Indian Ocean: geographical location. Indian Ocean (geographical location, natural features, types of economic activities)

The nature of the Indian Ocean has many similarities with nature Pacific Ocean, there are especially many similarities in the organic world of the two oceans.

Geographical position. The Indian Ocean has a unique position on the planet: most of it lies in the Southern Hemisphere. In the north it is limited to Eurasia and has no connection with the North Arctic Ocean.

The ocean shores are slightly indented. There are relatively few islands. Large islands are located only on the border of the ocean. There are volcanic and coral islands in the ocean (see map).

From the history of ocean exploration. The shores of the Indian Ocean are one of the areas of ancient civilizations. Some scientists believe that navigation began in the Indian Ocean. The first means of overcoming expanses of water could be bamboo rafts, which are still used in Indochina. Catamaran-type ships were created in India. Images of such ships are carved on the walls of ancient temples. Ancient Indian sailors in those distant times sailed to Madagascar, East Africa, and possibly to America. The Arabs were the first to write descriptions of ocean voyage routes. Information about the Indian Ocean began to accumulate since the voyage of Vasco da Gama (1497-1499). At the end of the 18th century. The first measurements of the depths of this ocean were carried out by the English navigator J. Cook.

Comprehensive study of the ocean began in late XIX V. The most significant research was carried out by the British expedition on the Challenger ship. However, until the middle of the 20th century. The Indian Ocean has been poorly studied. Nowadays, dozens of expeditions on research vessels from many countries are studying the nature of the ocean and revealing its riches.

Features of the nature of the ocean. The structure of the bottom topography is complex. Mid-ocean ridges divide the ocean floor into three parts (see map). In the western part there is a ridge connecting south of Africa with the Mid-Atlantic Ridge. The center of the ridge is characterized by deep faults, areas of earthquakes and volcanism on the ocean floor. Rifts earth's crust continue into the Red Sea and reach land.

The climate of this ocean is influenced by its geographical location. A special feature of the climate is the seasonal monsoon winds in the northern part of the ocean, which is located in the subequatorial zone and is subject to significant influence from land. Monsoons have a huge impact on weather conditions in the northern part of the ocean.

In the south, the ocean experiences the cooling influence of Antarctica; This is where the harshest areas of the ocean lie.

Properties are associated with climate characteristics water masses. The northern part of the ocean warms up well, is deprived of the influx of cold water and is therefore the warmest. The water temperature here is higher (up to +30°C) than at the same latitudes in other oceans. To the south, the water temperature decreases. The salinity of ocean waters at the surface is generally higher than the average salinity of the World Ocean, and in the Red Sea it is especially high (up to 42%).

In the northern part of the ocean, the formation of currents is influenced by seasonal changes in winds. Monsoons change the direction of movement of waters, cause their vertical mixing, and rearrange the system of currents. In the south the currents are integral part general scheme currents of the World Ocean (see Fig. 25).

The organic world of the Indian Ocean is similar to the flora and fauna of the western Pacific Ocean. Tropical water masses are rich in plankton, which is especially rich in unicellular algae. Because of them, the surface layer of water becomes very cloudy and changes color. There is a lot of plankton glowing at night organisms. There are various types of fish: sardinella, mackerel, sharks. In the southern part of the ocean there are white-blooded fish, such as ice fish, etc. Shelf areas and shallow waters near coral reefs are especially rich in life. Algae thickets form underwater meadows. IN warm waters The Indian Ocean is home to giant sea turtles, sea snakes, a lot of cuttlefish and squid, and near Antarctica - whales and seals.

The Indian Ocean is located several natural belts(see Fig. 33). In the tropical zone, under the influence of the surrounding land, complexes with different properties water masses In the western part of this belt there is little precipitation, evaporation is high, and almost no water comes from land. The water masses here have high salinity. The northeastern part of the belt, on the contrary, receives a lot of precipitation and fresh water from rivers flowing from the Himalayas. A complex with highly desalinated surface waters is created here.

Kinds economic activity in the ocean. The natural resources of the Indian Ocean as a whole have not yet been sufficiently studied and developed. The ocean shelf is rich in minerals. In the sedimentary rocks at the bottom of the Persian Gulf there are huge deposits of oil and natural gas. Oil production and transportation pose a risk of water pollution. In countries located off the northwestern coasts of the ocean, where there is almost no fresh water, salt water is being desalinated. Fishing is also developed.

Numerous shipping routes pass through the Indian Ocean. There are especially many sea roads in the northern part of the ocean, where small ones are still used. sailing ships. The direction of their movement is associated with the monsoons.

What influence does its physical and geographical location have on the nature of the Indian Ocean?
What is the interaction between the ocean and the surrounding land?
Place the information presented in the text on a contour map; conventional signs come up with it yourself.

Scientific research conference

Topic: “Natural, social and ecological problems development of the Indian Ocean".

Target: Deepen and systematize knowledge about the natural features of the Indian Ocean; continue to improve practical skills to characterize the climatic conditions of the ocean, the properties of water masses, natural resources, give examples of representatives organic world, identify sources of ocean water pollution; develop communication skills, ability to work in small groups.

Lesson type: learning new material

During the classes:

Organizing time:

greeting students;
verification of those present (slide No. 1)

Motivation for educational and cognitive activities:

When a person doesn't know

what pier is he heading to?

there will be no wind for him

incidental.

(slide number 2)

Seneca

Every person has a place in life where he is happy, where his main dreams come true, a place where the soul constantly strives.

Where it is so calm and clean. Bottle mail has been delivered to the shores of our state. IN

In 1560, on the coast of England, a poor boatman found a sealed bottle with an unknown message. Since he could not read, he took it to the local judge. As it turned out, this was an extremely important military message.

To prevent the disclosure of military secrets, the Queen of England appointed a special position of the Royal Bottle Opener. Only this official had the right to open the bottle mail. I appoint (Secretary) as the Royal Bottle Opener.

The letter got wet and part of it is lost, but we will try to read it.

Letter: In December 2004 there was catastrophic earthquake, the epicenter of which is in ... the ocean 250 km from ... the island. Help us find out why the earthquake started and how long will we endure the disaster?

- Guys, determine on which continent or island this happened, on the shores of which ocean. Local residents also left us the coordinates of that place

(0°N, 100°E)

On which island? And on the shore of which ocean? (slide number 3)

Today our “creative laboratory” consists of scientists of various specializations: historians, statisticians, climatologists, zoologists, local residents, ecologists, and a secretary.

They gathered for a conference with the goal (slide No. 4) to discuss current state nature of the Indian Ocean, its use natural resources and problems arising as a result of intensive economic activity in the ocean.

We had guests at the conference - a representative of the Greenpeace organization, a representative of the school environmental organization "Green Sprout"

Learning new material:

Conference sections: (slide No. 5)

Section 1 – historians

Section 2 – extras

Section 3 – climatologists

Section 4 – zoologists

Section 5 – local residents

Section 6 - ecologists

Section I – historians (2 people)

What is the purpose of research in the Indian Ocean?

(slide number 6)

1 speaker.

The shores of the Indian Ocean are one of the areas of ancient civilizations. The exploration of the ocean began from the north by Indian, Egyptian and Phoenician sailors, who 3 thousand years BC.

sailed through the Arabian and Red Seas, along the Persian Gulf. The first descriptions of voyage routes in the Indian Ocean were compiled by the Arabs. For European geographical science information about the ocean began to accumulate since the voyage of Vasco da Gama (1497 - 1499). When Vasco da Gama first sailed through the waters of the Indian Ocean to the shores of India, he did not even imagine its size.

In the northern hemisphere, the ocean is more like a large sea, deeply cut into the land. However, for some time the Indian Ocean remained a less explored area of the Earth. At the end of the 18th century. The first depth measurements were carried out here by J. Cook. (Working with the map)

2nd speaker.

Compared to other oceans, scientists have paid less attention to the Indian Ocean. Therefore, in 1960, on the initiative of the UN, the International Indian Ocean Expedition began, which lasted 6 years.

Over 20 countries took part in it. Scientists have completed a study of the mid-ocean ridge of the ocean, which confirmed the existence of unified system middle ridges.

Question: For what purpose was this expedition organized?

Answer: The Indian Ocean mid-ocean ridge fault zone is a “living” part of the earth’s crust.

This is evidenced by the presence of hot springs and frequent earthquakes. Sunda Islands – 100 active volcanoes. In December 2004, a catastrophic earthquake occurred, the epicenter of which was in Indian, 250 km away. from the northern outskirts of Sumatra. People were affected in Indonesia, Sri Lanka, India, Thailand, Malaysia, Burma, Bangladesh and the Maldives.

The disaster also affected some African countries - Seychelles, Somalia, Tanzania, Kenya.

Section II – extras (2 people)

What is being investigated, the main problem: Compare ocean statistics and determine the significance of the Indian Ocean.

(slide number 7)

1 speaker. (slide no. 8 – 10)

Scheme No. 1. Size of the Indian Ocean relative to other oceans

Scheme No. 2. Maximum depths of the World Ocean

Scheme No. 3. Maximum precipitation

Scheme No. 4. Salinity of the World Ocean
Scheme No. 5. Temperature of the world's oceans

After analyzing the statistical data, we can conclude that the Indian Ocean and the Pacific have the most similarities.

2 speaker

After analyzing the statistical data, we suggest you decode the information.

Task No. 1: performed on forms.

(slide number 11)

"Digital dictation"

– After listening to the statement, determine which ocean we are talking about. If we are talking about the Pacific Ocean, write down the number “1”; if we are talking about the Indian Ocean, write down the number “2”.

Pacific Ocean – 1
Indian Ocean – 2

(Task explanation)

1) The third largest ocean on Earth.
2) The name of the ocean was given by F.

Magellan.
3) The Mariana Trench is located in this ocean.
4) The northern part of the ocean is washed by the continent of Eurasia.
5) One of the ocean seas has the highest salinity in the world.
6) This ocean is connected to the Arctic Ocean by the Bering Strait.
7) The richest oil field on the shelf of the Persian Gulf.
8) Warmest ocean by temperature surface waters.
9) In the west, the ocean washes Eurasia, in the east – America.
10) In the northern part of the ocean there is a powerful Monsoon current.

Section III – climatologists (3 people)

What is being investigated, the main problem: Why is the Indian Ocean the warmest?

(slide number 12)

Microphone method

I think that the climatic conditions of the Indian Ocean are determined by the location of most of it in equatorial and tropical latitudes. The climate is also influenced by the huge landmass (mainland Eurasia) to the north, as well as the monsoon circulation. (Work at the map)
Therefore, I believe that the monsoon circulation forms monsoon current gyres here (Southern Trade Wind Current, Somali Current, Monsoon Current). This phenomenon is observed only in this ocean.
They change their direction 2 times a year.
As a result, the water warms up at the equator to + 27 0С +320С, in the north + 40 0С (Bay of Bengal).
Zoning is also evident in the distribution of precipitation: equator 2000 – 3000 mm. per year, tropics 100 mm.
per year (Persian Gulf).
Precipitation affects salinity

Equator – 34%0

tropics – 37%o

Red Sea – 40-42%0

Task No. 2: Apply geographic nomenclature to the contour map.

(slide number 12)

IV section – zoologists (2 people)

What is being investigated, the main problem: What determined the originality and uniqueness of the animal and flora. (slide number 13)

1 speaker. (slide number 14)

We explored animal world Indian Ocean and found out that in the first half of the twentieth century, a fish was caught near the tropical coast of Africa that became a real sensation.

We are talking about the prehistoric fish coelacanth (coelacanth), which was thought to have become extinct 70 million years ago. However, in 1938, a coelacanth was first caught alive in African waters. Modern coelacanths are among the rarest living creatures that have remained virtually unchanged for 400 million years. They have a special skull shape, reminiscent of a braincase. For example, instead of the hard spine characteristic of all vertebrates, coelacanths have a thick-walled elastic tube.

2nd speaker. (slide number 15)

The organic world is extremely rich in the northern part of the tropical region of the ocean (Red and Arabian seas, Persian and Bengal bays). Numerous species of fish are found here - sardinella, various sharks, mackerel, flying fish. This wealth is associated with the entry of large amounts of nutrients into the ocean along with the river waters of the continents.

The temperate and polar latitudes of the Indian Ocean are home to many squids and mammals: whales, pinnipeds, and dolphins. Among the birds there are albatrosses, frigates, and penguins.

Task No. 3: complete the task in the form for matching logical pairs. Students hand in their answer sheets to be checked by the jury. (slide number 16)

Section V – local population (2 people)

What is being investigated, the main problem: What social and economic problems do the local population have?

Why does it attract tourists here so much? (slide number 17)

(Indian dance). (slide number 18)

Teacher: Dear scientists, of course you found out which state introduced its culture to us?

Speaker: The corner of the temples, the beaches of Goa and the shooting of Indian cinema can unfold right before your eyes.

The islands of Bali, Seychelles, the Red Sea, and the Maldives are one of the most popular year-round destinations in world tourism.

This is not surprising: stable heat air and water all year round and beautiful nature provide an excellent beach holiday, and excursion program in Indonesia is exotic and diverse.

Mostly married couples come here on honeymoon trips.

Report. The Indian Ocean is currently the most dangerous in the world. And not because of sharks, although they are found here in abundance, but because of sea robbers - pirates.
Modern pirates are not the old warriors with an eye patch and a wooden leg. These are criminals on high-speed ships, armed with the latest technology. They attack and rob yachts, cargo ships and tankers, killing crews and passengers.
The first information about pirates who began operating off the coast of Somalia appeared back in the 90s of the last century.

However, at that time their actions were scattered and unsystematic. At the beginning of the new century, the activity of Somali pirates intensified. From March 2005 to June 2006 alone, they attacked dozens of merchant ships in the Indian Ocean.

Even then, the transitional government of Somalia repeatedly appealed to East African countries with a request for assistance in curbing pirates.
May 20, 2007

The UN has called for international action against the “scourge of piracy” off the coast of Somalia.
Currently, several ship groups and individual ships are resisting pirates to one degree or another.

In general, the problem of piracy off the coast of Somalia is fraught with at least three consequences for the world community:

Firstly, it created a real threat to the safety of maritime navigation in this zone and has already negatively affected a number of economic processes.

Thus, pirates disrupted the tuna fishing season, forcing over 50 fishing vessels to leave for nearby ports.

Secondly, the proceeds from piracy, which come from ransoms for hijacked ships and their crews, may be partly used to fuel the numerous armed conflicts in Somalia. In addition, individual captured ships themselves can become a source of weapons for various groups.
Thirdly, the actions of pirates can result in a major disaster at any moment. ecological disaster, as almost happened with the Takayama tanker.

However, the Indian Ocean has now become dangerous for exploration due to pirates who are increasingly attacking civilian ships.

Section VI – ecologists (2 people)

What is being investigated, the main problem: What environmental problems arise in the Indian Ocean and why?

(slide number 19)

Ecological problems.

1 speaker.

Oil pollution
Social level of the population (sewage is dumped into rivers, Poor states, standard of living)
Agricultural emissions waste, chemical waste. Harmless, practically unknown organisms, natural phenomena acquire unexpectedly threatening properties. Who cared about algae ten years ago? Meanwhile, due to the unreasonable dumping of waste from industrial and agricultural enterprises into the seas and rivers, they began to develop very quickly different types algae, taking a large amount of oxygen and thereby depriving other sea inhabitants of it.
Oil and petroleum stains on the surface sea water interfere with the lives of birds and other animals. Chemical emissions, poisoning marine animals, then send people who feed on them. Is there a way out?

Students share their opinions.

World Oceans Day is a UN commemorative day. Celebrated annually

2nd speaker.

Influences before you various types human economic activity on the nature of the Indian Ocean.

Make a cause-and-effect chain.

(Conducted by the student with the class.)

"Ecological training"

Offshore mining
Pollution of ocean and coastal waters with harmful substances
Impoverishment of the organic world
Deterioration of air composition and quality
Human health is deteriorating

— In any natural community, everything is interconnected, and a person must know these connections so as not to destroy the harmony of natural life.

The ocean plays a huge role in shaping the Earth's climate .

IV. Consolidation of the studied material:

Secretary: The conference addressed 6 problematic issues, all of which were recorded by me. (The solution to the problem is recorded by the secretary, and the ships put on sails of a certain color as decisions are made.)

(slide number 20)

In the first section, what is the purpose of research in the Indian Ocean?

Decision-making: Expeditions are carried out to study “living” areas of the earth’s crust, to avoid serious consequences, and to warn the population.

In the second section - compare the statistical data of the oceans and determine the significance of the Indian Ocean.

Decision-making: Statistics give us the opportunity to compare and contrast.

After analyzing the diagrams, we decided that the Indian Ocean is the warmest, the saltiest and ranks 3rd in area relative to other oceans.

In the third section - why the Indian Ocean is the warmest.

Decision-making: Having examined the climatic conditions of the Indian Ocean, we can safely say that it is rightfully the warmest, since most of it is located in the equatorial and tropical zones.

In the fourth section - what determined the originality and uniqueness of the animal and plant world.

Decision-making: Since this ocean is the warmest, this determined the uniqueness and diversity of the organic world, the presence of endemics and relics.

In the fifth section - what social and economic problems exist among the local population.

Why does it attract tourists here so much?

Decision-making: After analyzing the situation of social and economic problems, we found out that such a phenomenon as pirates has appeared in the Indian Ocean. How to fix this problem? Need to improve the level economic development in countries adjacent to the water area, provide work.

In the sixth section - what environmental problems arise in the I.O. and why?

Decision-making:

- Put wastewater treatment plants at oil production installations

— Monitor the composition and quality of water and air

— Introduce and control penalties

— Instill environmental education among the local population

Conduct environmental campaigns and events among young people

Guys, we have compiled a collective appeal to the representative of the Greenpeace organization with radical measures to solve environmental, social and economic problems.

And we would like to convey the second letter to the representative of the school environmental organization “Green Sprout”, as an appeal to all schoolchildren. We recommend that you use the developed material at school environmental conferences.

Lesson summary:

Conference members check the forms and grade the class work.

Teacher:

You can actually be strong

And the winds may carry you along.

But if you don't see the goal,

You'll never get there. (slide number 21)

So, guys, I ask you to imagine the emotions that you received in the lesson. If the information that you heard and saw today was interesting and new, fill your sails with the wind and send them on trips to other oceans to learn a lot more new things (green).

If the lesson was ordinary and you didn’t learn anything new, then set your blue sails. And if you were just watching our conference from shore, set your red sails.

I declare the meeting of the sections of the scientific research conference closed.

VI. Homework:

— Study § 11 – 12 (slide number 22)

The lesson is over, thank you everyone.

The Indian Ocean makes up 20% of the World Ocean by volume. It is bounded by Asia to the north, Africa to the west and Australia to the east.

In the zone 35° S. passes the conventional border with the Southern Ocean.

Description and characteristics

The waters of the Indian Ocean are famous for their transparency and azure color. The fact is that few freshwater rivers, these “troublemakers,” flow into this ocean. Therefore, by the way, the water here is much saltier than in others. It is in the Indian Ocean that the saltiest sea in the world, the Red Sea, is located.

The ocean is also rich in minerals. The area near Sri Lanka has been famous for its pearls, diamonds and emeralds since ancient times. And the Persian Gulf is rich in oil and gas.
Area: 76.170 thousand sq. km

Volume: 282.650 thousand cubic km

Average depth: 3711 m, greatest depth - Sunda Trench (7729 m).

Average temperature: 17°C, but in the north the waters warm up to 28°C.

Currents: two cycles are conventionally distinguished - northern and southern. Both move clockwise and are separated by the Equatorial Countercurrent.

Main currents of the Indian Ocean

Warm:

Northern Passatnoe- originates in Oceania, crosses the ocean from east to west. Beyond the peninsula, Hindustan is divided into two branches. Part flows to the north and gives rise to the Somali Current. And the second part of the flow heads south, where it merges with the equatorial countercurrent.

South Passatnoe- begins at the islands of Oceania and moves from east to west all the way to the island of Madagascar.

Madagascar- branches off from the South Passat and flows parallel to the Mozambique from north to south, but slightly east of the Madagascar coast. Average temperature: 26°C.

Mozambican- another branch of the South Trade Wind Current. It washes the coast of Africa and in the south merges with the Agulhas Current. Average temperature - 25°C, speed - 2.8 km/h.

Agulhas, or Cape Agulhas Current- a narrow and fast current passing along east coast Africa from north to south.

Cold:

Somali- a current off the coast of the Somali Peninsula, which changes its direction depending on the monsoon season.

Current of the West Winds encircles the globe in southern latitudes. In the Indian Ocean from it is the South Indian Ocean, which, near the coast of Australia, turns into the Western Australian Ocean.

Western Australian- moves from south to north along the western coast of Australia. As you approach the equator, the water temperature rises from 15°C to 26°C. Speed: 0.9-0.7 km/h.

The underwater world of the Indian Ocean

Most of the ocean is located in the subtropical and tropical zones, and is therefore rich and diverse in species.

The tropical coastline is represented by vast thickets of mangroves, home to numerous colonies of crabs and amazing fish - mudskippers. Shallow waters provide excellent habitat for corals. And in temperate waters brown, calcareous and red algae grow (kelp, macrocysts, fucus).

Invertebrates: numerous mollusks, great amount species of crustaceans, jellyfish. There are many sea snakes, especially poisonous ones.

Sharks of the Indian Ocean are the special pride of the water area. The largest number of shark species live here: blue, gray, tiger, great white, mako, etc.

Of the mammals, the most common are dolphins and killer whales. And the southern part of the ocean is the natural habitat of many species of whales and pinnipeds: dugongs, fur seals, seals. The most common birds are penguins and albatrosses.

Despite the richness of the Indian Ocean, seafood fishing here is poorly developed. The catch is only 5% of the world's. Tuna, sardines, stingrays, lobsters, lobsters and shrimp are caught.

Indian Ocean exploration

Coastal countries of the Indian Ocean - hotspots ancient civilizations. That is why the development of the water area began much earlier than, for example, the Atlantic or Pacific Ocean. Approximately 6 thousand years BC. The waters of the ocean were already plied by the shuttles and boats of ancient people. The inhabitants of Mesopotamia sailed to the shores of India and Arabia, the Egyptians conducted a lively maritime trade with the countries of East Africa and the Arabian Peninsula.

Key dates in the history of ocean exploration:

7th century AD - Arab sailors compiled detailed navigation maps coastal zones Indian Ocean, exploring the waters near the eastern coast of Africa, India, the islands of Java, Ceylon, Timor, and the Maldives.

1405-1433 - Zheng He's seven sea voyages and exploration trade routes in the northern and eastern parts of the ocean.

1497 - Vasco de Gama's voyage and exploration of the eastern coast of Africa.

(Expedition of Vasco de Gama in 1497)

1642 - two raids by A. Tasman, exploration of the central part of the ocean and discovery of Australia.

1872-1876 - the first scientific expedition of the English corvette Challenger, studying the biology of the ocean, relief, and currents.

1886-1889 - expedition of Russian explorers led by S. Makarov.

1960-1965 - international Indian Ocean expedition established under the auspices of UNESCO. Study of hydrology, hydrochemistry, geology and ocean biology.

1990s - present day: studying the ocean using satellites, compiling a detailed bathymetric atlas.

2014 - after the crash of a Malaysian Boeing, detailed mapping of the southern part of the ocean was carried out, new underwater ridges and volcanoes were discovered.

The ancient name of the ocean is Eastern.

Many species of wildlife in the Indian Ocean have an unusual property - they glow. In particular, this explains the appearance of luminous circles in the ocean.

In the Indian Ocean, ships are periodically found in good condition, however, where the entire crew disappears remains a mystery. Over the last century, this happened to three ships at once: the Cabin Cruiser, the tankers Houston Market and Tarbon.

Physical geography of continents and oceans

INDIAN OCEAN: GEOGRAPHICAL POSITION

Indian Ocean - third largest The Earth's oceans (after the Pacific and Atlantic) are mostly located in the southern hemisphere. In the north and northeast it is limited by Eurasia, in the west by Africa, and in the southeast by the Antarctic convergence zone (if we recognize the existence of the Southern Ocean). The area of the ocean (up to the coast of Antarctica) is 76.2 million km 2, the volume of its waters is 282.6 million km 3 (Fig. 3).

Rice. 3. Boundaries of the oceans.

In the northwest and north, i.e. from Africa and Eurasia, large peninsula, separating a number of seas and bays of different origins, different depths and bottom structures. These are the Somali and Arabian peninsulas, bordering the Red Sea and the Gulf of Aden, connected by the Bab el-Mandeb Strait. Further to the east, between the Arabian Sea and the Bay of Bengal, which is actually also a marginal sea, the triangular block of the Hindustan Peninsula juts far into the ocean. The Arabian Sea, through the Gulf of Oman and the Strait of Hormuz, is connected to the Persian Gulf, which is actually an inland sea of the Indian Ocean.

Like the Red Sea, the Persian Gulf stretches from southeast to northwest. These are the most northward parts of the Indian Ocean. Only in contrast to the narrow and deep graben of the Red Sea, the Persian Gulf is located entirely within the shelf, occupying part of the Mesopotamian foredeep. In other areas, the Indian Ocean shelf is no more than 100 km wide. The exception is the shelf of Northern, North-Western and Western Australia, including the shelf of the Great Australian Bight.

To the east and southeast of the Bay of Bengal, the Indian Ocean includes the Andaman Sea between the Andaman and Nicobar Islands, Sumatra and the Indochina and Malacca Peninsulas, as well as the Arafura and Timor Seas, located mainly within the Sahul (northern) shelf of Australia. In the south, the Indian Ocean freely connects with the Pacific and Atlantic oceans. The conventional boundaries between them are drawn accordingly at 147° east. and 20°E (see Fig. 3).

There are few large mainland islands in the Indian Ocean. They are located at short distances from the continents of which they are parts. Only the largest among them - Madagascar (the fourth largest island on Earth) - is separated from Africa by the Mozambique Strait, 400 km wide. The Indian Ocean also includes part of the islands of the Sunda archipelago - Sumatra, Java, etc. To the southeast, in close proximity to Hindustan, is the island of Sri Lanka.

Numerous islands and archipelagos are scattered in the open Indian Ocean. volcanic origin. In the northern part of the ocean, many of them are topped with coral structures.

Pacific Ocean
Indian Ocean
- Ocean floor, mid-ocean ridges and transition zones

Geographical position. - the third largest ocean on Earth in terms of area and depth, covering about 20% of its water surface. Its area is 76 million km2. It extends from the coast of East Africa to Indonesia and Australia and from the coast of India to Antarctica. Most of it is located in the Southern Hemisphere. Coastline The ocean is slightly indented. Large islands in the ocean are: Sri Lanka, Madagascar, Kalimantan, etc. It includes 6 seas, among them: the Red and Arabian Seas, as well as the bays: Bengal, Persian, Great Australian.

Relief. Average ocean depth is approx. 3700 m, and the maximum reaches 7729 m in the Java Trench. At the bottom of the Indian Ocean there are huge sections of the earth's crust - the African, Indo-Australian and Antarctic plates. A system of mid-ocean ridges extends in the western part of the ocean. They are associated with deep faults, areas of earthquakes and volcanism. Between the ridges there are numerous basins. The ocean shelf is poorly developed, only in the Persian Gulf it increases.

Minerals. In the shelf zone, tin ores, phosphorites, and gold were discovered in rock deposits. The Persian Gulf and its adjacent shelves contain the world's largest oil and gas fields. At the bottom of the Indian Ocean basins in large quantities Ferromanganese nodules were discovered.

Climate. The Indian Ocean is located in the equatorial, subequatorial and tropical climate zones. The northern part is influenced by land. Seasonal winds are formed here - monsoons. In summer, monsoons carry huge amounts of moisture onto land (up to 3000 mm) in the Bay of Bengal region. To the south – from 10° to 30° S. w. an area is formed high pressure where the southeast trade wind prevails, in moderate latitudes there are strong, stable westerly winds. The southern Indian Ocean experiences a significant cooling influence from Antarctica - these are the most severe areas of the ocean.

Currents and properties of ocean waters. Currents in the northern part depend on the monsoon winds, and their direction changes depending on the direction of the summer and winter monsoons. The Monsoon, Somali and Trade Wind currents form a strong circulation in the equatorial latitudes of the Indian Ocean. In the southern part of the ocean, currents enter into a single ring-shaped movement of the waters of the World Ocean.

The Indian Ocean has a large water salinity than other oceans. There is a pronounced zonality in the distribution of salinity here: the highest salinity, up to 42‰, is in the Red Sea and the Persian Gulf, the average salinity is 35‰, and in the Antarctic waters it drops to 33‰.

The Indian Ocean is also characterized by zonality in distribution surface water temperatures . Between the equator and 10° N. w. it is 30 °C, and to the north and south it drops to 24 °C. The closer to Antarctica the temperature, the water drops from 15 °C to –1 °C.

Organic world . The waters of the Indian Ocean serve as a habitat for various representatives of the animal world - sharks, whales, jellyfish, sea turtles, seals, and elephant seals. The species composition of fish is rich - sardinella, anchovy, mackerel, etc. The tropical region of the ocean is one of the areas of wide distribution of coral polyps and the development of reef structures. A characteristic component of the landscape of tropical ocean coasts are mangroves, where many oysters, shrimp, and crabs live. Pearls have been mined in the ocean for a long time.