This is due to the fact that in the Cenozoic the entire continent experienced uplift, especially active at the edges; 70% of the continent's area is covered by high stepped plains, plateaus and plateaus; 20% is in the mountainous areas and only 10% is occupied by the lowlands, which occupy the coastal parts. its heights are generally more than 200m, and the southern and eastern ones are above 500 - 1000m. Therefore, according to the features of the relief, it is customary to divide into “low” - Northern and Western and “high” - Eastern and Southern.
At the base of the continent lies the ancient fragment of Gondwana - the ancient Precambrian African-Arabian platform, which also includes c. The foundation of this African-Arabian platform is composed of Precambrian crystalline and metamorphic rocks, which protrude onto the day surface in many. In geology, this position is called a shield (a shield is the exit to the surface of a crystalline basement platform not covered by a sedimentary cover). Everyone in the foundation is known age divisions Precambrian - from the lower Archean (more than 3 billion years) to the upper Proterozoic.
In the northwest, the youngest geosynclinal region of the continent, the Atlasids, adjoins the Precambrian base of the platform. It belongs to the zone of Mesozoic-Tertiary mountain structures, which also includes the Southern, Western and Southern. The structure of Atlasida includes structures of Caledonian, Hercynian, Mesozoic and Alpine age. The most ancient are the southern mountain chains, which represent the outskirts of the platform, which experienced uplift and rejuvenation of the relief in connection with the cycle. The northern ranges of the Atlas formed at the end of the Alpine cycle. At the end of the Tertiary period there was a general uplift of the whole and it was separated from the mountain structures of the southern part of the Iberian Peninsula. mountain system The Atlas consists of three longitudinal ridges stretching from southwest to northeast for more than 1000 km with a width of 150 km. The northern part of the Atlas, the one that is closest to it, is called Tell Atlas. This place is famous for containing very a large number of limestone and because of this it ranks first in Africa in the extraction of this rock. In relief this place has the appearance of a limestone spine bearing common name– Dorsal (from the French “spine”). The Tell Atlas to the south of the city drops off abruptly, where it turns into a very narrow foothill valley - Chapanal. The width of this valley is quite narrow and is 5-6 km. This valley then abruptly turns into the ancient Kabylia mountain range. In relief, this massif represents the ancient crater of the extinct Kabilan. This is very beautiful place! It is picturesque because the crater is quite wide, up to 15 km in diameter, in which the lake is located. This lake always has colored water, and in different time the colors are different every year. IN cold period– red, and in the warm period – blue. Then this mountain range turns into a gentle step, which then turns into shots. Shots are extensive salt marshes. The trap part of the Atlas is already the Atlas itself. This place is called High Atlas. Here is the highest point of the entire Atlas - Mount Toubkal (4150m). This mountain is active volcano. The last eruption here occurred in 1815, but it was not active and destructive, at first there was a small eruption, after which the lava was slowly squeezed out of the cone. However, a very serious earthquake occurred in this area in 1825 and 1954, killing more than 7-10 thousand people. In addition, near the Algerian-Moroccan border there is a former graben - the Tell Horst, which divided Eurasia from Africa. This system was called Er-Rif. Er Rif is not a continuation of the Atlas, it is an independent mountain segment. Er Reef has the shape of a crescent, convex to the southwest and 350 km long. Er-Rif, like the Atlas, consists of three longitudinal ridges called: Sebtides, Gomarids and Peratids. The first ridge of Sebtida forms the powerful Beni-Busera massif, which is very well expressed in relief by a sharply dome-shaped uplift of sandy-clayey formation. This is where the most high peak Ar-Rifa - Jebal Saniro (2456m). The Gomarids and Peratids merge with each other in relief and have a flat granite structure, which local residents received the name “Guliver Valley”. In front of the Er-Rif and Atlas system there is a tectonic trough of the South Rif Corridor, which in relief has the general name of the Moroccan Meseta. This trough is covered by a very thick Tortonian marl molasse, because of this the entire soil of the Moroccan Meseta has a whitish-porous color and this is the only place in where no.
The Atlas mountain system in the south passes into the forward trough of the platform, but in the relief it is indicated by depressions only in the east, near the Gulf of Gabes. This place is called Schott-Melgir, which is located 30 m below sea level. The remaining large part of the foredeep is covered with thick sedimentary strata, which on the surface are composed of dissected dry valleys.
The entire northern part of the continent is occupied by the vast territory of the Sahara, which extends from Atlantic Ocean to , and in the south it reaches approximately 17° N latitude. Most of The Sahara is tectonically composed of the Sahara-Arabian Plate. The Sahara-Arabian plate exhibited repeated fluctuations and some of its parts were flooded by seas (epicontinental transgressions). The surface is covered with thick sediments of various ages and origin, lying horizontally on deeply subsided rocks of the crystalline base, and corresponds to the Libyan-Egyptian depression (syneclise). In the central part of the Sahara, the base of a platform with folding of Precambrian and Caledonian age protrudes to the surface in the form mountain ranges and high plateaus, collectively called the Central Sahara Massifs, with altitudes of more than 2000m. Here the ancient foundation is uplifted in the Ahaggar and Tibesti volcanic massifs. The foundation in the Sahara region is also raised on the Adrar-Iforas and Lir plateaus - this is the area of the southern spur of Ahaggar. The uplift along which the lava erupted arose along the lines of fault horsts in a northeastern direction. Along fault lines there are post-volcanic phenomena, volcanoes and volcanic ones.
The Tibesti Highlands is a volcanic massif, the highest point of which is the extinct volcano Emi-Kousi (3415m) and has a huge crater measuring 12 km in diameter. Emi Koussi is the highest peak in the entire Sahara region. As residual phenomena, post-volcanic phenomena such as geysers and hot mineral springs occur on Tibesti, especially common in the southeast.
The Ahaggar Highlands is also a volcanic massif consisting of flat-topped stepped plateaus (heights of about 800m), which stretch from north to south and basalt ridges (heights of about 2000m), above which rises the highest peak of this massif - the phonolite peak of Mount Takhat (3005m). The relief of all these massifs has a dissected structure, with rocky and steep slopes that have accumulated a coarse mass of clastic material at the foot of the massifs.
Lava outpouring in the Sahara region also occurred in northern region Fezzan and in the east on the Kordofan plateau.
(Lesson development)
Target
To form students’ ideas about the features of the relief and minerals of Africa, about the rules for compiling characteristics of landforms using a physical map.
Tasks
Identify the features of the placement of African relief forms.
Establish the reasons influencing the formation of the relief based on a comparison of the physical map and the “Structure and Development” map earth's crust».
Identify patterns in the distribution of mineral resources on the continent depending on the structure of the earth’s crust and the location of landforms.
Identify the influence of relief on the nature of the continent.
Teach students to characterize the shape of the relief according to standard plan using a physical map, improve students’ skills in independently acquiring new knowledge in the classroom.
Equipment
Maps: “Structure of the earth’s crust”, “ Physical card Africa", atlases, outline maps, textbook, notebook, plan of characteristics of landforms, pictures of landforms.
Plan of characteristics of the relief form.
A. Where is it located? this form relief?
B. The magnitude of this landform (extent from north to south, direction of its elongation).
Q. What tectonic structure is this landform located on?
G. Average height.
D. The greatest height, its name.
E. minerals.
During the classes
1. Reproduction of basic knowledge
1) What is a plain? What types of plains are known?
2) What is called a mountain and a mountain range?
3) What factors influence the formation of relief?
4)What platform is Africa located on?
2. Conversation with students
1. Using the physical map of Africa, name the main features of the continent’s relief.
(Sample answer.)
Africa is dominated by high plains and lowlands. Mountains occupy a large area. The most great plain Sahara. Here the altitudes range from 500 m to 3000 m. This plain has uneven terrain. The mountainous regions of Africa are located in the north-west, east, south of the continent).
2.Why in Africa main form Are the terrain plains?
(Students look for the answer based on a comparison of the map of the structure of the earth's crust and the physical map).
3.Name the prevailing heights and the greatest height.
4.What is it called highest height?
5.Where the lowlands are located, their sizes.
6.What explains the location of mountains in the east and south
7.Why are the Great African Rifts located in the east of the continent?
8.What landforms are located in the fault area?
(Find the answer in the text of the textbook).
Answer: In the area of the African faults there are horsts and grabens, uplifts, and the relief is dissected.
3.Practical work on the contour map
Label the names of major landforms on contour map: Sahara, Kalahari, Atlas Mountains, Cape and Drakensberg Mountains, Ethiopian Highlands and Eastern African plateau, in red indicate the Great African Rifts.
(Memorize this nomenclature, conduct a mutual survey with your desk neighbor).
Description of landforms orally according to a standard plan using a map
Exercise. Orally describe the relief of the Atlas, Sahara, Kalahari, Drakensberg Mountains according to a standard plan using atlas maps and paintings.
(The teacher gives only qualitative grades for the answer in the journal.)
4.Make a syncwine in your notebook with the word “Relief”
Plain and mountain
Changes, collapses, rises
Relief affects nature
Conclusion
Invite students to draw a conclusion on the topic; if it is insufficient, then draw it yourself.
The topography of Africa is dominated by flat terrain, since the mainland is on a platform. Plains different heights. There are highlands, plateaus and lowlands.
The mountains occupy a small area. They are located in the area of moving parts of the earth's crust.
The most difficult terrain is in the Great African Rift region. There are volcanoes, horsts and grabens. The plains pass freely air masses, the mountains are holding them back.
Practical work
The relationship between the structure of the earth's crust, relief and minerals. Fill out the table.
According to Sahara, the table is filled out like this: one student says the answer out loud, the others enter the data. Next, students do the work independently, using the appropriate cards. At the end of the work, write a conclusion. This work is appreciated by everyone. The teacher helps those who find it difficult to complete the assignment.
| Landform | Tectonic structure | Minerals | Conclusion |
| Sahara | platform | Sedimentary, oil, gas | |
| Kalahari | platform | Oil, diamonds | |
| Atlas | Mobile zone | Phosphates, silver. ore | |
| Drakonovy | Plate fracture | Diamonds, uranium ores | |
| East African plateau | Mobile zone | Ores: copper, chrome |
Homework
1.Know the main features of the African topography.
2.Repeat the nomenclature.
Articles. Development of geography lessons
Goals and objectives:
educational: study the relief features of the continent, identify the causes of these features. Concretize the already known pattern of placement of large relief forms. Teach composition brief description large relief forms according to the plan. Consider the patterns of distribution of mineral deposits, explain the reasons for their location. Name and show large forms relief, mineral deposits of Africa.
developing: development mental activity students when working with information sources, cartographic material; development of attention, memory, imagination.
educational: develop the ability to listen to your classmates.
Lesson equipment: physical map of the world, CD-ROM “Geography. Our home is Earth. Continents. Oceans. Peoples. Countries. 7th grade".
Main content. Sequence of studying the relief (plan). Predominant landforms, history of their formation and mutual arrangement. Differences in relief between High and Low Africa; reasons for the differences. Minerals and patterns of distribution of their deposits on the mainland.
Basic ideas and concepts. Relief, platform, internal and external relief-forming processes, volcano, highland, minerals.
Nomenclature for preparing for the Unified State Exam: Atlas Mountains, Ethiopian Highlands, East African Plateau, Kilimanjaro and Cameroon volcanoes.
Means of education.
- Physical map of Africa, map of the structure of the earth's crust.
- CD-ROM “Geography. Our home is Earth. Continents. Oceans. Peoples. Countries. 7th grade".
- Workbook: Sirotin V.I. Geography. Beginner course. 7th grade: workbook with a complex of contour maps - M.: Bustard, 2007.
- Atlas: Geography of continents and oceans 7th grade: Atlas. - M.: Bustard, 2008.
- Textbook: V.A. Korinskaya, I.V. Dushina, V.A. Shchenev. Geography of continents and oceans. - M.: Bustard, 2007.
Methods and forms of educational activities. Heuristic conversation based on analysis and comparison of maps. A problematic presentation of the question of the formation of the continental topography. Modular training (individual card - form). Working with items using a computer. Solving crossword puzzles and test tasks. Students' work on a contour map. Student reports on an advanced assignment on the topic of relief and minerals of Africa. Description of individual landforms based on maps and other sources of knowledge.
During the classes
Organizing time.
Hello guys, sit down. Today we will continue our journey across the continent of Africa.
It is washed by two oceans,
There are many rivers and different countries on it.
The Sahara Desert lies there
Through the Dunes sand is coming caravan.
There are the Atlas Mountains, and Algeria is nearby.
The Nile begins from the blue lakes.
There's the Kalahari with a colored river
He gives the animals to drink his water.
The topic of the lesson is “Relief of Africa”. The purpose of the lesson is to study the features of the continent's topography and identify the causes of these features. Consider the patterns of distribution of mineral deposits, explain the reasons for their location. But first, let’s consolidate our knowledge of the geographical location of Africa and the history of its exploration.
Students receive individual card- a form with tasks and begin independent execution tasks.
Individual card - form ___________________________ (Student's last name)
Block 1. Purpose: Checking homework.
Take turns doing practical task to consolidate the nomenclature on the topic “ Geographical position Africa" on the computer.
Do the crossword and geographical dictation on your own.
1) Crossword “Physical-geographical position of Africa” (1)
Horizontally: 3. Cape, the most eastern point Africa. 5. The most large peninsula Africa. 6. The strait separating Africa from a large mainland island. 9. Cape, the most western point Africa. 10. The most large bay in west Africa. 11. Canal separating Africa from Eurasia.
Vertically: 1. The strait separating Africa from Eurasia. 2. The sea washing the north of Africa. 4. Cape, the most southern point Africa. 7. The most large island off the eastern coast of Africa. 8. The sea washing the northeastern coast of Africa.
2) Geographical dictation
Exercise. Write down the numbers of the correct answers in the table.
Review questions on the topic “Geographical location of Africa” |
Write down the numbers of the correct answers |
| The largest island off the coast of Africa. | |
| Africa area. | |
| Northernmost point. | |
| The highest altitude in Africa is 5895 m. It is called... | |
| Africa intersects almost in the middle... | |
| Africa is separated from Europe by a shallow and narrow strait. | |
| Southernmost point. | |
| In the northeast it is connected to Eurasia by an isthmus. | |
| The largest peninsula in Africa. | |
| Great Gulf of Africa - Guinea. | |
| Westernmost point. | |
| He crossed Africa from west to east, explored the Zambezi, discovered Victoria Falls, described the upper reaches of the Congo, Lake Nyasa. | |
| Easternmost point. | |
| He collected more than 6,000 samples of cultivated plants and established that Ethiopia is the birthplace of valuable varieties of wheat. |
3) Practical work at the computer.
Take turns completing practical task No. 1 to consolidate geographical names on the topic “Geographical location of Africa.”
Summarize (count the points) - 1 correct answer - 1 point.
Block 2. Study of new material on the topic “Relief of Africa”.
Target: get acquainted with the features of the continent's topography, identify the reasons for these features. Prove that the relief of the continent is influenced by internal (exogenous) and external (endogenous) processes.
1. Repetition of what has been learned about relief. Oral work with the teacher.
1 oral answer – 1 point.
1) What is relief?
2) What is the division of landforms by height?
2. Working with cards: “Physical map of Africa”, “Map of the structure of the earth’s crust”.
Practical work.
1. Analysis of the physical map and comparison with the map of the structure of the earth’s crust.
Reception characteristics of the continental relief:
1) the predominant form of relief in height and their relative placement.
2) the predominant types of plains in height
3) the predominant types of mountains in height
3. Working with the textbook p. 115 “Great East African Rifts.”
1. Which one tectonic structure lies at the heart of the continent of Africa?
2. What is the cause of faults?
3. How will the relief, and subsequently the area of Africa, change?
Conclusion: the continent is based on the ancient African-Arabian platform, hence the predominance of plains; Fold belts occupy a smaller area, therefore, mountains occupy a smaller area.
4. Description of one of the relief forms according to the plan.
1) In what part of the continent is the landform located?
2) In what direction does it stretch?
3) What are the approximate dimensions?
4) What are the highest altitudes, prevailing altitudes?
5) What is the origin of the landform?
5. Phys. just a minute
Now I invite everyone to exercise,
Small steps - one, two, three
Light jumps - one, two, three
That's all the exercise - one, two, three
Soft landing - one, two, three.
6. Practical work:“Relief forms, their structure and age; characteristic minerals."
Map "Structure of the Earth's Crust" |
"Physical Map of Africa" |
||
Platform or pleated belt, age |
Landform |
Height average and highest |
Minerals |
New (age from 30 million years to our time). |
|||
Ethiopian Highlands |
|||
The highest altitude is 5895 m. |
|||
Atlas Mountains |
|||
Conclusion: The platforms are associated with _____________________ (landforms) and sedimentary minerals, and pleated belts correspond to ____________________ (landforms) and ____________________ minerals.
Calculate your points: practical work – 5 points.
7. Messages from students on the topic of the lesson ( advance task ). For the message - 5 points.
8. Open your workbooks on page 40, outline the mountains, highlands, and plateaus of the mainland. Label the locations of the deserts.
Calculate the points: for the task - 2 points.
Block 3. Reinforcing the material learned in the lesson.
1. Working with a computer on the topic of the lesson:
Attention to the screen! ( Electronic manual. "Africa" (with sound)):
- Relief of Africa
- longest fault system
- minerals
- natural resources
2. Find out from the description:
1. This one geographical feature Africa is part of the African Platform. Its slopes are covered with hard-leaved forests. It is located south of the tropics. Maximum height 3482m. More precipitation falls on the eastern slopes. It is washed by the current of Cape Agulhas. Citrus fruits, olives, and peanuts are grown from cultivated plants.
2. There is a fault line here. Earthquakes are frequent. Dozens of volcanic cones tower over the area. In the west and south the slopes are steep and steep. Well expressed altitudinal zone. Above 1800 meters, evergreen forests give way to savannas. Here is one of the sources of the Nile. (Ethiopian Highlands).
3. Conclusions on the topic of the lesson:
1) Almost the entire continent is an ancient African-Arabian platform - part of the split Gondwana.
2) The northern and southern parts of the continent developed differently, so their modern topography is significantly different.
3) In the north there are more subsidence zones that were repeatedly flooded by seas. Therefore, deposits of sedimentary origin are common: coal, salts, manganese ores.
4) In the south and east, plateaus and highlands are located on the shields. Block fault zone. Vertical and horizontal movements of large blocks of the earth's crust occurred along the cracks. Horsts (uplifts) were formed - blocky ridges of the East African Plateau, grabens (lowerings) - the Drakensberg Mountains. They mine gold, diamonds, and uranium ores.
5) The coast of the Gulf of Guinea (an outcrop of ancient crystalline rocks) - significant reserves of oil and gas.
4. Practical work at the computer. Take turns completing practical task No. 3 to consolidate names geographical objects on the topic "Relief of Africa".
Calculate points: correct answer to 1 question – 1 point.
Lesson summary. Rating.
Score for the work:
40 points or more – “5”; 30-40 points – “4”; 15-30 points – “3”; 15 points or less – “2”. Don’t be upset, in the next lesson you will have the opportunity for more, you just have to want it.
Homework
§ 25; Contour Map Assignment: Label Africa's major landforms and minerals. Indicate the boundaries of the Great East African Rifts.
Assignment for the curious: 1. The average altitude of Africa is 650 m above sea level, but there are points whose absolute altitude reaches 4.5 thousand m or more.
2.Name the four most high points Africa whose names begin with the letter "K".
Point with arrow(reflection)
And in conclusion I want to say,
You couldn't find a better geography subject.
The world of geography is huge,
You strive to know him.
Literature
1. Mitrofanov I.V. Thematic games on geography. – M.: TC Sfera, 2002.