Lakes of tectonic origin. Glacial lakes of Russia Onega and other lakes

A lake is a body of water that forms on the surface of land. Lakes have no direct connection with oceans and seas. Most of 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 lakes, scientists have identified a number of characteristics characteristic of this type of reservoir.

1. Water mirror area.
2. Length coastline.
3. Length of the lake. To measure this indicator, the two most distant points of the coastline are taken. During measurement, the average width is determined - this is the ratio of area to length.
4. The volume of the basin, which is filled with water, is determined.
5. The average depth of the reservoir is established, and the maximum depth is also determined.

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

Origin of lakes

All existing lakes divided into underground and above ground. 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 foothills and mountain troughs.

Most of the large basins have a complex tectonic origin. Rupture and folding movements took part in their formation. All tectonic lakes are distinguished by their large sizes and significant depths, and 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.

There is a certain pattern in the location of tectonic lakes: they are concentrated along faults in the earth or in rift zones, but can frame shields. Examples of such lakes are Ladoga and Onega, located along the Baltic shield.

Types of lakes

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

1. Drainless. Rivers flow into these types of reservoirs, but none of them flow out. Most of them are located in areas with insufficient humidity: in the desert, semi-desert. The Caspian Sea-lake belongs to this type.
2. Sewage. Rivers flow into these lakes and also flow out of them. Such species are most often found in areas of excess moisture. A different number of rivers flow into such lakes, but usually only one flows out. An example of a tectonic lake of the drainage type is Baikal, Teletskoye.
3. Flowing reservoirs. Many rivers flow into and out of these lakes. Examples are lakes Ladoga and Onega.

In any body of water, food comes from precipitation, rivers, and underwater resources. Some of the water evaporates from the surface of reservoirs, flows out or goes underground. Because of this feature, the amount of water in the pool fluctuates. For example, Chad occupies an area of ​​about twelve thousand square kilometers during drought, but during the rainy season the basin occupies 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. Large Endogenous factors play a role in the origin of tectonic lakes. The basins of these reservoirs are formed on subsided areas of the earth's crust. Typically such basins are very elongated and deep.

Baikal

The deepest and big lake 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, it ranks only second 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 °C, and in summer +16 °C. In the south and north, different amounts of precipitation fall throughout the year - from 200 to 900 mm. From January to May Baikal is covered clear ice. This is due to the 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 arose as a result of the processing of tectonic depressions in the earth's crust by glaciers. Examples of such lakes are Onega and Ladoga. In Kamchatka and the Kuril Islands there are volcanic lakes. There are lake basins that appeared due to continental glaciations.

In the mountains, some lakes were formed due to rubble, for example Lake Ritsa in the Caucasus. Small bodies of water appear above karst sinkholes. There are saucer-shaped lakes that arise on loose rocks. When permafrost melts, shallow lakes can form.

Lakes of glacial-tectonic origin are located not only in the mountains, but also on the plains. Water fills basins literally plowed out by glaciers. As the glacier moved from northwest to southeast along the cracks, the ice seemed to make a furrow. It filled with water: this is how many reservoirs were formed.

Ladoga lake

One of the large 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 southern part - up to seventy meters. Ladoga is fed by 35 rivers, and only one begins - the Neva.

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

Ladoga lake It 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 southern part it is about twenty degrees.

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

Onega and other lakes

The largest number of islands is 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 originates.

There are many tectonic lakes in Russia, among which are the drainage basin that includes Ilmen, Saimaa, and Lake Onega.

There are lakes of similar origin in Krasnaya Polyana, for example Khmelevskie. Their formation was facilitated by the deflection that arose during the destruction of the earth's crust. The resulting deflections 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 here large lakes and several small reservoirs and swamps.

Large lakes located on the territory of Russia are of great economic importance. These are huge reserves fresh water. Shipping is developed in the waters of many large lakes. On the banks there are recreation centers and fishing spots. Very big lakes, such as Ladoga, fishing is carried out.

Tectonic lakes are formed in places of faults and shifts in 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 ocean level. Tectonic lakes include Dalnee and Kurilskoye. Kuril 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 shores are steep. Numerous mountain streams flow from them. The lake is drainage; the Ozernaya River originates from it. Hot springs come to the surface along the shores of the lake.

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

Tectonic processes manifest themselves in different ways. For example, the Caspian Sea is confined to a trough at the bottom ancient sea Tethys. In the Neogene, an uplift occurred, as a result of which the Caspian Basin became isolated. Its waters gradually desalinated under the influence of precipitation and river runoff. Lake basin Victoria in East Africa formed as a result of the uplift of the surrounding land. Big Salt Lake in Utah also arose due to the tectonic uplift of the territory through which the lake previously drained. Tectonic activity often results in the formation of faults (cracks in the Earth's crust), which can become lake basins if the area then undergoes a reverse fault or if a block enclosed between the faults subsides. In the latter case, they say that the lake basin is confined to a graben. Several lakes within the East African Rift System have this origin. Among them is the lake. Tanganyika, formed about 17 million years ago and characterized by a very great depth (1470 m). Continuing this system to the north are the Dead Sea and Lake Tiberias. Both of them are very ancient. Maximum depth Lake Tiberias is currently only 46 m high. Lake Tahoe on the border of California and Nevada in the USA, Biwa (a source of freshwater pearls) in Japan and Lake Baikal are also confined to the grabens. The bottom profile of tectonic lakes is sharply outlined and has the appearance of a broken curve. Glacial deposits and sediment accumulation processes 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 rocks that are poorly susceptible to erosion, which is one of the reasons for the weak sedimentation process. The waters of the lakes are thermally heterogeneous: during the period of 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 are formed in some places over time. Tectonic lakes arise in these depressions. The three largest lakes in Kyrgyzstan: Issyk-Kul, Son-Kul and Chatyr-Kul were formed tectonically.

They are formed in places of faults and shifts in 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 ocean level. Tectonic lakes include Dalnee and Kurilskoye. Kuril 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 shores are steep. Numerous mountain streams flow from them. The lake is drainage; the Ozernaya River originates from it. Along the shores of the lake, hot springs come to the surface, and in the middle of it rises an island called the Heart-Stone. Not far from the lake there is a unique outcrop of pumice called Kutkhiny Baty. Currently, the lake is declared a nature reserve and zoological monument.

The bottom profile of tectonic lakes is sharply outlined and has the appearance of a broken curve. Glacial deposits and sediment accumulation processes have little changed the clarity of the tectonic lines of the lake basin. The influence of a glacier on the formation of a basin can be noticeable; it leaves traces of its presence in the form of scars, sheep’s foreheads, which are clearly visible on rocky shores and islands. The shores of the lakes are composed mainly of hard rocks that are poorly susceptible to erosion, which is one of the reasons for the weak sedimentation process. 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 (0-5 m) 15-20%. The waters of the lakes are thermally heterogeneous: during the period of 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 Sunes are large and medium-sized: Palje, Sundozero, Sandal, as well as the very small lakes Salvilambi and Randozero, located on the private catchments of lakes Palje and Sandal.

As a result of the movement of the earth's crust, depressions are formed in some places over time. Tectonic lakes arise in these depressions. The three largest lakes in Kyrgyzstan: Issyk-Kul, Son-Kul and Chatyr-Kul were formed tectonically.

There are many lakes in the forest-steppe Trans-Urals. There 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 were modified as a result of the influence of erosion processes. Many lakes in Trans-Urals are confined to ancient river drainage hollows (Etkul, Peschanoye, Alakul, Kamyshnoye, etc.).

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Not having a direct connection to the sea. Lakes occupy about 1.8% of the land surface, but are distributed extremely unevenly.

Lakes vary in size by area. Especially the largest of them are even called seas ().

Based on the origin of lake depressions, they are distinguished:

• tectonic. These are usually the deepest lakes formed on site (Baikal - depth 1620 m; - 1470 m). The depth of most lakes of tectonic origin is usually less than 1000 m. The bottoms of the deepest lakes lie below ocean level (the bottom of Lake Baikal is 1165 m below ocean level;
• volcanic. These are lakes formed in craters or calderas, as well as in depressions on the surface of lava flows: lakes, Kronotskoye Lake, lakes and Java;
• glacial. These are lakes that formed in areas subject to continental glaciation. They were created either as a result or as a result of glaciation. The glacial erosion type includes lakes located in, in (), (Russia), in the northeast. The shape of these lakes is long, narrow, and they are elongated in the direction of the glacier movement. Lakes that arose as a result of lacustrine accumulation are confined to areas of hilly-moraine relief (see Glaciation). Some lakes occupy lowlands between hills and usually have a lobed shape and shallow depths (). Others arose among moraine topography. They are wide, oval and small: , White;
• karst. They are located in or in sinkholes and occur in areas composed of soluble rocks. Thermokarst basins are formed in the regions, due to the melting of fossil ice and permafrost, as well as ground subsidence. Many tundra lakes are thermokarst;
• coastal lakes. They were formed as a result of the separation of part of the sea from the rest by sediments of sand or silt. There are many estuaries and lagoons on the coast and;
• dammed lakes occur when a watercourse is dammed by landslides, landslides, lava flows, etc. Thus, in 1911, Lake Sarez was formed with a depth of 505 m. It was dammed by a colossal mountain collapse. Dammed lakes are also common. Many lakes of Sikhote-Alin (Russia), Lake Sevan, Lake Tana () were formed as a result of the damming of the river by lava flows;
• - ponds and;
• oxbow lakes formed during meandering of river beds.

The water mass of lakes is predominantly of origin and enters the lake by condensation on the water surface, when water enters from rivers and streams and due to ground nutrition. The flow of lake water occurs through evaporation and runoff. In some lakes, the modern water mass has replaced the sea mass that occupied the basin in the recent geological past. On the site of modern Ladoga and, as well as in glacial times, there was the Ioldian Sea. After its collapse, lakes formed, first with salty sea water, and then with fresh water. Such lakes are called relict or residual. The animals that live there adapt to the lake's living conditions.

Based on the inflow and outflow of water mass, all lakes are divided into:

• good flow. Rivers flow into and out of them. The water in these lakes is constantly changing. Such lakes are located in zones of excess atmospheric moisture (Baikal, Geneva);
• low-flow. Rivers also flow into them, but much fewer flow out. These lakes are located in an area with insufficient moisture (Balaton, Tanganyika);
• drainless. Formed in zones and. Rivers flow into such lakes, but not a single one flows out (, Dead Sea);
• deaf. They feed on rain or melt water, since rivers do not flow into them or flow out of them. These are small lakes and zones or craters. Outside these groups were karst lakes, since their nutrition is provided primarily by.

Lakes can also be divided into:

• fresh(their salinity does not exceed 1%o);
• salty(their salinity ranges from 1 to 47%o);
• (their salinity exceeds 47%o). From them, salts can precipitate (Elton, Baskunchak).

Salinity Dead Lake 270%©.

Ozer. In countries with warm climates, it fluctuates slightly throughout the year. In summer, the water temperature decreases with depth. In winter, the top layer of water cools below freezing, and the lake becomes covered with ice, and with depth the water temperature rises. The saltier the water, the lower its freezing point. Large and deep lakes take longer to freeze than shallow lakes. Thus, Baikal freezes only at the beginning of January, when all the reservoirs around have long been covered with ice.

According to their biological properties, lakes are divided into:

• to a depth of 1 m there are thickets of sedge, arrowhead, etc.;
• to a depth of 2-3 m - reeds, reeds;
• up to a depth of 4m - submerged plants: pondweed and others.
• lakes poor in nutrients. They are transparent, deep and cold;
• lakes with rich They are usually shallow, well warmed up;
• lakes, poor in life, with brown water that lacks oxygen.

Most lakes are characterized by abundant vegetation, especially in the coastal zone. It is arranged in tiers:
Lakes go through several stages in their development. In more humid climates they become overgrown and turn into. In dry climates, lakes dry out; they become salty and have poor vegetation.

The movement of water in lakes, as well as in the seas, manifests itself in the form of currents, but very slow ones, as well as waves reaching large sizes only in large lakes. For example, up to 2-2.5 m are observed in and on. When there are drops in different parts of the lake, standing waves are also observed.

Lakes play a very important role both in nature and in human life. Like the seas, they have a warming effect on the world. Lakes also influence the topography, since they also carry out erosion and accumulative work.

The science of limonology deals with the study of lakes. Based on their origin, scientists distinguish several types, including 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 formed in the East African Rift System, where a number of lakes were concentrated:

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

In their form, tectonic lakes are very narrow and deep bodies of water, with steep banks. Their bottom is usually located below ocean level. It has a clear outline, resembling a curved broken curved line. At the bottom you can find traces of various landforms. The shores of tectonic lakes are made of hard rocks and are poorly 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 uniform, but generally has a low temperature.

The largest tectonic lakes in the world

In the Suna River basin there are both large and medium-sized tectonic lakes:

• Randozero;
• Palier;
• Salvilambi;
• Sandalwood;
• Sundozero.

Among the lakes of tectonic origin in Kyrgyzstan, Son-Kul, Chatyr-Kul and Issyk-Kul should be mentioned. On the territory of the Trans-Ural Plain there are also several lakes formed as a result of a tectonic fault in 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, Biwa and Van.

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

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