How to distinguish a salt lake from a fresh one. & 44. Waste and drainless, fresh and salt lakes. Why are the lakes fresh

On geographic maps the lakes are colored alternately blue and sometimes lilac. Blue means that the lake is fresh, and lilac means that it is salty.

The salinity of water in lakes is different. Some lakes are so saturated with salts that it is impossible to drown in them, and they are called mineral. 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. There is little precipitation in deserts, rivers often dry up or there is none at all, and therefore the lakes are salty.

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

The most fresh of the lakes of the planet - this is Baikal in Asia, Onega and Ladoga in Eastern Europe, Upper in North America. But the most insipid of them is Lake Benern, the largest of the lakes. Western Europe... Its water is closest to distilled water, there are slightly more soluble minerals in Baikal and Lake Onega.

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

Mountain salts are especially poor glacial lakes, whose waters are fed by glaciers and snowfields.

If the reservoir is not flowing, then the water in it becomes at 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. These lakes, in addition to Lake Tuz in Turkey, include Lake Eyr 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 that you can walk on in summer. This closed 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 sevenfold, occupying a huge area of \u200b\u200b25,000 square kilometers. In summer, when the water evaporates, the lake becomes very small, and a dense crust of salt forms on its surface with a thickness of several centimeters to two meters.

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 sea level. In one liter of water Dead sea it 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 its eastern part is salty. The reason for this peculiarity lies in the fact that the Ili River flows into the western part of the lake, and the eastern one lies surrounded by deserts, where the water evaporates very strongly. Therefore, on geographical maps western part Balkhash is shown in blue, and the eastern one - in lilac.

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

The lake is very shallow (2 to 4 meters deep). Its shores are flat and swampy, and from the north the desert approaches them closely. The hot sun dried up all the northern and eastern tributaries of Chad, turning them into waterless channels - wadis. And only the rivers Shari and Lagoni, 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, large, shallow and closed lakes on Earth have completely salty water, and the upper layer of Lake Chad is fresh. The riddle turned out to be simple.

About 900 kilometers northeast of Chad lies the vast Bodele Basin, which lies about 80 meters below the lake level. To her from the lake stretched a water stream hidden underground. So, by means of underground runoff, Lake Chad slowly but constantly renews its waters, preventing them from becoming salty.

Even more surprising is the Mogilnoye lake. 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, practically lifeless, consists of liquid silt and is saturated with hydrogen sulfide. The second "floor" is highlighted in cherry color - this color is given to it by purple bacteria. They act as 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 normal sea water and its salinity is the same as in the sea. This layer is filled with life, jellyfish, crustaceans, stars, sea anemones, sea bass, cod live here. They only look much smaller than their counterparts at sea. The fourth "floor" is intermediate: the water in it is no longer sea water, but not fresh, but slightly brackish. The fifth "floor" is a six-meter layer of clean spring water suitable for drinking. Animal world here it is common 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, seawater seeps through it where the "sea" layer is. 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 fresh lighter water is at the top. That is why they do not mix. Oxygen does not enter the depths of the lake, and the bottom layers are contaminated with hydrogen sulfide.

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

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

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

The lakes have a wide variety of 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 salt per liter of water); such lakes are called mineral. It all depends on what kind of tribute the rivers bring them. If the climate is humid and the rivers are full of water, it means that the rocks in the catchment area are well washed, and therefore the river and lake waters are poorly mineralized.

In drier climates, where precipitation is scarce and rivers are shallow, their waters contain significantly more salts. Therefore, in deserts, salty (mineral) lakes are the most widespread. A striking example of this is Central Kazakhstan, where there are few fresh lakes, and salty lakes are found almost at every step. And yet fresh water bodies prevail among the world's greatest lakes.

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 without drainage - and after some time it will become salty. Take the Caspian Sea, for example. This huge body of water was largely saline because it had no outlet to the ocean. There have been many similar cases on Earth.

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 sea level. In one liter of Dead Sea water, it 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 its eastern part is salty. The reason for this peculiarity lies in the fact that the Ili River flows into the western part of the lake, and the eastern one lies surrounded by deserts, where the water evaporates very strongly. Therefore, on geographical maps, the western part of Balkhash is shown in blue, and the eastern part is lilac.

Geography lesson in grade 6

Teacher: T.I. Neborak

Lesson topic: "Blue eyes of the planet" (Lakes).

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

Tasks:

educational: to form students' ideas about the lake, types of lake basins, sewage and internal drainage, fresh and salt lakes;

developing: development of individual cognitive interests in students;

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

Lesson type:explanation of the new material.

Upon completion of the lesson, the student must:

Know: what is a lake; types of lake basins; sewage and closed, salt and fresh lakes;

Be able to: show lakes on the map.

Technologies: lesson using ICT and problem learning.

Equipment:

TCO tool: computer, projector, screen.

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

Lesson steps: 1. Organizational

2. Studying new material with a phased consolidation.

3. Lesson summary.

4. Homework

During the classes.

1. Organizational.

Hello guys! Today the geography lesson will be taught by me - 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.

The glass is blue, the frame is green.

Young mountain ash are looking at him,

Colored their own, guiding kerchiefs

Young birch trees are looking at him,

Adjusting their hair in front of him.

Both the month and the stars - everything is reflected in it ...

What is this mirror called? (Lake).

Teacher. Correctly. This lake. The topic of our lesson is "Blue eyes of the planet". (Lakes). Slide number 2.

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

The variety of lakes on our planet and their origin;

Which lakes are called wastewater and which are closed-flowing;

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

Teacher.Today we will keep notes in the lesson neither in notebooks, but in Route Sheets, ( Appendix # 1) which are on your desk. Slide number 4.

Teacher.Our study path is long and so we hit the road without delay.

Teacher. Guys, how many of you have seen the lake? Hands up.

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

The task... Try to formulate a definition of the concept of "lake".

(Children answer).

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

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

We write the definition into 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 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 difficult, but we will now try to answer it.

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

Teacher. So, pay attention to the screen.

Teacher's story.

Tectonic in troughs (residual). They were formed due to the slow descent 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, these lakes are very deep. (Tanganyika, Nyasa on mainland Africa. And what do you think, but in Russia there are such lakes). - The deepest lake is Baikal. It is unique. It is unparalleled in fame and glory. The greatest depth is 1620m. Baikal contains one tenth of the fresh water of the entire Earth. Baikal ranks first in the world in terms of water transparency. 336 rivers and rivulets flow into the lake, and one Angara flows out. Slide number 8.9.

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

Slide number 10.11.

4. The dams were formed as a result of the collapse or shedding of rocks into the river valley. An example is Lake Sarez in the Pamirs.

(Student story). On a February night in 1911, the inhabitants of Bartang woke up from an incredible roar coming from the bowels of the earth. The rumble was accompanied by a deafening stone crash. It seemed that somewhere above, an invisible genie was raging, breaking the Pamir giant. Giant rock fragments flew from the peaks. Frightened people felt as if on unsteady waves; the ground walked underfoot. There was a strong earthquake. And over the village of Usoy, clouds of great dust swirled for several days. And when the dust cleared away, in the riverbed people saw a stone wall not made by hands, half a kilometer high. The wall formed from the fragments of rocks blocked off the 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. (Kronotskoe, Kuril.) Slide number 14.15.

6. Oxbow lakes are often found in river floodplains; they represent 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 on the earth's surface, hollows are filled with water. (Many in the Urals, the Caucasus). Slide number 17.

Dynamic pause. (Close screen)

Teacher. The Route Sheets contain a table "Types of lake basins". Working with the textbook pp. 96-97 and based on the material that I have told you, you fill out the table. We will work in pairs. I handed you cards in advance, on which is written only one type of origin of the lake basins, and 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	Subsidence of sections of the earth's crust along a fault	Baikal, Nyasa, Tanganyika.
Glacial	The hollow has been deepened by ancient glaciers.	Onega, Ladoga.
Zaprudny	The river bed is blocked by a landslide or solidified lava flow.	Sarez.
Volcanic	Extinct volcano craters	Kronotskoe, Kuril.
Karst	Formed after the failure of the upper layer covering the underground cavity, and fills it with water.
	Sections of the former river bed, which has changed its direction.	Small ones are not indicated on the cards.

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

(Those interested in groups report on the work done).

Teacher. Guys, do you know the name of the lakes in the Kargat region? (the eastern part of the lake Ubinskoe, Kargan, Malye and Bolshie Toroki, Atkul, Kankul, Kaili, Bizyura). The lakes of our area are the remains of the ancient lake system. Slide number 19.

Teacher.A lake is a depression filled with water. Where do you think the water in these depressions comes from? What do the lakes eat? (atmospheric precipitation, underground waters, waters of flowing rivers). Slide number 20.21.

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

In the diagram you see a lake and a river. Please note that rivers can flow into lakes and outflow .

Children's answers.

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

Waste lake is a lake into which rivers flow in and out (or just flow out)

Endless lakes are 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)

Onega and Ladoga lakes are also examples of wastewater lakes.

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

Why? (children's answers)

The Caspian and Balkhash lakes are also examples of closed lakes.

Enter 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? (amount of minerals in 1 liter of water). And how is it expressed? (in ppm-thousandths of a number). Slide number 24.25.

Teacher. According to salinity, all lakes can be divided into two groups: fresh - up to 1% o; salty - from 1% o to 35% o. Fresh on the map are marked 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 is pink. Why do you think? (salty, most often drainless lakes, since mineral substances brought by rivers gradually accumulate in the lakes)

Teacher. Lake Baikal is fresh or salty ? (Children's answers)

The task: write examples of lakes in the table.

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

Student messages about the Dead Lake. Slide number 26.Hear what a man who has visited its shores tells about one of the saltiest lakes of the Dead Lake: “We were standing on a deserted shore, whose dull look 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 just washed our face with thick, like cool brine water. After a few minutes, the face and hands were covered with a white coating of salt, and an unbearably bitter taste remained on the lips. Sometimes a fish swims from the Jordan River to the Dead Lake. She dies in a minute. We found one such fish washed ashore. She was as hard as a stick, in a strong salty shell. "

Teacher. How does man use the lake? Slide number 28. (catches fish, for navigation, breeds waterfowl, mines salt, the coast of lakes is a favorable area not only for life, but also for recreation, restoration of health).

Teacher. Lakes have been used by humans since ancient times. But today, like other reservoirs, 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 people for help, shedding pure tears.

Slide number 29.Even the smallest 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 the future generation.

3. Lesson summary.

Teacher. Our lesson is coming to an end. I would like to know how fruitful he was. Answer the questions: what new have you learned? what have you learned? Start your answers with the words ... Slide number 30.

I found out…

I can…

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

And yet, I would like to know the attitude to the lesson of each of you. Choose the one that best reflects your mood, and I'll 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 planets "(lakes).

Lake - _____________________________________________________________________

_____________________________________________________________________________

Types of lake basins

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

By flow rate and water input


Drainless

Salinity

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

Homework: read the text of the textbook paragraph 31, using the plan to describe Lake Baikal, prepare reports on unusual lakes (optional).

Fill in the table:

Description of Lake Baikal according to the standard plan

Lake description plan	Characteristics of the lake
1. Title
2. On which continent is located and in which part of it
3. Between which meridians and parallels is
4. Origin of the basin
5. Waste or closed. Inflowing and outflowing rivers
6. Salty or unleavened

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

A lake is one of the components of the hydrosphere, the Earth's water envelope. Lakes are natural reservoirs. They represent a kind of bowl (lake bed) filled to the brim with water. There are more than five million lakes on Earth, total area which is more than 2.7 million sq. kilometers.

Science planetology defines a lake as an object that is stable

existing in time and space and filled with liquid matter. The dimensions of the lake, according to the same science, are average between the sea and the pond. If we consider 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 bodies of water are not part of the oceans.

The chemical composition of the lake water is considered to be fairly stable. The water in the lakes practically does not circulate, so the filling fluid is rarely renewed. Lakes perform an important function - they keep water in their basins and give them back at different periods of time.

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

Large lakes can have a softening effect on the climatic conditions of the adjacent territories. The lakes existing 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 subdivided into waste and closed ones.

Endless lakes

There are many land areas on Earth with river systemsthat are not associated with the oceans. River basins located in such areas are called closed drainage basins. And the bottom of such pools is, as a rule, a closed lake. Science gives this definition: a closed lake is a body of water that has no underground drainage and surface runoff. Simply put, one or more rivers can flow into such reservoirs, but none of them flows out.

Endless lakes are formed in areas with an arid climate, where moisture is much lower than evaporation. Endless lakes are scattered all over the planet; they are found on all continents, even in Antarctica. There such lakes are located in Victoria Land and the McMurdo Dry Valley.

The most famous are Frixell, Vostok, Ellsworth, Don Juan. The area of \u200b\u200bLake Frixell is 7 square kilometers, and its entire surface is constantly 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 Earth's surface. Don Juan is not at all big lake, it is interesting, first of all, by the fact that on this moment claims to be the saltiest lake in the world. The salt content in Lake Frixell is over 40%, the salinity of the famous Dead Sea is just under 35%. Due to the high salt content, the reservoir does not freeze even at temperatures of -53 degrees.

Another surprising fact about Fixell: there is a lot of nitrous oxide in its waters, which is formed as a result of the vital activity of microorganisms. Meanwhile, scientists failed to find a single microorganism in the waters of the lake.

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

In Australia, such bodies of water include Eyre, Korangamit, George, Torrance. In North America - Lake Pyramids, Sevier, Mona, Atitlan. Most of Central and Western Asia is an inland basin. Sasykkol, Balkhash, Zhalanoshkol, Issyk-Kul are located in this area. By origin, the Caspian and Aral seas are 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 you can objects 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 wastewater lake.

The drainless lakes are almost always salty. This is explained by the fact that rivers do not flow out of them that could carry this salt.

Waste lakes

Wastewater lakes include lakes that have runoff (as a rule, these are rivers). Most of the lakes of this type are located in areas with a temperate and humid climate. It is interesting that several rivers can flow into such reservoirs, and only one can flow out. Dissolved substances (for example, salt) are removed from the water using effluent. However, in some lakes, water exchange can be slowed down, which leads to salt accumulation and other biochemical processes. The way the water changes in the reservoir determines the amount of water in the lake, its chemical composition and the ability to self-purify.

One of the subspecies of wastewater lakes is 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 Chudskoe, Kubenskoe, Zaysan. Water consumption in such lakes is mainly due to runoff and evaporation. The flow rate in these lakes is one of the most important characteristics, since 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. The fact is that the sea is part of the World Ocean. If completely separated from the ocean by land, then this is a lake. The area of \u200b\u200bthe 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 include those lakes whose salt content is minimal, that is, less than 1%. Freshwater lakes can be either sewage or flowing. Non-drainage is 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 story... In the country of Nicaragua, for example, there is a lake of the same name. It is of tectonic origin, with an area of \u200b\u200babout 8 thousand square kilometers. The uniqueness of Nicaragua is that it is the only freshwater lake on our planet with sharks. The distance from the lake to the Pacific Ocean is very small, so scientists assume that earlier the territory on which the reservoir is located was a sea bay.

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 world's oceans. More than three hundred rivers flow into it, most of which flow down 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 the hot heat zone are distinguished by the fact that the water near their surface is warm. With increasing depth, the water temperature decreases. The name of this phenomenon is direct thermal stratification. Interestingly, the lakes that are in the cold zone have the lowest water temperature (about 0 degrees Celsius), but the deeper 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 indicated in blue and others in purple. This is simply explained - fresh lakes are distinguished with blue, salty lakes with purple.
There are more fresh lakes on our planet than salt ones.
The largest freshwater lake on the planet is located in North America. This is Lake Superior, it is part of the Great Lakes group.
There are also some kind of "champions" in salinity. These are considered reservoirs, the salt content of which is more than 25 grams per liter. Examples are Tuz (Turkey), Air (Australia), Dus-Khol (Tuva).
The most unsalted lakes are those 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 salty and deepest is the Dead Sea. Its depth in some places reaches 400 meters. Its salt content is 437 grams per liter of water.
There are also quite 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 from above, is fresh, and closer to the bottom - salty. This is explained by the fact that fresh water (rainwater) does not mix with salt water when it enters the lake. Thus, Lake Chad is two-layer.
The largest depressions, in which lakes subsequently formed, are of tectonic origin.

Lakes are depressions in the land, filled with water, formed naturally and occupying about 2% of all land. The deepest lake, Baikal, and the largest lake in the world, Caspian, are located in Russia.

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

Lake types

By the nature of the flow, lakes are divided into:

a) drainless;

b) sewage.

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

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

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

The lacustrine basins of exogenous origin are also diverse. The oxbow lakes, which are found in river valleys and have an oblong shape, have arisen in the places of former river beds. The lakes formed as a result of the long-term advance of glaciers on land, that is, during the ice age, are of glacial origin. 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 the northwest of Russia. In places where the retreating glacier left its fragments, wide, shallow oval-shaped lakes arose. Many of these 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 basins, resulting from uneven thawing of permafrost, are often found in the tundra and taiga.

Dam lakes appeared in the mountains when, as a result of strong earthquakes, rivers were blocked by obstructions or lava flows. This is how Lake Tana was formed in Africa. And in the Pamirs in 1911, right in front of people, Lake Sarez was formed, when, during an earthquake, a fragment of a mountain ridge fell into the river valley and blocked it with a dam more than 500 m high.

Many hollows - artificial reservoirs - were 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, Lake Onega 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 of the earth's crust, were cut off from the ocean by land, are called relict lakes. Conventionally they are called seas, they include Caspian lake - the remainder of a large sea basin, the largest lake in the world (area of \u200b\u200babout 371 thousand km2), and the Aral Sea.

The sources of lake waters are underground sources, precipitation and rivers flowing into them. Part of the water evaporates from the surface of the lake, goes to the underground drain, is carried out from the lake to the rivers. Due to the inflow and outflow, the water level fluctuates, and therefore the area of \u200b\u200bthe lakes also changes. So, Lake Chad in Africa in the rainy season has an area of \u200b\u200bup 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 a decrease in the amount of precipitation in the lake basin. 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 the water, the lakes are divided into: fresh, brackish and salty. Fresh lakes contain less than 1% of dissolved salts, brackish lakes - more than 1%, and salty lakes - over 24.7%.

Freshwater lakes include flowing and wastewater lakes, since the inflow of fresh water in them exceeds the flow rate. The drainless lakes are mostly salty or brackish. Salinity in these lakes increases due to the smaller inflow of water relative to its discharge. Salt lakes are located in the steppe and desert zones (Baskunchak, Elton, Dead, Bolshoye Solenoe 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 the water of rivers and temporary water flows that accumulate at the bottom. Remnants of vegetation are also deposited at the bottom, gradually filling the hollows. As a result of such accumulations, the lakes become shallow and can turn into swamps. The lakes are located zonally. In Russia, the largest number of lakes is located in areas of ancient glaciation: in Karelia, on the Kola Peninsula. Here the lakes are flowing with fresh water and quickly overgrown. In the steppe and forest-steppe zones southern regions there are very few lakes. In the desert zone, there are drainless salt lakes, which dry up over time, forming salt marshes. In all belts there are tectonic lakes that are deeper, so changes in them are difficult to distinguish.

Remember: From what sources do the lakes feed? What is Evaporation? Keywords: feeding of lakes, waste and closed lakes, fresh and salt lakes.

1. Waste and closed lakes... The lakes are fed by river, underground runoff and atmospheric precipitation. Depending on the flow rate of water, the lakes are wastewater and endless. Lakes that have a river flow, that is, from which rivers flow, are so c e lakes, and lakes that have no drain - unsteady... Waste lakes are found mainly in areas of excessive moisture, endless - in areas of insufficient moisture.

The level of lakes in connection with the arrival and discharge of water does not remain constant, it changes. Especially large fluctuations in the level of lakes are observed in arid and dry areas. This is associated with changes in the areas of lakes.

** During the rainy season of wet years, the Australian Lake Air North is a large body of water with an area of \u200b\u200bup to 9,300 km 2, and in the dry seasons of dry years, water is stored only in a few bays of the southern part of the lake.

Fresh and salt lakes... By the amount of dissolved substances, the lakes are divided into p e s e (salt content less than 1 g in a liter of water), solon about (from 1 to 24 g of salts per liter) and saline, or m in eral (salt content is more than 24 g in a liter of water). In lakes with high salinity, salts precipitate. Usually, sewage lakes are fresh, as the water in them is constantly renewed. The drainless lakes are most often brackish or salty. This is because evaporation predominates in the flow rate of such lakes. All minerals brought by rivers and groundwater remain and accumulate in the reservoir.

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

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

1. What are the lakes in terms of water flow and salinity? 2. Why water in closed lakes is 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 (wastewater and internal drainage): Baikal, Caspian Sea, Ladoga, Onega, Victoria, Tanganyika, Aral Sea, Chad, Air North.

Draw a drainage and drainless lake?

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

& 45. Glaciers

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. The accumulations of ice on the earth's surface are glaciers. They are not the kind of ice that covers our rivers and lakes in winter.

* On Earth, glaciers occupy an area of \u200b\u200babout 16.1 million km 2, which is about 11% of the land. There are glaciers in all latitudes, but the largest area of \u200b\u200bglaciation occurs in the polar regions.

Glaciers form as a result of the accumulation and transformation of solid atmospheric precipitation, mainly snow. If more snow falls than it can melt, it builds up, compacts and turns into clear bluish ice.

Figure: 132. Scheme of the structure of the glacier

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

Glaciers move slowly. The speed of movement of glaciers in most mountainous countries ranges from 20 to 80 cm per day or 100 - 300 m per year. In the ice sheets of Greenland and Antarctica, 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 glaciers.

C o r n e, or mother, ice occupy the land surface regardless of its relief, which does not affect the shape of the glacier (Fig. 133). They have a flat-convex surface in the form of domes or shields. Ice accumulates in the middle and slowly spreads to the sides. Glacier tongues often descend on 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).

Figure: 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. At one time, the ice sheets spread over most of Europe, North Asia and North America.

Figure: 133. Antarctica Cover Glacier

* Continental glaciers occupy 98.5% of the area of \u200b\u200bmodern glaciation. Antarctica is almost entirely covered with ice (the area not covered with ice is 5% of the total). The average thickness of the ice cover in Antarctica is 2200 m, the maximum is 4776 m. The island of Greenland carries a powerful ice sheet .

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

Figure: 135. Mountain glaciers

* The most common are valley mountain glaciers that move from feeding areas along mountain valleys way down. 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. The importance of glaciers.Glaciers have large reserves of fresh water. They have many times more water than rivers and lakes combined. Mountain glaciers often feed streams and rivers.

Glaciers, like flowing waters, change the landforms. 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 highland and polar countries.

The solid material transported and deposited by glaciers is called m o r e n about.Moraine consists of sands, sandy loams, loams, clays, gravel, boulders and is deposited when glaciers melt. It composes moraine plains, ridges, hills, hills (Fig. 136).

1. What natural formations are called glaciers? 2. What is a snow boundary? 3. What is the difference between continental (cover) glaciers and mountain ones? 4. What is the significance of glaciers? five*. Show the ratio of continental and mountain glaciers on a pie chart.

On geographical maps, the lakes are painted either blue or lilac. Blue means that the lake is fresh, and lilac means 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. 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. There is little precipitation in deserts, rivers often dry up or there is none at all, therefore the lakes are salty.

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

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

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

Mountain glacial lakes, whose waters are fed by glaciers and snowfields, are especially poor in salts.

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

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

The lake is very shallow (2 to 4 meters deep). Its shores are flat and swampy, and from the north the desert rises 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 rivers Shari and Lagoni, 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 large, shallow and closed lakes on Earth have completely salty water, and the upper layer of Lake Chad is fresh. The riddle turned out to be simple.

Even more surprising is the Mogilnoye Lake. 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, practically lifeless, consists of liquid silt and is saturated with hydrogen sulfide. The second "floor" stands out with a cherry color - this color is given to it by purple bacteria. They act as 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 normal sea water and its salinity 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 water, but not fresh, but slightly brackish. The fifth "floor" is a six-meter layer of clean spring water suitable for drinking. The fauna is common here 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, seawater seeps through it where the "sea" layer is. 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 fresh, lighter water - at the top. That is why they do not mix. Oxygen does not enter the depths of the lake, and the bottom layers are contaminated with hydrogen sulfide.

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

why other salty lakes are fresh and got the best answer

Answer from Rain Wives [guru]
On geographical maps, the lakes are painted either blue or lilac. Blue means that the lake is fresh, and lilac means 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. 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. There is little precipitation in deserts, rivers often dry up or there is none at all, therefore the lakes are salty.
Among the large lakes in the world, most of all are fresh. This is due to the fact that the water in them is running and does not stagnate, which means that the salts brought by the rivers are carried away by them to the seas and oceans.
The most fresh of the planet's lakes are Lake Baikal in Asia, Onega and Ladoga in Eastern Europe, and Upper in North America. But the most insipid of them all should be considered Lake Benern - the largest of the lakes in Western Europe. Its water is closest to distilled, slightly more soluble minerals in Baikal and Lake Onega.
The freshwater lake of the largest water surface area - Lake Superior - is one of the Great Lakes of North America. Its area is 83 350 square kilometers.
Mountain glacial lakes, whose waters are fed by glaciers and snowfields, are especially poor in salts.
If the reservoir is not flowing, then the water in it becomes at 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. These lakes, in addition to Lake Tuz in Turkey, include Lake Eyr 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 that you can walk on in summer. This closed 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 sevenfold, occupying a huge area of \u200b\u200b25,000 square kilometers. In summer, when the water evaporates, the lake becomes very small, and a dense crust of salt forms on its surface with a thickness of several centimeters to two meters.
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 sea level. In one liter of Dead Sea water, it 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 its eastern part is salty. The reason for this peculiarity lies in the fact that the Ili River flows into the western part of the lake, and the eastern one is surrounded by deserts, where the water evaporates very strongly. Therefore, on geographical maps, the western part of Balkhash is shown in blue, and the eastern part is lilac.
The huge Lake Chad, located on the outskirts of the Sahara, is fresh at the top and brackish at the bottom. Fresh river and rain water, falling into the lake, does not mix with brackish water, but as if floats on it. Freshwater fish live in the upper layer, and sea fish that got into the lake in ancient times stay at the bottom.
A source:

Answer from Department for interaction with POVK[newbie]
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Answer from Albina Sapitsyna[active]
PATAMU))))))

Answer from Katya Shubina[newbie]
Not quite right with the drain. but the point is to feed the lakes if the lake is fed from a salt spring ( mineral spring) then it is salty, Example Lake Yarovoe itself is salty and next to the lake Hot key unleavened. Nearby it is in 10-15 meters.

Answer from Victoria volgina[newbie]
Salt water is found in closed lakes in hot arid climates. Due to the high evaporation, the salts in the water accumulate in the lake, making it 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 look at a list of the most freshwater lakes. We will also tell interesting facts about them.

Why are the lakes fresh?

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

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

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

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

Baikal is 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. 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. You can drink it even without pretreatment;
on the coldest days of winter, when Baikal solidifies, 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 pond received the poetic name "lake of the sun" due to the largest number of sunny days that are observed on its territory.
mystical secrets also did not pass by 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 glowing objects are often visible in the sky over the lake. Locals mistake them for UFOs.

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

Great Lake Superior

Lake Superior, in North America, is included in the group of five bodies of water, called the Great. They are interconnected by straits and rivulets and occupy a considerable area - 244 sq. m! The most discussed among them is the Top. This reservoir is the largest freshwater lake in the world, with an area of \u200b\u200b82.5 thousand square meters. m, the greatest depth - 406 m. Even the famous Baikal is inferior to the Upper one, the area of \u200b\u200bwhich is 31,722 sq. m.

By the standards of our planet, the Upper is one of the youngest natural formations in the crust, as 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 the old days, smugglers used a thick layer of frozen water to cross to the other side of the reservoir on foot. However, even in warmer months, the water temperature in the lake does not exceed 4 degrees Celsius.

Tanganyika - the longest body of water on the planet

Tanganyika bears the title of the world's longest freshwater lake. Its length coastline - 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. Over the millions of years of its existence, one of the largest freshwater lakes in the world did not dry up, therefore its flora and fauna did not change during this time.

Tanganyik is home to 200 species of fish, 170 species of which live exclusively in these waters. Moreover, 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. Desert depths extend below 100 m.

The surface of Lake Tanganyika is larger in area than Belgium.

When the first European explorers visited the reservoir in 1600, they found sturgeon 2.7 meters long and a pike that was 2 meters long. 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, raised by the local population to the status of a deity. According to local legends, more than three hundred human victims are on his account. Perhaps more, as the crocodile is often enjoyed by local sailors.

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

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 more than 70 years old, he continues to grow and terrify the local population. Africans consider him a devil who cannot be killed.

Titicaca - "mountain puma"

Titicaca is one of the largest freshwater lakes in the world, located in South America... The area of \u200b\u200bthe reservoir is 3872 sq km, maximum depth - 281 m. The reservoir is located at an altitude of 3812 m above sea level and is of incredible beauty.

Its name, unusual for our ears, consists of two words of Spanish origin and translates 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. On the surface of the lake there are more than 40 islands, some of which are the burial places of the Inca tribes' leaders.

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 shores, as well as a variety of flora and fauna. There are crustaceans, fish and even sharks in Titicaca. Once the lake was a bay, which, as a result of one of the natural disasters, turned into a lake and rose together 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 at the bottom of Titicaki is buried ancient citywhich is over 1500 years old. As a result of long-term excavations, archaeologists have found numerous artifacts - dishes, sculptures and even parts of stone structures. Scientists believe they have discovered the remains of the Inca civilization - Tiwanaku. A powerful earthquake or flood likely 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 \u200b\u200b17,700 sq. km. It is the largest freshwater lake in Europe with picturesque shores and a maximum depth of 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, the scientist Valeriy Yurkovitsa believes, the cause of the formation of the lake was the fall of a meteorite, which formed the deep-water part of the reservoir 40 thousand years ago.

Lake Ladoga appeared as a result of the impact of a meteorite, which formed a crater and became a 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 secrets lakes - the so-called barrantids. These are sounds of unknown origin, which often arise in the depths, frightening the local population;
in addition, according to the testimony of many eyewitnesses, the Ladoga monster lives in the lake, reminiscent of the famous Nessie;
of Lake Ladoga only one river flows out - the Neva, but it belongs to the most full-flowing rivers in Europe due to the volumetric catchment area of \u200b\u200bthe 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 not suitable 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%. His 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, maximum depth - 1025 meters.

The Caspian Sea is a kind of unique body of water that can be classified as a closed lake with sea salinity. However, if we go deeper into the numbers, the salinity level of the Caspian is still lower than in the sea. Therefore, today the Caspian Sea, while retaining its former name, is considered a lake.