Lakes of tectonic origin. Tectonic lakes: examples, list. The largest glacial-tectonic lakes

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

general characteristics

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

Bottom sediments

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

Features of education

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

Classification

According to their origin, reservoirs are divided into:

Volcanic reservoirs

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

Other types

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

The largest glacial-tectonic lakes

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

Tectonic lakes: examples, characteristics

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

bottom profile

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

Spreading

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

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

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

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

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

Unique body of water

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

terrain

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

Distinctive features

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

Water

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

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.

1. Water surface area.
2. Coastline length.
3. 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.
4. The volume of the basin, which is filled with water, is determined.
5. Installed average depth reservoir, 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 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 complex 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.

In disposition tectonic lakes some regularity can be traced: 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.

1. 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.
2. 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.
3. 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 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, 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 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. Here 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.

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. Greatest depth lakes 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 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 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. 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. 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.).

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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:

1. Anthropogenic (artificial) - created by man;
2. 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 an energy reservoir for a hydroelectric 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.