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 running along the east coast of 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).

Invertebrate animals: numerous mollusks, a huge number of 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

The coastal countries of the Indian Ocean are centers of 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 coasts 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 of the coastal zones of the Indian Ocean, explored the waters near the eastern coast of Africa, India, the islands of Java, Ceylon, Timor, and the Maldives.

1405-1433 - seven sea voyages of Zheng He and exploration of 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.

The Indian Ocean is the third largest ocean on earth. The Indian Ocean washes three continents at once: Africa from the east, Asia from the south, Australia from the north and northwest. The name Indian Ocean is found already at the beginning of the sixteenth century by Schöner under the name Oceanus orientalis indicus, in contrast to the Atlantic Ocean, then known as Oceanus occidentalis.

In the northwest and north, i.e., from Africa and Eurasia, large peninsulas cut into the Indian Ocean, 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.

Fig.1. Indian Ocean

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

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

History of Indian Ocean exploration

The history of the study of the Indian Ocean can be divided into three periods: from merchant shipping and military campaigns of ancient times to the beginning of deep-sea exploration in the last quarter of the 18th and early 19th centuries; from research expeditions of the last quarter of the 17th – 19th centuries to the first complex oceanographic expeditions of the last quarter of the 19th century; from these expeditions to the complex international research of our time, inclusive.

In the first period, the peoples living on the shores of the Indian Ocean traveled for trade purposes, simultaneously creating maps and gaining knowledge about currents, winds and other navigation conditions.

One of the brightest events can be called the journey of the Tver merchant Afanasy Nikitin to India in 1466-1472. A major contribution was also made by D. Cook, who sailed along the coast on the ships "Resolution" and "Adventure" in 1772-1775; during his journey, he obtained data on water temperature to a depth of 180 m. Oceanographic research was also carried out by I. F. Kruzenshtern and Yu. F. Lisyansky (1803-1806). The next important contribution was the research of Charles Darwin, who obtained geological, environmental and biological data. At the same time, Darwin formed a theory of the origin of atolls, which is still valid. The first deep-sea measurements of the Indian Ocean (up to 5000 m) were probably carried out by D. Ross in 1840 - 1843. The development of deep-sea research was also facilitated by the work on laying underwater telegraph cables.

The beginning of the second period of study of the Indian Ocean was marked in 1873-1876. the first round-the-world oceanographic expedition of the Challenger, led by Professor Wyvil Thomson, a member of the British Royal Society. This expedition carried out comprehensive research, including physical, chemical, biological and geological observations.

This was followed by a series of studies of a narrower focus; it is significant that a large number of countries that are leaders in science participated in the study of the Indian Ocean. Subsequent studies were of a narrower nature (for example, gravimetric studies on submarines in 1923 by Vening-Mason).

Expeditionary activities within the framework of the International Geophysical Year (IGY) 1957-1959. opened a new stage in the study of the world's oceans. Although this expedition paid most attention to the Atlantic and Pacific Oceans, the Indian Ocean was not left out either. The largest expedition at that time was the International Indian Ocean Expedition (IIOE) program, which covered almost the entire Indian Ocean with observations (1960-1965). It is very pleasant that 10 Soviet ships took part in this program.

Studies of the continental margins of the Indian Ocean

A detailed study of the continental margins has a relatively short history (about 50 years), even despite the numerous efforts made, many aspects remain unclear and contradictory. Submarine continental margins are among the most difficult areas to work in because they are characterized by significant variations in seafloor depths and configurations of sedimentary cover and crust, large differences in physical properties, and significant changes in rock composition within the same region.

Ancient submarine margins are even more difficult to identify and study because they are characterized by severe deformations. Therefore, a wide range of possible, acceptable interpretations and concepts of origin and evolution arises. It is much easier to explore deep ocean basins, where water columns reach 4-5 km, which serve as a filter to eliminate the influence of problematic areas on geophysical curves; the structure of such areas is much simpler than those located closer to the shore.

Objects of study, goals and objectives of research

In the mid-20th century, global international research in geology began. Of course, experiments and expeditions were carried out at an earlier time, but they all had rather broad tasks and were rather generalized in nature. The need for more narrow observations became obvious when more advanced instruments and methods began to appear that made it possible to record the most accurate results. However, there were more pressing reasons. Thus, using the example of expeditions carried out within the framework of the International Geophysical Year (1957-1959), one of the tasks of which was to study the possibilities of recreational and food resources of the Indian Ocean, the need of people to modernize the social sphere is clearly expressed. So, the object of study is the continent-ocean transition zones and the processes occurring in these areas.

By definition, the subject of study is the characteristics of the objects of study. There are three main types of edges: passive, active, transform. Sometimes, the structure of the outskirts makes it difficult when trying to classify it into one of three types, but modern methods make it possible to achieve a more or less accurate determination. Sedimentation, tectonic movements, shelf formation - all these are characteristics of processes, and therefore also the subject of study.

The goal of researchers currently is to collect information about the outskirts of the Indian Ocean, by which we mean a complex of systematized knowledge. For example, thanks to a detailed study of continent-ocean transition zones, scientists are able to reconstruct a picture of the past. As a result of a number of experiments, it is possible to establish the causes and consequences of certain events in the geological history of the Earth. For example, it was possible to establish that the Indian Ocean was formed at the junction of the Jurassic and Cretaceous periods as a result of the breakup of Gondwana. Then there was a separation of Africa and the Deccan from Australia with Antarctica, and later - of Australia from Antarctica (in the Paleogene, about 50 million years ago).

As tasks, we should highlight the integration of Earth sciences and knowledge of applied sciences into specific problems - the geology of continental margins. Using modern technology and a wide range of methods to obtain more accurate results.

The first ideas about the nature of the Indian Ocean developed among the old peoples who inhabited its shores and beyond. For trading and combat purposes, they bathed in different parts of the ocean.

In the V-IV millennia AD. e. The Sumerians sailed along the Persian Gulf and went to the Arabian Sea. Phoenician sailors from 6 centuries AD. e., sailing from the Red Sea, rounding Africa and after 3 years they returned home, passing the Strait of Gibraltar. The Mediterranean peoples actively used monsoon winds for their own sea voyages in the Indian Ocean.

The Greeks and Romans were already in the 1st century AD. e. laid out a sea route through the Bay of Bengal and established an association with China. Of course, the ocean waters were explored by sailors from India, Indonesia and others. Arabs in the 7th and 8th centuries. They swam a lot in the Indian Ocean. They summarized the acquired information about its nature in handwritten books. In 1466-1472 Tver merchant Immortal Nikitin made a journey to India and conquered the Indian Ocean.

His travel notes “Journey from Beyond the 3rd Sea” give a colorful and honest reflection not only of his life in this country, but also of his trading route there from Eastern Europe. In the 15-16th centuries. A period of active exploration of the ocean by Europeans begins. In 1497-1498 The Portuguese Vasco po Gama discovered a sea route to India through the western coast of Africa. Because of the Portuguese, Dutch, French, Spanish, and English sailors, including its various parts, are striving to enter the Indian Ocean.

The first oceanographic studies, along with geographical descriptions and clarification of the coastal strip of the Indian Ocean, began to live on sea expeditions from the end of the 18th century.

Thus, during the bathing of D. Cook (1772-1775), the water temperature was measured at a depth of 200 meters. Oceanographic work in the Indian Ocean was carried out by another Russian round-the-world expedition of I.F. Kruzenshtern and Yu.F. Lisyansky (1803-1806), during the expedition before the management of O.E. Kotzebue (1815-1818 and 1823-1826 gg.), many discoveries were made. The works of Charles Darwin appeared as a huge contribution to the formation of science in the quantity and geography of the ocean.

In the 19th and early 20th centuries, the most extensive exploration of the ocean began. The development of deep-sea exploration was facilitated by work on the laying of underwater telegraph cables in the Arabian Sea and the Bay of Bengal (1857-1869). During the round-the-world expedition on the Challenger (1873-1876), group oceanological studies were carried out, including hydrological, geological and biological observations.

In 1898-1899 Germany organized a special deep-sea expedition in the Indian Ocean. She holds the award for being the source of the opening of the East Indian and Arabian-Indian ridges. In 1906, measurements of another German vessel led to the invention of the Javan (Sunda) deep-sea trench.

Since the mid-20th century, work in the Indian Ocean has become more focused. Significant results were brought by oceanographic research carried out by the marine detachments of the diesel-electric ships “Ob” and “Lena” under the program of the International Geophysical Year (1955-1957). The research vessel “Vityaz” (1959-1962, 1965) made a significant contribution to the study of the Indian Ocean.

A major event was the discovery of the West Indian Ridge and its study by oceanologists

SHA. Thanks to the identification of the missing southwestern branch of the Mid-Indian Ridge, the existence of a single global system of median ridges of the World Ocean was established.

INTRODUCTION

Indian Ocean

Above the blackness of your abysses

Wonderful lights were burning,

And your swell moved heavily,

Exploding fire of silent mines.

She blinded our eyes

And we grew pale in the fast light,

And blue fire networks

Flowed along slow waves.

And again, noisy and deep,

You rebelled and caught fire -

And staggered from star to star

With a great cane, an unsteady foresail.

Behind the shaft the oncoming shaft ran

With the breath of the fiery monsoon,

And the diamond tail of Scorpio

I trembled over your blackness.

Ivan Bunin

Geographical location, history of discovery and development

The nature of the Indian Ocean, to a greater extent than other oceans, has features of tropical exoticism. The most characteristic feature of the geographical location of the Indian Ocean is that 84% of its area is located in the Southern Hemisphere. It has no direct connection with the Arctic Ocean.

The Indian Ocean is located between Africa, Asia, Australia and Antarctica, i.e. It is largely limited by land, but at the same time has water boundaries over a large area. The western border of the Indian Ocean is the 20th meridian? e.d. on the stretch between Antarctica (Princess Ranghil Coast) and Cape Agulhas at the southern tip of Africa. In the northeast, the ocean is limited by the northern entrance to the Strait of Malacca, the southwestern and southern shores of the Greater and Lesser Sunda Islands, the southwestern coast of New Guinea to the mouth of the Benebek River, from here by water to Cape York (the northern tip of Australia). In the east, the ocean boundary runs along the coast of Australia to Cape South-East, then crosses the Bass Strait to the north-western tip of Tasmania, then along its western coast to Cape South, from which it runs along the meridian 147? e.d. When distinguishing the Southern Ocean, the southern boundary of the Indian Ocean is drawn along the Antarctic convergence line, which lies between latitudes 48? (at 20? E) and 54? (at 150? East).

If we take the coast of Antarctica as the southern border of the Indian Ocean, then the ocean has an area of ​​76.2 million km 2, a volume of 282.6 million km 3, an average depth of 3711 m, and a greatest depth of 7729 m (the Sunda Trench). The Indian Ocean has approximately the same extent in latitude (11,450 km along the parallel 10? S) and longitude (10,180 km along the meridian 60? E). The southern tropic lies at approximately equal distances from the northern and southern boundaries of the ocean. The Indian Ocean in the northern part is significantly separated by continents and archipelagos. Only in the southern part is it widely connected with the Atlantic and Pacific oceans, which generally ensures good water exchange.

There are many islands in the Indian Ocean. The largest of them - Madagascar, Sri Lanka, Greater Sunda - are of continental origin and are located near the continents. In the open part of the ocean lie the volcanic islands: Comoros (the largest of them is Ngazidja with the active volcano Kargala), Mascarene (the largest island is Reunion), Andaman, Nicobar, Seychelles. Coral islands are especially numerous in the Indian Ocean, most of which are typical atolls. A typical example is Diego Garcia Atoll. It is an almost continuous ring of land, open only at a slight pull in the northern part.

In addition to atolls, many coral islands in their formation are associated with the development of barrier and coastal coral reefs. Such islands form archipelagos, for example Bahrain and Tanzania, which includes the islands of Zanzibar, Pemba and smaller ones. Many islands of the Indian Ocean, especially coral ones, are characterized by modern coastal erosion, changing their outlines.

The Indian Ocean includes six seas: the Red, Arabian, Andaman and Laccadive seas wash the coast of South-West and South Asia, and the Timor and Arafura seas are located off the northern coast of Australia.

The Indian Ocean seas share many common features. With the exception of the Red Sea, they occupy a marginal position. All seas warm up well and have fairly small seasonal changes in surface water temperature. The most significant feature of these seas is the pronounced monsoons, which determine the main features of the nature of the seas. At the same time, each of them clearly expresses its own individuality, which creates its own “portrait” of the sea.

The history of exploration of the Indian Ocean can be divided into 3 periods: from ancient voyages to 1772; from 1772 to 1873 and from 1873 to the present. The first period is characterized by the study of the distribution of ocean and land waters in this part of the globe. It began with the first voyages of Indian, Egyptian and Phoenician sailors, who 3000-1000 BC traveled through the northern part of the Indian Ocean, and ended with the voyage of James Cook, who in 1772-75 penetrated the South to 71° south latitude. The second period was marked by the beginning of deep-sea exploration, first carried out by Cook in 1772 and continued by Russian and foreign expeditions. The main Russian expeditions were O. Kotzebue on the Rurik (1818) and Pallena on the Cyclone (1858-59). The third period is characterized by complex oceanographic research.

The penetration of Europeans (Portuguese, then the Dutch, French and English) into the Indian Ocean basin dates back to the 16th-17th centuries, and by the mid-19th century, most of its shores and islands were secured by Great Britain, which exported from here the most important raw materials and food products for its economy. . Naval (and later air force) bases were created at all entrances to the Indian Ocean: in the Atlantic Ocean - Simon's Town, in the Pacific Ocean - Singapore, in the Red Sea - Aden, on the approaches to India - Trincomalee. In the northeastern part of the Indian Ocean there were colonies of France, the Netherlands (Netherlands Indies), and Portugal.

After the end of World War II (1939-1945), the collapse of the colonial system of imperialism made fundamental changes to the political map of the Indian Ocean basin.

Introduction

1.History of the formation and exploration of the Indian Ocean

2.General information about the Indian Ocean

Bottom relief.

.Characteristics of the waters of the Indian Ocean.

.Bottom sediments of the Indian Ocean and its structure

.Minerals

.Indian Ocean climate

.Flora and fauna

.Fisheries and marine activities

Introduction

Indian Ocean- the youngest and warmest among the world's oceans. Most of it is located in the southern hemisphere, and in the north it extends far into the mainland, which is why ancient people considered it just a big sea. It was here, in the Indian Ocean, that man began his first sea voyages.

The largest rivers in Asia belong to the Indian Ocean basin: the Salween, the Irrawaddy and the Ganges with the Brahmaputra, which flow into the Bay of Bengal; Indus, flowing into the Arabian Sea; The Tigris and Euphrates merge slightly above their confluence with the Persian Gulf. Of the large rivers in Africa that also flow into the Indian Ocean, the Zambezi and Limpopo should be mentioned. Because of them, the water off the ocean coast is cloudy, with a high content of sedimentary rocks - sand, silt and clay. But the open waters of the ocean are amazingly clear. The tropical islands of the Indian Ocean are famous for their cleanliness. A variety of animals have found their home on coral reefs. The Indian Ocean is home to the famous sea devils, rare whale sharks, largemouths, sea cows, sea snakes, etc.

1. History of formation and research

Indian Oceanformed at the junction of the Jurassic and Cretaceous periods as a result of the collapse of Gondwana (130-150 million years ago). Then there was a separation of Africa and the Deccan from Australia with Antarctica, and later - of Australia from Antarctica (in the Paleogene, about 50 million years ago).

The Indian Ocean and its shores remain poorly studied. The name of the Indian Ocean appears already at the beginning of the 16th century. by Schöner under the name Oceanus orientalis indicus, in contrast to the Atlantic Ocean, then known as Oceanus occidentalis. Subsequent geographers called the Indian Ocean mostly the Sea of ​​India, some (Varenius) the Australian Ocean, and Fleuriet recommended (in the 18th century) even calling it the Great Indian Gulf, considering it as part of the Pacific Ocean.

In ancient times (3000-1000 BC), sailors from India, Egypt and Phenicia traveled through the northern part of the Indian Ocean. The first navigation maps were compiled by the ancient Arabs. At the end of the 15th century, the first European, the famous Portuguese Vasco da Gama, circumnavigated Africa from the south and entered the waters of the Indian Ocean. By the 16th-17th centuries, Europeans (the Portuguese, and later the Dutch, French and English) increasingly appeared in the Indian Ocean basin, and by the middle of the 19th century, most of its shores and islands were already the property of Great Britain.

History of discoverycan be divided into 3 periods: from ancient voyages to 1772; from 1772 to 1873 and from 1873 to the present. The first period is characterized by the study of the distribution of ocean and land waters in this part of the globe. It began with the first voyages of Indian, Egyptian and Phoenician sailors, who 3000-1000 BC. traveled through the northern part of the Indian Ocean, and ended with the voyage of J. Cook, who in 1772-75 penetrated the South to 71° S. w.

The second period was marked by the beginning of deep-sea exploration, first carried out by Cook in 1772 and continued by Russian and foreign expeditions. The main Russian expeditions were O. Kotzebue on the Rurik (1818) and Pallena on the Cyclone (1858-59).

The third period is characterized by complex oceanographic research. Until 1960 they were carried out on separate ships. The largest works were carried out by expeditions on the ships "Challenger" (English) in 1873-74, "Vityaz" (Russian) in 1886, "Valdivia" (German) in 1898-99 and "Gauss" (German) in 1901-03, Discovery II (English) in 1930-51, the Soviet expedition to the Ob in 1956-58, etc. In 1960-65, the Intergovernmental Oceanographic Expedition under UNESCO carried out an international Indian Ocean expedition, which collected new valuable data on hydrology, hydrochemistry, meteorology , geology, geophysics and biology of the Indian Ocean.

. General information

Indian Ocean- the third largest ocean on Earth (after the Pacific and Atlantic), covering about 20% of its water surface. Almost all of it is located in the southern hemisphere. Its area is 74917 thousand km ² ; average volume of water - 291945 thousand km ³. In the north it is bounded by Asia, in the west by the Arabian Peninsula and Africa, in the east by Indochina, the Sunda Islands and Australia, and in the south by the Southern Ocean. The border between the Indian and Atlantic Oceans runs along the 20° meridian of eastern longitude (Meridian of Cape Agulhas), between the Indian and Pacific Oceans runs along the 147° meridian of east longitude (meridian of the southern cape of Tasmania). The northernmost point of the Indian Ocean is located at approximately 30°N latitude in the Persian Gulf. The Indian Ocean is approximately 10,000 km wide between the southern points of Australia and Africa.

The greatest depth of the Indian Ocean is the Sunda or Java Trench (7729 m), the average depth is 3700 m.

The Indian Ocean washes three continents at once: Africa from the east, Asia from the south, Australia from the north and northwest.

The Indian Ocean has the least number of seas compared to other oceans. In the northern part there are the largest seas: the Mediterranean - the Red Sea and the Persian Gulf, the semi-enclosed Andaman Sea and the marginal Arabian Sea; in the eastern part - the Arafura and Timor Seas.

In the Indian Ocean are the island states of Madagascar (the fourth largest island in the world), Sri Lanka, Maldives, Mauritius, Comoros, and Seychelles. The ocean washes the following states in the east: Australia, Indonesia; in the northeast: Malaysia, Thailand, Myanmar; in the north: Bangladesh, India, Pakistan; in the west: Oman, Somalia, Kenya, Tanzania, Mozambique, South Africa. In the south it borders with Antarctica. There are relatively few islands. In the open part of the ocean there are volcanic islands - Mascarene, Crozet, Prince Edward, etc. In tropical latitudes, coral islands rise on volcanic cones - the Maldives, Laccadives, Chagos, Cocos, most Andaman, etc.

. Bottom relief

The ocean floor is a system of mid-ocean ridges and basins. In the area of ​​​​Rodriguez Island (Mascarene archipelago) there is a so-called triple junction, where the Central Indian and West Indian ridges, as well as the Australian-Antarctic Rise, converge. The ridges consist of steep mountain ranges, cut by faults perpendicular or oblique to the axes of the chains and divide the basalt ocean floor into 3 segments, and their peaks are, as a rule, extinct volcanoes. The bottom of the Indian Ocean is covered with sediments of the Cretaceous and later periods, the thickness of which varies from several hundred meters to 2-3 km. The deepest of the ocean's many trenches is the Java Trench (4,500 km long and 29 km wide). Rivers flowing into the Indian Ocean carry with them huge quantities of sediment, especially from India, creating high sediment thresholds.

The Indian Ocean coast is replete with cliffs, deltas, atolls, coastal coral reefs and salt marshes covered with mangroves. Some islands - for example, Madagascar, Socotra, the Maldives - are fragments of ancient continents. Numerous islands and archipelagos of volcanic origin are scattered in the open part of the Indian Ocean. In the northern part of the ocean, many of them are topped with coral structures. Andaman, Nicobar or Christmas Island - are of volcanic origin. The Kerguelen Plateau, located in the southern part of the ocean, is also of volcanic origin.

An undersea earthquake in the Indian Ocean on December 26, 2004 caused a tsunami that was considered the deadliest natural disaster in modern history. The magnitude of the earthquake was, according to various estimates, from 9.1 to 9.3. This is the second or third strongest earthquake on record.

The epicenter of the earthquake was in the Indian Ocean, north of the island of Simeulue, located off the northwestern coast of the island of Sumatra (Indonesia). The tsunami reached the shores of Indonesia, Sri Lanka, southern India, Thailand and other countries. The height of the waves exceeded 15 meters. The tsunami caused enormous destruction and a huge number of deaths, even in Port Elizabeth, South Africa, 6900 km from the epicenter. According to various estimates, from 225 thousand to 300 thousand people died. The true death toll is unlikely to ever be known, as many people were swept out to sea.

As for the properties of the bottom soil, then, like in other oceans, sediments on the bottom of the Indian Ocean can be divided into three classes: coastal sediments, organic silt (globigerine, radiolar or diatom) and special clay of great depths, the so-called red clay. Coastal sediments are sand, located mostly on coastal shallows to a depth of 200 meters, green or blue silt near rocky shores, with a brown color in volcanic areas, but lighter and sometimes pinkish or yellowish near coral coasts due to the predominant lime. Globigerine mud, composed of microscopic foraminifera, covers the deeper parts of the ocean floor to a depth of almost 4500 m; south of the parallel 50° S. w. calcareous foraminiferal deposits disappear and are replaced by microscopic siliceous, from the group of algae, diatoms. In terms of the accumulation of diatom remains on the bottom, the southern Indian Ocean is particularly different from other oceans, where diatoms are found only locally. Red clay occurs at depths greater than 4500 m; it is red, or brown, or chocolate in color.

Indian Ocean climate fossil fishery

4. Water characteristics

Surface water circulationin the northern part of the Indian Ocean it has a monsoon character: in summer - northeastern and eastern currents, in winter - southwestern and western currents. In the winter months between 3° and 8° S. w. The inter-trade wind (equatorial) countercurrent develops. In the southern part of the Indian Ocean, water circulation forms an anticyclonic circulation, which is formed from warm currents - the Southern Trade Wind in the North, Madagascar and Agulhas in the West and cold currents - the Western Winds in the South and Western Australian in the East South of 55° S. w. Several weak cyclonic water circulations develop, closing off the coast of Antarctica with an eastern current.

Indian Ocean water beltbetween 10 ° With. w. and 10 ° Yu. w. called the thermal equator, where the surface water temperature is 28-29°C. To the south of this zone the temperature drops, reaching about 1°C off the coast of Antarctica. In January and February, the ice along the coast of this continent melts, huge blocks of ice break off from the Antarctic ice sheet and drift towards the open ocean. To the north, the temperature characteristics of the waters are determined by the monsoon air circulation. In summer, temperature anomalies are observed here, when the Somali Current cools the surface waters to a temperature of 21-23°C. In the eastern part of the ocean at the same latitude, the water temperature is 28°C, and the highest temperature mark - about 30°C - was recorded in the Persian Gulf and the Red Sea. The average salinity of ocean waters is 34.8‰ The waters of the Persian Gulf, Red and Arabian Seas are the most saline: this is explained by intense evaporation with a small amount of fresh water brought into the seas by rivers.

Tides in the Indian Ocean, as a rule, are small (off the coast of the open ocean and on the islands from 0.5 to 1.6 m), only at the tops of some bays they reach 5-7 m; in the Gulf of Cambay 11.9 m. The tides are predominantly semidiurnal.

Ice forms in high latitudes and is carried by winds and currents along with icebergs in a northerly direction (up to 55° S in August and up to 65-68 S in February).

. Bottom sediments of the Indian Ocean and its structure

Bottom sedimentsIndian Ocean have the greatest thickness (up to 3-4 km) at the foot of the continental slopes; in the middle of the ocean - small (about 100 m) thickness and in places where dissected relief is distributed - intermittent distribution. The most widely represented are foraminifera (on continental slopes, ridges and on the bottom of most basins at depths of up to 4700 m), diatoms (south of 50° S), radiolarians (near the equator) and coral sediments. Polygenic sediments - red deep-sea clays - are common south of the equator at a depth of 4.5-6 km or more. Terrigenous sediments - off the coast of continents. Chemogenic sediments are represented mainly by ferromanganese nodules, and riftogenic sediments are represented by products of destruction of deep rocks. Outcrops of bedrock are most often found on continental slopes (sedimentary and metamorphic rocks), mountains (basalts) and mid-ocean ridges, where, in addition to basalts, serpentinites and peridotites, representing the slightly altered material of the Earth's upper mantle, were found.

The Indian Ocean is characterized by the predominance of stable tectonic structures both on the bed (thalassocratons) and along the periphery (continental platforms); active developing structures - modern geosynclines (Sunda arc) and georiftogenals (mid-ocean ridge) - occupy smaller areas and are continued in the corresponding structures of Indochina and the rifts of East Africa. These main macrostructures, which differ sharply in morphology, structure of the earth's crust, seismic activity, volcanism, are divided into smaller structures: plates, usually corresponding to the bottom of oceanic basins, block ridges, volcanic ridges, in places topped with coral islands and banks (Chagos, Maldives, etc. .), fault trenches (Chagos, Obi, etc.), often confined to the foot of blocky ridges (East Indian, Western Australian, Maldives, etc.), fault zones, tectonic ledges. Among the structures of the Indian Ocean bed, a special place (in terms of the presence of continental rocks - granites of the Seychelles Islands and the continental type of the earth's crust) is occupied by the northern part of the Mascarene Ridge - a structure that is, apparently, part of the ancient continent of Gondwana.

. Minerals

The most important mineral resources of the Indian Ocean are oil and natural gas. Their deposits are located on the shelves of the Persian and Suez Gulfs, in the Bass Strait, and on the shelf of the Hindustan Peninsula. The Indian Ocean ranks first in the world in terms of reserves and production of these minerals. Ilmenite, monazite, rutile, titanite and zirconium are exploited on the coasts of Mozambique, Madagascar and Ceylon. There are deposits of barite and phosphorite off the coast of India and Australia, and deposits of cassiterite and ilmenite are exploited on an industrial scale in the offshore zones of Indonesia, Thailand and Malaysia. On the shelves - oil and gas (especially the Persian Gulf), monazite sands (coastal region of South-West India), etc.; in reef zones - ores of chromium, iron, manganese, copper, etc.; on the bed there are huge accumulations of ferromanganese nodules.

. ClimateIndian Ocean

Most of the Indian Ocean is located in warm climate zones - equatorial, subequatorial and tropical. Only its southern regions, located at high latitudes, are strongly influenced by Antarctica. The equatorial climate zone of the Indian Ocean is characterized by the constant predominance of moist, warm equatorial air. Average monthly temperatures here range from 27° to 29°. The water temperature is slightly higher than the air temperature, which creates favorable conditions for convection and precipitation. Their annual amount is large - up to 3000 mm or more.

. Flora and fauna

The Indian Ocean is home to the most dangerous mollusks in the world - cone snails. Inside the snail there is a rod-like container with poison, which it injects into its prey (fish, worms); its poison is also dangerous for humans.

The entire Indian Ocean lies within the tropical and southern temperate zones. The shallow waters of the tropical zone are characterized by numerous 6- and 8-rayed corals and hydrocorals, which, together with calcareous red algae, can create islands and atolls. Among the powerful coral structures lives a rich fauna of various invertebrates (sponges, worms, crabs, mollusks, sea urchins, brittle stars and starfish), small but brightly colored coral fish. Most of the coasts are occupied by mangroves, in which the mudskipper stands out - a fish that can exist in the air for a long time. The fauna and flora of beaches and cliffs that dry out at low tide are quantitatively depleted as a result of the depressing effect of sunlight. In the temperate zone, life on such sections of the coast is much richer; Dense thickets of red and brown algae (kelp, fucus, reaching enormous sizes of microcystis) develop here, and a variety of invertebrates are abundant. The open spaces of the Indian Ocean, especially the surface layer of the water column (up to 100 m), are also characterized by a rich flora. Among unicellular planktonic algae, several species of peredinium and diatom algae predominate, and in the Arabian Sea - blue-green algae, which often cause so-called water blooms when they develop en masse.

The bulk of ocean animals are crustaceans - copepods (more than 100 species), followed by pteropods, jellyfish, siphonophores and other invertebrate animals. The most common unicellular organisms are radiolarians; Squids are numerous. Of the fish, the most abundant are several species of flying fish, luminous anchovies - myctophids, coryphaenas, large and small tuna, sailfish and various sharks, poisonous sea snakes. Sea turtles and large marine mammals (dugongs, toothed and toothless whales, pinnipeds) are common. Among the birds, the most typical are albatrosses and frigatebirds, as well as several species of penguins that inhabit the coasts of South Africa, Antarctica and islands lying in the temperate zone of the ocean.

At night, the surface of the Indian Ocean shimmers with lights. Light is produced by small marine plants called dinoflagellates. The glowing areas sometimes have the shape of a wheel with a diameter of 1.5 m.

. Fisheries and marine activities

Fishing is poorly developed (the catch does not exceed 5% of the world catch) and is limited to the local coastal zone. There is tuna fishing near the equator (Japan), and whale fishing in Antarctic waters. Pearls and mother-of-pearl are mined in Sri Lanka, the Bahrain Islands and the northwestern coast of Australia.

The countries of the Indian Ocean also have significant resources of other valuable types of mineral raw materials (tin, iron and manganese ores, natural gas, diamonds, phosphorites, etc.).

Bibliography:

1.Encyclopedia "Science" Dorling Kindersley.

.“I'm exploring the world. Geography" V.A. Markin

3.slovari.yandex.ru ~ TSB books / Indian Ocean /

4.Large encyclopedic dictionary of Brockhaus F.A., Efron I.A.

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