What is the origin of Lake Baikal. General information. Geography of Lake Baikal
One of the first explanations regarding the appearance of Lake Baikal was put forward by members of the expedition of the St. Petersburg Academy of Sciences at the end of the 18th century. German researchers Johann Georgi and Peter Pallas, who collaborated with the Academy at the invitation of Catherine II, believed that the lake basin was formed after a tectonic failure of part of the land, which was caused by a natural disaster.
The reason for the failure, Georgi believed, was a powerful earthquake, which could well even affect the course of the course of local rivers.
A century later, the political exile Jan Chersky, a Pole, put forward his own version of the origin of Baikal. He relied on his observations and research, which he made during his travels around the lake. The talented scientist suggested that the basin and the mountains around it arose after the slow earth's crust in a horizontal direction.
Since then, many scientists have put forward their own arguments in favor of one hypothesis or another, which often differed only in small details. V.A. came closest to the modern understanding of the problem of Baikal formation. Obruchev. In his opinion, Baikal was formed together with mountain system Siberia.
Obruchev believed that the depression, which later became a lake, arose after the subsidence of land along two fracture surfaces that followed in a vertical direction.
A modern view on the problem of the emergence of Baikal
Only scientific achievements last century. When geologists and geophysicists discovered the existence of a global system of faults in the earth's crust, it turned out that the appearance of Baikal became part of the processes that took place on a global scale. The researchers found that several depressions on Earth have a nature similar to Baikal. Examples are lakes Tanganyika and Nyasa, as well as the Red Sea.
According to scientists, the tectonic processes that led to the formation of the lake began more than 30 million years ago.
The Baikal basin is considered today central part rift of the same name, that is, a depression formed after the shift of the earth's crust. The length of the rift is more than two thousand kilometers. The depression is located between two powerful lithospheric plates. At first, geophysicists believed that the lake basin arose as a result of the collision of these plates, but then there was an assumption that an increase in the temperature of the mantle located under the Baikal depression was added to their interaction.
Height above sea level: 455.5 m
Length 636 km, Width 80 km, Square 31,722 km², Volume 23,615 km³
Coastline length: 2100 km
Maximum depth: 1637 m Average depth 744.4 m
Transparency: 40 m, at a depth of up to 60 m
Catchment area: 560 thousand km²
Baikal is located in the center of Asia, in Russia, on the border Irkutsk region and the Republic of Buryatia. The lake stretches from north to southwest for 636 km in the form of a giant crescent. The width of Baikal ranges from 25 to 80 km.
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 water surface area, 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).
Baikal is the deepest lake on Earth
The maximum depth of the lake - 1,637 meters was discovered in 1983 by L. G. Kolotilo and A. I. Sulimov during hydrographic work by the expedition of the GUNiO MO USSR at a point with coordinates 53 ° 14′59 ″ n. sh. 108°05′11″ E , which makes it the deepest lake on planet Earth.
If we take into account that the water surface of the lake is located at an altitude of 455.5 m above sea level, then the lower point of the basin lies 1,186.5 m below the level of the world ocean, which makes the Baikal bowl also the deepest continental depression.
The average depth of the lake is also very large - 744.4 meters. It exceeds the maximum depths of many very deep lakes.
Water reserves in Baikal are gigantic - 23615.390 km³ (about 19% of world reserves fresh water- 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.
Water properties
Baikal water is extremely transparent. The main properties of Baikal water can be briefly described as follows: there are very few dissolved and suspended mineral substances in it, negligible organic impurities, and a lot of oxygen.
Temperature surface layers water in Baikal in summer - +8 ... + 9 ° С. Water in some bays warms up to the highest mark of +23 °С in August. The most warm water in the bays: Mukhor (Small Sea), Chivyrkuisky Bay, Posolsky Sor. The temperature of the deep layers is about +4 °C. The water in the lake is so transparent that individual stones and various objects can be seen at a depth of 40 m.
Pure and clearest water Baikal contains so few mineral salts (100 mg/l) that it can be used instead of distilled water.
Islands and peninsulas
There are 27 islands on Baikal (Ushkany Islands, Yarki Island and others), the largest of them is Olkhon(730 km²); the largest peninsula is Svyatoy Nos.
A well-known scientist involved in the research of Lake Baikal, I. D. Chersky, noted 174 capes.
The largest bays are: Barguzinsky (725 sq. km), Chivyrkuisky (270 sq. km), Proval (197 sq. km).
Climate
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 2,524 hours and is a record for Russia. Days without sun in the same year locality there are only 37, and on Olkhon island — 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 Alexander Tatarinov, Doctor of Geological and Mineralogical Sciences in 2009, which received indirect confirmation during the second stage of the Worlds 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 Eurasia 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).
Origin of Lake Baikaldescribed in the legends of the Buryats - the indigenous inhabitants of the Baikal region. They gave the name to Lake Baigal. According to legend, the earth cracked, and fire broke out from there. In horror, people shouted: "Bye, gall!" (“fire, stop!”). The fire went out and the crack filled with water. So, according to legend, the lake and its name appeared. There are other beautiful legends about the origin of the lake. According to one of them, the old man Baikal mourned his runaway daughter Angara and cried out a whole lake. According to another legend, a golden chariot with a fiery dragon descended from the sky. From the blow of his tail, the earth shook, a crevice formed, ice melted on the tops of the mountains, and a lake formed. These are all beautiful myths, but what really happened?
Location and dimensions
Baikal is in the south Eastern Siberia. The lake has the shape of a crescent and is elongated in a direction approximately from north to south. The longitudinal dimension is about 640 km. The transverse size ranges from 25 km to 79 km. The contour of the coastline is 2 thousand km. This is one of largest lakes on the ground.
The basin of the lake is divided into three separate parts - Southern, Middle, Northern. They have different depths. The deepest of them is the Middle - 1642 m. The northern and middle basins are separated by the Akademichesky ridge. Only in some parts of the lake the peaks of the ridge protrude above the water and form islands. Between the Southern and Middle depressions is the Selenga bridge. This structure is hidden by the waters of Lake Baikal.
The sides of the basin are asymmetric. western slope goes sharply down, and the eastern one is more gentle. The relief of the slopes is also different. East coast with underwater valleys, canyons, and the western one is almost without dismemberment. The bottom of all depressions is leveled and has a slight slope towards the western coast. The bottom depth gradually decreases due to river sediments.
The lake is surrounded by mountains. They are made up of:
- Granite.
- Marble.
- Gneiss.
- Slate.
- Jade.
- Magnetite.
- Quartz.
- Lapis lazuli.
earthquakes
In the Baikal zone, the seismic background is high, and earthquakes are very frequent. Their strength is small - 1-2 points. But there are catastrophic aftershocks. So, as a result of an earthquake in the middle of the 19th century. with a force of 10 points, Proval Bay was formed. Its depth reaches 6 m, and the area is almost 200 km². Almost 100 years later, as a result of the same event, the bottom of the Middle Basin sank by 15-20 m.
Not now active volcanoes, but geologists are still studying their past activities. The origin of Lake Baikal and the current formation is associated with seismic activity in this zone. So, it is known that the shores of this lake diverge by 2 cm per year.
Glaciers
IN glacial period the relief of Lake Baikal has undergone changes. These traces are visible in the wreckage rocks under ice, sediment and bottom sediments. Geologists suggest that the thickness of the descending glaciers was 80-120 m. Perhaps there was no permanent ice cover. Otherwise life in the lake could not be. However, among the inhabitants now living in the lake there are golomyankas, sponges, amphipods, sculpins, flatworms. These organisms originated before this period.
Age
It is believed that Baikal is supposedly 25 million years old. However, this fact causes surprise and controversy about the age of the lake. The fact is that the lake usually does not live that long. This applies especially to those lakes that are of glacial origin. They exist for 10-15 thousand years, then they are filled with silt and disappear. There is speculation that it may be younger. At the same time, it is believed that the deep-sea part is 150 thousand years old, and the coastal part is only 8 thousand years old.
Versions
There is no consensus on the formation of Baikal. One thing is obvious, that it is located in the rift basin. Several versions of the formation of this lake were put forward:
- As a result of the failure of land during an earthquake (Pallas' hypothesis).
- As a result of compression of the earth's crust in a horizontal direction (Chersky's hypothesis).
- As a result of land subsidence along fault surfaces (Obruchev's hypothesis).
- As a result of processes in the world rift system, the Baikal rift (fault of the earth's crust).
And which version is closer to you?
Baikal(bur. Baigal dalai, Baigal nuur) - lake tectonic origin in the southern part of Eastern Siberia, the deepest lake in the world and the largest (by volume) reservoir of watery fresh water. It contains about 19% of the global supply of fresh water. The lake is located in the rift plain in Eastern Siberia on the border of the Irkutsk region and the Republic of Buryatia. 336 rivers flow into it, many of which are the Selenga, Upper Angara, Barguzin and others, and one river flows out - the Angara.
Information about Baikal:
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 huge crescent. The width of Lake Baikal ranges from 24 to 79 km. There is no other deepest lake on earth. The bottom of Baikal is 1167 meters below the level of the World Ocean, and the mirror of its waters is 453 meters higher.
The area of the aquatic surface is 31,722 km² (excluding islands), which is approximately equal to the area of \u200b\u200bsuch states as Belgium, the Netherlands or Denmark. Baikal ranks sixth among the largest lakes in the world in terms of the area of its water surface.
The lake is located in a specific basin, surrounded on all sides by mountain ranges and hills. With all this, the western coast is rocky and steep, the relief of the eastern coast is more gentle (in some places the mountains recede from the coast for 10 km).
Depth
Baikal is the most deepest lake planet Earth. Modern meaning the greatest 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. latitude. 108°05"11" E
The greatest depth was mapped in 1992 and proved in 2002 as a result of a joint Belgian-Spanish-Russian project to create the latest bathymetric map of Baikal, when the depths were digitized at 1,312,788 points of the lake’s 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 creators of the discovery of the greatest depth, 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 greatest depths many very deep lakes.
Apart from 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 data, the subglacial Lake Vostok in Antarctica has a depth of more than 1200 m, but it must be taken into account that this subglacial “lake” is not a lake in the sense that we are used to, because there are four kilometers of ice above the water and it is a kind of closed container, where the water is under tremendous pressure, and the "surface" or "level" of water in different parts of this "lake" differs by more than 400 meters. Consequently, 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 huge - 23,615.39 km³ (about 19% of the global fresh water reserves - all fresh lakes in the world contain 123 thousand km³ of water). In terms of water reserves, Baikal occupies the 2nd place 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 5 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 constant tributaries. The largest of them are Selenga, Upper Angara, Barguzin, Turka, Snezhnaya, Sarma. One river flows out of the lake - the Angara.
Water characteristics
Baikal water is very transparent. The main characteristics of Baikal water can be briefly described as follows: it contains very few dissolved and suspended mineral substances, negligible organic impurities, and a lot of oxygen.
The water in Baikal is cool. 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 did the surface water temperature in the northern part of Baikal rise to a record 22-23°C.
The water in the lake is so transparent that individual pebbles and various objects can be seen at a depth of 40 m. At this time Baikal water happens to be blue. In summer and autumn, when a mass of plant and animal organisms develop in the water warmed by the sun, its transparency drops to 8-10 m, and the color becomes blue-green and green. The purest and most transparent water of Lake 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 completely, not counting a small, 15-20 km long section 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 right after the ice breaks up the lake and complete it with the freezing of Lake Baikal, in other words, 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 have a local name "stanovye cracks", break the ice into separate fields. The length of such cracks is 10-30 km, and the width is 2-3 m. Breaks occur once a year in approximately the same areas of the lake. They are accompanied by a sonorous 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 this moment fall into the abyss. Thanks to the cracks in the ice, the fish in the lake do not die from a lack of oxygen. Baikal ice, in addition, is very transparent, and the sun's rays fall through it, therefore planktonic aquatic plants that produce oxygen rapidly develop in the water. It is possible to follow along the shores of Lake Baikal in winter ice grottoes and splashes.
Baikal ice presents scientists with many mysteries. So, in the 1930s, specialists from the Baikal Limnological Station found unusual forms of ice cover, corresponding only to Baikal. For example, “hills” are cone-shaped ice mounds up to 6 m high, hollow inside. Appearance they resemble ice tents, "open" in the opposite direction from the coast. The hills can be placed separately, and from time to time they form small " mountain ranges". There are also a number of other types of ice on Baikal: “sokuy”, “kolobovnik”, “autumn”.
In addition, in the spring of 2009, the Internet was widely distributed satellite imagery various parts of Lake Baikal, where they were found dark rings. According to scientists, these rings appear 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) direction appears. In the zone where the direction achieves the highest velocities, the 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 developed to a greater or lesser extent; the bed of 3 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 2 ridges - Akademichesky and Selenginsky.
More expressive is the Academic Ridge, which stretches along the bottom of Lake Baikal from Olkhon Island to the Ushkany Islands (which are its most highest part). Its length is about 100 km, highest altitude above the bottom of Lake Baikal 1848 m. The thickness of bottom sediments in Baikal reaches about 6 thousand m, and highest mountains on Earth, with a height of more than 7000 m.
Islands and peninsulas
There are 27 islands on Baikal (Ushkany Islands, Olkhon Peninsula, Yarki Peninsula and others), the largest of them is Olkhon (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) is one of the areas with the highest seismicity: earthquakes constantly occur here, the strength of most of which is one or two points on the MSK-64 intensity scale. But 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 force of the head 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 Baikal influences the climate of the coastal area. Winter is milder here summer time- cooler. The arrival 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 Huge Goloustnoye, it reaches 2524 hours, which is more than in the Black Sea resorts, and is a record for Russia. There are only 37 days in the absence of the sun in the same inhabited Friday, and 48 on the Olkhon Peninsula.
The special features of the climate are justified by the Baikal winds, which have their own names - barguzin, sarma, verkhovik, kultuk.
Origin of the lake
The origin of Baikal still causes scientific controversy. Scientists usually determine the age of the lake at 25-35 million years. This fact also makes Baikal a unique natural object, because most of lakes, separately of glacial origin, live on average 10-15 thousand years, and later they are filled with silty sediments and become swampy.
But there is also a version about the youth of Baikal, put forward by A.V. Tatarinov in 2009, which received circumstantial evidence during the second step of the Mirs expedition to Baikal. Namely, the activity of mud volcanoes at the bottom of Lake Baikal allows scientists to believe that the modern coastal strip of the lake is only 8 thousand years old, and the deep-water part is 150 thousand years old.
Of course, only 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 transform fault zone, others imply 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 lake districts. There are speculations 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).
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