Lakes of tectonic origin are usually the deepest. Tectonic lakes of Russia

The science of limonology deals with the study of lakes. By origin, scientists distinguish several types, among which there are tectonic lakes. They are formed as a result of the movement of lithospheric plates and the appearance of depressions in the earth's crust. This is how the most deep lake in the world - Baikal and the largest in area - the Caspian Sea. A large fault has formed in the East African rift system, where a number of lakes are concentrated:

• Tanganyika;
• Albert;
• Nyasa;
• Edward;
• The Dead Sea (is the lowest-lying lake on the planet).

In their form, tectonic lakes are very narrow and deep reservoirs, with sheer shores. Their bottom, as a rule, is located below the level of the ocean. It has a clear outline, resembling a curved broken curved line. Traces of various landforms can be found at the bottom. The shores of tectonic lakes are made up of hard rocks and are weakly eroded. On average, the deep-water zone of lakes of this type is up to 70%, and shallow water - no more than 20%. The water of tectonic lakes is not the same, but in general it has a low temperature.

The largest tectonic lakes in the world

There are both large and medium-sized tectonic lakes in the Suna river basin:

• Randozero;
• Palier;
• Salvilambi;
• Sandal;
• Sundozero.

Among the lakes tectonic origin Kyrgyzstan should be called Son-Kul, Chatyr-Kul and Issyk-Kul. On the territory of the Trans-Ural Plain there are also several lakes formed as a result of a tectonic fault of the solid shell of the earth. These are Argayash and Kaldy, Uelgi and Tishki, Shablish and Sugoyak. In Asia, there are also tectonic lakes Kukunor, Khubsugul, Urmia, Biva and Van.

In Europe, there are also a number of lakes of tectonic origin. These are Geneva and Weettern, Como and Constance, Balaton and Lake Maggiore. Among the American lakes of tectonic origin, the Great North American Lakes should be mentioned. The same type of Winnipeg, Athabasca and the Great Bear Lake.

tectonic lakes located on the plains or in the area of ​​intermountain troughs. They have considerable depth and enormous dimensions. Not only the folds of the lithosphere, but also ruptures of the earth's crust take part in the process of formation of the lake basins. The bottom of tectonic lakes is below the ocean level. Such reservoirs are found on all continents of the earth, however, the largest number of them is located precisely in the fault zone of the earth's crust.

Origin lake basins
Sedimentation in lakes

lakes- natural reservoirs with stagnant or low-flowing water, formed as a result of flooding of land depressions (hollows) with water masses. Lakes have no connection with the ocean and, unlike rivers, have a slow water exchange.

Each lake consists of three interconnected natural components:

1. hollows - landforms of the earth's surface,
2. water mass with substances dissolved in it,
3. plants and animals that inhabit the water.

Origin of lake basins

Lake basins arise as a result of various relief-forming processes and are divided into several groups according to their origin.

The manifestation of endogenous activity is associated with the formation of tectonic and volcanic basins.

Basins of tectonic origin formed as a result of the movement of parts of the earth's crust. Many lakes that have arisen in basins of tectonic origin occupy a vast area, are characterized by great depth and have ancient age. Characteristic examples of lakes belonging to this group are the Great African Lakes (including Tanganyika with a depth of -1470 m), confined to the East African rift system, where the processes of stretching and subsidence of the continental crust take place. Lake Baikal in Russia (which is the largest freshwater reservoir and has a maximum depth of -1620 m among lakes), Lake Biwa in Japan (famous for freshwater pearls mined in it) and others have a similar origin. Basins are often confined to isometric troughs (Chad, Eyre) or large tectonic faults. Formation is also associated with tectonic processes. residual lakes, which are the remains of ancient oceans and seas. So, Caspian lake separated from the Mediterranean and Black Seas as a result of tectonic movements of the earth's crust.

Basins of volcanic origin confined to craters and calderas extinct volcanoes or located among the frozen lava fields. In the latter case, lake basins are formed when hot lava flows from under a colder surface lava horizon, which contributes to the subsidence of the latter (this is how Yellowstone Lake was formed), or when rivers and streams are dammed by lava or mud flow during volcanic eruptions. Basins of this origin are found in areas of modern or ancient volcanic activity (Kamchatka, Transcaucasia, Iceland, Italy, Japan, New Zealand and etc.).

The variety of exogenous processes leads to the formation of various groups of lake basins.

A large number of lake basins have glacial origin. Their formation may be associated with the activity of mountain and lowland glaciers. In the mountains, glacial lake basins are represented by moraine-dammed and cirque. Moraine-dammed ones are formed when river valleys are dammed up by glaciers. When the cirque basins are filled with water, small picturesque lakes with clear and cold water are formed.
On the plains, basins of glacial origin are common in the territory subjected to Quaternary glaciation. Among them, one can distinguish hollows of exaration, glacial-accumulative and moraine-dammed origin. Exaration basins are associated with mined-out moving ice by negative relief forms. A famous example of a lake that owes its origin to the destructive activity of glaciers is Loch Ness in Scotland, formed in a glaciated river valley. Thousands of lakes formed in the basins of glacial ploughing, are found on the territory of the Scandinavian Peninsula, in northern Canada. Glacial-accumulative basins are formed in the area of ​​development of moraine deposits. Lake basins in the area of ​​the moraine-plain relief are wide, have an oval shape and shallow depth (Chudskoye, Ilmen); in the conditions of a hilly-recessional and hilly-ridged relief, they have an irregular shape, islands, and a complex coastline, dissected by peninsulas and bays (Seliger). Moraine-dammed basins arise when a moraine pre-glacial river valley is dammed up (for example, Lake Saimaa in Finland).

In areas of permafrost, basins of thermokarst origin, which owe their origin to the melting of fossil ice and frozen rocks and subsidence of the soil. Many basins of tundra lakes have this origin. All of them have a small depth and are small in area. Another area of ​​development of thermokarst basins is the area of ​​distribution of Quaternary fluvioglacial deposits. Here, during the melting of ice caps, huge blocks were buried under a layer of sediments carried out by melted glacial waters. dead ice. Many of them melted only after hundreds of years, and in their place there were basins filled with water.

Lake basins of karst origin are formed in areas composed of soluble (karst) rocks. The dissolution of rocks leads to the formation of deep, but usually insignificant basins. Here, failures often occur due to the collapse of the vaults of underground karst cavities. Examples of karst basins are the famous "Failure" in Pyatigorsk (known from the novel by Ilf and Petrov "The Twelve Chairs") and Lake. Zhirot in french alps, having a depth of -99 m with an area of ​​​​only 57 hectares.

Lake basins of suffusion origin are formed during subsidence of soils due to the removal of loose silt particles by groundwater. Basins of this genesis are found in the steppe and semi-desert zones of Central Asia, Kazakhstan and the West Siberian Plain.

Basins of fluvial origin associated with the geological activity of rivers. Most often these are oxbow and deltaic lakes. Sometimes the formation of lakes is due to the obstruction of the riverbed by alluvial sediments of another river. For example, the formation of Lake St. Croy (USA) is associated with the damming of the river. St. Croy alluvial deposits of the river. Mississippi. Due to the dynamism of erosive and accumulative fluvial processes and the small size of basins, the latter are relatively quickly filled with sediment and overgrown in some places and re-formed in others.

Some lake basins are formed as a result of springing by landslides, mountain landslides or mudflows of rivers. Usually such lakes do not exist for long - there is a breakthrough of sediments that form a "dam". So, in 1841. The Indus in present-day Pakistan was dammed by a landslide caused by an earthquake, and six months later the "dam" collapsed, and a lake 64 km long and 300 m deep was drained in 24 hours. Lakes in this group can remain stable provided that excess water is drained through erosion-resistant hard rock. For example, Lake Sarez, formed in 1911 in the valley of the river. Murghab in the Eastern Pamirs still exists and has a depth of -500 m (the tenth deepest lake in the world).
The process of damming the river with a powerful collapse also contributed to the formation of one of the "pearls" of the Caucasus - Lake Ritsa in Abkhazia. A giant landslide on the slope of Mount Pshegish dammed the Lashipse River. The waters of the river flooded the gorge (tracing a large tectonic fault in the strata of rocks) for more than 2 km, the water rose by 130 m. A river with a different name, Yupshara (in Abkhazian “split”), is knocked out from under a natural stone dam.

lakes artificial origin associated with the filling of artificial basins (quarries, etc.) with water, or with the damming of river flows. During the construction of dams, reservoirs of various sizes are formed - from small ponds to huge reservoirs (located in Africa are the Victoria reservoir on the Victoria Nile River, Volta on the Volta River and Kariba on the Zambezi River; the largest in Russia is the Bratsk reservoir on the Angara River). Some dams were built to generate electricity for aluminum smelting from large deposits of bauxite. It should be added that dams are created not only by man. Dams built by beavers can reach lengths of more than 500 m, but they exist only for a short time.

Basins of coastal marine origin are formed mainly as a result of the separation of sea bays by bars from the sea in the process of movement of the alongshore sediment flow. At the initial stage, the basin is filled with salt sea ​​waters, later formed salt Lake gradually softens.

Hollows of organogenic origin occur in the sphagnum swamps of the taiga, forest-tundra and tundra, as well as on coral islands. In the first case, they owe their origin to the uneven growth of mosses, in the second - to coral polyps.

Lakes on the scale of geological time exist for a relatively short time. The only exceptions are some lakes with basins of tectonic origin, confined to active zones of the earth's crust, and large residual lakes. Over time, the basins are filled with sediments or become swampy.

Sedimentation in lakes

Lake deposits are represented by terrigenous, chemogenic and organogenic sediments. The composition of sediments accumulating in lakes is primarily determined by climatic zoning.

In the lakes of humid areas, predominantly silt-clay deposits accumulate, often with big amount organics. Dead organisms, as well as material carried into the lake, are deposited at the bottom and form gyttia(from Swedish gyttja - silt, mud) - lake deposits, consisting of organic residues. organic matter Gyttium is formed mainly due to the decay products of plant and animal organisms living in water, and to a lesser extent due to the remains of terrestrial plants brought from the surrounding land. The mineral part consists of sandy-clay material and oxides of calcium, iron and magnesium precipitated from water. Gyttia is also called sapropel(from the Greek sapros - rotten and pelos - silt, mud - "putrefactive silt"). In Lake Nero, located near the city of Rostov-Yaroslavsky (Rostov Veliky), the layer of sapropel reaches 20 m. Sapropels are used as fertilizer or as a mineral feed for livestock; sometimes for balneological purposes (mud therapy).

In semi-desert and desert arid zones, lakes are endorheic with intense evaporation. Since rivers and underground waters always bring salt, and only pure water, then there is a gradual increase in the salinity of lake waters. The concentration of salts can increase so significantly that from the water (brine) supersaturated with salts, salt is deposited on the bottom of the lake (self-settling lakes). Salinization of continental lakes accumulates carbonate, soda, sulfate, salt and other chemogenic deposits. In Russia, modern soda lakes are known in Transbaikalia and Western Siberia; abroad, Lake Natron in Tanzania and Lake Searls in California are very famous. Natural soda deposits are associated with fossil deposits of such lakes.
In general, arid regions are characterized by halogen-carbonate deposits, poor in organic matter.

In a number of cases, the origin of lake basins plays a decisive role in the nature of sedimentation. Glacial lakes are characterized by banded clays formed by a combination of lacustrine and glacial deposits. In karst lakes, carbonates accumulate, sometimes heaps of blocks of landslide origin.

Familiarization with varieties, geographical location, temperature regime of waters and chemical composition of lakes in Russia.

Study of the location, area and depth indicators of the largest domestic reservoirs - Baikal, Ladoga and Onega lakes.

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Significant water reserves are concentrated in lakes. There are more than 2.5 million lakes in Russia. The largest lakes are the Caspian, Ladoga, Onega and Baikal.

Caspian lake is the most big lake in the world, the deepest is Lake Baikal. The lakes are very unevenly distributed.

In particular, in the Vilenovsky basins, the West Siberian Plain and the northwestern layer of Europe - in Karelia. All these areas are in too much humidity. In the south, in the zone of the steppe and semi-sedimentary zone with a weak climate, the number of lakes decreases sharply, and many lakes have salt or salt. Salt is such huge large lakes as the Caspian, as well as lakes Elton and Baskunchak, where salt is eliminated.

Hydrographic characteristics of large lakes in Russia

There are different lakes and sources of basins.

Lakes of tectonic origin are located in trenches and cracks in the earth's crust. The largest tectonic lake Baikal is located in the Graben, reaching a depth of 1637 m.

Ice-tectonic lake basins were created as a result of processing liquid depressions of the glacial crust of the glacier: Imandra, Ladoga, Onega.

in Kamchatka and Kuril Islands The lake is mainly of volcanic origin. In the northwest of the European Plain, the sources of lake basins are connected with continental ice. Many caves are located between the hills of the sea: Seliger, Valdai.

Due to landslides in mountain valleys there was a lake of a lake: Sarez in the Pamirs, Ritsa in the Caucasus. Small lakes are formed by karst nests.

In the south of Western Siberia, there are many lakes in the form of plates, which were created as a result of stoning stones. When ice melts on the surface of the permafrost, shallow slab-like waters also form. Lake people are located on the flood plains of low-lying rivers. On the Black and Sea of ​​Azov there are estuary lakes.

All the largest and largest lakes in Russia are often used in the national economy. Catch and catch in them. Especially a lot of fish, including the most valuable sturgeon, end up in the Caspian.

In Baikal, the harvest is omul. Lakes are also used for navigation - geoglobus.ru. Numerous minerals were acquired in the lakes of lakes: oil and mirbilite in the Caspian lake, salt in Elton and Baskunchak. Water for freshwater lakes is used for drinking. There are many sanatoriums and rest houses on the shores of many lakes.

There are nine lake districts on the territory of Russia:

1) northwestern lake, iceberg iceberg;
2a) Azov-Black Sea estuaries associated with marine activities;
2b) North Caucasian-glacial and karst lake;
3) salt formation of the Caspian Lake;
4) West Siberian-Tuscan and bitter-salty lakes;
5) Altai - sea ​​view lakes (Teletskoye, Markakol);
6) Zabaikalsky - the remaining lakes;
7) Lower Amur lakes, which have a hydrological connection with the Amur River;
8) Yakuti - lakes of thermocouples;
9) Lake Kamchatka - lakes of volcanic origin (Kronotsky, Kurilsky).

A lake is a body of water with slow water exchange. Lakes are classified according to various criteria: in origin (tectonic, volcanic, dammed, glacial, sinkhole, karst, etc.); by salinity (fresh, brackish, saline, brine, etc.); by trophicity (oligotrophic, mesotrophic, eutrophic, etc.); by position in the landscape (lowland, floodplain, highland, etc.); by depth (shallow, deep, super-deep); by morphology (rounded, elongated, ribbon-shaped, crescent-shaped, bead-shaped, etc.); by flow (non-drainage, low-flow, periodically flow-through, temporary, relict); by types of use (fisheries, for water supply, for the extraction of salt, sapropel ore, therapeutic mud, etc.); according to condition (clean, polluted, overgrown, etc.).

How long do lakes live?

Most often, it is relatively short - a few thousand or tens of thousands of years. This applies primarily to glacial and oxbow lakes. Karst, volcanic and especially tectonic lakes can exist for millions and tens of millions of years. For example, one of the lakes in Australia was formed about 700 million years ago.

How many lakes are on earth?

An exact count has not yet been made. There are probably about 2 million lakes in Canada and Alaska, about 100 thousand in Finland and the Scandinavian Peninsulas. About 100 thousand in Great Britain and Ireland as well as Denmark, Belgium, Holland and France. Hydrologists believe that there are about 5 million lakes on the earth.

Tectonic lakes.

They are formed in places of faults and shifts of the earth's crust. As a rule, these are deep narrow reservoirs with straight sheer banks, located in deep through gorges. Kurile Lake is located in the south of Kamchatka in a deep picturesque basin surrounded by mountains. The greatest depth of the lake is 306 m. Its banks are steep. Numerous mountain streams flow from them. The lake is sewage, the Ozernaya River originates from it. Hot springs come to the surface along the shores of the lake, and in its middle there is an island called the Heart-stone. Not far from the lake there is a unique outcrop of pumice stones, which are called Kutkhin Baty. Currently, the lake has been declared a nature reserve and a zoological monument of nature.

The profile of the bottom of tectonic lakes is sharply defined, has the form of a broken curve. Glacial deposits and the processes of sediment accumulation have little changed the clarity of the tectonic lines of the lake basin. The influence of the glacier on the formation of the basin can be noticeable, it leaves traces of its presence in the form of scars, sheep's foreheads, which are clearly visible on the rocky shores and islands. The shores of the lakes are composed mainly of hard stone rocks that are weakly susceptible to erosion, which is one of the reasons for the weak process of sedimentation. These lakes belong to the group of lakes of normal depth (a=2-4) and deep (a=4-10). The deep-water zone (more than 10 m) of the total volume of the lake is 60-70%, shallow water (0-5m) 15-20%. The waters of the lakes are thermally heterogeneous: during the period of the greatest heating of surface waters, low bottom temperatures, which is facilitated by stable thermal stratification. Aquatic vegetation is rare, only in a narrow strip along the shores of closed bays. Typical lakes in the river basin. The suns are large and medium-sized: Palye, Sundozero, Sandal, as well as very small lakes Salvilambi and Randozero, located on private watersheds of lakes Palye and Sandal.

As a result of the movement of the earth's crust, depressions form in some places over time. It is in these depressions that tectonic lakes arise. Three most large lakes Kyrgyzstan: Issyk-Kul, Son-Kul and Chatyr-Kul are formed by tectonic way.

There are many lakes in the forest-steppe Trans-Urals. Here are such large reservoirs as Uelgi, Shablish, Argayash, B. Kuyash, Kaldy, Sugoyak, Tishki, etc. The depths of the lakes on the Trans-Ural Plain noticeably decrease and do not exceed 8-10 m. By origin, these lakes belong to the erosion-tectonic type. Tectonic depressions have been modified as a result of the impact of erosion processes. Many lakes of the Trans-Urals are confined to ancient hollows of river flow (Etkul, Peschanoe, Alakul, Kamyshnoe, etc.).

Lake Baikal. General information

Lake Baikal

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 high values. For example, xr. Khamar-Daban (Sokhor peak) - 2304 m, and 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 Lake 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, 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 flowing from Baikal is the 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, 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. 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 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 Evenk 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. 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 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. 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.

Definition 1

In the aspect of planetology, a lake is an object stably existing in space and time, which is filled with a substance in liquid form.

In a geographical sense, it can be represented as a closed depression of land, into which water is systematically. For a sufficiently long period of time, the chemical composition of lakes does not change. The liquid filling it is renewed, but much less frequently than in a river. At the same time, the currents present in it do not act as the main factor by which it is possible to determine the general regime.

Remark 1

Lakes mainly provide a balancing of river flow, as complex chemical reactions take place in their waters.

In the process of interactions, some elements pass into the liquid, while others settle in bottom sediments. In some water bodies that do not have such a runoff, the salt content increases significantly due to evaporation. As a result, there is a cardinal change in the mineral and salt composition of the lakes. Large objects soften the climatic conditions of the territories close to them through large-scale thermal inertia, thereby reducing seasonal and annual weather fluctuations.

Tectonic lakes: characteristics, examples

Definition 2

Tectonic lakes are reservoirs that were formed in areas of faults and shifts in the earth's crust.

Basically, these objects are narrow and deep, and also distinguished by rectilinear steep banks. Such lakes are located mainly in deep through gorges. The tectonic lakes of Russia (examples: Far and Kuril in the territory of Kamchatka) are characterized by a low-lying bottom. Thus, the Kuril reservoir flows in the southern part of Kamchatka, in a colorful deep basin. This area is completely surrounded by mountains. The maximum depth of the lake is about 360 m, and a huge amount of mountain streams constantly flows from the steep banks. The Ozernaya River flows out of this reservoir, along the banks of which quite hot springs come to the surface. In the center of the reservoir there is an island in the form of a small dome-shaped elevation, popularly referred to as the "heart-stone". Not far from the lake there are unique pumice deposits called Kutkhiny Baty. Today, Lake Kurilskoye is considered a reserve and declared a natural zoological monument.

Interestingly, tectonic lakes are located only in explosion pipes and extinct craters. Such reservoirs are often found in European countries. For example, volcanic lakes are observed in the Eifel region (in Germany), near which a weak manifestation of volcanic activity in the form of hot springs is recorded. A water-filled crater is the most common type of such reservoirs.

Example 1

For example, Lake Crater of Mazama Volcano in Oregon formed about 6.5 thousand years ago.

Its diameter reaches 10 km, and its depth is more than 589 m. Part of the reservoir was formed by volcanic valleys in the process of blocking by continuous lava flows, in which water accumulates over time and a lake is formed. This is how the Kivu reservoir appeared, which is a depression of the East African rift structure, which is located on the border of Zaire and Rwanda. Flowing more than 7 thousand years ago from Tanganyika, the Ruzizi River flowed through the Kivu Valley to the northern regions, towards the Nile. But since that period, the channel has been "sealed" in with the eruption of a nearby volcano.

Profile of the bottom of tectonic lakes

The tectonic reservoirs of the world have a clearly defined bottom relief, presented as a broken curve.

Accumulative processes and glacial deposits in sediments did not have a significant effect on the relief of the basin lines, but in a number of special occasions influence can be quite significant.

Glacial-tectonic lakes can have a bottom covered with "scars" and "ram's foreheads", which can be observed on rocky shores and islands. The latter are formed mainly from hard rocks, which are practically not amenable to erosion. As a result of this process, a small rate of accumulation of precipitation occurs. Similar tectonic reservoirs of Russia are classified by geographers as: a = 2-4 and a = 4-10. The deep-water surface (over 10 m) of the total volume reaches approximately 60-70%, shallow-water (up to 5 m) - 15-20%. Such lakes are characterized by diverse waters in terms of thermal parameters. The low temperature of bottom waters persists during the period of maximum surface heating. This is due to thermally stable stratifications. Vegetation in these areas is extremely rare, as it can only be found along the coast in closed bays.

Features of the formation of reservoirs

Lakes arise for a variety of reasons. Their natural creators are:

• water;
• wind;
• tectonic forces.

On the earth's surface, basins are often washed out with water. Due to the action of the wind, a depression is created, after which the glacier polishes the depression, and the mountain collapse gradually dams the river valley. This is how the bed for the future reservoir is formed.

By origin, the lakes are divided into:

• river reservoirs;
• seaside lakes;
• mountain reservoirs;
• glacial lakes;
• dam reservoirs;
• tectonic lakes;
• failed lakes.

Tectonic lakes appear as a result of filling small cracks in the crust with water. Thus, the shifts formed the Caspian Sea - the largest body of water in Russia and the entire planet. Before lifting Caucasian ridge The Caspian Sea was directly connected with the Black Sea. Another striking example of a large-scale fault in the earth's crust is the East African structure, which extends from the southwestern region of the continent north to southeast Asia. Here is a chain of tectonic reservoirs. The most famous are Tanganyika, Albert Edward, Nyasa. To the same system, experts include the Dead Sea - the lowest tectonic lake in the world.

Seaside lakes are estuaries and lagoons, which are mainly located in the northern regions of the Adriatic Sea. One of the specifics of failed reservoirs is their systematic disappearance and emergence. This natural phenomenon is directly dependent on the unique dynamics of groundwater. An ideal example of this object is Lake Ertsov, located in South Ossetia. Mountain reservoirs are located in ridge basins, and glacial lakes are formed during the displacement of the layer of multi-year ice.

The lake is an element of the hydrosphere. This is a reservoir that arose naturally or artificially. It is filled within its bed with water and has no direct connection to the sea or ocean. There are about 5 million such reservoirs in the world.

general characteristics

In terms of planetology, a lake is an object that exists stably in space and time, filled with a substance that is in liquid form. In a geographical sense, it is presented as a closed depression of the land, into which water enters and accumulates. The chemical composition of lakes remains constant for a relatively long time. The substance that fills it is renewed, but much less frequently than in a river. At the same time, the currents present in it do not act as the predominant factor that determines the regime. Lakes provide regulation Chemical reactions take place in the waters. In the course of interactions, some elements settle in bottom sediments, while others pass into the water. In some water bodies, which usually do not have a runoff, the salt content increases due to evaporation. As a result of this process, there is a significant change in the salt and mineral composition of the lakes. Due to the large thermal inertia, large objects soften the climatic conditions of the adjacent zones, reducing seasonal and annual meteorological fluctuations.

Bottom sediments

With their accumulation, significant changes in the relief and dimensions of lake basins occur. When water bodies are overgrown, new forms are formed - flat and convex. Lakes often form barriers to groundwater. This, in turn, causes swamping of adjacent land areas. In lakes there is a continuous accumulation of mineral and organic elements. As a result, thick strata of deposits are formed. They change along the way. further development reservoirs and turning them into land or swamps. Under certain conditions, bottom sediments are transformed into mountain fossils of organic origin.

Features of education

Reservoirs occur for a variety of reasons. Their natural creators are wind, water, tectonic forces. On the surface of the earth, depressions can be washed out by water. Due to the action of the wind, a depression is formed. The glacier polishes the depression, and the mountain collapse dams the river valley. So it turns out a bed for the future reservoir. After filling with water, a lake appears. In geography, water bodies are classified depending on the method of formation, the presence of life, and the concentration of salts. Only in the most saline lakes there are no living organisms. Most of the reservoirs were created as a result of displacements of the earth's crust or volcanic eruptions.

Classification

According to their origin, reservoirs are divided into:

Volcanic reservoirs

Such lakes are located in extinct craters and explosion pipes. Such reservoirs are found in Europe. For example, volcanic lakes are present in the Eifel region (in Germany). Near them there is a weak manifestation of volcanic activity in the form of hot springs. The most common type of such lakes is a crater filled with water. Oz. The crater of the Mazama volcano in Oregon was formed more than 6.5 thousand years ago. Its diameter is 10 km and its depth is 589 m. Part of the lakes was formed in the process of blocking volcanic valleys by lava flows. Gradually, water accumulates in them and a reservoir is formed. So, for example, there was a lake. The Kivu is a depression of the East African Rift Structure, located on the border of Rwanda and Zaire. Flowing once from the lake. Tanganyika r. Ruzizi flowed along the Kivu valley to the north, towards the Nile. But from the moment the channel was blocked after the eruption of a nearby volcano, it filled the depression.

Other types

Lakes can form in limestone voids. Water dissolves this rock, forming huge caves. Such lakes can occur in areas of underground salt deposits. Lakes can be artificial. They are intended, as a rule, to store water for various purposes. Often the creation of artificial lakes is associated with various earthworks. However, in some cases, their appearance is a side effect of them. So, for example, artificial reservoirs are formed in developed quarries. Among largest lakes it is worth noting the Nasser, located on the border of Sudan and Egypt. It was formed by damming the valley of the river. Nile. Another example of a large artificial lake is Lake. Mid. It appeared after the installation of a dam on the river. Colorado. As a rule, such lakes serve local hydroelectric power stations, provide water to nearby settlements and industrial areas.

The largest glacial-tectonic lakes

One of the main reasons for the formation of reservoirs is due to this displacement, in a number of cases, the sliding of glaciers occurs. Reservoirs are very common on the plains and in the mountains. They can be found both in hollows and between hills in depressions. Glacial-tectonic lakes (examples: Ladoga, Onega) are quite common in the Northern Hemisphere. Avalanches left enough deep depressions after myself. They accumulated melt water. Deposits (moraine) dammed depressions. This is how reservoirs were formed in the Lake District. At the foot of Bolshoi Arber there is a lake. Arbersee. This reservoir remained after the Ice Age.

Tectonic lakes: examples, characteristics

Such reservoirs are formed in areas of shifts and faults of the crust. Usually, the tectonic lakes of the world are deep and narrow. They are characterized by steep straight banks. These reservoirs are located mainly in through deep gorges. The tectonic lakes of Russia (examples: Kuril and Dalnee in Kamchatka) are characterized by a low-lying bottom (below ocean level). Yes, oz. Kuril is located in the southern part of Kamchatka, in a picturesque deep basin. The area is surrounded by mountains. The maximum depth of the reservoir is 360 m. It has steep banks, from which many mountain streams flow. The river flows out of the reservoir. Ozernaya. Hot springs come to the surface along the banks. In the center of the lake there is a small elevation - an island. It is called "heart-stone". Not far from the lake there are unique pumice deposits. They are called Kutkhins baty. Today lake. Kurilskoye is a nature reserve and declared a zoological natural monument.

bottom profile

The glacial-tectonic lakes of the world have a sharply defined relief. It is presented as a broken curve. Glacial deposits and accumulative processes in sediments may not have a significant effect on the clarity of basin lines. However, in some cases the impact can be quite noticeable. Glacier-tectonic lakes can have a bottom covered with "scars", They are quite well visible on the islands and rocky shores. The latter are composed mainly of hard stone rocks. They are weakly susceptible to erosion, which, in turn, causes a low rate of precipitation accumulation. Such tectonic ones are classified as a=2-4 and a=4-10. The deep-water zone (over 10 m) of the total volume is 60-70%, shallow-water (up to 5 m) - 15-20%. Tectonic lakes are distinguished by the heterogeneity of water in terms of thermal parameters. During maximum surface heating, low temperature bottom waters. This is due to stable thermal stratifications. Vegetation is quite rare. It can be found along the shores in closed bays.

Spreading

Where, besides Kamchatka, are tectonic lakes found? The list of the most famous reservoirs of the country includes such formations as:

1. Sandal.
2. Sundozero.
3. Palier.
4. Randozero.
5. Salvilambi.

These reservoirs are located in the Suna River basin. Tectonic lakes are also found in the forest-steppe Trans-Urals. Examples of reservoirs:

1. Welgi.
2. Argayash.
3. Shablish.
4. Tishki.
5. Sugoyak.
6. Kaldy.
7. B. Kuyash and others.

The depth of reservoirs on the Trans-Ural plain does not exceed 8-10 m. By origin, they are classified as lakes of the erosion-tectonic type. Their depressions were modified, respectively, under the influence of erosion processes. Many reservoirs in the Trans-Urals are confined to ancient river hollows. These are, in particular, such tectonic lakes as Kamyshnoe, Alakul, Peschanoe, Etkul and others.

Unique body of water

In the southern part of Eastern Siberia there is a lake. Baikal is a tectonic lake. Its length is more than 630 km, and the length of the coastline is 2100 km. The width of the reservoir varies from 25 to 79 km. The total area of ​​the lake is 31.5 sq. km. This reservoir is considered the deepest on the planet. It contains the largest volume of fresh water on Earth (23 thousand m 3). This is 1/10 of the world's supply. Complete renewal of water in the reservoir takes 332 years. Its age is about 15-20 million years. Baikal is considered one of the oldest lakes.

terrain

Baikal lies in a deep depression. He is surrounded mountain ranges covered with taiga. The area near the reservoir is characterized by a complex, deeply dissected relief. Not far from the lake itself, there is a noticeable expansion of the mountain strip. The ridges here run parallel to each other in the direction from the northwest to the southeast. They are separated by depressions. River valleys run along their bottom, in some places small tectonic lakes are formed. Displacements of the earth's crust take place in this area today. This is indicated by relatively frequent earthquakes near the basin, hot springs coming to the surface, as well as subsidence of large areas of the coast. The water in the lake is blue-green. It is distinguished by exceptional transparency and purity. In some places you can clearly see the stones lying at a depth of 10-15 m, thickets of algae. A white disk lowered into the water is visible even at a depth of 40 m.

Distinctive features

The shape of the lake is a crescent being born. The pond stretched between 55°47" and 51°28" N. latitude and 103°43" and 109°58" east. longitude. The maximum width in the center is 81 km, the minimum (opposite the delta of the Selenga river) is 27 km. The lake is located above sea level at an altitude of 455 m. 336 rivers and streams flow into the reservoir. Half of the water comes into it from the river. Selenga. One river flows out of the lake - the Angara. However, it should be said that in the scientific community there are still discussions about the exact number of flows flowing into the reservoir. Most scholars agree that there are fewer than 336.

Water

The liquid substance that fills the lake is considered unique in nature. As mentioned above, the water is surprisingly clear and clean, rich in oxygen. In the recent past, it was even considered healing. Baikal water was used to treat various diseases. In spring, its transparency is higher. In terms of performance, it approaches the standard - the Sargasso Sea. In it, the transparency of the water is estimated at 65 m. During the period of mass flowering of algae, the indicator of the lake decreases. Nevertheless, even at this time, in a lull from the boat, you can see the bottom at a fairly decent depth. High transparency is caused by the activity of living organisms. Thanks to them, the lake is poorly mineralized. Water is close in structure to distilled water. The importance of the lake Baikal is hard to overestimate. In this regard, the state provides special environmental protection to this area.