The lake is an element of the hydrosphere. This is a body of water that has arisen naturally or artificially. It is filled within its bed with water and does not have a direct connection to the sea or ocean. In the world there are about 5 million of such reservoirs.
general characteristics
In terms of planetology, the lake is an existing object stably in space and time, filled with a substance in liquid form. In a geographical sense, it is presented as a closed recess of the land into which water accumulates and where. The chemical composition of the lakes remains constant for a relatively long time. The substance filling it is renewed, but much less frequently than in the river. Moreover, the currents present in it do not act as the predominant factor determining the regime. Lakes provide regulation of river flow. Chemical reactions take place in the waters. During the interactions, some elements settle in the bottom sediments, others pass into the water. In some bodies of water, usually without runoff, the salt content increases due to evaporation. As a result of this process, a significant change in the salt and mineral composition of the lakes occurs. Due to the large thermal inertia, large objects soften the climatic conditions of the adjacent zones, reducing seasonal and annual meteorological fluctuations.
Bottom sediments
During their accumulation, significant changes in the relief and sizes of lake basins occur. With the overgrowing of water bodies, new forms are formed - plain and convex. Lakes often form barriers to groundwater. This, in turn, causes waterlogging of adjacent land areas. In the lakes there is a continuous accumulation of mineral and organic elements. As a result, thick sedimentary strata are formed. They change in the course of further development of water bodies and their transformation into land or swamps. Under certain conditions, bottom sediments are transformed into mountain minerals of organic origin.
Education Features
Ponds arise for a variety of reasons. Their natural creators are wind, water, tectonic forces. On the surface of the earth, basins can be washed out with water. Due to the action of the wind, a depression is formed. The glacier polishes the hollow, and the mountain collapse damages the river valley. So it turns out a bed for the future reservoir. After filling with water, a lake appears. In geography, water bodies are classified depending on the method of formation, the presence of life, and the concentration of salts. Only in the most saline lakes there are no living organisms. Most of the reservoirs are created due to displacements of the earth's crust or volcanic eruptions.
Classification
By their origin, water bodies are divided into:
- Tectonic lakes. They are formed due to the filling of cracks in the crust with water. Thus, the Caspian Sea, the largest lake in Russia and the entire planet, was formed by displacements. Before the rise of the Caucasus ridge, the Caspian Sea was associated with the Black. Another example of a large-scale fault is the East African Rift Structure. It extends from the southeast region of the continent to the north to the southwest of Asia. Here lies a chain of tectonic lakes. The most famous are Lake. Albert, Tanganyika, Edward, Nyasa (Malawi). The Dead Sea belongs to the same system. It is considered the lowest tectonic lake in the world.
- River ponds.
- Seaside lakes (estuaries, lagoons). The most famous is the Venetian lagoon. It is located in the northern region of the Adriatic Sea.
- Disastrous lakes. One of the features of some of these reservoirs is their periodic appearance and disappearance. This phenomenon depends on the specific dynamics of groundwater. A typical example of a karst lake is Lake. Ertsov, located in South. Ossetia.
- Mountain ponds. They are located in the spinal basins.
- Glacial lakes. They form when the thickness of the ice is shifted.
- Dam Lake. Such ponds are formed during the collapse of the mountainous part. An example of such a lake is Lake. Ritsa, located in Abkhazia.
Volcanic ponds
Such lakes are located in extinct craters and explosion tubes. Such ponds are found in Europe. For example, volcanic lakes are present in the Eifel region (in Germany). Near them, a weak manifestation of volcanic activity in the form of hot springs is noted. The most common type of such lakes is a crater filled with water. Oz. The crater of Mazama Volcano in Oregon was formed more than 6.5 thousand years ago. Its diameter is 10 km and its depth is 589 m. Some of the lakes are formed in the process of blocking volcanic valleys by lava flows. Gradually, water accumulates in them and a reservoir forms. So, for example, appeared lake. Kivu is the hollow of the East African Rift Structure, located on the border of Rwanda and Zaire. Once flowing out of the lake. Tanganyika River 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 hollow.
Other species
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, for storing 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 Lake. Nasser, located on the border of Sudan and Egypt. It was formed by damming the river valley. Nile. Another example of a large artificial lake is Lake. Mid. It appeared after the installation of the dam on the river. Colorado. As a rule, such lakes serve local hydroelectric power stations and provide water to nearby settlements and industrial zones.
The largest glacial tectonic lakes
One of the main reasons for the formation of water bodies is the movement of the earth's crust. Due to this displacement, glaciers creep in some cases. Ponds are very common on the plains and in the mountains. They can be found both in basins and between hills in depressions. Glacial-tectonic lakes (examples: Ladoga, Onega) are quite common in the Northern Hemisphere. Avalanches left rather deep depressions after themselves. Melted water accumulated in them. Deposits (moraine) dammed the depressions. Thus, reservoirs were formed in the Lake District. At the foot of Bolshoi Arber is located lake. Arbersee. This body of water remained after the ice age.
Tectonic lakes: examples, characteristics
Such ponds are formed in areas of crustal faults and faults. Usually, the tectonic lakes of the world are deep and narrow. They are distinguished by steep straight-line shores. These bodies of water are found mainly in through deep gorges. The tectonic lakes of Russia (examples: Kurilskoye and Dalnee in Kamchatka) are distinguished by a low bottom (below the oceanic level). So, lake Kurilskoye is located in the southern part of Kamchatka, in a picturesque deep hollow. 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. From the reservoir flows p. Lake. Hot springs come to the surface along the shores. In the center of the lake there is a small elevation - an island. It is called the "heart-stone." Not far from the lake there are unique pumice deposits. They are called Kutkhins baht. Today Lake Kurilskoye is a nature reserve and declared a zoological natural monument.
Bottom profile
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 sharpness of the lines of the basins. However, in some cases, the impact can be quite noticeable. Glaciers-tectonic lakes may have a bottom covered with "scars", "ram's foreheads." They are quite visible on the islands and rocky shores. The latter are composed mainly of hard rock. They are slightly susceptible to erosion, which, in turn, leads to a low rate of accumulation of precipitation. Such tectonic lakes of Russia 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 (up to 5 m) - 15-20%. Tectonic lakes are characterized by heterogeneity of water according to thermal indicators. During maximum surface warming, a low temperature of bottom waters is maintained. This is due to stable thermal stratifications. Vegetation is quite rare. It can be found along the shores in enclosed bays.
Spread
Where, besides Kamchatka, are tectonic lakes found? The list of the most famous reservoirs in the country includes such entities as:
- Sandalwood
- Sundozero.
- Palle.
- Randozero.
- Salvilambi.
These reservoirs are located in the basin of the Suna River. Tectonic lakes also occur in the forest-steppe Trans-Urals. Examples of water bodies:
- Welgie.
- Argayash.
- Shablish.
- Silence.
- Sugoyak.
- Kaldy.
- B. Kuyash and others.
The depth of water bodies on the Trans-Ural Plain does not exceed 8-10 m. By their origin they are referred to lakes of an erosion-tectonic type. Their depressions were modified, respectively, under the influence of erosion processes. Many bodies of water in the Trans-Urals are confined to ancient river basins. These are, in particular, tectonic lakes such as Kamyshnoye, Alakul, Peschanoe, Etkul and others.
Unique pond
In the southern part of Eastern Siberia there is a lake. Baikal is a tectonic lake. Its length is more than 630 km., And the length of the coastline is 2100 km. The width of the reservoir varies from 25 to 79 km. The total area of the lake is 31.5 square meters. km This pond is considered the deepest on the planet. It contains the largest volume of fresh water on Earth (23 thousand m 3 ). This is 1/10 of the global stock. Full renewal of water in the reservoir occurs over 332 years. Its age is about 15-20 million liters. Baikal is considered one of the oldest lakes.
Terrain
Baikal lies in a deep depression. It is surrounded by mountain ranges covered with taiga. The terrain near the reservoir has a complex, deeply dissected relief. Not far from the lake itself, a marked expansion of the mountain strip is noted. Ranges run here parallel to each other in the direction from the northwest to the southeast. They are separated by hollow depressions. River valleys run along their bottom, and small tectonic lakes are formed in some places. Displacements of the earth's crust take place in this area today. This is indicated by relatively frequent earthquakes near the basin, outcrops of hot springs, as well as the sinking of large areas of the coast. The water in the lake is blue-green. It is characterized by exceptional transparency and purity. In some places, you can clearly see stones lying at a depth of 10-15 m, overgrown with algae. A white disc lowered into the water is visible even at a depth of 40 m.
Distinctive features
The shape of the lake is a crescent moon. The reservoir stretched between 55 ° 47 'and 51 ° 28' sowing. latitude and 103 ° 43 'and 109 ° 58' east longitude. The maximum width in the center is 81 km, the minimum (opposite the Selenga River Delta) is 27 km. The lake is located above sea level at an altitude of 455 m. 336 rivers and streams flow into the body of water. Half of the water enters it from the river. Selenga. One river flows out of the lake - the Angara. However, it should be said that in the scientific community there are still discussions about the exact number of flows flowing into the body of water. Most scientists 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. Various diseases were treated with Baikal water. In spring, its transparency is higher. In terms of indicators, it is approaching the standard - the Sargasso Sea. In it, water transparency is estimated at 65 m. During the period of mass flowering of algae, the lake indicator decreases. Nevertheless, even at this time in the calm 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 weakly mineralized. Water is similar in structure to distilled. The importance of Lake Baikal is hard to overestimate. In this regard, the state provides special environmental protection to this area.