Origin of Lake Baikal. Age of the Baikal basin. Geography of Lake Baikal

Baikal - freshwater lake on South Eastern Siberia, it stretched from 53 to 56°N. and from 104 to 109°30’ E Its length is 636 km, and the coastline is 2100 km. The width of the lake varies from 25 to 79 km. The total area of ​​the lake (mirror area) is 31,500 sq. km.

Baikal is the most deep lake in the world (1620 m). It contains the largest reserves on earth fresh water- 23 thousand cubic km, which is 1/10 of the world's fresh water supply. A complete change of such a huge amount of water in Baikal takes 332 years.

This is one of the oldest lakes, its age is 15-20 million years.

336 rivers flow into the lake, including the Selenga, Barguzin, Upper Angara, and only one Angara flows out. Baikal has 27 islands, the largest of which is Olkhon. The lake freezes in January, opens in May.

Baikal lies in a deep tectonic depression and is surrounded by taiga-covered mountain ranges; the area around the lake has a complex, deeply dissected relief. Near Baikal, the band of mountains expands noticeably. The mountain ranges here stretch parallel to one another in the direction from the northwest to the southeast and are separated by hollow-shaped depressions, along the bottom of which rivers flow and in some places there are lakes. The height of most of the ridges of Transbaikalia rarely exceeds 1300 - 1800, but most high ridges reach high values. For example, xr. Khamar-Daban (Sokhor peak) - 2304 m, and the Barguzinsky ridge. about 3000 m.

Tectonic movements continue here even now. This is evidenced by frequent earthquakes in the region of the basin, outcrops of hot springs, and, finally, subsidence of significant sections of the coast.

The waters of Baikal have a blue-green color, are distinguished by exceptional purity and transparency, often even greater than in the ocean: you can clearly see stones lying at a depth of 10-15 m and thickets of greenish algae, and a white disk lowered into the water is visible at a depth of 40 m.
Baikal lies in the temperate zone.

Geography of Lake Baikal.

Lake Baikal is located in the south of Eastern Siberia. In the form of a crescent being born, Baikal stretched from southwest to northeast between 55°47′ and 51°28′ north latitude and 103°43′ and 109°58′ east longitude. The length of the lake is 636 km, the maximum width in the central part is 81 km, the minimum width opposite the Selenga delta is 27 km. Baikal is located at an altitude of 455 m above sea level. Length coastline about 2000 km. The area of ​​the water mirror, determined at the water's edge of 454 m above sea level, is 31,470 square kilometers. The maximum depth of the lake is 1637 m, average depth- 730 m. 336 permanent rivers and streams flow into Baikal, while half of the volume of water entering the lake comes from the Selenga. flows out of Baikal the only river— Angara. However, the question of the number of rivers flowing into Baikal is rather controversial, most likely there are fewer than 336. There is no doubt that Baikal is the deepest lake in the world, the closest contender for this title, African lake Tanganyika, lags behind by as much as 200 meters. There are 22 islands on Baikal, although, as mentioned above, there is no unanimity on this issue. Most large island— Olkhon.

Age of Lake Baikal.

The age of the lake is usually given in the literature as 20-25 million years. In fact, the question of the age of Baikal should be considered open, since the use of various methods for determining the age gives values ​​from 20-30 million to several tens of thousands of years. Apparently, the first estimate is closer to the truth - Baikal is really very ancient lake.
It is believed that Baikal arose as a result of the action of tectonic forces. Tectonic processes are still going on, which is manifested in the increased seismicity of the Baikal region. If we assume that the age of Baikal is indeed several tens of millions of years, then this is the oldest lake on Earth.

Origin of name.

Numerous scientific studies have been devoted to the problem of the origin of the word "Baikal", which indicates a lack of clarity in this matter. There are about a dozen possible explanations for the origin of the name. Among them, the most probable is the version of the origin of the name of the lake from the Turkic-speaking Bai-Kul - a rich lake. Of the other versions, two more can be noted: from the Mongolian Baigal - a rich fire and Baigal Dalai - big lake. The peoples who lived on the shores of the lake called Baikal in their own way. Evenks, for example, - Lamu, Buryats - Baigal-Nuur, even the Chinese had a name for Baikal - Beihai - the North Sea.

The Evenki name Lamu - the Sea was used for several years by the first Russian explorers in the 17th century, then they switched to the Buryat Baigal, slightly softening the letter "g" by phonetic replacement. Quite often, Baikal is called the sea, simply out of respect, for its violent temper, for the fact that the far opposite shore is often hidden somewhere in the haze ... At the same time, the Small Sea and the Big Sea are distinguished. Small Sea - what is located between north coast Olkhon and the mainland, everything else is the Big Sea.

Baikal water.

Baikal water is unique and amazing, like Baikal itself. It is unusually transparent, pure and saturated with oxygen. In not so ancient times, it was considered healing, with its help, diseases were treated. In spring, the transparency of Baikal water, measured using the Secchi disk (a white disk with a diameter of 30 cm), is 40 m (for comparison, in the Sargasso Sea, which is considered the standard of transparency, this value is 65 m). Later, when a massive algae bloom begins, the transparency of the water decreases, but in calm weather, the bottom can be seen from a boat at a fairly decent depth. This high transparency is due to the fact that Baikal water, due to the activity of living organisms living in it, is very weakly mineralized and close to distilled. The volume of water in Baikal is about 23 thousand cubic kilometers, which is 20% of the world's fresh water reserves.

Climate.

The climate in Eastern Siberia is sharply continental, but the huge mass of water contained in Baikal and its mountainous surroundings create an unusual microclimate. Baikal works like a big thermal stabilizer - in winter it is warmer in Baikal, and in summer a little cooler than, for example, in Irkutsk, located at a distance of 60 km from the lake. The temperature difference is usually around 10 degrees. A significant contribution to this effect is made by forests growing on almost the entire coast of Lake Baikal.

Baikal's influence is not limited to regulation temperature regime. Due to the fact that evaporation cold water from the surface of the lake is very insignificant, clouds cannot form over Baikal. In addition, the air masses that bring clouds from the land heat up when passing the coastal mountains, and the clouds dissipate. As a result most time over Baikal the sky is clear. This is also evidenced by the numbers: the number of hours of sunshine in the area of ​​Olkhon Island is 2277 hours (for comparison, on the Riga seashore in 1839, in Abastumani (Caucasus) - 1994). You should not think that the sun always shines over the lake - if you are not lucky, then you can run into one or even two weeks of disgusting rainy weather even in the sunny place Baikal - on Olkhon, but this is extremely rare.

The average annual water temperature on the surface of the lake is +4°C. Near the coast in summer the temperature reaches +16-17°C, in shallow bays up to +22-23°C.

Wind and waves.

The wind on Baikal blows almost always. More than thirty local names of winds are known. This does not mean at all that there are so many different winds on Baikal, just that many of them have several names. The peculiarity of the Baikal winds is that almost all of them almost always blow along the coast and there are not as many shelters from them as we would like.

Prevailing winds: northwest, often called mountain winds, northeast (barguzin and verkhovik, also known as angara), southwest (kultuk), southeast (shelonnik). The maximum wind speed recorded on Lake Baikal is 40 m/s. In the literature, there are also large values ​​- up to 60 m / s, but there is no reliable evidence for this.

Where there is wind, there, as you know, there are waves. I note right away that the opposite is not true - the wave can be even with complete calm. Waves on Lake Baikal can reach a height of 4 meters. Sometimes values ​​​​of 5 and even 6 meters are given, but this is most likely an estimate “by eye”, which has a very large error, as a rule, towards overestimation. The height of 4 meters was obtained using instrumental measurements in the open sea. The excitement is strongest in autumn and spring. In the summer on Lake Baikal, strong excitement is rare, and calm often occurs.

A lake is a closed land depression that collects and accumulates surface and The groundwater. Unlike rivers, these are reservoirs of slow water exchange. total area of all lakes on Earth is 2.7 million square kilometers. They occupy about 1.8% of the land surface.

Lakes are always and everywhere formed according to one scenario - for various reasons, a depression, a low or a fault is formed on the ground - a hollow. If in the future it will be filled with water, a lake will turn out. Everything else is not significant. The location and origin of the lakes is associated with the climate of the area, which determines their nutrition and evaporation, as well as with factors that contribute to the formation of lake depressions. Where the climate is humid, the lakes are full-flowing, fresh and numerous. For the most part, they are flowing here. In arid areas, the lakes are shallow, often salty and endorheic. Thus, the hydrochemical features of lakes are determined by their geographical location.

Lakes are usually classified according to four criteria: the origin of lake basins; the origin of the water mass; water regime and mineral composition(salinity).

Origin of lake basins

By origin, 5 groups of lake basins are distinguished. Tectonic lake basins - are formed as a result of cracks, faults and lowering of the earth's crust. Such lakes are distinguished by their steep slopes and depth. As an example - Lake Baikal, the Dead Sea, Chad, Titicaca.

Volcanic lake basins - are formed in the craters of volcanoes or in the lowlands of lava fields. As an example, we can mention the Kuril Lake in Kamchatka, the lakes of Java and New Zealand. In the photo - lakes in the craters of the Kelimutu volcano.

Glacial (moraine) lake basins - dug by moving glaciers with subsequent erosion and accumulation of water in front of glacial landforms. When a glacier melts, the material brought by it is deposited in the form of hills, ridges, hills and depressions. Such lakes are usually narrow and long, elongated along the melting line of the glacier - the lakes of Finland, Karelia, the Alps, the Urals, and the Caucasus.

Karst lake basins - they arose as a result of failures, sedimentation of soil and erosion of soft rocks - limestone, gypsum, dolomite. As a result, small but deep lake basins are formed.

Damped (dammed or dammed) lake basins - arise as a result of blocking the riverbed by rockfalls. This is how Lake Sevan, a number of lakes in the Alps, the Himalayas and the Caucasus were formed.

But depressions suitable for filling with water can appear in other ways. It all depends on the location and climate - the proximity of the sea, rivers, strong winds, groundwater, permafrost layers in the soil. The result is the same - the formation of a hollow and filling it with water.

Other types of lakes

Limannye lakes are located along the shores of the seas. They represent coastal areas of the sea, separated from it by coastal spits.

Organogenic lakes eventually appear among swamps and coral reefs. Floodplain lakes are associated with changes in the river channel - lakes of the Kuban floodplains, ilmens of the Volga delta. Such lakes have a characteristic horseshoe shape.

The wind creates eolian lakes, which are formed in the hollows of blowing - Lake Teke, Lake Selecty in Kazakhstan and a number of others arose in this way.

Suffosion lakes appear where groundwater is actively washing away small pieces of rock, causing soil to settle. Such lakes are typical for the south of Western Siberia.

Thermokarst sinkhole lakes (pictured) appear when permafrost areas melt. Dips in the ground are formed, filled with melt water. There are many such lakes in the Kolyma Lowland - the very lake region of Russia.

According to the origin of water masses, lakes are divided into two types - atmospheric and relict. atmospheric lakes have never been part of the oceans. There are many such lakes on Earth. Relic (or residual) lakes appeared on the site of the retreating seas - the Caspian, Aral, Ladoga, Onega, Ilmen and others.

According to the water regime, two types of lakes are distinguished - waste and non-drainage. Waste lakes are lakes in which water is exchanged, rivers flow into them and flow out of them. They are usually fresh. Such lakes are often located in areas of excessive moisture.

mineral lakes

endorheic lakes have inflowing rivers, but no outflowing ones. Evaporation predominates in the water flow of such lakes, and all mineral substances remain in the reservoir. Most of them are salty. Such lakes are located in areas of insufficient moisture.

According to salinity, four types of lakes are distinguished - fresh, salty, brackish and mineral. Fresh lakes- if the salinity does not exceed 1 ppm. Salt lakes - if the content of soluble substances in them is in the range of 24.7 - 47 ppm. Brackish - salinity up to 24 ppm. Mineral - 47 ppm. It can be soda, sulfate, chloride lakes. In mineral lakes, salts can precipitate, for example, lakes Elton and Baskunchak, which are a source of salt production. On the picture - salt Lake in Kenya.

Lakes play an important role in the planet's ecosystem. They create a special microclimate favorable for different forms of life. Even when salty, they attract many different organisms. And freshwaters form their own balanced and surprisingly rich ecosystems. Geological forces tend to level the surface of the continent through erosion, the accumulation of sediment leads to a decrease in the depth of the lake and its gradual disappearance. In the waters of lakes, biological and chemical reactions occur, as a result of which some elements pass into bottom sediments or, conversely, dissolve in water. Bottom sediments change the topography of the lake bottom and, under certain conditions, can be transformed into rocks organic origin. Overgrowth of lakes creates new landforms.

Most of the lakes are relatively young formations. One of the most ancient is Baikal. Its age is 25 - 30 million years. The largest of the lakes is the Caspian. Its area is about 368 thousand square kilometers. The deepest - Baikal - 1620 meters. I would like to hope that these amazing natural formations will remain in their original state for a long time to come.

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Baikal is a landmark not only of Russia, but of the whole world. This lake attracts many people of the planet not only for its unique beauty but, above all, the unique purity of its waters. Baikal has unique features. It has no equal in the world in terms of age, depth, reserves and properties of fresh water, diversity and endemism of organic life.

origin of name

In the distant past, the peoples inhabiting the shores of Lake Baikal each called the lake in their own way. The Chinese in ancient chronicles called it "Beihai" - "northern sea", the Evenks called it Lamu - "sea", the Buryat-Mongols - "Baigaal-dalai" - "big reservoir". The origin of the name "Baikal" is not precisely established. The most common version is that "Baikal" is a Turkic-speaking word, comes from "bay" - rich, "kul" - lake, which means "rich lake". The first Russian explorers of Siberia used the Evenki name "Lamu". After Kurbat Ivanov's detachment came to the shore of the lake, the Russians switched to the Buryat name "Baigaal". At the same time, they linguistically adapted it to their language - Baikal, replacing the "g" characteristic of the Buryats with the more familiar "k" for the Russian language.

Age

Baikal is one of the oldest lakes on the planet; scientists determine its age at 25 million years. Most lakes, especially those of glacial and oxbow origin, live for 10-15 thousand years, and then they are filled with sediments and disappear from the face of the Earth. There are no signs of aging on Baikal, like many lakes in the world. On the contrary, research recent years allowed geophysicists to hypothesize that Baikal is a nascent ocean. This is confirmed by the fact that its shores diverge at a speed of up to 2 cm per year, just as the continents of Africa and South America diverge.

Depth

Among the lakes the globe Lake Baikal ranks 1st in depth. On Earth, only 6 lakes have a depth of more than 500 meters. The greatest depth mark in the southern basin of Lake Baikal is 1423 m, in the middle one - 1637 m, in the northern one - 890 m. For comparison, I will give a table:

Baikal depression

The Baikal depression is slightly wider modern lake but much deeper than that. The depth of the depression is determined by the height of the mountains above it, the depth of the lake and the thickness of the bottom lining it. bottom sediments. The most deep point Baikal's root basin lies about 5-6 thousand meters below the level of the world's oceans. The "roots" of the basin cut through the entire earth's crust and go into the upper mantle to a depth of 50-60 km. This is the deepest basin of the earth's land.

The mystery of the origin of Baikal has long haunted people. Where did this sea come from the purest water, surrounded by picturesque mountains and pristine nature? The first explanation can be found in the Buryat legend, the essence of which was that at first there was a continuous fire, then the earth collapsed and became the sea. The well-known hypothesis of the creation of all these miracles in seven days, which easily explains everything and even more, however, has significant chronological difficulties and does not correspond well to archaeological data.

And so there were people to whom both theories seemed insufficiently convincing, and they began to invent their own. Back in the 18th century, German scientists Peter Simon Pallas and Johann Gottlieb Georgi, members of the Siberian expedition of the St.

Yes, yes, there were times when "brains" "flowed" here, to us, and not to reverse direction, and foreign scientists considered it an honor to work at the St. Petersburg Academy of Sciences. A serious study of Baikal began with the studies of German scientists invited by Catherine II.

Pallas believed that the Baikal basin arose as a result of a land failure caused by a natural disaster. A similar point of view was shared by another member of the Siberian expedition - Georgi, but he detailed the picture. According to Georgi, the reason for the failure of the land was an earthquake, and before it, on the site of present-day Baikal, the Upper Angara flowed, which flowed into the Yenisei, taking in all the tributaries of the still unborn Baikal.

A century later, a former soldier of a fortress battalion, a political exile, a Pole Jan Chersky, a man whose determination could only compete with his iron will, on his own, in the barracks, having mastered the wisdom of science, put forward new theory formations of Baikal. Based on his own observations during travels, or, as he called them, excursions around the Baikal region, Chersky suggested that Baikal and its mountainous surroundings were formed as a result of very slow horizontal compression of the earth's crust.

Many scientists had their own opinion about how Baikal arose. It makes no sense to list all the numerous, often differing only in details, views. Close to the modern understanding of the way of education Baikal basin approached Vladimir Afanasyevich Obruchev (1863-1956), who suggested that the emergence of Baikal is closely related to the formation mountain system Siberia as a whole. Baikal, according to Obruchev, arose as a result of subsidence of a part of the land along two vertical fracture surfaces. “The Baikal depression was created by the same young movements, the evidence of which is distributed over a large stretch from the middle of the Khangai upland in the Mongolian People's Republic to the river Uchura on the Aldan plateau, i.e. over 2400 versts. During this period, the earth's crust began to swell during the Tertiary period, of course, very slowly and gradually in the form of a long and wide swell, called the Baikal domed uplift. This uplift, which engulfed the foundation, consisting of the most ancient Precambrian rocks, was broken by longitudinal and transverse cracks into separate wedges, which, in their upward movement, lagged behind one another, and some even sank down. Raised wedges formed mountain ranges- Khamar-daban, Tunkinsky and Kitoi Alps, Onotsky and Primorsky ridges, Olkhon Island, Chivyrkuysky, South and North Muysky ridges, Delyun-Uran, Kodar and Udokan, and the descending ones formed deep valleys, the deepest of which filled with water and formed lakes - Kosogol, the Small Sea and Baikal”, - this is how V.A. Obruchev. The system of faults along which the blocks of the earth's crust settled, forming the Baikal basin, is now called the Obruchev fault.

Scientific achievements of the second half of the 20th century made it possible to make significant progress in studying the problem of Baikal formation. Importance had the discovery of a global fault system - the world rift system. It turned out that the emergence of Baikal is a consequence of a process on a planetary scale; there were many depressions in the earth's crust that have a similar origin. For example, lakes Khubsugul, Tanganyika, Nyasa, Red Sea. At the end of the last century, geologists and geophysicists from the USSR, the USA, Belgium, France, Germany, Japan, Mongolia, and China were engaged in studying the Baikal basin and its surroundings.

The Baikal basin is the central link of the so-called Baikal rift, which stretches for 2.5 thousand kilometers and is located on the border of two continental lithospheric plates - the Eurasian and Indo-Australian. At first, it was believed that the Baikal rift owes its existence to the collision of these plates, but after receiving a number of new scientific data, a point of view appeared that the emergence and development of the Baikal rift cannot be explained only by the interaction of lithospheric plates. In particular, some researchers believe that the Baikal rift arose much earlier than the beginning of the interaction of the mentioned lithospheric plates. To explain the observed picture, these scientists assign an important role to the anomalous heating of the mantle under the Baikal Rift.

Paleogeographic reconstruction of the evolution of the Baikal basin (based on the work of V.D. Mats and I.M. Efimova “Paleogeographic scenario of the Late Cretaceous-Cenozoic of the central part of the Baikal region”, 2011)

The Baikal basin consists of three independent depressions - the South Baikal, the Middle Baikal, separated by an uplift in the area of ​​the Posolskaya Bank, and the North Baikal, separated from the Middle Baikal by the underwater Academic Ridge, crossing Baikal along the line Olkhon Island - the Ushkany Islands archipelago.

Without going into details about which scientific environment there is still no consensus, a very simplified process of the formation of the Baikal basin can be represented as follows. The earth's crust, lifted by the heated mantle matter floating up and spreading to the sides, formed the surrounding lake. mountain ranges. At the same time, the horizontal spreading of the mantle substance caused the formation of faults and the subsidence of blocks of the earth's crust, which ultimately led to the formation of the Baikal depression. It is hard to imagine molten granite or rock masses behaving like plasticine, but science assures us that this is not only possible, but actually occurs. This process has been going on for tens of millions of years, and continues to this day.

With the development of geophysical methods and the accumulation of knowledge, certain details of the chronological sequence of the formation of Lake Baikal began to appear. Three stages can be distinguished in the geological history of the Baikal Rift: Archaeo-Baikal, Proto-Baikal, and Paleo-Baikal.

Archeobaikalian stage covers the time interval 70-30 million years ago. Initially, large mountain ranges are absent. The climate is tropical mean annual temperature+ 20 ° -23 °, while the temperature in winter is not lower than + 15 ° - + 20 ° (this is in Siberia!) Several large lakes are already located on the site of the South Baikal and Middle Baikal depressions. It was at this time that the formation of the Baikal rift began. Rifting is associated with stretching of the lithosphere, the probable cause of which is the heating of the upper mantle.

Proto-Baikal stage, 30.0-3.5 million years ago. It got colder to a subtropical climate with an average annual temperature of +15° - +20°. At this time, vertical movements and the formation of the rift as a whole, provoked by the collision of the Eurasian and Indo-Australian lithospheric plates, intensified. Education has begun mountain ranges and deepening of lake basins. In the South and Middle Baikal depressions, a single lake was formed, the depth of which could reach 500 m. Into this lake, in the area of ​​the modern Upper Head of the Holy Nose, forming a giant delta, the Upper Praangara flowed along the eastern border of the North Baikal depression he almost guessed it!). In the second half of the Proto-Baikal stage, about 10 million years ago, water from the lake that occupied the South and Middle Baikal depressions began to flow through the formed passage in the Akademichesky ridge into the North Baikal depression. By the end of the proto-Baikal stage, the lake reached a depth of 1000 meters.

Paleobaikalian stage, from 3.5 million years ago to the present. With the beginning of the stage, large vertical movements became more active - the mountains became higher, the depressions deeper, the river network began to be rebuilt. In the first half of the stage, the depth of Paleobaikal was about 1000 meters. Modern deep-water zones were formed at the end of the Paleo-Baikal stage - 150-120 thousand years ago. 2.82-2.48 million years ago the climate became noticeably cooler, the average annual temperature dropped to +5°. After another million years, it got colder again, this time it came to glaciation in the Baikal mountains. Glaciers have had a significant impact on the mountain landscape. As time went on, glaciations were replaced by interglacials. During glaciations, the level of the lake decreased, sometimes to such an extent that Paleobaikal became drainless for some time. The flow stopped for no more than 10 thousand years. The runoff from Paleobaikal occurred along the Pramanzurka River, which flows into the Lena. The source of Pramanzurka was located slightly north of the modern delta of the Goloustnaya River. Approximately 1 million years ago, due to the rise of the Primorsky Range, the runoff channel along the Pramanzurka River was broken. As a result of this event, the waters of the lake rose to the level of a new runoff along the Paleoirkut, which flowed from Baikal in the area of ​​the Kultuk Bay and carried its waters to the Yenisei River basin. Finally, about 60 thousand years ago, due to the lowering of the Larch block, the source of Baikal formed through the Angara. By this time, Baikal acquired its modern shape.

The described picture of the emergence of the basin and the mountainous environment of Baikal is based on the paleogeographic reconstruction carried out in the study by V.D. Mats and I.M. Efimova in 2011. This is just one look at the problem of the formation of Baikal. Other researchers are ready to dispute almost everything, from the age of the Baikal Rift to the existence of a runoff in the Irkut in the past. One thing is certain: Baikal is an incredibly generous gift of Nature, and we need to work hard to prove that we are worthy of such a gift.

Baikal(bur. Baigal dalai, Baigal nuur) is a lake of tectonic origin in the southern part of Eastern Siberia, the deepest lake in the world and the largest (by volume) reservoir of liquid fresh water. It contains about 19% of the world's fresh water. The lake is located in rift valley in Eastern Siberia on the border Irkutsk region and the Republic of Buryatia. 336 rivers flow into it, including the Selenga, Upper Angara, Barguzin, and others, and one river, the Angara, flows out.

Information about Baikal:

• Area - 31,722 km 2
• Volume - 23,615 km 3
• The length of the coastline is 2100 km
• The greatest depth is 1642 m
• Average depth - 744 m
• Height above sea level - 456 m
• Water transparency - 40 m (at a depth of up to 60 m)

Geographical location and dimensions of the basin

Baikal is located in the center of Asia, in Russia, on the border of the Irkutsk region and the Republic of Buryatia. The lake stretches from northeast to southwest for 620 km in the form of a giant crescent. The width of Lake Baikal ranges from 24 to 79 km. There is no other lake so deep on earth. The bottom of Lake Baikal is 1167 meters below the level of the World Ocean, and the mirror of its waters is 453 meters higher.

The water surface area is 31,722 km² (excluding islands), which is approximately equal to the area of ​​countries such as Belgium, the Netherlands or Denmark. In terms of the area of ​​the water surface, Baikal ranks sixth among the largest lakes in the world.

The lake is located in a kind of basin, surrounded on all sides by mountain ranges and hills. At the same time, the western coast is rocky and steep, the relief east coast- more gentle (in some places the mountains recede from the coast for tens of kilometers).

Depth

Baikal is the deepest lake on the planet Earth. Modern meaning the maximum depth of the lake - 1637 m - was established in 1983 by L.G. Kolotilo and A.I. Sulimov during the performance of hydrographic work by the expedition of the GUNiO of the USSR Ministry of Defense at the point with coordinates 53°14′59″ N. 108°05′11″ E

The maximum depth was mapped in 1992 and confirmed in 2002 as a result of a joint Belgian-Spanish-Russian project to create a new bathymetric map of Baikal, when the depths were digitized at 1,312,788 points of the lake water area (the depth values ​​were obtained as a result of recalculation acoustic sounding data combined with additional bathymetric information, including echolocation and seismic profiling; one of the authors of the maximum depth discovery, L.G. Kolotilo, was a participant in this project).

If we take into account that the water surface of the lake is located at an altitude of 453 m above sea level, then the lower point of the basin lies 1186.5 m below the level of the world ocean, which makes the Baikal bowl also one of the deepest continental depressions.

The average depth of the lake is also very large - 744.4 m. It exceeds maximum depths many very deep lakes.

In addition to Baikal, only two lakes on Earth have a depth of more than 1000 meters: Tanganyika (1470 m) and the Caspian Sea (1025 m). According to some reports, the subglacial Lake Vostok in Antarctica has a depth of more than 1200 m, but it must be borne in mind that this subglacial “lake” is not a lake in the sense that we are used to, since there are four kilometers of ice above the water and it is a kind of closed container, where the water is under enormous pressure, and the "surface" or "level" of water in different parts of this "lake" differs by more than 400 meters. Thus, the concept of "depth" for the subglacial Lake Vostok is fundamentally different from the depth of "ordinary" lakes.

Water volume

The water reserves in Baikal are gigantic - 23,615.39 km³ (about 19% of the world's fresh water reserves - in all fresh lakes the world contains 123 thousand km³ of water). In terms of water reserves, Baikal ranks second in the world among lakes, second only to the Caspian Sea, but the water in the Caspian Sea is salty. There is more water in Baikal than in all five Great Lakes taken together, and 25 times more than in Lake Ladoga.

Tributaries and runoff

336 rivers and streams flow into Baikal, but this number takes into account only permanent tributaries. The largest of them are Selenga, Upper Angara, Barguzin, Turka, Snezhnaya, Sarma. One river flows out of the lake - the Angara.

Water properties

Baikal water is extremely transparent. The main properties of Baikal water can be briefly described as follows: it contains very few dissolved and suspended mineral substances, negligibly few organic impurities, and a lot of oxygen.

The water in Baikal is cold. The temperature of the surface layers even in summer does not exceed +8…+9°C, in some bays - +15°C. The temperature of the deep layers is about +4°C. Only in the summer of 1986 the temperature surface water in the northern part of Baikal rose to a record 22-23°C.

The water in the lake is so transparent that individual stones and various objects can be seen at a depth of 40 m. At this time, the Baikal water is blue. In summer and autumn, when a lot of plant and animal organisms develop in the water warmed by the sun, its transparency decreases to 8-10 m, and the color becomes blue-green and green. Pure and clearest water Baikal contains so few mineral salts (96.7 mg/l) that it can be used instead of distilled water.

The freezing period is on average January 9 - May 4; Baikal freezes over entirely, except for a small area, 15-20 km long, located at the source of the Angara. The sailing period for passenger and cargo ships is usually from June to September; research vessels begin navigation after the ice breaks up the lake and complete it with the freezing of Lake Baikal, that is, from May to January.

By the end of winter, the ice thickness on Baikal reaches 1 m, and in the bays - 1.5-2 m. severe frost cracks, which are locally called "stave gaps", break the ice into separate fields. The length of such cracks is 10-30 km, and the width is 2-3 m. Breaks occur annually in approximately the same areas of the lake. They are accompanied by a loud crack, reminiscent of thunder or cannon shots. It seems to a person standing on the ice that the ice cover is bursting just under his feet and he will now fall into the abyss. Thanks to cracks in the ice, fish in the lake do not die from lack of oxygen. Baikal ice is also very transparent, and the sun's rays penetrate through it, so planktonic algae, which release oxygen, flourish in the water. On the shores of Lake Baikal can be observed in winter ice grottoes and splashes.

Baikal ice presents scientists with many mysteries. So, in the 1930s, specialists from the Baikal Limnological Station discovered unusual forms of ice cover, typical only for Lake Baikal. For example, “hills” are cone-shaped ice hills up to 6 m high, hollow inside. Appearance they resemble ice tents, "open" in the opposite direction from the coast. Hills can be located separately, and sometimes form miniature "mountain ranges". Also on Baikal there are several more types of ice: "sokuy", "kolobovnik", "autumn".

In addition, in the spring of 2009, Internet satellite imagery different parts of Baikal where dark rings were found. According to scientists, these rings arise due to the rise of deep waters and an increase in the temperature of the surface layer of water in the central part of the ring structure. As a result of this process, an anticyclonic (clockwise) current is formed. In the area where the current reaches maximum speeds, vertical water exchange increases, which leads to accelerated destruction of the ice cover.

Bottom relief

The bottom of Lake Baikal has a pronounced relief. Along the entire coast of Baikal, coastal shallow waters (shelves) and underwater slopes are more or less developed; the bed of the three main basins of the lake is expressed; there are underwater banks and even underwater ridges.

The Baikal basin is divided into three basins: Southern, Middle and Northern, separated from each other by two ridges - Akademichesky and Selenginsky.

The most expressive is the Academic Ridge, which stretches along the bottom of Lake Baikal from Olkhon Island to the Ushkany Islands (which are its most high part). Its length is about 100 km, maximum height above the bottom of Lake Baikal 1848 m. The thickness of bottom sediments in Baikal reaches about 6 thousand m, and as established by gravimetric survey, one of the highest mountains on Earth, more than 7000 m high, is flooded in Baikal.

Islands and peninsulas

There are 27 islands on Baikal (Ushkany Islands, Olkhon Island, Yarki Island and others), the largest of them is Olkhon Island (71 km long and 12 km wide, located almost in the center of the lake near its west coast, area - 729 km², according to other sources - 700 km²), largest peninsula- Holy Nose.

seismic activity

The Baikal region (the so-called Baikal rift zone) belongs to areas with high seismicity: earthquakes regularly occur here, the strength of most of which is one or two points on the MSK-64 intensity scale. However, there are also strong ones; So, in 1862, during the ten-point Kudarinsky earthquake in the northern part of the Selenga delta, a land area of ​​​​200 km² with 6 uluses, in which 1300 people lived, went under water, and Proval Bay was formed. Strong earthquakes were also recorded in 1903 (Baikal), 1950 (Mondinskoe), 1957 (Muiskoe), 1959 (Middle Baikal). The epicenter of the Middle Baikal earthquake was located at the bottom of Lake Baikal near the village of Sukhaya ( southeast coast). His strength reached 9 points. In Ulan-Ude and Irkutsk, the strength of the main shock reached 5-6 points, cracks and minor damage were observed in buildings and structures. The last strong earthquakes on Baikal occurred in August 2008 (9 points) and in February 2010 (6.1 points).

Climate

Baikal winds often raise a storm on the lake. The water mass of Lake Baikal influences the climate of the coastal area. Winters are milder here, and summers are cooler. The onset of spring on Baikal is delayed by 10-15 days compared to the surrounding areas, and autumn is often quite long.

The Baikal region is distinguished by a large total duration of sunshine. For example, in the village of Bolshoe Goloustnoye it reaches 2524 hours, which is more than in the Black Sea resorts, and is a record for Russia. Days without sun in the same year locality there are only 37, and on the island of Olkhon - 48.

The special features of the climate are due Baikal winds, which have their own names - barguzin, sarma, verkhovik, kultuk.

Origin of the lake

The origin of Baikal still causes scientific controversy. Scientists traditionally determine the age of the lake at 25-35 million years. This fact also makes Baikal unique. natural object, since most lakes, especially glacial origin, live an average of 10-15 thousand years, and then they are filled with silty sediments and become swampy.

However, there is also a version about the youth of Baikal, put forward by Doctor of Geological and Mineralogical Sciences A.V. Tatarinov in 2009, which received indirect confirmation during the second stage of the Mirs expedition to Baikal. In particular, the activity of mud volcanoes at the bottom of Lake Baikal allows scientists to assume that the modern coastline of the lake is only 8 thousand years old, and the deep-water part is 150 thousand years old.

What is certain is that the lake is located in a rift basin and is similar in structure, for example, to the Dead Sea basin. Some researchers explain the formation of Baikal by its location in the zone of a transform fault, others suggest the presence of a mantle plume under Baikal, and others explain the formation of the basin by passive rifting as a result of the collision of the Eurasian plate and Hindustan. Be that as it may, the transformation of Baikal continues to this day - earthquakes constantly occur in the vicinity of the lake. There are suggestions that the subsidence of the basin is associated with the formation of vacuum chambers due to the outpouring of basalts on the surface (Quaternary period).

Sources and additional information:

• ru.wikipedia.org - article about Baikal in Wikipedia;
• lake-baikal.narod.ru - Lake Baikal in questions and answers. Basic figures;
• magicbaikal.ru - site "Magic of Baikal";
• shareapic.net - map of Lake Baikal;
• chemezova.ru — helpful information about the rest of Baikal.