winter here is cold, sunny and with little snow, as in Siberia. Summers are cloudy and cool, with a large amount of precipitation (up to 600-800 mm) falling in the form of showers. This type of summer weather is associated with the influx of sea air from the Pacific Ocean.
Thus, within the temperate zone, summer throughout the country becomes warmer with moving south, but in winter, frosts intensify when moving from the western borders of the country (-8 ° C) to the east to -50 ° C in Yakutia. This is explained by the fact that the farther to the east, the less heat comes from the Atlantic Ocean. And only further east, as we approach the Pacific Ocean, winter again becomes somewhat warmer.
Agro-climatic resources are the properties of the climate that provide opportunities for agricultural production. They are characterized by the duration of the period with an average daily temperature above +10 °C; the sum of temperatures for this period; the ratio of heat and moisture (moisture coefficient); moisture reserves created in winter by snow cover.
Different parts of the country have different agro-climatic resources. In the Far North, where there is excessive moisture and little heat, only focal agriculture and greenhouse-hothouse farming are possible. Within the taiga north of the Russian Plain and most of the Siberian and Far Eastern taiga, it is warmer - the sum of active temperatures is 1000-1600 °, rye, barley, flax, and vegetables can be grown here. In the zone of steppes and forest-steppes - Central Russia, in the south of Western Siberia and the Far East, moisture is sufficient, and the sum of temperatures is from 1600 to 2200 °, here you can grow rye, wheat, oats, buckwheat, various vegetables, sugar beet, fodder crops for livestock needs .
The most favorable agro-climatic resources are the steppe regions of the south-east of the Russian Plain, the south of Western Siberia and Ciscaucasia. Here the sum of active temperatures is 220-3400° and it is possible to grow winter wheat, corn, rice, sugar beet, sunflower, heat-loving vegetables and fruits.
INLAND WATERS
Inland waters - rivers, lakes, swamps, glaciers, The groundwater; artificial reservoirs - reservoirs, canals, etc.
The importance of inland waters is very great for human life and activities and for nature. The internal waters of Russia are rich and varied.
The rivers of Russia belong to the basins of the oceans: the Arctic, Pacific, Atlantic and to the basin of internal flow (basin is the territory from which the river and its tributaries collect water). The nutrition and regime of rivers are related to climate.
The rivers of the Arctic Ocean basin are the longest and deepest. The longest river is the Lena, the most full-flowing is the Yenisei, the Ob has the largest catchment area. The food of the rivers is mixed with the advantage of snow. Spring flood. Rivers freeze. The largest rivers of Siberia begin in the mountains (Altai, Sayans, mountains of the Baikal region) - there they have a mountainous character. The rivers of the East European Plain of the Arctic Ocean basin have a flat character throughout.
The rivers of the Pacific Ocean basin: the main one is the Amur with tributaries (Zeya, Bureya, Ussuri). The food is predominantly rain, summer floods are typical, and catastrophic spills occur from monsoon rains.
The rivers of the Atlantic Ocean basin: the Neva, the Western Dvina flow into the Baltic Sea; Dnieper, Don, Kuban - in Black and Azov. Food is mostly snowy. Small spring flood. The Neva periodically floods St. Petersburg due to surges from the Baltic Sea.
The rivers of the internal flow basin are the Volga (the largest - its basin occupies 30% of the East European Plain), Ural, Emba, Terek. Food is mostly snowy. The Volga forms a vast delta. It is connected by canals with the Moscow River (Moscow Canal), with the Don (Volga-Don).
Lakes. The Caspian Sea-lake, Baikal is the deepest lake in the world, because it is located in a tectonic basin. The lakes are unevenly distributed. There are many in the north-west of the European part - Ladoga, Onega (glacial-tectonic basins); Seliger, Valdai (hollows between moraine hills). There are lakes of volcanic origin in Kamchatka and the Kuriles.
Glaciers. On the territory of Russia, the bulk of glaciers are concentrated on the Arctic islands and in mountainous regions. The largest areas of mountain glaciation are characteristic of the Caucasus (over 1400 glaciers). There are also small glaciers in the mountains of Altai, Kamchatka, northern and northeastern Siberia. Cover glaciation is widespread on the islands of Novaya Zemlya, Severnaya Zemlya, Franz Josef Land and other islands of the Arctic.
Groundwater - significant reserves: West Siberian artesian basin, Moscow. Kamchatka - thermal waters.
Swamps - distributed on flat plains with sufficient moisture - Western Siberia, the North of the European part, Meshchera.
Water resources - rivers, lakes and groundwater - are the main source of the country's water supply. Water is needed by public utilities, industrial enterprises, and agriculture for irrigation. On the whole, the country is well endowed with them, but they are unevenly distributed over its territory: they are well endowed water resources northern regions, Siberia (80% fresh water concentrated in Lake Baikal), however, all the most developed parts of the country experience a lack of water, especially in the southern half of the European part of the country.
The main problem of water supply is the lack of clean water, pollution of the waters of rivers and lakes by domestic and industrial wastewater, wastewater from livestock complexes. It is necessary to introduce systems of recycling water supply, purification Wastewater and their use.
The rivers of Russia have large hydropower resources, they are mainly concentrated in the Siberian rivers Yenisei, Angara, it is there that the largest hydroelectric power plants were built. The construction of a hydroelectric power station is not only profitable, but also has negative consequences: flooding of lands, changes in the level of groundwater, microclimate, deterioration of conditions for the reproduction of many valuable fish species.
natural areas.
Forest and soil and land resources
The regular change in natural components when moving from the equator to the poles, associated with a decrease in the angle of incidence of the sun's rays, is called natural zonality.
The position of Russia in the northern part of Eurasia determined the location on its territory of the following natural zones, replacing each other when moving from north to south: arctic deserts, tundra, forest tundra, forest (includes subzones of taiga, mixed and broad-leaved forests), forest-steppes, steppes, semi-deserts, subtropical zone.
Altitudinal zonality - the change of natural complexes with altitude in the mountains is due to climate change with altitude. The set of altitudinal belts in the mountains depends on the geographical position of the mountains themselves, which determines the nature of the lower belt, and the height of the mountains, which determines the nature of the upper tier. The sequence of altitudinal belts coincides with the sequence of changes in natural complexes on the plains. But in the mountains, the belts change faster, there are belts that are typical only for the mountains. These are belts of subalpine and alpine meadows.
Forest resources are one of the most important types of biological resources. Forest resources are renewable.
Russia is rich in forest resources (45% of the country's territory is covered with forests), has the largest timber reserves in the world (more than 20% of the world's reserves). The forest strip stretches throughout the country from west to east. Forests are diverse in species composition (1500 species of trees and shrubs). The species composition of forests is changing due to climate change. Forests of coniferous trees (larch, pine, spruce, cedar pine) predominate, their wood is a valuable industrial resource. Spruce wood is used to make paper. The wood of broad-leaved trees is used for the production of furniture, parquet.
Forests are unevenly distributed throughout the country. Most of the forest resources are concentrated in areas of the North, Siberia and the Far East, which are sparsely populated.
Currently, logging areas in the Asian part of the country are concentrated in a narrow strip in the south. In the future, the logging zone should expand and move to the north. At present, large timber processing complexes operate in Arkhangelsk, Syktyvkar, Yeniseisk, Ust-Ilimsk, Krasnoyarsk, Komsomolsk-on-Amur.
For the rational use of forest resources, it is necessary to process raw materials in a comprehensive manner, not to cut down forests in excess of their growth, and to carry out reforestation work.
The main types of soils. Soil is a special natural formation; the surface layer of the earth, which has fertility. The founder of soil science, the outstanding Russian scientist V.V. Dokuchaev, established that the main types of soils on the globe are located in zones. Soil types are distinguished depending on their fertility, structure, mechanical composition, etc.
Tundra-gley soils are common in the north of the country. They are thin, have a low humus content, and are waterlogged.
Podzolic soils are formed under coniferous forests in areas of excessive moisture, and soddy-podzolic soils are formed under mixed forests. Precipitation wash the soil and carry out nutrients from the top layer to the bottom. The upper part of the soil takes on the color of ash. These soils are poor in humus and mineral elements. They occupy more than half of the country's territory. The fertility of podzolic soils increases towards the south.
Quite fertile gray forest soils are formed under deciduous forests (there is more plant litter, washing out is not so intense).
To the south, in the zone of forest-steppes and steppes, chernozems are formed - the most fertile soils. A lot of humus accumulates from the remains of vegetation, there is practically no flushing regime. The content of humus in the chernozem can reach 6-10% or more. The thickness of the humus horizon can reach 60-100 cm. They have a granular structure. Less than 10% of the territory is occupied by chernozems.
In the southern part of the steppes with a drier climate, chestnut soils are formed. The content of humus in them is less than in chernozems, since there is less plant litter here.
In desert areas with poor vegetation, brown soils of semi-deserts and gray soils are formed. These soils contain little humus and are often saline.
The diversity of soil types and the features of their distribution are reflected on soil maps.
Land resources are part of the Earth's surface, on which various objects of the economy, settlements can be located. Land resources are evaluated according to two indicators: per capita land availability and land quality.
Russia is one of the countries most endowed with land resources, but at the same time it has a small amount of land favorable for human life and economic activity. Large areas of Russia are occupied by tundra, taiga, mountain ranges, swamps and wetlands. Only 13% of the country's area is agricultural land, i.e. land used in agriculture(arable lands, orchards, hayfields, pastures), and the share of the most valuable lands, arable lands, is only 8%.
Most of the agricultural land is located in the south of the country. The most fertile lands are used for arable land - chernozems, gray forest and dark chestnut lands. The main agricultural zone of the country is located in the zone of mixed forests, forest-steppes and steppes.
There is a decrease in the amount of arable land due to the use of agricultural land for the construction of reservoirs, industrial enterprises, roads, etc. Therefore, it is necessary to rationally use the land and increase their fertility.
The soil is subject to erosion under the influence of rain and melt water, wind. Improper plowing of the land and excessive grazing also contribute to the development of soil erosion.
Land improvement works in order to increase their fertility are called melioration. The main types of reclamation are: agromelioration (plowing and sowing across the slope; deep plowing to increase water absorption), forest reclamation (creation of forest protection belts, planting forests along the slopes of gullies and ravines), water (draining of wetlands and irrigation of arid lands), chemical and cultural and technical.
Land reclamation and reclamation are the main measures for the protection and rational use of soil and land resources.
Examples of USE Assignments with Comments
1. Where are there active volcanoes in Russia?
1) in Western Siberia 3) in Altai
2) in Kamchatka 4) in the Urals
The answer is 2.
2. Where are large diamond deposits being developed in Russia?
1) Republic of Sakha (Yakutia) 3) Lipetsk region
2) Republic of Kalmykia 4) Kurgan region
The answer is 1.
3. Which of the following lakes is located in the European part of Russia?
1) Ladoga 3) Teletskoye
2) Khanka 4) Kronotskoye
The answer is 1.
4. Which river is a tributary of the Volga?
1) Irtysh 3) Yana
2) Pechora 4) Kama
The answer is 4.
5. The climate of which of the following territories is formed under the influence of monsoons?
1) Primorye 3) Caucasus
2) Kola Peninsula 4) Chukotka
The answer is 1.
6. Which of the points marked with letters on the map of Russia has the coldest winters?
1) A 2) B 3) C 4) D
To correctly answer questions of this type, one should be able to apply knowledge about the patterns of climate change in Russia and climate-forming factors to compare average winter air temperatures at different points. It is known that in winter a powerful anticyclone forms over the territory of Eastern Siberia, which determines very low air temperatures. Point D is marked on the territory of Eastern Siberia near the cold pole of the Northern Hemisphere. So, it is there that it is coldest in winter.
The answer is 4.
7. From which natural area will the traveler move when flying from point A to point B?
1) from the tundra zone to the mixed forest zone
2) from the taiga zone to the steppe zone
3) from the Arctic desert zone to the taiga zone
4) from the zone of mixed forests to the zone of deserts
To answer questions of this type, you should have an idea of how approximately the natural areas on Russian territory. In the north of the European part, the tundra occupies only narrow sections of the coast, and taiga is widespread to the south. Point A is marked at a considerable distance from the coast, approximately in Karelia. So, it is located in the taiga zone.
In the south of the European part of Russia there are steppes (semi-deserts are common on a narrow section of the coast of the Caspian Sea).
The answer is 2.
Tasks for Self-Check
Part A
1. In winter, anticyclones have a predominant effect on the climate
1) the Black Sea coast of the Caucasus
2) Central Siberian Plateau
3) Rostov region
4) Kaliningrad region
2. A sharply continental type of climate in the temperate climate zone is typical for
1) Eastern Siberia 3) Karelia
2) Primorye 4) Volga region
3. In which of the following regions are podzolic soils most widespread?
1) Karelia 3) Orenburg region
2) Rostov region 4) Kalmykia
4. Which of the territories marked with letters on the map of Russia is characterized by earthquakes?
1) A 2) B 3) C 4) D
5. Which of the following regions of Russia usually has the hottest and driest summers?
1) Kaliningrad region
2) Bryansk region
3) Astrakhan region
4) Sakhalin region
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