Main questions: What are the main landforms? What external and internal processes form the relief? What minerals are associated with folded belts and sedimentary cover?
Geological structure. The mainland is part of North American lithospheric plate, located at its western edge. The eastern and western parts of the continent differ in geological structure. Remember what parts the great mother Pangea split into?
The basis of the eastern part of the mainland is formed by the ancient North American Platform... In the northeast, the base of the platform is raised and emerges as Canadian Shield... In the western and southern parts of the continent, the crystalline basement is overlapped by a stratum sedimentary rocks... This part of the platform is structurally a slab. The North American Platform is bordered by ancient fold belts, in the west by younger ones than in the east. In the Paleozoic, folded systems joined the platform Appalachian, Greenland and the Canadian Arctic Archipelago, in the Mesozoic - systems Cordillera... Their youngest ridges arose in the Cenozoic during the interaction of the North American and Pacific lithospheric plates.
Relief. The relief of the northern and eastern parts of the region was influenced by the ancient continental glaciation. In the Mississippi Valley, the southern boundary of the maximum extent of the glacier reached the 38th parallel. Under its thickness were Laurentian Upland and the peninsula Labrador... The relief forms created by the glacier are widely represented here (hills and ridges with heights of 300-600 m, rounded rocks lamb foreheads(fig. 9.1.) and long narrow bays fjords... Glacier sediments - moraines- folded in the north hilly, with heights up to 200-500 m, surface Central Plains... The glacier brought here numerous boulders, created the basins of modern lakes.
To the west of the Central Plains from north to south, almost 4000 km stretch Great plains, cut by numerous deep ravines, and "steps" descending to the Central Plains. (Fig.11.1). Some parts of the Great Plains are unsuitable for use on the farm. They got the name badlands("Bad lands") (Figure 12.1).
In the south, the Great and Central Plains become flat and swampy The Mexican and The Atlantic lowlands. Along the eastern edge of the mainland, there are severely eroded flat-topped Appalachian(G. Mitchell, 2037 m). In the foothills of the Appalachians is the largest Mammoth cave... The western part of the mainland is occupied by the powerful mountain system of the Cordilleras (Figure 13.1). In its northern part in Alaskan the ridge is the highest point of the continent - the mountain McKinley(6194 m).
The Cordillera consist of three mountain ranges stretching from north to south, separated by belts of plateaus and intermontane valleys. The eastern belt is represented by a wide chain of high Rocky mountains. At their western foothills, there is a chain of high-mountain plateaus and plateaus (Fig. 14.1). Among them are volcanic Yellowstone and plateau Great Pool rugged by the deepest river canyons Colorado (Figure 15.1).
A system of mountain ranges flanks plateaus and plateaus in the west and is represented by a chain of extinct volcanoes Cascading mountains. The rivers abound with picturesque waterfalls and rapids. There are many hot springs. To the south, "snowy mountains" rise Sierra nevada... In the far west are California valley and Death Valley (fig. 16.1), the lifeless surface of which has an absolute elevation of -86 m.
Third, westernmost and youngest belt Beregovy x ridges stretches along the Pacific coast. The coastal ridges and the California Valley are part of the Pacific Ring of Fire. In the south of the mainland, all the mountain belts of the Cordilleras converge, forming Mexican highlands (fig. 17.1), most of which is covered with solidified lava. The southern part of the highlands is represented by a chain of active volcanoes (Orizab a, 5700 m).
North America is rich minerals... From combustible mineral resources are the most significant reserves of oil, gas, coal. Place of Birth oil and gas are located on the Pacific coast of the United States, the Mexican lowland, on the shelf of the marginal seas of the Arctic Ocean, Alaska, the south of the Central and Great Plains. Hard coal rich in the east of the Central Plains and the foothills of the Appalachians. Place of Birth brown coal located on the Great Plains, in the intermontane basins of the Cordilleras, in Alaska.
Largest reserves iron ore concentrated in the crystalline rocks of the Canadian Shield in the area of Lake Superior and the Labrador Peninsula, in the Northern Appalachians, on about. Newfoundland and Greenland. Non-ferrous metal ores are widespread: copper(Rocky Mountains, Mexican Highlands, Canadian Shield), lead-zinc(Mississippi Valley, Cordillera), bauxite(about. Jamaica), nickel(Laurentian Upland, Cuba). Powerful reserves uranium ores are concentrated on the Colorado plateau, gold- in the Yukon basin and in the southwestern United States. Among non-metallic minerals are allocated by reserves phosphorites(Florida Peninsula), asbestos(Appalachian Mountains) and potassium salts(south of the Great Plains, Great Lakes region).
1. What are the main landforms of North America. 2 *. What is the relationship between the geological structure and the relief of the territory? 3. What minerals are mined on the mainland? 4*. What influence did the glacier have on the formation of the relief of North America?
Almost all of Africa is part of the ancient continent of Gondwana, formed in the Precambrian and disintegrated at the end of the Paleozoic and Mesozoic. The African continent is mainly ancient, Precambrian, African Platform, composed of crystalline, igneous and metamorphic rocks, covered mainly by a sedimentary cover that occupies 2/3 of the continent. In the north-west and south, the Hercynian and Alpine folded formations - the Atlas and Cape mountains - adjoin the platform.
The African platform is complicated by syneclises and anteclises, broken by tectonic cracks. The largest syneclises are Karoo, Kalahari, Congo (Zaire), Chad (Mali-Nigerian), Aravan Taudeni (El Juf) and Libyan-Egyptian. Syneclises are expressed in the relief by extensive hollows. Anteclises divide the basins and surround them with gentle uplifts. The largest shields and uplifts of the Archean-Proterozoic basement are the Ahaggarsky, Regibatsky, Leono-Liberian, Nubian-Arabian, Tanganyiksky, Central African, Madagascar massifs. The most significant protrusions of the ancient basement are located along the eastern edge of the mainland. The world's greatest system is also located here. East African rifts stretching 6500 km from the Gulf of Aqaba through the Kras-
Geological structure, relief, minerals 133
Sea, Ethiopian Highlands, East African Plateau and the lower course of the Zambezi River.
Within the African Plate, the Sahara Plate (part of the wider Sahara-Arabian Plate) and the South African Shield are distinguished. The border between them is drawn from the Cameroon volcano to the northern part of the Red Sea.
Sugar plate includes the Sahara, Sudan and Northern Guinea. The plate was mainly an area of marine, and in the Mesozoic - continental sedimentation-accumulation. As a result of the Lower Paleozoic transgression in the western part of the Sahara and Sudan, strata of sandstones and shales were formed. At the end of the Paleozoic and up to the Cretaceous period, arid conditions prevailed and the accumulation of red-colored continental sediments, mainly sandstones and conglomerates, took place in the depressions and depressions of the relief. In the Cretaceous, the Sahara Plate was again swept by transgression. In the Tertiary period, the sea left Western Sahara and Sudan, but remained for quite a long time in the Libyan-Egyptian syneclise. Sediments of this time are mainly represented by limestones, sandstones and thick clay strata.
South African Shield(East and South Africa) during the entire post-Proterozoic experienced mainly uplift. In the troughs of the shield, continental deposits of great thickness (up to 10 km) accumulated. In South Africa, these deposits form geological systems - Cape (Lower Paleozoic), Karoo (Upper Paleozoic-Mesozoic) and Kalahari (Tertiary). The Cape Formation composes the Cape Mountains, the Karoo Formation - a foothill trough along the northern
slopes of the Cape Mountains, the Kalahari formation fills the hollow of the same name. These formations and their analogs are also widespread in East Africa.
The Congo Basin, in terms of its geological structure and development history, is a transitional area to the Sahara Plate. Since the end of the Paleozoic, it has been characterized by significant mobility, as a result of which it was flooded by shallow seas at least twice in the Mesozoic.
Africa is a continent of huge stepped plains, plateaus, plateaus and uplands, crowned with flat remnant peaks. Plains and plateaus lie mainly within the continent, occupying vast tectonic depressions. In relief South Africa the Kalahari depression is clearly distinguished, in Central Africa - the Congo depression, in Sudan - the Nigerian, Chadian, White Nile basins, in the Sahara - El-Juf, Libyan-Egyptian, etc. platforms. The alternation of inland plains in the place of tectonic depressions with plateaus in the place of uplifts is a characteristic feature of the relief of Africa. Mountainous areas occupy slightly more than 20% of its area, lowlands - less than 10%.
Africa is a high continent. In terms of average altitude (750 m above sea level), it is second only to Antarctica and Eurasia. The highest heights are concentrated in the east, where the Ethiopian Highlands, the East African Plateau and the Drakensberg Mountains rise. Here is the highest point of the mainland - the volcanic massif Kilimanjaro with a height of 5895 m. Africa -
The length of the territory also determined the diversity of the relief: the European part of the country has a completely different appearance than the Asian one, and the differences in regions are great. 70% of Russia is occupied by plains, among which the the East European Plain
(within which there are small, up to 250 - 400 m, hills) in the western part of Russia, and the West Siberian Plain - to the east of the Urals. They are divided Ural ridge
Most of which are mountains with a height of 800 - 1200 meters. Between the Yenisei and Lena is located Central Siberian plateau
Dismembered by a dense network of river valleys. Mountainous areas with highly rugged relief predominate in the east (Aldan Upland, Verkhoyansk Range, Stanovoe Upland) and in the south of the republic ( North Caucasus, Altai, Sayany, etc.), as well as along the Pacific coast /1,c.422-423/.
The relief is directly related to the geological structure crust which is also highly patchy. So, the East European Plain approximately corresponds Russian,
a West Siberian - Siberian platform
These are very ancient parts of the crust with a Precambrian folded foundation / 1, p. 423 /, and active mountain-building processes have already completed there.
Between them is a younger Ural-Altai platform
Formed in the Paleozoic. Air and water did not manage to destroy the Ural and Altai mountains (formed as a result of the movement of the earth's crust in the Cenozoic era) / 2, p.297 /, although they worked on them very thoroughly.
A younger region adjoins the Russian platform from the south North Caucasus
Which is characterized by a very significant seismic activity. To the east of the Siberian platform is the Primorsko-Chukotka region, which has a Mesozoic folded base. This is a geologically young region with a predominance of uplands / 2, p.297 /.
The mountainous regions of Kamchatka and the Pacific coast correspond to the belts of the latest folding and volcanism. Geosynclinal development there has not yet been completed, which caused the seismic and volcanic activity of the region and left a significant imprint on the entire life of Kamchatka and the Far East / 3, p. 100-101 /. And there is a silver lining: geothermal sources directly related to volcanism represent a solid reserve of cheap energy.
The distribution of underground minerals
So, coal basins
mainly correspond to the Carboniferous, Permian, Cretaceous periods. The most important coal basins are
The largest deposits oil and gas
associated with Mesozoic and Tertiary sediments in the North Caucasus and Paleozoic sediments in the Volga-Ural and Ukhta-Pechersky oil and gas regions, as well as in the Mesozoic sediments in the territory of Eastern Siberia and Yakutia / 4, p. 76 /.
Iron ore
Precambrian basement corresponds to KMA and ore deposits of Karelia. Large ore reserves have also been found in the Paleozoic of Siberia and the Urals. Deposits are also associated with the Ural Paleozoic. bauxite, copper ore, asbestos, potassium salts
As well as precious and semi-precious stones. Apatity
the Kola Peninsula is also rich (Proterozoic), where there are also copper and nickel
In the North Caucasus (Mesozoic) they extract tungsten, molybdenum, lead, zinc
On Far East(Mesozoic) - lead, zinc, tin
Other minerals are also mined (mainly in the Mesozoic). gold, platinum, silver, mercury
The economic significance of these resources for Russia can hardly be overestimated: it is their export that keeps the Russian economy afloat, precisely due to the fact that the cost of energy resources in the country is lower than on the world market, the economic recession in Russia in last years was less harsh than in other republics the former Soviet Union... However, we must not forget that mineral reserves are by no means unlimited, and many important sources are already close to depletion. Often, mining also negatively affects environment... Thus, being the indisputable economic trump card of Russia, they carry and whole line problems, without the solution of which it is impossible to preserve the most valuable resources for posterity.
Germany, Angola
November 11, 1975 is a memorable date in the history of the Angolan people. On this day, the Portuguese colony ceased to exist, and the whole world learned about the birth of the People's Republic of Angola - a new independent state. This event was preceded by a long and stubborn struggle of the Angolan people for ...
Economy of Argentina (translation of an English-language article with attachments)
Argentina has experienced weak economic growth since 1940. From the mid-1970s, the economy began to grow significantly. But since the last half of the 1980s, the country has experienced the worst economic stagnation in a century. Investment and savings have been decreasing since ...
This diversity is explained, first of all, by the large size of the territory and the complex geological history this territory. The largest plains: East European (Russian),. They are located on and have a two-tiered structure. The West Siberian Plain is located on the West Siberian Plate. It is often called the lowland, because half of its territory has a height of less than 100 meters and only at the edges does its height reach 150-200 m.
Divide Eastern European and West Siberian Plain, low mountains (the most high peak these mountains - Mount Narodnaya 1895 m). These are ancient folded-block mountains, heavily destroyed and slightly updated in the Neogene.
Of great importance in western Yakutia, potash and sodium chloride, mica in Eastern Siberia, as well as graphite in the Urals, Eastern Siberia and the Far East.
The country has significant reserves of peat, oil shale, building sands, limestone, chalk and gypsum.
By reserves of many minerals Russian Federation occupies leading places in the world, so 1st place in reserves and iron ore, 3rd place in proven reserves of coal, etc. and develops its economy almost entirely on its own mineral resources. Despite this, it must be remembered that the minerals accumulated over the long history of the Earth's development are exhaustible and non-renewable. Their careful is necessary, rational use... For this, new technologies are being developed that ensure minimal losses during mining and processing, it is necessary to extract from the ore as much as possible all the useful components that are in it. In addition, the search and development of new deposits.
Study plan of the topic 2. MAIN FEATURES OF THE RELIEF OF RUSSIA AND THE STRUCTURE OF THE EARTH'S CREST GEOLOGICAL CALCULATION OF THE MOUNTAIN OF FOLDED AREAS. PLATFORM PLAINS MINERAL FOSSILS OF RUSSIA DEVELOPMENT OF RELIEF FORMS. INTERNAL PROCESSES AND NATURAL PHENOMENA RELATED TO THEM EXTERNAL PROCESSES FORMING THE RELIEF AND SPANAL EFFECTS RELATED TO THEM Consolidation of the studied material
The main features of the relief of Russia and the structure of the earth's crust Plains prevail in the relief of Russia. The territory of Russia has a general slope to the north. The highest point of Russia is Elbrus (5642 m). The lowest point is located in the Caspian lowland (-28 m). The longest mountains are the Ural (2,100 km). The largest plain of Russia - West Siberian (3 million km2) The territory of Russia was formed due to the convergence and collision of large lithospheric plates. Platforms are relatively stable areas of lithospheric plates on which plains are located. Movable fold belts arose in the edge parts of lithospheric plates when they collided with each other. In the relief, mountain structures correspond to them.
Geological chronology Geological chronology, or geochronology, is a term adopted in geology to denote the time and sequence of formation rocks... The time during which each group of rocks accumulated is called an era. All eras are divided into shorter periods of time - periods.
Geochronological table Era Period Folding Cenozoic Quaternary period Neogene Paleogene Cenozoic (Alpine and Pacific) Mesozoic Cretaceous Jurassic Triassic Mesozoic Paleozoic Perm Carbon Devonian Silurian Ordovician Cambrian Hercynian Caledonian Proterozoic Archean Baikal
Mountains of folded regions All modern mountain ranges of our country are of the same age - Neogene-Quaternary. In the area of Cenozoic folding, young folded mountains arose. Revived mountains correspond to all other folded regions; only the age of the young mountains coincides with the age of folding. In the revived mountains, only the age of the basement coincides with the age of folding.
Platform plains Platform plains with a Precambrian basement are called ancient, and those with a Paleozoic basement are called young. Areas where the foundation rocks crumpled into folds come to the surface are called shields. The rest of the platform territory, which has a sedimentary cover of various thicknesses, is called plates.
Mineral resources of Russia Mineral resources of platforms Non-metallic minerals concentrated in the rocks of the platform cover: coal, oil, gas, oil shale. Ore minerals are confined to shields or to those parts of the plates where the thickness of the sedimentary cover is small and the foundation comes close to the surface. For example: Kursk Magnetic Anomaly - iron ore deposit. Mineral resources of folded regions Ore minerals are associated with folded regions of mountains: iron ore, polymetallic ores, mercury, gold, etc .; precious and semi-precious stones. Large accumulations of ores of industrial importance are called deposits. Groups of closely spaced deposits of the same mineral are called mineral pools.
The development of landforms. Internal processes and related natural phenomena. Internal processes slow vertical folded and discontinuous oscillatory movements tectonic movements neotectonic magmatism earthquakes movements lava plateaus volcanoes retreat and advancing seas
Reinforcement of the studied material Choose the correct answer. 1. The relief of Russia is dominated by: a) plains; b) mountains; 2. The territory of Russia has a general bias towards: a) the south; b) north; c) west; d) east 3. Relatively stable areas of lithospheric plates are called: a) platforms; b) folded belts; c) shields; d) plains; 4. When lithospheric plates collide, there are: a) shields; b) platforms; c) movable folded belts; d) hills; 5. Which of the listed mountain structures is young: a) Sikhote-Alin; b) the Caucasus; c) Ural; d) Altai; e) Sayan; 6. What tectonic structure lies at the base of the Central Siberian Plateau: a) Scythian plate; b) Siberian platform; c) Russian platform; d) West Siberian plate; 7. Large accumulations of ores of industrial importance are called: a) deposits; b) swimming pools; 8. Establish the correspondence: A. Internal processes, a) the action of glaciers, B. External processes; b) neotectonic movements, c) river flow, d) wind;