Lakes of tectonic origin are usually the deepest. Lakes: characteristics and types. Other types of reservoirs

A lake is a body of water that forms on the surface of the land. Lakes do not have a direct connection to the oceans and seas. Most of the reservoirs are tectonic lakes. In total, on our planet, they occupy almost two percent of the land surface.

Characteristics of lakes

After a long study of the lakes, scientists have identified a number of characteristics inherent in this type of water bodies.

Water surface area.
Coastline length.
The length of the lake To measure this, the two most remote points of the coastline are taken. During the measurement, the average width is determined - this is the ratio of area to length.
The volume of the basin, which is filled with water, is determined.
Installed average depth reservoir, the maximum depth is also determined.

The largest lake in the world is the Caspian, and the deepest is Baikal.

lake name	Max. surface area, thousand km 2	Max. depth, m	What continent is it on
Caspian lake
			North America
Victoria
			North America
Ladoga
Onega

Origin of lakes

All existing lakes are divided into underground and terrestrial. The basins themselves can be of endo- and exogenous origin. This factor determines the shape and size of the reservoir. Tectonic lakes are located in the largest basins. They can be located in tectonic depressions, like Ilmen, in grabens (Baikal), or in foothill and mountain foredeep.

Most of the large basins have a complex tectonic origin. Discontinuous, folded movements participated in their formation. All tectonic lakes are distinguished by their large size and significant depths, the presence of rocky slopes. The bottom of most reservoirs is located at the level of the World Ocean, and the mirrors are much higher.

Some regularity can be traced in the location of tectonic lakes: they are concentrated along the faults of the earth or in rift zones, but they can frame shields. Examples of such lakes are Ladoga and Onega, located along the Baltic Shield.

Lake types

There is a classification of lakes according to the water regime.

Drainless. Rivers flow into these types of reservoirs, but none of them flows out. Most of them are located in areas with insufficient humidity: in the desert, semi-desert. This type includes the Caspian Sea-lake.
Waste. Rivers flow into these lakes, and they also flow out of them. Such species are most often found in the zone of excessive moisture. A different number of rivers flow into such lakes, but usually only one flows out. An example of a tectonic lake of a sewage type is Baikal, Teletskoye.
Flowing reservoirs. Many rivers flow into and out of these lakes. Examples are lakes Ladoga and Onega.

In any reservoir, food occurs due to precipitation, rivers, and underwater resources. Partially, water evaporates from the surface of reservoirs, flows out or goes underground. Due to this feature, the amount of water in the pool fluctuates. For example, Chad covers an area of about twelve thousand square kilometers during a drought, but during the rainy season, the basin covers an area twice as large - about 24 thousand square kilometers.

The largest lakes in the world are of tectonic origin. An example would be Baikal, Ladoga and Lake Onega. Big endogenous factors play a role in the origin of tectonic lakes. The basins of these reservoirs are formed on the sunken parts of the earth's crust. Typically, such basins are strongly elongated and deep.

Baikal

The deepest and largest lake in the world with fresh water. Baikal is located in Siberia. The area of this basin is more than 31 thousand square kilometers, the depth is over 1500 meters. If you look at Baikal in terms of water volume, then it takes only the second place after the Caspian Sea-lake. The water in Baikal is always cold: in summer - about nine degrees, and in winter - no more than three. The lake has twenty-two islands: the largest is Olkhon. 330 rivers flow into Baikal, but only one flows out - the Angara.

Baikal influences the climate of Siberia: it softens winters and makes summers cooler. average temperature in January - about -17 °С, and in summer +16 °С. In the south and in the north, a different amount of precipitation falls throughout the year - from 200 to 900 mm. From January to May Baikal is covered clear ice. This is due to very clean and transparent water - you can see everything that happens in the water at a depth of up to forty meters.

Other types of reservoirs

There are glacial-tectonic lakes that have arisen as a result of the processing of tectonic depressions in the earth's crust by glaciers. Examples of such lakes are Onega, Ladoga. There are volcanic lakes in Kamchatka and the Kuriles. There are lake basins that appeared due to continental glaciations.

In the mountains, some lakes were formed due to blockages, for example, Lake Ritsa in the Caucasus. Small reservoirs arise above karst failures. There are saucer-shaped lakes that arise on loose rocks. Melting permafrost can form shallow lakes.

Lakes of glacial-tectonic origin are located not only in the mountains, but also on the plains. The waters fill the hollows, literally plowed by glaciers. During the movement of the glacier from the northwest to the southeast along the cracks, the ice, as it were, made a furrow. It filled with water: this is how many reservoirs were formed.

Ladoga lake

One of the largest glacial-tectonic lakes is Ladoga. It is located in Leningrad region and in Karelia.

The area of the lake is more than seventeen thousand square kilometers: the width of the reservoir is almost 140 kilometers, and the length is 219 km. The depth throughout the entire basin is uneven: in the northern part it ranges from eighty to two hundred meters, and in the south - up to seventy meters. Ladoga is fed by 35 rivers, and only one - the Neva - takes its beginning.

There are many islands on the lake, among which the largest are Kilpola, Valaam, Mantinsari.

Ladoga lake freezes in winter and opens in April. The water temperature on the surface is uneven: in the northern part it is about fourteen degrees, and in the south - about twenty degrees.

The water in the lake is hydrocarbonate type with weak mineralization. It is clean, transparency reaches seven meters. Throughout the year there are storms (they are strongest in autumn), calm (most often in summer).

Onega and other lakes

Most of the islands are on Onega Island: there are more than a thousand of them. The largest of them is Klimetsky. More than fifty rivers flow into this reservoir, and only the Svir takes its beginning.

There are many tectonic lakes in Russia, among which there is a drainage basin, including Ilmen, Saima, Lake Onega.

There are lakes of similar origin in Krasnaya Polyana, for example Khmelevsky. Their formation was served by a deflection that arose in the process of destruction of the earth's crust. The deflections that appeared as a result of this led to the formation of basins that were filled with water. As a result, Khmelevsky lakes were formed in this place, which became a national park. There are four large lakes and several small reservoirs, swamps.

Large lakes located on the territory of Russia are of great economic importance. These are huge reserves of fresh water. Navigation is developed in the waters of many large lakes. On the shores there are recreation centers, fishing places are equipped. In very large lakes, such as Ladoga, fishing is carried out.

A lake is a body of water with slow water exchange. Lakes are classified according to various features: 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 remain, 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. The three largest lakes in 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 fresh water reserves on earth - 23 thousand cubic km, which is 1/10 of the world's reserve fresh water. 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 (top of Sohor) - 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, maximum width in the central part 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 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 really very ancient lake.

It is believed that Baikal arose as a result of the action of tectonic forces. Tectonic processes are still going on, which is manifested in the increased seismicity of the Baikal region. If we assume that the age of Baikal is indeed several tens of millions of years, then this is the oldest lake on Earth.

origin of name

Numerous scientific studies have been devoted to the problem of the origin of the word "Baikal", which indicates a lack of clarity in this matter. There are about a dozen possible explanations for the origin of the name. Among them, the most probable is the version of the origin of the name of the lake from the Turkic-speaking Bai-Kul - a rich lake. Of the other versions, two more can be noted: from the Mongolian Baigal - a rich fire and Baigal Dalai - 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. Small Sea - what is located between north coast Olkhon and the mainland, everything else is the Big Sea.

Baikal water

Baikal water is unique and amazing, like Baikal itself. It is unusually transparent, pure and saturated with oxygen. In not so ancient times, it was considered healing, with its help, diseases were treated. In spring, the transparency of Baikal water, measured using the Secchi disk (a white disk with a diameter of 30 cm), is 40 m (for comparison, in the Sargasso Sea, which is considered the standard of transparency, this value is 65 m). Later, when a massive algae bloom begins, the transparency of the water decreases, but in calm weather, the bottom can be seen from a boat at a fairly decent depth. 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.

Tectonic lakes are formed in places of faults and shifts of the earth's crust. As a rule, these are deep narrow reservoirs with straight steep banks, located in deep through gorges. The bottom of such lakes located in Kamchatka is below the ocean level. Tectonic lakes include Dalnee and Kuril. 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.

Tectonic depressions arise as a result of movements of the earth's crust, and many lake basins of tectonic origin have large area and ancient age. They occupy depressions resulting from tectonic movements of the earth's crust: faults, normal faults, grabens, intermountain and flat troughs. As a rule, they are very deep, some tectonic lakes are superior to the sea. It is not by chance that the Caspian and Aral lakes are called seas. The Caspian lake is 4 times larger than the White, almost 3 times the Adriatic and 2 times - Aegean Seas. And the deepest lakes in the world - Baikal and Tanganyika - are much deeper than our northern seas - the Barents, Kara, East Siberian and others.

Tectonic processes manifest themselves in different ways. For example, the Caspian Sea is confined to a deflection at the bottom ancient sea Tethys. In the Neogene, an uplift occurred, as a result of which the Caspian depression. Its waters gradually desalinated under the influence of atmospheric precipitation and river runoff. The basin of the lake Victoria in East Africa was formed by the uplift of the surrounding land. The Great Salt Lake in Utah also arose due to the tectonic uplift of the area through which the flow from the lake was previously carried out. Tectonic activity often leads to the formation of faults (cracks in the earth's crust), which can turn into lake basins if a reverse fault occurs in the area or if a block enclosed between faults sinks. In the latter case, the lacustrine basin is said to be associated with a graben. Several lakes within the East African Rift System have this origin. Among them - lake. Tanganyika, which was formed about 17 million years ago and is very deep (1470 m). On the continuation of this system to the north are the Dead Sea and Lake Tiberias. Both are very ancient. The maximum depth of Lake Tiberias is currently only 46 m. Lakes Tahoe on the border of the states of California and Nevada in the USA, Biwa (the source of freshwater pearls) in Japan and Lake Baikal are also associated with grabens. The profile of the bottom of tectonic lakes is sharply defined and has the form of a broken curve. Glacial deposits and 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. The waters of the lakes are thermally heterogeneous: during the period of the greatest heating of surface waters, low bottom temperatures remain, which is facilitated by stable thermal stratification. Aquatic vegetation is rare, only in a narrow strip along the shores of closed bays. 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. The three largest lakes in Kyrgyzstan: Issyk-Kul, Son-Kul and Chatyr-Kul were formed tectonically.

Origin of 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:

hollows - landforms of the earth's surface,
water mass with substances dissolved in it,
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 are of 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. Thus, the 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 conditions of hilly-western and hilly-ridged terrain, they have an irregular shape, islands, 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. 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 reservoirs on the Victoria Nile River, Volta on the Volta River and Kariba on the Zambezi River; the largest in terms of volume in Russia is the Bratsk reservoir on the river Angara). 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 formed mainly as a result of the separation sea bays bars from the sea area during the 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 regions, predominantly silty-argillaceous deposits accumulate, often with a large amount of organic matter. 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. The organic matter of gyttium is formed mainly due to the decay products of plant and animal organisms living in water, 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 salts, and only pure water evaporates, 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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Baikal as the deepest lake on Earth and the largest freshwater reservoir with high-quality clean water.

Study of its location and extent in Russia. Study of the water surface area, maximum depth and volume of lake water. Fauna of Baikal.

presentation, added 10/06/2014

Physical and geographical characteristics of the lakes of Pivnichnaya America

Physical and geographical characteristics of lakes and internal waters of Pivnichnaya America. Hydroresources of lakes and problems of their pollution, recommendations for the improvement of ecosystems. The lakes are a zone of accumulation of mineral and organic rivers (typically lacustrine kopalini).

term paper, added 04/09/2009

Small lakes and rivers of Siberia

General information about Eastern Siberia as one of the largest regions of Russia.

History of its research and study. General characteristics of small rivers and lakes in Eastern Siberia, their hydrological features, value and significance, economic use.

abstract, added 04/22/2011

Biogeography of Lake Ladoga

Study of the history of the formation of Lake Ladoga.

Analysis of the influence of the lake on climatic conditions. The area of the drainage basin and the island. Descriptions of coastal and aquatic vegetation, animal world. Description of the main environmental problems of the lake.

abstract, added 05/16/2013

great african lakes

The concept and features of lakes, assessment of their role and importance in nature, distribution area. general characteristics largest lakes East Africa: Victoria, Albert, Edward, Kivu, Tanganyika, Nyasa, their geographical position and assessment of water reserves.

term paper, added 03/26/2013

Lake Baikal

Formation and development of lakes, their geographical significance in nature: geotectonic features of the Baikal depression and Lake Baikal.

Ecological significance of the aquatic environment of the lake, its flora and fauna.

Technogenic impact on the lake ecosystem.

abstract, added 01/26/2010

Obtaining quantitative estimates of the regulatory capacity of Lake Onega

Hydrography of the catchment area of the Onega Lake basin.

Quantile analysis of long-term variability of hydrometeorological characteristics. Features of long-term instability of temperatures and precipitation. Methods of the theory of periodically correlated random processes.

thesis, added 04/27/2018

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.

The Caspian Lake is the largest 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 of 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).

The profile of the bottom of tectonic lakes is sharply defined and has the form of a broken curve. Glacial deposits and 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 remain, 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. The three largest lakes in Kyrgyzstan: Issyk-Kul, Son-Kul and Chatyr-Kul were formed tectonically.

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