The mystery of the origin of Baikal has long haunted people. Where did this sea of pure water come from, 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 in the opposite 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 a new theory of the formation 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. Vladimir Afanasyevich Obruchev (1863-1956) came close to the modern understanding of the method of formation of the Baikal basin, who suggested that the emergence of Baikal is closely connected with the formation of the mountain system of 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 area from the middle of the Khangai highlands 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 Muya ridges, Delyun-Uran, Kodar and Udokan, and sank formed deep valleys, the deepest of which were 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. Of great importance was 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, 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 basins - 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 Akademichesky ridge crossing Baikal along the line Olkhon Island - the Ushkany Islands archipelago.
Without going into details, on which there is still no consensus in the scientific community, the process of formation of the Baikal basin can be very simplified as follows. The earth's crust, lifted by the heated mantle matter floating up and spreading to the sides, formed the mountain ranges surrounding the lake. 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, the average annual temperature is + 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. The formation of mountain ranges and the deepening of lake depressions began. 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 is a freshwater lake in the south of Eastern Siberia, it stretches from 53 to 56 ° N latitude. 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 deepest lake in the world (1620 m). It contains the largest reserves of fresh water on earth - 23 thousand cubic kilometers, which is 1/10 of the world's fresh water reserves. 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 the highest ridges reach large 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. The length of the coastline is 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, the average depth is 730 m. 336 permanent rivers and streams flow into Baikal, while half of the water entering the lake comes from the Selenga. The only river that flows out of Baikal is the Angara. However, the question of the number of rivers flowing into Baikal is rather controversial, most likely there are less than 336 of them. There is no doubt that Baikal is the deepest lake in the world, the closest contender for this title, the 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. The largest island is 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 indeed a 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 - a large 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, they distinguish between the Small Sea and the Big Sea. The Small Sea is what is located between the northern coast of 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 30 cm in diameter), 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. Such a high transparency is due to the fact that Baikal water, due to the activity of living organisms that live 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.
The influence of Lake Baikal is not limited to the regulation of the temperature regime. Due to the fact that the evaporation of cold water from the surface of the lake is very small, 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, the sky over Baikal is clear most of the time. 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, you can run into one or even two weeks of disgusting rainy weather even in the sunniest place of 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.
Baikal has rift origin. A rift is a break in the upper solid layer of the Earth - the earth's crust. The Baikal Rift extends from Mongolia to Yakutia and is located in the center of the Asian continent. The length of the rhymes is about 2500 km. In the center of the rift, at its deepest point, is Lake Baikal. What is the maximum fracture depth? Scientists have calculated that during the existence of Baikal, the bottom of the depression in which the lake is located was filled with rock fragments, sediments of dead plants and animals to a depth of about 8 km. If we add up the maximum depth of Lake Baikal - 1637 m - and the thickness of the sediments, we get that the depth from the surface of the lake to its stone base will be more than 9.6 km!
There was a scientific assumption that the formation of the Baikal Rift began as a result of a collision of continents about 60 million years ago. Hindustan, which at that time was a separate continent, slowly drifting north, collided with Eurasia. This led to catastrophic changes in the earth's surface, the formation of the Himalayan mountains, and also served as an impetus for the formation of the Baikal rift basin.
However, later studies showed that these processes could not be the root cause of the formation of Baikal. Baikal is located on the border of the junction of two platforms of the earth's crust - the Siberian and Central Asian folded belt, which were formed much earlier than the processes of mountain building in the Himalayas began. The earth's crust at the junction of the platforms is thinner. In this place in the mantle of the Earth there is an upward flow of magma - a flow of liquid hot material. It rises up to the junction of the platforms, and spreads under them to the sides, stretching the earth's crust.
Diagram of the emergence of a rift
Under the influence of high temperatures, the rise of molten material and stretching, the earth's crust thins and cracks, which is accompanied by fault formation and earthquakes. These processes were the primary cause of the formation of the rift zone. And the movement of Hindustan could only give an additional impetus and accelerate the formation of the rift at the later stages of its development.
Territories where earthquakes often occur are called seismically active. This can be called the Baikal rift zone, and especially the region of Lake Baikal. Earthquakes are recorded by special instruments - seismographs. They are evaluated by two main characteristics - energy and intensity. Earthquake energy is measured on the Richter magnitude scale. The maximum magnitude value is 9. Using the Richter scale, the strength of earthquakes in the epicenter is compared, i.e. at a point on the Earth's surface above the source of an earthquake.
In addition to energy, an earthquake is characterized by intensity, i.e. its influence on people, buildings, the surrounding nature. The intensity of earthquakes decreases with distance from the epicenter. A 12-point scale is used to assess intensity.
Around Baikal there are more than 30 seismic stations with seismographs. With their help, scientists have calculated that more than 5,000 to 8,000 earthquakes a year occur within the Baikal Rift. About 2,000 earthquakes a year are recorded directly on Lake Baikal. The work of a seismograph and the registration of earthquakes on a computer can be observed in the Baikal Museum in the village of Listvyanka.
With the help of high-precision observations using satellites, it was found that as a result of the stretching of the earth's crust, the Baikal Basin is expanding at a rate of several millimeters per year. Some scientists suggest that in 100-150 million years these processes can lead to the splitting of the Asian continent at the site of Baikal and the formation of an ocean. Therefore, we can meet the judgment that despite the ancient age, Baikal continues to change, increase in size, which means that it can be argued that it is still “young”.
Scheme of Proval Bay
Seismically active areas include the Severo-Muya basin - a territory that extends northeast from the northern coast of Lake Baikal. The lake is also a zone of high seismicity. The depressions of Southern and Northern Baikal, the heights from Olkhon Island to the Svyatoy Nos Peninsula, the territory between the deltas of the Selenga and Buguldeyka rivers are active.
One of the strongest earthquakes on Baikal, known in the history of observations, occurred in the Tsagan steppe, in the delta of the Selenga River. The first, most powerful tremors began on December 31, 1861 at about 2:00 pm. Houses and outbuildings were destroyed before the eyes of the people. According to eyewitnesses, silty water was thrown out of the wells to a height of two meters. From some cracks formed in the ground, water and sand mixed with silt and mud were thrown out. As a result of the earthquake, a piece of land with an area of about 200 square meters sank under water in a few days. km and the Proval Bay was formed. The magnitude of the earthquake at the epicenter was maximum - 12 points. Five Buryat villages, 867 houses and yurts, and more than 12,000 heads of cattle went under water. Three people died.
Weaker tremors lasted several days. The echoes of the earthquake reached the cities located hundreds of kilometers from the Tsagan steppe. An earthquake of about 8 points was noted in Irkutsk.
Also, as a result of earthquakes and faults in the earth's crust, Olkhon Island separated from the mainland. The Olkhon Gate Strait was formed. On satellite images it is clearly seen that the coast of Olkhon in this place repeats the outlines of the Baikal coastline.
A powerful earthquake in Lake Baikal occurred in August 1959. Its epicenter was in the southern basin of the lake. At the epicenter, the bottom of Baikal was lowered by 15–20 m. This information was obtained immediately after the earthquake, because by a coincidence, it was at this time in this place that the research vessel of the Limnological Institute carried out measurements of the bottom of Baikal to clarify the depth map.
Space photo. Olkhon Island, Olkhon Gate Strait
The last major earthquake with an epicenter in South Baikal occurred in August 2008 near the village of Kultuk. The magnitude of the earthquake was 8 points. In Kultuk, Slyudyanka, Baikalsk, located on the shores of South Baikal, buildings were badly damaged. Furnaces and chimneys were destroyed in the houses, cracks formed in the walls. Numerous screes, rockfalls and landslides occurred on steep mountain slopes.
cartographic basis. Maps of Lake Baikal.
Atlas “Lake Baikal. Past. The present. Future". FSUE "VostSib AGP", 2005.
Is it possible to predict earthquakes? An accurate prediction of the time, place and strength of an earthquake, even with the most modern equipment, science cannot currently do. However, in science there is such a thing as seismic weather. Scientists suggest that in the coming years it will worsen. This is due to the increased activity of the sun. In addition, long-term observations of seismicity show that, approximately once every 50 - 60 years, "outbursts" of earthquakes occur in the Baikal-Mongolian region. The previous time, high seismic activity was observed in the 50s - 60s of the last century, therefore, another outbreak should be expected around 2015.
The activity of the earth's crust in the Baikal rift zone is also evidenced by numerous hot springs of mineral water, which are located right on the shores of Lake Baikal. The most famous of them are the springs of the Zmeinaya Bay (Chvyrkuisky Bay), the Frolikha Spring and the Khakusy Bay (north-east coast), the Goryachinsk region (east coast). The springs are healing and are used in the treatment of various diseases.
Hot springs on Baikal
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Based on many years of research, geologists came to the conclusion that the formation of the Baikal rift zone was not accompanied by active volcanic activity, as, for example, occurred during the formation of the East African Rift Zone and Lake Tanganyika, similar in origin to Lake Baikal.
Volcanic activity in the region of Lake Baikal during the formation of the rift zone was insignificant. The volcanoes closest to Baikal are the volcanoes of the Tunkinskaya valley, as well as the Kropotkin volcano and the Peretolchin volcano in the Eastern Sayan. They are currently not active.
A lake is a closed land depression that collects and accumulates surface and groundwater. Unlike rivers, these are reservoirs of slow water exchange. The 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 essential. 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. Pictured is a 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 relief of the lake bottom and, under certain conditions, can be transformed into rocks of 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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Lake Baikal is one of the most beautiful and picturesque places not only in the Asian part of our country, but on the whole planet. This ancient lake (its age is approximately 25-35 million years), lying in a rift basin, is located in the southern part of Eastern Siberia. It is the largest reservoir of fresh water on Earth, 22% of all the purest and most transparent water in the world and 85% of Russia are concentrated here. The volume of water is 23 thousand km 3 (these are the five Great Lakes in the United States taken together). In addition to the value of huge fresh water reserves, which due to its low mineralization (100 g/l) can be safely equated with distilled water, it should also be noted that Baikal is the deepest lake in the world and since 1996 has been included in the UNESCO World Heritage List.
Geographical position
Lake Baikal, which has the shape of a crescent elongated from southwest to northeast, is located almost in the very center of the Eurasian continent, in Central Asia, in the southern part of Eastern Siberia. The ancient rift basin of glacial origin, in which the lake basin is located, lies in the Baikal mountain region, surrounded by high peaks of mountain ranges and hills overgrown with dense forests (the border of the Irkutsk region and the Republic of Buryatia in the Russian Federation).
Characteristics of Lake Baikal
The area of the lake is 31.7 thousand km 2, this is the seventh place in the world after the Caspian Sea-lake, lakes Victoria, Taganika, Huron, Michigan, Upper or the area of the countries of Belgium or the Netherlands. The lake is 636 km long, the widest is in the center (81 km), the narrowest is near the delta of the Serenga River (27 km).
The average depth of the lake is 744.4 m higher than the maximum depths of many lakes in the world, its maximum depth, measured by Soviet scientists Kolotilo and Sulimov in 1983, was 1640 m, which made Baikal the deepest lake in the world.
The lake lies in a glacial rift basin, surrounded on all sides by mountain ranges and hills. The length of the coastline is 2 thousand km, the western coast is rocky and steep, the eastern coast is more gentle, the mountains are located tens of kilometers from the coast. The water area of the lake has six bays (Barguzinsky, Chivyrkuisky, Proval, Posolsky, Cherkalov, Mukhor), two dozen bays (Listvennaya, Peschanaya, Aya, many closed shallow bays called sory. The only river flows out of the lake - the Angara, flows into more than 336 rivers and rivulets, among the large ones one can name the Selenga, Upper Angara, Barguzin, Snezhnaya, Kichera, etc.
Temperature regime of water
Water, due to its low mineralization, is distinguished by amazing purity, transparency (can be seen to a depth of 40 meters), oxygen saturation. In spring, the water is especially transparent and has a rich blue-blue color; in summer, as a result of the development of organic matter, the transparency decreases and the waters acquire a blue-green tint. The average annual temperature of the water surface is about +4°С, in summer the water is +16, +17°С, in the sors it reaches +22,+23°С.
Baikal is almost completely covered with ice (1-2 meters) from January to May (with the exception of a small area 15-20 km at the source of the Angara). One of the amazing mysteries of Lake Baikal is the appearance in winter of huge dark rings on the ice, which are visible only from a height. Presumably, they are formed as a result of the release of methane from the depths of the lake, and this contributes to the formation of huge steams with a diameter of hundreds of meters with a very thin layer of ice.
Winds on Baikal
Distinctive features of Baikal's climate are its winds, they blow almost always, their maximum wind speed is 40 m/s. There are more than 30 names of the winds blowing there: the wind of the northwestern direction is mountainous, the northeastern wind is barguzin, verkhovik), the southeastern wind is shelonnik, the southwestern wind is kultuk, the sarma is the wind blowing in the center of Baikal. They blow mainly along the coast, on which there are practically no places to hide from such a piercing and strong wind.
Nature of Lake Baikal
The flora and fauna of the lake is diverse and unique. Oxygenated water allows a large number of living organisms to live here, more than 2600 species and subspecies of aquatic inhabitants live here, most of them are endemic. More than 58 species of fish live in the water column, such as omul, grayling, whitefish, taimen, Baikal sturgeon, lenok, golomyanka (a unique fish consisting of 30% fat).
The coast is covered with more than 2,000 species of plants, about 2,000 species of birds nest here, a unique marine mammal lives here - the Baikal seal, in the mountainous part of the Baikal region - the smallest deer in the world - the musk deer.
(Olkhon - the largest island of Lake Baikal)
The northeastern coast of the lake is part of the protected area of the Barguzinsky State Natural Biosphere Reserve, since 1996 Baikal has been included in the UNESCO World Heritage List.
Settlements and cities
Large cities located a few dozen kilometers from the lake are Irkutsk, Ulan-Ude (130 km east of the lake) and Severobaikalsk (in the northern part of the lake coast). From Irkutsk (70 km from Baikal), the closest to the oldest Baikal settlement at the headwaters of the Angara - Listvyanka, it is over three hundred years old. The tourist infrastructure is well developed here and there is the Lake Museum dedicated to the history of Baikal, its flora and fauna. Also in the village there is a nerpinarium, where they show an exciting water show with the participation of Baikal seals and the legendary Shaman-stone, a reserved rock at the source of the Angara, ancient shamanic rites were held here in ancient times.
Climate and seasons
(Clear water of Lake Baikal in summer)
Eastern Siberia lies in a temperate sharply continental climatic zone, however, the huge masses of water contained in Lake Baikal have a special effect on the climate of the coast and due to this, unusual microclimate conditions are formed with warm mild winters and cool summers. The water masses of the lake act as a huge natural stabilizer and make winters warmer and summers cooler than, for example, in the same Irkutsk, located at a short distance from the lake (70 km). The air temperature in summer can reach up to +35°С.
(Transparent ice on Lake Baikal in winter)
In winter, the waters of Lake Baikal are bound by incredibly transparent and smooth ice. The temperature above the surface of the lake in the middle of winter is about -21°С, and on the coasts it is 5-10 degrees higher, on average -10°С - 17°С. Due to the slight evaporation of cold water from the surface of the lake, clouds are very rarely formed here, so the area of Lake Baikal is characterized by a high total duration of sunshine, cloudy and cloudy days are infrequent.
