How to distinguish a salt lake from a fresh one. Why is the sea salty and some lakes even saltier

We remember: What sources feed the lakes? What is evaporation? Keywords:feeding of lakes, waste and endorheic lakes, fresh and salt lakes.

1. Waste and endorheic lakes. The lakes are fed by river, underground runoff and atmospheric precipitation. Depending on the flow of water, the lakes are sewage and endorheic. Lakes with river flow, that is, from which rivers flow, are s t o c h n e lakes, and lakes that do not have a runoff - b i s t o c h n e. Waste lakes are located mainly in areas of excessive moisture, drainless - in areas of insufficient moisture.

The level of lakes in connection with the inflow and outflow of water does not remain constant, it changes. Especially large fluctuations in the level of lakes are observed in arid and dry regions. Changes in the area of lakes are associated with this.

** The Australian Lake Eyre North in the rainy season of wet years is a large body of water up to 9300 km 2, and in the dry seasons of dry years, water is retained only in a few bays in the southern part of the lake.

Fresh and salt lakes. According to the amount of dissolved substances, lakes are divided into fresh(salt content less than 1 g per liter of water), salty(from 1 to 24 g of salts per liter) and salty, or min eral(salt content more than 24 g per liter of water). In lakes with high salinity, salts precipitate. Usually sewage lakes are fresh, as the water in them is constantly updated. Endorheic lakes are most often brackish or salty. This is because evaporation dominates the water flow of such lakes. All minerals brought by rivers and groundwater remain and accumulate in the reservoir.

** One of the largest salt lakes on Earth - the Great Salt Lake in North America (salinity from 137 to 300 0 / 00) (Fig. 131). The most salty lake in the world is the Dead Sea - the maximum salinity is 310 ppm.

As a result of sediment deposition and vegetation overgrowth, lakes gradually become shallow, and then turn into swamps. They, like rivers, are the most important natural wealth. Lakes are used for navigation, water supply, fishing, irrigation, recreation, treatment, and obtaining various substances.

1. What are the lakes in terms of water consumption and salinity? 2. Why is the water in endorheic lakes most often brackish or salty? 3. Name the largest lake in your area. How is it used by the local population?

Practical work.

Divide these lakes into two groups (drainage and drainless): Baikal, Caspian Sea, Ladoga, Onega, Victoria, Tanganyika, Aral Sea, Chad, Air North.

Draw a sewage and drainless lake?

3. Describe on the map one of the world's lakes according to the plan (see Appendix 2).

& 45. Glaciers

We remember: What land waters have we studied? Remember what glaciers are. Name the properties of ice .

Keywords:snow, glaciers, continental and mountain glaciers, moraine

1. Glaciers and their formation. Accumulations of ice on the earth's surface are glaciers. They do not have the ice that covers our rivers and lakes in winter.

* On Earth, glaciers occupy an area of about 16.1 million km 2, which is approximately 11% of the land. Glaciers are found in all latitudes, but the largest area of glaciation occurs in the polar regions.

Glaciers are formed as a result of the accumulation and transformation of solid atmospheric precipitation, mainly snow. If more snow falls than it can melt, it accumulates, compacts and turns into transparent bluish ice.

Rice. 132. Scheme of the structure of the glacier

* The height at which as much snow falls in a year as it melts is called the snow boundary (line). In tropical latitudes, the snow limit is located at an altitude of 5000 - 6000 m and drops to the ocean level in polar latitudes. Below this limit, during the year less snow falls than can melt, and therefore its accumulation is impossible. Higher, due to low temperatures, snowfall exceeds its melting, and snow accumulates and transforms into ice. Here is the feeding area of the glacier. From here, ice, being a plastic substance, flows down in the form of a glacial tongue (Fig. 132).

Glaciers are moving slowly. The speed of movement of glaciers in most mountainous countries is from 20 to 80 cm per day, or 100 to 300 m per year. In the ice sheets of Greenland and Antarctica, the ice moves even more slowly - from 3 to 30 cm per day (10 - 130 m per year).

2. Cover and mountain glaciers. Glaciers are divided into cover and mountain.

C o r o v n e, or ma t e r i k o v e, glaciers occupy the surface of the land, regardless of its relief, which does not affect the shape of the glacier (Fig. 133). They have a plano-convex surface in the form of domes or shields. Ice accumulates in the middle part and slowly spreads to the sides. Glacier tongues often descend to the coastal part of the ocean, as, for example, in Antarctica. In this case, blocks of ice break off from it, turning into floating ice mountains - icebergs (Fig. 134).

Rice. 134. Formation of icebergs

The height of icebergs above the water surface is on average 70 - 100 m, most of them are under water.

** One of the icebergs off the coast of Antarctica was 45 km wide and 170 km long with an ice thickness of more than 200 m.

Icebergs move under the influence of currents and winds to warmer latitudes, where they melt. They are dangerous for navigation. Modern ships are equipped with means of their detection.

Continental ice sheets are developed in Antarctica and Greenland, on the islands of the Arctic Ocean. Ice sheets once extended across most of Europe, northern Asia, and North America.

Rice. 133. Ice sheet of Antarctica

* Continental glaciers occupy 98.5% of the area of modern glaciation. Antarctica is almost completely covered with ice (the area not covered with ice is 5% of the total). The average thickness of the ice cover of Antarctica is 2200 m, the maximum is 4776 m. A powerful ice sheet is carried by the island of Greenland .

Mountain glaciers, unlike coverslips, are smaller and differ in a variety of shapes. The shape of mountain glaciers is determined by relief. Some, like caps, cover the peaks, others are located in bowl-shaped depressions on the slopes, and others fill the mountain valleys (Fig. 135).

Rice. 135. Mountain glaciers

* The most common are valley mountain glaciers, which move down from the feeding areas along mountain valleys. They can receive tributaries and have icefalls. The thickness of mountain glaciers is usually 200 - 400 m. The world's largest mountain glaciers are the Malaspina glacier in Alaska in North America (100 km long) and the Fedchenko glacier in the Pamirs in Asia (71 km).

3. Significance of glaciers. Glaciers have large reserves of fresh water. They contain many times more water than rivers and lakes combined. Mountain glaciers often feed streams and rivers.

Glaciers, like flowing waters, change the relief of land. During their movement, they develop glacial valleys, expand and deepen them, erase irregularities that impede their movement, demolish loose rocks, transfer and deposit various materials in other places. At the same time, the work of glaciers takes place where there are no rivers - in high-mountainous and polar countries.

Solid material transported and deposited by glaciers is called sea. Moraine consists of sands, sandy loams, loams, clays, gravel, boulders and is deposited during the melting of glaciers. It composes moraine plains, ridges, hills, uplands (Fig. 136).

1. What natural formations are called glaciers? 2. What is a snow border? 3. How do continental (cover) glaciers differ from mountain ones? 4. What is the importance of glaciers? 5*. Show on a pie chart the ratio of continental and mountain glaciers.

Geography lesson in 6th grade

Teacher: Neborak T.I.

Lesson topic: "Blue Eyes of the Planet" ( lakes).

Target: get acquainted with the variety of lakes of our planet and their origin.

Tasks:

educational: to form students' ideas about the lake, types of lake basins, waste and drainless, fresh and salt lakes;

developing: development of individual cognitive interests of students;

educational : to instill in students a sense of love for their homeland, pride in their land.

Lesson type: explanation of new material.

At the end of the lesson the student should:

Know: what is a lake; types of lake basins; waste and non-drainage, salt and fresh lakes;

Be able to: show lakes on the map.

Technologies: lesson using ICT and problem-based learning.

Equipment:

TCO tool: computer, projector, screen.

Didactic and visual material: Route sheets, textbooks, a map of the hemispheres and a physical map of Russia, atlases, slides are shown in parallel.

Lesson stages: 1. Organizational

2. The study of new material with a phased consolidation.

3. The results of the lesson.

4. Homework

During the classes.

1. Organizational.

Hello guys! Today I will teach geography lesson - Tatyana Ilyinichna Neborak. I hope that our cooperation will be not only pleasant, but also fruitful.

2. Learning new material.

(against the background of music).

Teacher. Listen and guess the riddle that will tell us the topic of today's lesson. Slide number 1.

There is a mirror in the middle of the field.

Blue glass, green frame.

Young mountain ash look at him,

Colored their own, directing headscarves

Young birch trees look at him,

Straightening her hair in front of him.

And the month, and the stars - everything is reflected in it ...

What is this mirror called? (Lake).

Teacher. Right. This lake. The topic of our lesson is “The Blue Eyes of the Planet”. (Lakes). Slide number 2.

Teacher. During the lesson, we will consider the following questions:

The variety of lakes of our planet and their origin;

Which lakes are called sewage, and which are drainless;

Let's get acquainted with the concepts of salt and fresh lakes. Slide number 3.

Teacher. We will keep notes in the lesson today not in notebooks, but in Route sheets, ( Annex No. 1) that are on your desk. Slide number 4.

Teacher. Our study road is long and therefore we set off without delay.

Teacher. Guys, which of you saw the lake? Hands up.

Teacher. I invite you to close your eyes for a few seconds and imagine a lake. (Music). Now let's open our eyes and tell what we saw. Before my eyes, the lake was round and shallow. And what word do you associate it with? (small and large, deep and shallow, etc.). (children's answers)

Exercise. Try to formulate the definition of the concept of "lake".

(Children answer).

Teacher. Let's compare with the definition that the authors of the textbook offer us. p. 95. Who was the first to find the definition?

A lake is a closed body of water formed on the land surface in a natural depression.

We write down the definition in the Route sheet. Slide number 5.

Teacher. This depression is called the lake basin.

Teacher. Guys, the lake is not part of the ocean, like the sea. (explanation)

Teacher. We have already found out that a lake is a natural depression or a lake basin formed on the earth's surface. What natural processes and phenomena can lead to the formation of lake basins? Yes, the question is complicated, but we will try to answer it now.

For further work, we will need atlases on page 16 "Physical map of Russia".

Teacher. So, attention to the screen.

Teacher's story.

Tectonic in troughs (residual). They were formed due to the slow sinking of vast areas of the earth's crust, which were filled with water. (Aral, and the largest lake in the world - Caspian). Slide number 6,7.

2. Tectonic in faults. During the movement of sections of the earth's crust, faults were formed, which were filled with water. As a rule, such lakes are very deep. (Tanganyika, Nyasa on the African mainland. What do you think, but in Russia there are such lakes). - The deepest lake is Baikal. It is unique. It knows no equal in fame and glory. The greatest depth is 1620m. Baikal contains one tenth of the fresh water of the entire Earth. In terms of water transparency, Baikal ranks first in the world. 336 rivers and streams flow into the lake, and one Angara flows out. Slide number 8,9.

3. Lakes of glacial origin were formed on the site of depressions deepened by a glacier. (Onega. Lake Ladoga has a glorious history: during the Great Patriotic War, the Road of Life passed through its ice - the only connection between the country and besieged Leningrad).

Slide number 10,11.

4. Dams were formed as a result of a collapse or shedding of rocks into the river valley, an example is Lake Sarez in the Pamirs.

(Student's story). On a February night in 1911, the inhabitants of Bartang woke up from an incredible rumble coming from the bowels of the earth. The rumble was accompanied by a deafening stone rumble. It seemed that somewhere above an invisible genie was raging, breaking the Pamir giant. Giant fragments of rocks flew from the peaks. Frightened people felt as if they were on unsteady waves; the ground was moving underfoot. There was a strong earthquake. And over the village of Usoy, clouds of large dust swirled for several days. And when the dust cleared, in the riverbed people saw a miraculous stone wall half a kilometer high. A wall formed from fragments of rocks blocked a stormy river. This is how the Sarez Lake was born in the Pamirs. Slide number 12,13.

5. Volcanic. Their lake basins are located in the crater of extinct volcanoes. (Kronotskoye, Kurilskoye.) Slide number 14,15.

6. Lakes-oxbow lakes are often found in floodplains, they are the remains of former river channels. These lakes are small, so they are not marked on the map. They have an arched shape. Slide number 16.

7. Karst. Easily soluble rocks (limestone, salt, etc.) are found in the earth's crust and on its surface. When they dissolve, voids, caves are formed, and hollows are formed on the earth's surface, which are filled with water. (Many in the Urals, Caucasus). Slide number 17.

Dynamic pause. (Close screen)

Teacher. There is a table "Types of lake basins" in the Route sheets. Working with the textbook pp. 96-97 and based on the material that I told you, you fill in the table. We will work in pairs. I gave you cards in advance, on which only one type of origin of lake basins is written. You will describe it.

Guys, pay attention to the example of filling. Slide number 18.

Basin type	Reason for education
Tectonic in troughs	Subsidence of vast areas of the earth's crust	Aral, Caspian
Tectonic in faults	Lowering sections of the earth's crust along the fault	Baikal, Nyasa, Tanganyika.
Glacial	The basin is deepened by ancient glaciers.	Onega, Ladoga.
Zaprudnye	The riverbed is blocked by a collapse or flow of hardened lava.	Sarez.
Volcanic	Craters of extinct volcanoes	Kronotskoye, Kurilskoye.
Karst	It is formed after the failure of the upper layer covering the underground cavity, and fills it with water.
	Sections of the former river bed that has changed its direction.	Small ones are not marked on the maps.

Teacher. Did you complete the task? Now let's make a general table.

(Those who wish to report on the work done in groups).

Teacher. Guys, do you know the name of the lakes of the Kargat region? (Eastern part of Lake Ubinskoye, Kargan, Small and Big Toroky, Atkul, Kankul, Kayly, Bizura). The lakes of our region are the remains of an ancient lake system. Slide number 19.

Teacher. A lake is a depression filled with water. Where do you think the water in these recesses comes from? What do lakes feed on? (precipitation by atmospheric, groundwater, waters of inflowing rivers). Slide number 20,21.

Teacher. All lakes can be divided into 2 groups according to the inflow and outflow of water.

In the diagram you see lakes and rivers. Please note that rivers can flow into and out of lakes .

Children's answers.

Teacher. We have two new concepts: waste and drainless lakes. Let's try to formulate definitions. Slide number 22.

A wastewater lake is a lake into which rivers flow in and out (or only flow out)

Endorheic lakes - lakes into which rivers only flow.

Teacher. What type of lakes do you think Lake Baikal belongs to? (children's answers)

Why? (children's answers)

Examples of sewage lakes are also Onega and Ladoga lakes.

What type of lakes does the Aral Sea-Lake belong to? (children's answers)

Why? (children's answers)

Examples of endorheic lakes are also the Caspian and Balkhash.

Write examples of lakes in the table. Slide number 23.

	Baikal, Onega, Ladoga
Drainless	Caspian, Balkhash, Aral

Teacher. Lakes differ not only in the flow of water, but also in the presence of salts. Let's remember, what is salinity? (the amount of minerals in 1 liter of water). And what does it express? (in ppm-thousandths of a number). Slide number 24,25.

Teacher. All lakes can be divided into two groups according to salinity: fresh - up to 1% o; salty - from 1%o to 35%o. Fresh on the map are indicated in blue, salty in pink.

Teacher: Find Lake Balkhash in the atlases. Pay attention to its color. Part of the lake is colored blue and the other pink. Why do you think? (salty lakes are most often endorheic, since mineral substances brought by rivers gradually accumulate in lakes)

Teacher. Is Lake Baikal fresh or salty? ? (children's answers)

Exercise: write examples of lakes in the table.

	Baikal, Ladoga, etc.
	Balkhash, Caspian, Dead (270 ppm)

Student reports about Dead Lake. Slide number 26. Listen to what a person who has visited its shores tells about one of the most saline lakes, Dead Lake: “We stood on a deserted shore, the dull look of which evoked sadness: a dead land - no grass, no birds. On the other side of the lake reddish mountains rose steeply from the green water. We decided to swim, but we were dissuaded. We only washed ourselves with water thick as a steep brine. A few minutes later, the face and hands were covered with a white coating of salt, and an unbearably bitter taste remained on the lips. Sometimes fish swim from the Jordan River into the Dead Lake. She dies in a minute. We found one such fish thrown ashore. She was hard as a stick, in a strong salty shell.

Teacher. How do people use lakes? Slide number 28.(fishing, for navigation, waterfowl are bred, salt is mined, the coast of lakes is a favorable zone not only for life, but also for recreation, recovery of health).

Teacher. Lakes have been used by humans since ancient times. But today, like other water bodies, many lakes are polluted with oil products, industrial and domestic waste, and pesticides from the fields. The “blue eyes” of the planet, including the lakes of the Kargat region, ask for help from people, shedding clean tears.

Slide number 29. Even the tiniest lake filled with “living water” should be treated as a most valuable gift in order to bring this cup of priceless life-giving moisture to future generations.

3. The results of the lesson.

Teacher. Our lesson is coming to an end. I would like to know how successful it was. Answer the questions: What did you learn? what have you learned? Start your answers with... Slide number 30.

I found out…

I can…

4. Homework. Slide number 31. Now pay attention to homework. Read 31 paragraphs, describe the lake Baikal according to a standard plan (on route sheets). Prepare messages about unusual lakes of the world (optional). (they do not write down in the diary because the homework is written on the route sheets).

And yet, I would like to know the attitude to the lesson of each of you. Choose the emoticon that most clearly reflects your mood. And I, in turn, will give you my emoticons as a keepsake of this lesson.

Thank you for the lesson. Slide number 32.

Route sheet

Lesson topic: “ Blue eyes of the planet”(lakes).

Lake - _____________________________________________________________________

_____________________________________________________________________________

Types of lake basins

Basin type	Reason for education	Examples
Tectonic in troughs (residual)
Tectonic in faults
Glacial
Zaprudnye
Volcanic
Karst

According to the consumption and income of water


Drainless

Salinity

Fresh up to 1%o
Salty from 1%o and above

Homework: read the text of the textbook item 31, using the plan to describe Lake Baikal, prepare messages about unusual lakes (optional).

Fill in the table:

Description of Lake Baikal according to a standard plan

Lake description plan	Characteristics of the lake
1. Name
2. What continent is it on and in what part of it
3. Between which meridians and parallels is
4. Origin of the basin
5. Waste or drainless. Inflowing and outflowing rivers
6. Salty or fresh

Unusual lakes of the world: ink lake, pan lake, burning lake, ghost lake, asphalt lake, sweet lake.

The lake is one of the components of the hydrosphere, the water shell of the Earth. Lakes are natural bodies of water. They are a kind of bowl (lake bed), filled to the brim with water. There are more than five million lakes on Earth, the total area of which is more than 2.7 million square meters. kilometers.

The science of planetology defines a lake as an object that is stable

existing in time and space and filled with liquid matter. The size of the lake, according to the same science, is the average between the sea and the pond. If we consider the lakes from the point of view of geography, then this is a depression in the earth's surface into which water flows and accumulates. It is important to know that such reservoirs are not part of the oceans.

The chemical composition of lake water is considered to be quite stable. Water in the lakes practically does not circulate, so the fill fluid is updated quite rarely. Lakes perform an important function - they retain water in their basins and release them at different times.

Such reservoirs have significant thermal inertia, therefore, contribute to climate mitigation in adjacent areas. In lakes, processes of accumulation of sediments (minerals and) are constantly taking place, which in turn form bottom sediments. During the subsequent development of the reservoir, bottom sediments can be transformed into land, swamps, or mountain sediments.

Large lakes are able to have a mitigating effect on the climatic conditions of adjacent territories. The lakes that exist on the planet are classified according to several criteria. They can be ground and underground, mountain, river, crater, failure. They can be anthropogenic, that is, artificial and natural. According to the water balance, they are divided into waste and non-drainage.

endorheic lakes

On Earth, there are many land areas with river systems that are not connected to the oceans. River basins located in such areas are called endorheic basins. And the bottom of such pools is, as a rule, an endorheic lake. Science gives the following definition: a drainless lake is a body of water that does not have a drain underground and surface runoff. Simply put, one or more rivers can flow into such reservoirs, but none of them flow out.

Endorheic lakes are formed in areas with an arid climate, where moisture is much lower than evaporation. Endorheic lakes are scattered all over the planet, they are on all continents, even in Antarctica. There, such lakes are located on the territory of the land of Victoria and the dry McMurdo Valley.

The most famous are Frixell, Vostok, Ellsworth, Don Juan. The area of Lake Fryxell is 7 sq. km, and its entire surface is permanently covered with ice about 5 meters thick. Vostok is the largest subglacial freshwater lake in Antarctica. Its uniqueness lies in the fact that for several million years it was isolated from the surface of the Earth. Don Juan is a very small lake, interesting, first of all, because it currently claims the status of the most salty lake in the world. The salt content in Lake Friksell is more than 40%, the salinity of the famous Dead Sea is slightly less than 35%. Due to the high salt content, the reservoir does not freeze even at a temperature of -53 degrees.

Another amazing fact about Fixell: its waters contain a lot of nitrous oxide, which appears as a result of the vital activity of microorganisms. Meanwhile, scientists failed to detect a single microorganism in the waters of the lake.

Lake Wanda- Another one of the mysteries of Antarctica. The fact is that, despite the low ambient temperatures, the waters of the lake always maintain a temperature of about +26 degrees. The reason was unknown until recently, and only recently scientists found out that the water is simply heated by the Sun. This happens because the ice above the lake has the shape of a lens, which means it focuses the sun's heat.

In Australia, such reservoirs include Air, Corangamite, George, Torrens. In North America - Pyramid Lake, Sevier, Mona, Atitlan. The inner basin is a large part of Central and Western Asia. Sasykkol, Balkhash, Zhalanoshkol, Issyk-Kul are located on this territory. The Caspian and Aral Seas are by origin not seas, but residual lakes, relics formed after the disappearance of the ancient Tethys Ocean.

Baikal- the largest freshwater lake in Russia, is the deepest in the world. The water in it is so clean and transparent that objects can be found at a depth of 40 meters. This lake is one of the oldest on Earth, it was formed 20-25 million years ago. 336 rivers flow into it, but only one flows out - the Angara. Thus, Baikal is a sewage lake.

Endorheic lakes are almost always salty. This is explained by the fact that no rivers flow out of them that could carry this salt.

Waste lakes

Waste lakes are lakes that have a runoff (as a rule, these are rivers). Most of the lakes of this type are located in areas with a temperate and humid climate. Interestingly, several rivers can flow into such reservoirs, and only one can flow out. Dissolved substances (such as salt) are removed from the waters with the help of effluents. However, in some lakes, water exchange can be slow, which leads to salt accumulation and other biochemical processes. The way the water changes in a reservoir determines the amount of water in the lake, its chemical composition, and its ability to self-purify.

One of the subspecies of sewage lakes are flowing. They differ in that the flowing river carries away about the same amount of water as the flowing river brings. The flowing ones include Chudskoye, Kubenskoye, Zaisan. Water consumption in such lakes occurs mainly due to runoff and evaporation. Flow in these lakes is one of the most important characteristics, as it affects the filling, composition and water exchange. The largest lake on our planet is the Caspian Sea. Despite the presence of the word "sea" in the name, technically the Caspian is not one. The fact is that the sea is part of the oceans. If completely separated from the ocean by land, then this is a lake. The area of the Caspian Lake is 371,000 square kilometers.

Fresh lakes

Lakes are divided into several categories according to different criteria. By mineralization, they are divided into fresh, ultra-fresh, brackish and salty. Fresh lakes are those lakes, the salt content in the waters of which is minimal, that is, less than 1%. Freshwater lakes can be both sewage and flowing. Drainless - always salty.
There are tens of thousands of freshwater lakes on the planet, some of them have truly amazing characteristics, have a unique location and an interesting history. In the country of Nicaragua, for example, there is a lake with the same name. It has a tectonic origin, an area of about 8 thousand square kilometers. The uniqueness of Nicaragua is that it is the only freshwater lake on our planet in which sharks live. The distance from the lake to the Pacific Ocean is very small, so scientists admit that earlier the territory on which the reservoir is located was a bay of the sea.

Another amazing creation of nature is Lake Titicaca. It is located at an altitude of 4000 meters above sea level, and was also once part of the oceans. More than three hundred rivers flow into it, most of which flow from glaciers. Titicaca was studied by scientists who came to the conclusion that thousands of years ago the lake was much lower - at an altitude of about 250 meters. Then the reservoir was a sea bay, and its waters are still inhabited mainly by marine species of crustaceans and fish.
Fresh lakes located in a hot thermal zone are distinguished by the fact that the water near their surface is warm. As the depth increases, the water temperature decreases. The name of this phenomenon is direct thermal stratification. Interestingly, the lakes that are in the cold zone have the water with the lowest temperature (about 0 degrees Celsius), but the greater the depth, the higher the temperature. If the temperature in a body of water is distributed in this way, it is called reverse thermal stratification.

Interesting Facts:

If you pay attention to the geographical map of the world, you will notice that some lakes are marked in blue, while others are purple. This is explained simply - fresh lakes are highlighted in blue, salty lakes are purple.
There are more fresh lakes on our planet than salty ones.
The world's largest freshwater lake is located in North America. This is Lake Superior, it is part of the Great Lakes group.
There are also peculiar "record holders" for salinity. These are water bodies, the salt content of which is more than 25 grams per liter. Examples are Ace (Turkey), Air (Australia), Dus-Khol (Tuva).
The most unsalted lakes are those that are in mountain glaciers.
One of the saltiest is Lake Tuz. It is 80 km long and about 45 km wide. When the lake overflows, it becomes huge - up to 25 thousand square kilometers. The salt content in its waters reaches 322 grams per liter of water.
The most salty and deepest is the Dead Sea. Its depth in some places reaches 400 meters. The salt content in it is 437 grams per liter of water.
There are some amazing lakes on the planet. For example, Balkhash, one part of which is salty and the other is fresh. And Lake Chad, located in Africa, is fresh from above, and closer to the bottom is salty. This is explained by the fact that fresh water (rain) does not mix with salt water when it enters the lake. Thus, Lake Chad is two-layered.
The largest basins, in which lakes subsequently formed, are of tectonic origin.

Lakes are depressions in the land filled with water, which arose naturally and occupy about 2% of the entire land. On the territory of Russia are located the deepest lake - Baikal and the largest lake in the world - the Caspian.

People use lakes for water supply. The lakes serve as communication routes, they are full of fish. At the bottom of some lakes, valuable minerals have been found: iron ores, salts, sapropel. The shores of the lakes are equipped for people's recreation, sanatoriums and rest houses have been built there.

Lake types

Lakes according to the nature of the runoff are divided into:

a) drainless;

b) waste.

Many rivers flow into flowing lakes and flow out of them, for example, they include Onega and Ladoga lakes. A waste lake is a lake that is replenished with water from a large number of rivers, and only one river originates from it. Lakes Baikal and Teletskoye belong to this type. Endorheic lakes are located mainly in arid regions and in the tundra, not a single river flows out of them. Representatives of such lakes are the Caspian, Aral, Balkhash.

Lake depressions arose as a result of various natural processes. The hollows that have arisen under the influence of the internal forces of the Earth are called endogenous. These include tectonic and volcanic. This is the origin of most large lakes in the world. Lakes that have arisen as a result of the activity of external forces are called exogenous, they are mainly shallow lakes. Tectonic basins were formed in places of sunken sections of the earth's crust. They could be formed as a result of faults along the cracks in the earth's crust or the deflection of its layers. In tectonic basins, the following lakes were formed: Aral - due to the deflection of the earth's layers, and Baikal, Upper, Huron, Michigan, Tanganyika- due to resets.

Volcanic basins are volcanic craters, depressions on the surface of lava flows, or flat areas covered by lava flows. In volcanic basins, Kronotskoye Lake in Kamchatka, lakes of New Zealand, the Kuril Islands and the island of Java were formed.

Lake basins of exogenous origin are also diverse. Oxbow lakes, found in river valleys and having an oblong shape, arose in the places of former river beds. Lakes of glacial origin are formed as a result of the long-standing advance of glaciers on land, that is, during the ice age. They were formed due to the movement of glaciers, which plowed huge furrows on the earth's surface, filled with water. Such glacial lakes are narrow and elongated in shape, located in Canada, Finland, in northwestern Russia. In places where the glacier retreated, leaving its fragments, wide, shallow oval lakes arose. Many such lakes are found in northern Europe and North America, for example, Ladoga, Big Bear.

In areas where water-soluble rocks - limestone, dolomite and gypsum - are found, basins of karst origin are often formed. Water fills the voids of the earth's crust, forming karst lakes, many of which are very deep, for example, Svityaz. Thermokarst depressions resulting from the uneven thawing of permafrost are often found in the tundra and taiga.

Dammed lakes arose in the mountains when, as a result of strong earthquakes, rivers were blocked by blockages or lava flows. This is how Lake Tana was formed in Africa. And in the Pamirs in 1911, Sarez Lake was formed right before the eyes of people, when during an earthquake a fragment of a mountain range collapsed into the river valley and blocked it with a dam more than 500 m high.

A lot of basins - artificial reservoirs - are created by man. So, on many large rivers of our country (Volga, Angara, Yenisei) large reservoirs have been created due to the construction of dams on them, therefore, the flow of these rivers is regulated.

Many lake basins are of mixed origin. For example, Ladoga and Onega lakes are of tectonic origin, but their basins have undergone changes under the influence of glaciers and rivers. The remains of ancient seas, which, due to vertical shifts in the earth's crust, were cut off by land from the ocean, are called relict lakes. Conventionally, they are called seas, they include the Caspian Lake - the remnant of a large marine basin, the largest lake in the world (an area of about 371 thousand km2), and the Aral Sea.

The sources of lake waters are underground springs, precipitation and rivers flowing into them. Part of the water evaporates from the surface of the lake, goes to the underground runoff, is carried out of the lake into the rivers. Due to the inflow and outflow, the water level fluctuates, and therefore the area of the lakes also changes. Thus, Lake Chad in Africa in the rainy season has an area of up to 26 thousand km2, and in the dry season it decreases to 12 thousand km2.

The water level in the lake changes due to climatic conditions, namely, when water evaporates from its surface or the amount of precipitation in the lake basin decreases. The water level in the lake can also change due to tectonic shifts.

Lake waters contain many dissolved substances and, depending on their amount in water, lakes are divided into: fresh, brackish and salty. Fresh lakes contain less than 1%o of dissolved salts, brackish lakes - more than 1%o, and saline lakes - over 24.7%o.

Freshwater lakes include flowing and wastewater lakes, since the influx of fresh water in them exceeds the flow. Endorheic lakes are mostly saline or brackish. The salinity in these lakes increases due to the smaller inflow of water relative to its flow. Salt lakes are located in the steppe and desert zones (Baskunchak, Elton, Dead, Big Salt and a number of others). Some lakes contain a high content of soda, for example, in the soda lakes of Southwestern Siberia.

Lake life

Lakes develop depending on changes in environmental conditions. A lot of inorganic and organic substances get into the lakes, brought by river water and temporary water flows that accumulate at the bottom. The remains of vegetation are also deposited on the bottom, gradually filling the hollows. As a result of such accumulations, lakes become shallow and can turn into swamps. The lakes are zoned. In Russia, the largest number of lakes are located in areas of ancient glaciation: in Karelia, on the Kola Peninsula. Here the lakes are flowing with fresh water and quickly overgrowing. There are very few lakes in the steppe and forest-steppe zones of the southern regions. In the desert zone there are drainless salt lakes, which eventually dry up, forming salt marshes. In all belts, there are tectonic lakes that have more depth, so changes in them are difficult to distinguish.

We remember: What sources feed the lakes? What is evaporation? Keywords:feeding of lakes, waste and endorheic lakes, fresh and salt lakes.

Practical work.

Divide these lakes into two groups (drainage and drainless): Baikal, Caspian Sea, Ladoga, Onega, Victoria, Tanganyika, Aral Sea, Chad, Air North.

Draw a sewage and drainless lake?

3. Describe on the map one of the world's lakes according to the plan (see Appendix 2).

& 45. Glaciers

We remember: What land waters have we studied? Remember what glaciers are. Name the properties of ice .

Keywords:snow, glaciers, continental and mountain glaciers, moraine

1. Glaciers and their formation. Accumulations of ice on the earth's surface are glaciers. They do not have the ice that covers our rivers and lakes in winter.

Rice. 132. Scheme of the structure of the glacier

2. Cover and mountain glaciers. Glaciers are divided into cover and mountain.

Rice. 134. Formation of icebergs

The height of icebergs above the water surface is on average 70 - 100 m, most of them are under water.

** One of the icebergs off the coast of Antarctica was 45 km wide and 170 km long with an ice thickness of more than 200 m.

Icebergs move under the influence of currents and winds to warmer latitudes, where they melt. They are dangerous for navigation. Modern ships are equipped with means of their detection.

Continental ice sheets are developed in Antarctica and Greenland, on the islands of the Arctic Ocean. Ice sheets once extended across most of Europe, northern Asia, and North America.

Rice. 133. Ice sheet of Antarctica

Rice. 135. Mountain glaciers

3. Significance of glaciers. Glaciers have large reserves of fresh water. They contain many times more water than rivers and lakes combined. Mountain glaciers often feed streams and rivers.

On geographical maps, the lakes are painted either blue or lilac. Blue color means that the lake is fresh, and lilac - that it is salty.

The salinity of the water in the lakes is different. Some lakes are so saturated with salts that it is impossible to drown in them, and they are called mineral lakes. In others, the water is only slightly salty in taste. The concentration of dissolved substances depends on what kind of water the rivers bring them. If the climate is humid and the rivers are full of water, the lakes are fresh. In deserts, there is little rainfall, rivers often dry up or they don’t exist at all, which is why the lakes are salty.

Among the large lakes of the world, most of all are fresh. This is due to the fact that the water in them is flowing and does not stagnate, which means that the salts brought by the rivers are carried away by them into the seas and oceans.

The freshest lakes on the planet are Baikal in Asia, Onega and Ladoga in Eastern Europe, Upper in North America. But the freshest of them should still be considered Lake Benern - the largest of the lakes in Western Europe. Its water is the closest to distilled, there are slightly more soluble minerals in Baikal and Lake Onega.

The freshwater lake of the largest area of the water surface - Lake Superior - one of the Great Lakes of North America. Its area is 83,350 square kilometers.

Mountain glacial lakes are especially poor in salts, the waters of which feed glaciers and snowfields.

If the reservoir is not flowing, then the water in it becomes first slightly brackish, and then salty.

The most saline lakes on our planet can be considered lakes in which the salt content per liter of water is more than 25 grams. Such lakes, in addition to Lake Tuz in Turkey, include Lake Eyre in Australia, the Dead Sea on the Arabian Peninsula, Molla-Kara in Turkmenistan, Lake Dus-Khol in Tuva and others.

In the center of Turkey, south of Ankara, at an altitude of 900 meters above sea level, there is a lake on which you can walk on foot in summer. This drainless lake Tuz has a length of 80 kilometers, a width of about forty-five kilometers and an average depth of two meters. It is not only small, but also very salty - up to three hundred and twenty-two kilograms of salt per ton of water. In spring, due to winter and spring precipitation, the lake overflows and increases almost seven times, occupying a huge area of 25,000 square kilometers. In the summer, when the water evaporates, the lake becomes very small, and a dense crust of salt forms on its surface from several centimeters to two meters thick.

The Dead Sea is the deepest and saltiest of the salt lakes. Its greatest depth is over 400 meters, and it is located 395 meters below the level of the oceans. One liter of Dead Sea water contains 437 grams of salt.

Some of the lakes are brackish-fresh. The most amazing of them is Lake Balkhash. Its western part is fresh, and the eastern part is brackish. The reason for this peculiarity lies in the fact that the Ili River flows into the western part of the lake, and the eastern part lies surrounded by deserts, where water evaporates very strongly. Therefore, on geographical maps, the western part of Balkhash is shown blue, and the eastern part is lilac.

The huge Lake Chad, located on the outskirts of the Sahara, is fresh on top and brackish at the bottom. Fresh river and rain water, falling into the lake, does not mix with brackish water, but rather floats on it. Freshwater fish live in the upper layer, and marine fish that got into the lake in ancient times stay at the bottom.

The lake is very shallow (from 2 to 4 meters deep). Its shores are flat and swampy, and from the north the desert comes close to them. The hot sun dried up all the northern and eastern tributaries of Chad, turning them into waterless channels - wadis. And only the Shari and Lagoni rivers flowing into it from the south feed the "Sahara Sea" with their waters. For a long time, Lake Chad, or Ngi-Bul, as the locals call it, was considered drainless, which was its main mystery. Usually in large, shallow and endorheic lakes on Earth, the water is completely salty, and the upper layer of Lake Chad is fresh. The riddle turned out to be simple.

Approximately 900 kilometers northeast of Chad is the vast Bodele Basin, lying approximately 80 meters below lake level. A water stream hidden under the ground stretched to it from the lake. So, through underground runoff, Lake Chad slowly but constantly renews its waters, preventing them from becoming salty.

Even more surprising is Lake Mogilnoye. It is located on Kildin Island, not far from the northern coast of the Kola Peninsula, and has a depth of 17 meters. The lake consists, as it were, of several layers - "floors". The first "floor" at the bottom of the lake, almost lifeless, consists of liquid silt and is saturated with hydrogen sulfide. The second "floor" stands out in cherry color - this color is given to it by purple bacteria. They are, as it were, a filter that traps hydrogen sulfide rising from the bottom. The "third" floor is a "piece of the sea", hidden in the depths of the lake. This is ordinary sea water, and its salinity here is the same as in the sea. This layer is filled with life, jellyfish, crustaceans, stars, sea anemones, sea bass, cod live here. Only they look much smaller than their counterparts at sea. The fourth "floor" is intermediate: the water in it is no longer sea, but not fresh either, but slightly brackish. The fifth "floor" is a six-meter layer of pure spring water suitable for drinking. The fauna here is typical for freshwater lakes.

The unusual structure is explained by the history of the lake. It is very ancient and was formed on the site of the sea bay. Mogilnoye Lake is separated from the sea only by a small bridge. At high tide, sea water seeps through it in the place where the "marine" layer is located. And the distribution of water in the lake by layers is due to the fact that salt water, as heavier, is at the bottom, and lighter fresh water is at the top. That's why they don't mix. Oxygen does not enter the depths of the lake, and the bottom layers become contaminated with hydrogen sulfide.

An unusual lake called Drutso is located in Tibet. The locals consider it magical. Every 12 years, the water in the lake changes: it becomes either fresh or salty.

The lake is a closed natural body of water. Such reservoirs are classified by volume, water balance, origin and other factors. Today we will consider a list of the freshest lakes. We will also tell interesting facts about them.

Why are lakes fresh?

In order for a lake to form, a depression must appear in the earth's crust as a result of a shift in tectonic plates, a meteorite impact or a glacier. There are also reservoirs formed in the craters of dormant volcanoes.

The water in the reservoir can be mineral, salty, brackish and fresh. In mineral lakes, more than 25% of salt water. So, the salinity of the Dead Sea is 200-300%. It is so salty that you can bask in the sun, lying on the water, as if on an air mattress, and not be afraid to drown.

In saline lakes - 10-12% salt, and in brackish - up to 8%. In fresh waters, the salt content is only 1%.

Salt lakes are found predominantly in arid climates. There, moisture evaporates especially intensively. In addition, sewage lakes, from which at least one river flows, are characterized by lower salinity. The drainless accumulate salt over the centuries of their existence. So, the Dead Sea is actually a closed lake.

Baikal - the deepest lake in the world

Baikal is one of the most unique lakes in the world, being the deepest in the world. This largest reservoir of fresh water, located in Russia, has long been called the sea by the local population. Baikal is located in the northern part of Siberia and still raises many questions from scientists.

The age of the lake, according to one version, is several hundred thousand years. However, according to another, Balkal was formed during the ice age, and its age is millions of years old. The depth of the reservoir is 1642 m.

Some interesting facts about Lake Baikal that you may not have known:

it is distinguished by the purest, almost crystal clear water. It can be drunk even without pre-treatment;
on the coldest days of winter, when Baikal freezes, at its bottom you can see a crack that stretches for 30 km along;
the reservoir is located in a seismically active area. Frequent earthquakes cause storms, during which the wave height reaches 4-5 m;
The poetic name "lake of the sun" was given to the reservoir due to the largest number of sunny days that are observed on its territory.
mystical secrets also did not bypass Baikal. People often drown there, but in one of the weeks of the year the number of victims is especially high. In addition, fishermen often see mirages of past events over the waters of Lake Baikal, and luminous objects are often seen in the sky above the lake. The locals mistake them for UFOs.

Perhaps someday humanity will unravel the mystery of one of the largest freshwater lakes in the world.

Great Upper Lake

Lake Superior, in North America, is part of a group of five reservoirs called the Great. They are interconnected by straits and rivers and occupy a considerable area - 244 sq. m! The most discussed among them is the Upper. This body of water is the largest freshwater lake in the world, with an area of 82.5 thousand square meters. m, the greatest depth is 406 m. Even the famous Baikal, whose area is 31,722 sq. km, is inferior to the upper one. m.

By the standards of our planet, the Upper is one of the youngest natural formations in the crust, since its age does not exceed 10,000 years. For comparison: Baikal is about 25 million years old.

From December to April, the lake is completely covered with ice. In former times, a thick layer of frozen water was used by smugglers to cross on foot to the other side of the reservoir. However, even in warmer months, the water temperature in the lake does not exceed 4 degrees Celsius.

Tanganyika - the longest body of water in the world

Tanganyika holds the title of the longest freshwater lake in the world. The length of its coastline is 1828 m. In terms of volume and depth, the reservoir is second only to the majestic Baikal. Experts estimate its age at 10-12 million years. The average depth of Tanganyika is 570 m, the maximum is 1470. For millions of years of its existence, one of the largest freshwater lakes in the world has not dried up, so its flora and fauna have not changed during this time.

There are 200 species of fish in Tanganyika, 170 species of which live exclusively in these waters. At the same time, 90% of the lake is devoid of most forms of life. Most of the inhabitants of the lake live in the upper layer, saturated with oxygen. Below 100 m the desert depths extend.

The surface of Lake Tanganyika is larger than Belgium.

When the first European explorers visited the reservoir in 1600, they found sturgeons 2.7 meters long and pike reaching 2 meters in length. Today, the main wealth of the reservoir is fish, of which there are 90 species.

Tanganyika Horror

The picturesque shores of the reservoir are a haven for many animals. One of the most interesting and terrifying of its inhabitants is the crocodile Gustav, elevated by the local population to the status of a deity. According to local legends, he accounted for more than three hundred human victims. Perhaps more, since the crocodile often feasts on local sailors.

At the same time, any attempts to catch a seventy-year-old cannibal remain in vain. The attempts made by the hunters end with human casualties and a night snack for Gustav. Even bullets cannot take it, as evidenced by the numerous traces from them on the scales of the crocodile.

Gustav is probably the largest crocodile in the world. Its length can only be guessed from photographs, but it has been established that it reaches 7 m. Today, Gustav is over 70 years old, he continues to grow and terrify the local population. Africans consider him a devil who cannot be killed.

Titicaca - "mountain cougar"

Titicaca is one of the largest freshwater lakes in the world, located in South America. The area of the reservoir is 3872 sq km, the maximum depth is 281 m. The reservoir is located at an altitude of 3812 m above ocean level and is of incredible beauty.

Its name, unusual for our hearing, consists of two words of Spanish origin and is translated as "mountain puma". The name is explained by the location of the reservoir, which is located in the Andes, on the border of Peru with Bolivia. There are more than 40 islands on the surface of the lake, on some of them the leaders of the Inca tribes are buried.

The lake was probably formed over a hundred million years ago. The age of the reservoir is evidenced by the fossilized remains of animals that were found on its banks, as well as a variety of flora and fauna. Titicaca is home to crustaceans, fish and even sharks. Once the lake was a bay, which, as a result of one of the natural disasters, turned into a lake and rose along with the Andes. The latter continue to grow today.

The ancient city of the Aztecs at the bottom of the reservoir

It is known that an ancient city, which is more than 1500 years old, is buried at the bottom of Titicaca. As a result of lengthy excavations, archaeologists have found numerous artifacts - dishes, sculptures and even parts of stone structures. Scientists believe that they have discovered the remains of the Inca civilization - Tiwanaku. Probably, a powerful earthquake or flood destroyed the city, burying local residents under the layers of destroyed structures and the water column.

- the largest in Europe

Lake Ladoga is located in the Republic of Karelia and covers an area of 17,700 square meters. km. This is the largest freshwater lake in Europe with picturesque shores and a maximum depth of up to 233 m in the northern part. It is noteworthy that in the southern part the depth of the reservoir does not exceed 70 m.

Scientists still cannot explain such a sharp change in depth. Perhaps, according to scientist Valery Yurkovitsa, the reason for the formation of the lake was the fall of a meteorite that formed the deep part of the reservoir 40 thousand years ago.

Lake Ladoga arose as a result of a meteorite impact, which formed a crater and became the deep-water part of the reservoir. There are 660 islets on the lake, there is also an incredibly rich flora and fauna.

Some interesting facts about Lake Ladoga:

in ancient times, the Scandinavians and Slavs called the reservoir the sea because of its large size;
one of the most interesting mysteries of the lake is the so-called barrantides. These are sounds of incomprehensible origin, which often appear in the depths, frightening the local population;
in addition, according to many eyewitnesses, the Ladoga monster lives in the lake, resembling the famous Nessie;
only one river flows out of Lake Ladoga - the Neva, but it belongs to the most full-flowing rivers in Europe due to the volumetric catchment of the reservoir;
The water temperature in the lake does not exceed 14 degrees Celsius. Only its southern part warms up to +24 in warm months. The rest of the lake is unsuitable for swimming.

The largest lake in the world

Despite the fact that in this article we are discussing freshwater lakes, it is impossible to ignore the largest body of water in the world.

The Caspian Sea is the world's largest lake with a salinity of 8-12%. Its picturesque shores lie at the border of Europe with Asia and are in the possession of five countries - Russia, Kazakhstan, Azerbaijan, Turkmenistan and Iran. Its area is 3,626,000 km², the maximum depth is 1025 meters.

The Caspian Sea is a kind of unique body of water, which can be classified as an endorheic lake with marine salinity. However, if you delve into the numbers, the salinity level of the Caspian is still lower than in the sea. Therefore, today the Caspian Sea, retaining its former name, is considered a lake.

Terrestrial reservoirs arose for various reasons. Their creators are water, wind, glaciers, tectonic forces. The water washed out the hollow on the surface of the earth, the wind blew out a depression, plowed and polished the glacier depression, the mountain landslide dammed the river valley - and the bed of the future reservoir is ready. The depressions will be filled with water - a lake will appear.

The lakes of the globe are divided into two large groups - fresh and salt water. If less than one gram of salts is dissolved in one liter of water, the water is considered fresh, if there are more salts, then salty.

The lakes have the most varied salinity - from fractions of a gram to several tens and hundreds of grams per liter of water. There are, for example, reservoirs in which the water is so saturated with salts that it surpasses the ocean in this respect (35 grams of salts per liter of water); such lakes are called mineral. It all depends on what kind of tribute the rivers bring to them. If the climate is humid and the rivers are full of water, then the rocks in the catchment area are well washed, and therefore the river and lake waters are poorly mineralized.

In a drier climate, where precipitation is scarce and rivers are shallow, their waters contain significantly more salts. Therefore, in the deserts, salt (mineral) lakes are the most widespread. A vivid example of this is Central Kazakhstan, where there are few freshwater lakes, and salty ones are found almost at every step. And yet, among the greatest lakes in the world, freshwater reservoirs predominate.

They are flowing, water does not stagnate in them, salts brought by rivers are discharged into the ocean or sea. And it is worth making such a reservoir drainless - and after some time it will become salty. Take, for example, the Caspian Sea. This huge body of water became largely saline because it had no outlet to the ocean. There were many similar cases on Earth.

In the center of Turkey, south of Ankara, at an altitude of 900 meters above sea level, there is a lake on which you can walk on foot in summer. This drainless Lake Tuz has a length of 80 kilometers, a width of about forty-five kilometers and an average depth of two meters. It is not only shallow, but also very salty - up to three hundred and twenty-two kilograms of salt per ton of water. In spring, due to winter and spring precipitation, the lake overflows and increases almost seven times, occupying a huge area of 25,000 square kilometers. In the summer, when the water evaporates, the lake becomes very small, and a dense crust of salt forms on its surface from several centimeters to two meters thick.

Lake

Lake - a natural closed reservoir formed on the surface of the land in a natural depression. The lake has no direct connection with the oceans. Unlike rivers, water does not flow in lakes.

The lakes on the maps are shown as volume objects in blue. On maps, they need to be shown along the coastline.

The largest lake in the world is the Caspian Sea. This lake is salty. It has no connection with the ocean, therefore it refers to lakes, although it used to be part of the ocean.

Rice. 1. Snapshot of the Caspian Sea

The deepest lake is Baikal, with a depth of 1642 meters. This lake contains 1/5 of all lake waters in the world and is the largest liquid freshwater object! The largest freshwater lake in terms of area in the world is Lake Superior (North America).

Rice. 2. Lake Baikal on the map

Types of lakes by origin of basins

lake basin - the place (deepening) in which the lake is located.

According to the origin of the basins, the following types of lakes are distinguished:

1. Tectonic

2. Glacial

3. Volcanic

4. Staritsy

6. Karst

7. Thermokarst

The deepest lakes tectonic, they are formed in cracks, breaks in the earth's crust during its movement. Examples: Baikal, Teletskoye, Victoria, Tanganyika.

Zaprudnye lakes are formed in the valleys of mountain rivers when the channel is blocked by collapsed rocks, glaciers, etc. Examples: Sarez, Ritsa.

Volcanic (crater) lakes are formed in the craters of extinct volcanoes. Examples: Toba, Kuril, Irasu.

Rice. 4. Kuril lake

Staritsy are formed in the valleys of the old channels of lowland rivers when the direction of the flow of the river and channel changes.

Rice. 5. Scheme of the process of formation of the oxbow lake

Karst lakes are formed as a result of soil failure over voids.

Glacial The lakes were formed as a result of the melting of an ancient glacier. There are many such lakes in the north of Eurasia and North America.

Rice. 6. Lakes of Karelia on the map

Other types of lakes

Lake waters are replenished due to precipitation, rivers, snowmelt, groundwater.

According to the position of the lake are divided into:

1. Ground

2. Underground

According to the water balance, the lakes are divided into:

1. Sewage (at least one river flows from such lakes)

2. Endorheic (rivers do not flow from such lakes)

According to the type of mineralization, the lakes are divided into:

1. Fresh

2. Mineral (salty)

One of the saltiest bodies of water on Earth is the Dead Sea, its salinity can reach 350 ppm! Initially, the lake was called "dead", because. it was thought that living organisms did not live in it due to the high concentration of salt.

Rice. 7. Dead Sea Salts

The highest mountain lake

The highest mountain lake in the world is located at the foot of the highest volcano in the world - Ojos del Salado (South America), which is located at an altitude of 6891 meters above sea level. This unnamed lake is a water-filled crater only 100 meters in diameter and up to ten meters deep.

meteorite lakes

This type of lakes is formed when meteorites fall in meteorite craters, then these craters are filled with water and turn into lakes. Example: Elgygytgyn.

Raspberry lakes

These lakes are distinguished by a light pink color and a pleasant smell. Such properties are given to these lakes by crustaceans, which, dying and decomposing, give salt the aroma of raspberries.

Bibliography

Main

1. Initial course of geography: textbook. for 6 cells. general education institutions / T.P. Gerasimova, N.P. Neklyukov. – 10th ed., stereotype. – M.: Bustard, 2010. – 176 p.

2. Geography. Grade 6: atlas. – 3rd ed., stereotype. – M.: Bustard; DIK, 2011. - 32 p.

3. Geography. Grade 6: atlas. - 4th ed., stereotype. – M.: Bustard, DIK, 2013. – 32 p.

4. Geography. 6 cells: cont. maps: M.: DIK, Drofa, 2012. - 16 p.

Encyclopedias, dictionaries, reference books and statistical collections

1. Geography. Modern illustrated encyclopedia / A.P. Gorkin. – M.: Rosmen-Press, 2006. – 624 p.

1. Federal Institute of Pedagogical Measurements ().

2. Russian Geographical Society ().

3. Geografia.ru ().