Lake types. Tectonic lakes of Russia

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 (fishery, for water supply, for the extraction of salt, sapropel ore, therapeutic mud and so on.); 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. Probably about 2 million lakes in Canada and Alaska, about 100 thousand in Finland and 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.

bottom profile tectonic lakes sharply outlined, has the form 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 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 warming surface water low bottom temperatures are maintained, 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 and 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 were 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 - freshwater lake on South Eastern Siberia, it stretched from 53 to 56°N. 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 on earth fresh water- 23 thousand cubic km, which is 1/10 of the world's fresh water supply. 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. mountain ranges stretch here parallel to one another in the direction from the northwest to the southeast and are separated by basin-like depressions, along the bottom of which rivers flow and lakes are located in some places. The height of most of the ranges of Transbaikalia rarely exceeds 1300 - 1800, but most high 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, 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, average depth- 730 m. 336 permanent rivers and streams flow into Baikal, while half of the volume of water entering the lake comes from the Selenga. flows out of Baikal the only river- 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, 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 - big 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. This high transparency is due to the fact that Baikal water, due to the activity of living organisms living 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.

1.2 Tectonic lakes

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. Caspian lake 4 times more than White, almost 3 times more than Adriatic and 2 times - Aegean Seas. And the most deep lakes world - Baikal and Tanganyika - much deeper than our northern seas- 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 formed as a result of the uplift of the surrounding land. big Salt Lake in Utah, too, arose due to the tectonic uplift of the territory through which the runoff 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, formed about 17 million years ago and very different great depth(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.

1.3 Volcanic lakes

The term "volcanic lake" appeared in the volcanological literature not so long ago. Over the past 15 - 20 years large group researchers use it quite widely, putting the following meaning into the term: A volcanic lake is a reservoir that occupies part of a negative volcanic relief (volcanic crater, maar, explosion funnel, caldera, part of a valley blocked by a lava flow), in which, to one degree or another, they have the place of receipt of endogenous (from the bowels of the earth) energy and matter.

The share of this input can be reduced to a minimum at the moment (for example, cold lakes in maars), but in such lakes water interacts with igneous rocks, which undoubtedly affects their composition. In addition, there is always the possibility of the resumption of frozen volcanic processes.

Volcanic lakes are an integral part of volcanic processes and the landscape. The main distinguishing feature of such lakes is the presence in the balance of energy and matter of water bodies of a source from the depths of the Earth (often very powerful), which can significantly affect the hydrodynamic and hydrochemical processes in the lake. The volcanic lake is like a window through which you can "look" into the depths.

Especially often volcanic lakes are found in the famous Pacific volcanic ring, which includes the volcanoes of Kamchatka, the Kuril and Japanese islands, Malay Archipelago, Philippines, New Zealand, Andes, Cordillera, Alaska, Iceland. On Japanese islands almost half of the lakes volcanic origin. Volcanic lakes can be found in Europe, Africa, Australia and even Antarctica. Here, about 3 km from the Soviet Antarctic station Bellingshausen, there is a young volcanic crater filled with the waters of Lake Glubokoe.

Volcanic lakes often have diverse flora and fauna, which actively participate in the biogeochemical cycle of matter. Due to this, various bottom sediments are formed, which have different sources of formation. Often in volcanic lakes find layers of ash brought from other volcanoes. In the bottom sediments of lakes, many chemical elements accumulate, and highly mineralized waters are often liquid ore.

The presence of large volumes of water in the crater of the volcano creates a danger during eruptions, which are accompanied by the release of a huge amount of stones and dirt, as well as the formation of powerful lahars (hot mudflows from a volcanic structure). All this is extremely dangerous for the population living near such volcanoes. Widely known crater lake volcano Kelud on the island of Java. The Kelud volcano itself is low - a little more than 1730 m, its top is destroyed and is a crater filled with a lake. During a volcanic eruption, this lake boiled and splashed more than once. From the end of the 18th century to the beginning of the 20th century, this happened 10 times. At the same time, flows hot water and dirt flowed down, destroying everything in its path. In 1919 As a result of such a catastrophe, more than 100 villages were destroyed in a few moments and more than 5 thousand people died. Now the level of the lake with the help of tunnels has been lowered to 50 m.

Or grazing; b) soil and land resources - land and its top layer - soil, which has a unique property to produce biomass, are also considered as natural resource and as a means of production in crop production; c) plant food resources - resources of biocenoses that serve as a food base for grazing livestock; G) water resources- water used in crop production for irrigation, and in ...

Dedicated brook trout sanctuaries show that the restoration of a seemingly extinct species is possible. As we can see, the Perm region has rich resources for the development of hunting and fishing tourism. 2.2. Recreational use of specially protected natural areas IN Perm region the following reserves are represented: Vishera natural ...

The uniqueness of natural lakes lies in a number of their special characteristics. They are characterized by slow water exchange, free thermal regime, a peculiar chemical composition, and fluctuations in the water level.

In addition, they create their own microclimate and cause changes in the surrounding landscape. They accumulate mineral and organic substances, some of them have value and usefulness.

Geographical object "lake" (value)

There are about 5,000,000 lakes in our world. lakes on globe occupy almost 2% of the surface, which is almost 2.6 million km 3. As a component of the hydrosphere, classical natural lakes, are reservoirs natural origin, which are lake bowls with water that do not have direct contact (contact) with the sea or ocean. There is a whole science that studies them - limnology. However, there are also anthropogenic lakes that have arisen as a result of human activities.

If we consider the lake as geographical feature, then its definition becomes clearer: it is a hole on land with closed edges, into which flowing water enters and, as a result, accumulates there.

Characteristics of lakes

In order to give an accurate description of a particular lake, one needs to determine its origin, position (above or below ground), type of water balance (waste or not), mineralization parameters (fresh or not), its chemical composition, etc.

In addition, the following parameters must be precisely defined: total area water surface, the total length of the coastline, the maximum distance between opposite banks, the average width of the lake (calculated by dividing the area by the previous indicator), the volume of water that fills it, its average and maximum depth.

Types of lakes by origin

The generally accepted classification of lakes according to the factor of origin is as follows:

Anthropogenic (artificial) - created by man;
Natural - arose naturally (exogenous or endogenous - either from within the Earth, or as a result of processes on its surface), without human intervention.

Natural lakes, in turn, have their own division according to the principle of origin:

Tectonic - cracks in the earth's crust that have arisen for one reason or another are filled with water. by the most famous lake this type is - Baikal.
Glacial - the glacier melts and the resulting water creates a lake in the basin of the glacier itself or any other. Such lakes, for example, in Karelia and Finland: lakes appeared along the trajectory of the glacier along tectonic cracks.
An oxbow, lagoon or estuary - a decrease in the water level cuts off part of the river or ocean.
Karst, suffusion, thermokarst, eolian - leaching, subsidence, thawing, blowing, respectively, create a depression that is filled with water.
A dammed lake occurs when a landslide or earthquake cuts off part of the water surface from the main water body with a land bridge.
In mountain basins and craters of volcanoes or channels of their eruption, water often also collects.
And others.

The importance of lakes in nature and for humans

Lakes are natural reservoirs of water that can regulate river flow: take in excess water and, conversely, give it away with a general decrease in the water level in the river. A large water mass has a large thermal inertia, the action of which can significantly moderate the climate of nearby territories.

Lakes are an important object for fishing, organizing the extraction of salt, laying waterways. Water from lakes is often used for water supply. Reservoirs can be used to organize the energy reservoir of a hydraulic installation. Sapropels are extracted from them. Some lake muds have medicinal properties and are used in medicine. The importance of lakes in the planet's ecosystem can hardly be overestimated, they are an organic element of the entire natural mechanism.

The largest lakes in the world

Among the lakes, there are two main record holders:

The Caspian Sea is the largest in area (376,000 km 2), but relatively shallow (30 m);

(Lake Baikal)

Baikal - depth record (1620 meters!).

The average record holders in terms of size in the lake brotherhood are tectonic lakes.

Tectonic depressions arise as a result of movements of the earth's crust, and many lake basins of tectonic origin are large and ancient. 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 the Aegean. 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 trough at the bottom of the ancient Tethys Sea. In the Neogene, an uplift occurred, as a result of which the Caspian depression became isolated. 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.

A lake is a body of water that forms on the surface of the land. lakes do not have 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 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.
The average depth of the reservoir is set, and 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 divided into underground and surface. 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 difficult tectonic origin. Discontinuous, folded movements participated in their formation. All tectonic lakes are different 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 with transparent ice. This is due to the very clean and clear 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 Onega Island A: 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, have a large 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, equipped fishing spots. In very large lakes, such as Ladoga, fishing is carried out.