The history of the formation of Lake Ladoga and its connection with the Baltic Sea

29.09.2019

In the concept of “lake,” the basin and the water mass that fills it represent an inextricable whole. For a lake to form, a basin must be formed and filled with water for a long time. The basin is often filled with river and underground waters, atmospheric precipitation, and less often with waters of marine origin.

The formation of lake basins occurs under the influence of endogenous (internal) and exogenous (external) processes. Typically, several processes are involved in the formation of the modern appearance of lake basins, but one or a group of these processes is leading. The best known is the genetic classification of lake basins proposed by M.A. Pervukhin (1937), the basic principles of which were taken as a basis when developing classifications by other authors. The main genetic types of lake basins, or otherwise lakes, according to the nature of their origin are as follows:

Tectonic- formed in deflections earth's crust on the plains (Ladoga, Onega, Ilmen), in troughs in the mountains (Markakol, Sonkel, Issyk-Kul, Alakol), in foothill depressions (Balkhash), in rift depressions (Baikal, Tanganyika). Most tectonic lakes are large in area and depth.

Volcanic- occur in craters and calderas of extinct volcanoes (Lake Kronotskoye, Kurilskoye in Kamchatka, Lake Turquoise on Simushir Island), in depressions of lava covers (Lake Komarinoe in Iceland), in maars (Lake Lacherskoye, Germany).

Meteoric- formed in depressions caused by falling meteorites (Lake Kaali in Estonia).

Glacial- their occurrence is associated with the exaration-accumulative activity of ancient and modern glaciers. Numerous lakes in Karelia and Finland owe their origin to the excavation activity of the glacier. They are often elongated in the direction of glacier movement. This group also includes tar and trough lakes. Tarn arose in karas and cirques - niche-shaped depressions on the upper slopes of trough mountains - in trough valleys (Lake Geneva, Baduk lakes in the Caucasus, etc.). Distributed in the Alps, the Caucasus, Tien Shan and other mountainous countries.

Failed- lakes whose basins arose as a result of leaching of soils and rocks by surface and mainly groundwater, as well as by thawing of permafrost soil or melting of ice in it. Failure lakes include: a) karst, b) suffosion and c) thermokarst lakes (alas in Yakut). The latter are common in the tundra and taiga zones of permafrost. The basins of suffosion and thermokarst lakes often have an oval shape, poorly indented shores and shallow depths.

Aeolian- lakes that arose in blowing basins, as well as between dunes and dunes. With rare exceptions, they are small in size and shallow (Lake Selety and Teke in Kazakhstan).

Podprudnye- the emergence of these lakes is associated with mountain falls, landslides blocking river valleys, damming of rivers by lava flows, and glacial moraines. Thus, dammed lakes are formed through the action of several processes. Thus, as a result of landslides caused by an earthquake, a lake appeared. Sarezskoye in the valley of the river. Murghab in the Pamirs, lake. Gekgel - in the valley of the river. Aksu in Azerbaijan, lake. Sevan, which arose in a tectonic depression dammed by a lava flow. Organogenic- intra-marsh lakes and lagoon lakes among coral structures (atolls).

16. Lake regions in Russia.

There are over 2 million lakes in Russia. These are mainly small lakes with a water surface area of less than 1 km2. There are few large lakes. Two lakes in Russia - Baikal and Ladoga - are among the 18 largest lakes in the world (the area of each of them is more than 10,000 km 2), Lake Onega is close to them. The deepest lake in the world is Lake Baikal (maximum depth 1637 m). The lake content of Russia is 2.1%.

In Russia, lakes are distributed extremely unevenly. While in some areas they are relatively rare or completely absent, in others, on the contrary, the number of lakes is very large, and they occupy a significant part of the surface, in some places up to 10-50% of the total area of the region. On the territory of Russia, the following lake areas can be distinguished, which are characterized by a large accumulation of lakes:

1. Northwestern lake region- one of the largest lake areas. In literature it is known as the Lake District. This vast area covers the territory of the Karelo-Finnish SSR, the Kola Peninsula, Leningrad, Pskov, Novgorod and Velikoluksk regions. On the territory of the Karelo-Finnish SSR alone, there are about 42,000 lakes, which occupy on average up to 10% of its surface. Within the Northwestern region, along with a large number of small and medium-sized lakes, there are such large lakes as Ladoga, Onega, Beloe, Ilmen, Chudsko-Pskovskoye, Vygozero, Segozero, Kovdozero, Pyaozero, and many others. etc. The abundance of lakes in the Northwestern region is closely related to Quaternary glaciation, and the origin of the basins is related to the accumulative and erosive activity of the glacier. It is characteristic that the border of this region coincides quite closely with the border of the last glaciation. Along with lakes of glacial origin, tectonic lakes are also common. The majority of lakes in Karelia and the Kola Peninsula belong to this type, developed in cracks and faults of hard rocks and having a characteristic orientation (their shape is elongated in the direction of the main faults of the earth’s crust). The lake basins of tectonic origin were subsequently significantly reshaped by the erosive activity of the glacier, which is especially clearly seen in the example of the northern shores of Lakes Ladoga and Onega. Among the swamps and swamp areas, there are often numerous lakes of secondary origin, formed during the development of swamps. There are many such secondary lakes in the territory of this region, especially among the swamps of the Lovat lowland (Polistovsky swamp massif, etc.). In places where easily soluble rocks (limestones) are shallow, karst lakes occur. These include many lakes of the Valdai Upland, lakes of Obonezhye (between lakes Onega and White), Onega basin, etc. Some of them periodically disappear.

2. Azov-Black Sea lake area includes a large number of unique lakes located along the coast of the Black and Azov Seas. The origin of these lakes is related to the activity of the sea, and most of them are estuaries. The most famous estuaries are: Khadzhibeysky, Kuyalnitsky, Tiligulsky, Molochny, etc.

The origin of the estuaries here is due to the advance of the sea onto the land and the flooding of river mouths. Their characteristic feature is that they are usually elongated in the direction of flooded river valleys, and are separated from the sea by sand spits-bars. In cases where an estuary is formed at the mouth of a large high-water river, then the connection with the sea is free, since excess water is discharged into the sea in a wide stream. In cases where estuaries are formed at the mouths of relatively small rivers, the spit-bar almost completely separates such a body of water from the sea, leaving only a narrow strait called the arma; The Dnieper estuary can be cited as an example. Estuaries into which rivers of insignificant water content flow are completely separated from the sea and lose connection with it; filtration through the bay is usually preserved.

In addition to estuaries, a significant number of lakes on the Azov-Black Sea coast belong to the lagoon type. Lagoons are formed as a result of the separation of shallow bays from the sea by spits-bars. Some of them, like estuaries, retain a connection with the sea through a branch, while some are severed and sometimes subsequently become desalinated. A typical lagoon body of water is Sivash, separated from the Sea of Azov by the long Arabat Spit. Other examples of lagoons are some lakes of Crimea, for example the famous Evpatoria lakes (Sasyk-Sivash, Saksky). Most of the lakes in this area are salt or mineral and have great importance for chemical and salt industry. The silt deposits (mineral mud) in many of these lakes have healing properties.

3. Caspian lake region covers a large group of lakes in the Caspian lowland. Most of the lakes in this area were formed from the overflow of steppe rivers during spring floods. Typical for the area are the shallow Kamysh-Samar lakes. In the Caspian lowland, temporary reservoirs called estuaries are also widespread, which usually form in low depressions and represent accumulations of melt water; with the onset of summer they dry out quickly.

4. West Siberian lake region includes numerous lakes of the steppe and forest-steppe zones of the West Siberian Lowland. There are several tens of thousands of lakes here; in most cases they are small and appear as flat, saucer-shaped depressions. In this area, several lake groups are distinguished: 1) lakes of the Barabinsk steppe, headed by lake. Chany, 2) lakes of the Kulunda steppe, among which the largest is lake. Kulunda, 3) lakes of the Ishim steppe, 4) lakes of the Trans-Urals. They are fed exclusively by melted snow waters. During the period of snowmelt, the lakes significantly increase in size, and in the summer they are greatly reduced, and at this time many dry up completely.

5. Altai lake region characterized by the presence of a large number of lakes, developed mainly in cirque basins, characterized by rounded outlines and small sizes. The largest lakes in the region are one of the most beautiful mountain lakes - Teletskoye and lake. Marka-Kul. A large shallow lake can also be conditionally included in the group of lakes in the region. Zaisan, located in the Irtysh valley.

6. Transbaikal lake region. The lakes here are mostly the remnants of disappeared larger bodies of water. Among them are the vast, now almost dry, basins of Zun-Torey and Barun-Torey.

7. Nizhne-Amur lake region. Within the lowlands that accompany the lower reaches of the Amur, there are a significant number of large reservoirs, and the area of some of them reaches 100-750 km 2. These are, for example, lakes: Petropavlovskoye, Bolen, Evvo, Kizi, Kadi, Orel, Chlya, Chukchagirskoye, etc.

8. Yakutsk lake region covers the territory of the Lena-Vilyui lowland and the Lena-Amga watershed. There are several tens of thousands of small lakes here. The origin of the lakes is associated with thermokarst phenomena.

History of the formation of the lake

Ladoga lake

Ladoga lake(Also Ladoga; historical name - Nevo) is a lake in Karelia (northern and eastern shores) and Leningrad region (western, southern and southeastern shores), the largest freshwater lake in Europe. Belongs to the Baltic Sea basin of the Atlantic Ocean.

The area of the lake without islands ranges from 17.6 thousand km² (with islands 18.1 thousand km²); volume of water mass - 908 km³; length from south to north is 219 km, greatest width is 138 km. The depth varies unevenly: in the northern part it ranges from 70 to 230 m, in the southern part - from 20 to 70 m. On the shores of Lake Ladoga there are the cities of Priozersk, Novaya Ladoga, Shlisselburg in the Leningrad region, Sortavala, Pitkyaranta, Lakhdenpokhya of Karelia. 35 rivers flow into Lake Ladoga, but only one, the Neva, originates. In the southern half of the lake there are three large bays: Svirskaya, Volkhovskaya and Shlisselburgskaya bays.

Etymology

In the ancient Russian Nestor Chronicle of the 12th century it is mentioned as “the great lake Nevo"(there is no doubt the connection with the name of the Neva River (also cf. Finn. neva"swamp, quagmire"). In ancient Scandinavian sagas and treaties with Hanseatic cities, the lake is called Aldoga(cf. Finnish) aalto- wave).

From the beginning of the 13th century the name came into use Ladoga lake, derived from the name of the city Ladoga, in turn named after the tributary of the same name in the lower reaches of the Volkhov River (Fin. alodejoki- a river in a low area). Other options for the origin of the name of the lake: from the Karelian word aalto(Karelian aalto- wave; hence Karelian. aaltokas- wavy); from a dialectal Russian word hello meaning open lake, expansive field of water.

Name Ladoga carries a river, a lake and a city. However, until recently it was not entirely clear which of the names was primary. The name of the city was derived from the name Lake Ladoga(from fin. *aaldokas, aallokas"worried" - from aalto"wave"), or from the name of the river Ladoga(now Ladozhka, from Finn. *Alode-joki, Where alode, aloe- “low terrain” and jok(k)i- “river”).

As T. N. Jackson writes, “by now it can be considered almost proven that the name of the river first arose, then the city, and only then the lake.” Therefore, she considers the primary hydronym Ladoga, from ancient Finnish. *Alode-jogi (joki)"lower river" The name of the city in Old Norse comes from the name of the river. Aldeigja, and it was already borrowed by the Slavic population and transformed with the help of metathesis ald → lad in other Russian Ladoga. The Scandinavian mediation between the Finnish and Old Russian words is fully confirmed by archaeological data: the Scandinavians first appeared on Ladoga in the early 750s, that is, a couple of decades earlier than the Slavs.

E. A. Khelimsky, on the contrary, proposes a German etymology. In his opinion, the primary name is the name of the lake - from ancient Scand. Aldauga“the Old Open-Sea-Like-Source.” This hydronym is associated with the name of the Neva (which follows from Lake Ladoga) in Germanic languages - “new”. Through an intermediate form Aldaugja this word was given by the Old Norse. Aldeigja"Ladoga (city)".

History of the formation of the lake

The basin of Lake Ladoga is of glacial-tectonic origin. In the Paleozoic 300-400 million years ago, the entire territory of the modern Lake Ladoga basin was covered by the sea. Sedimentary deposits of that time - sandstones, sands, clays, limestones - cover with a thick thickness (over 200 m) a crystalline foundation consisting of granites, gneisses and diabases. The modern relief was formed as a result of the activity of the ice sheet (the last Valdai glaciation ended about 12 thousand years ago). After the glacier retreated, the Littorina Sea was formed, the level of which was 7-9 m higher than the modern level of the Baltic Sea. In the north of the Karelian Isthmus, the Littorine Sea was connected by a wide strait with Lake Ladoga. The Mga River at that time flowed east and flowed into the lake near the modern source of the Neva.

In the area of Lake Ladoga, the land rose faster, and the lake eventually turned into a closed reservoir. The water level in it began to rise, and when it exceeded the watershed level, the lake waters, flooding the valley of the Mgi River, broke through into the valley of the Tosny River. Thus, 4 thousand years ago, a strait arose between Lake Ladoga and the Gulf of Finland, which became the valley of the Neva River. Over the past 2.5 thousand years, the relief has remained almost unchanged.

The northern part of Lake Ladoga lies on the Baltic crystalline shield, the southern part on the East European Platform. In the areas closest to Ladoga, the southern border of the shield runs approximately along the line Vyborg - Priozersk - the mouth of the Vidlitsa River - the source of the Svir River.

Climate

The climate over Lake Ladoga is temperate, transitional from temperate continental to temperate maritime. This type of climate is explained by atmospheric circulation and the geographical location characteristic of the Leningrad region. This is due to the relatively small amount of solar heat entering the earth's surface and atmosphere.

Due to the small amount of solar heat, moisture evaporates slowly. There is an average of 62 per year sunny days. Therefore, for most of the year, days with cloudy, cloudy weather and diffuse lighting predominate. The length of the day varies from 5 hours 51 minutes at the winter solstice to 18 hours 50 minutes at the summer solstice. The so-called “white nights” are observed over the lake, occurring on May 25-26, when the sun drops below the horizon by no more than 9°, and the evening twilight practically merges with the morning twilight. The white nights end on July 16-17. In total, the duration of white nights is more than 50 days. The amplitude of the average monthly amounts of direct solar radiation on a horizontal surface under clear skies ranges from 25 MJ/m² in December to 686 MJ/m² in June. Cloudiness reduces, on average, the annual total solar radiation by 21%, and direct solar radiation by 60%. The average annual total radiation is 3156 MJ/m². The number of hours of sunshine is 1628 per year.

The lake itself has a noticeable influence on climatic conditions. This is characterized by a smoothing of extreme values of climatic characteristics, as a result of which continental air masses, passing over the surface of the lake, acquire the character of marine air masses. The average air temperature in the area of Lake Ladoga is +3.2 °C. The average temperature of the coldest month (February) is −8.8 °C, the warmest (July) is +16.3 °C. The average annual precipitation is 475 mm. The lowest monthly precipitation falls in February - March (24 mm), the highest in September (58 mm).

Lake Ladoga is one of the largest fresh water bodies in Europe. In our article we want to talk about where the nature and climate are on its coast. It has quite interesting characteristics. The nature here is particularly beautiful.

Lake location

It is partially located in Karelia (eastern and northern shores) and in the Leningrad region (southern, southeastern, western). On its banks there are cities such as Novaya Ladoga, Priozersk, Shlisselburg, Sortavala, Lakhdenpokhya, Pitkyaranta.

Lake Ladoga on the map is located both in the Leningrad region and in Karelia. It's big enough. In addition, there are also islands on it. The area of Lake Ladoga is 17.9 square kilometers, excluding island areas. It extends from north to south for two hundred and nineteen kilometers. Its widest point is one hundred thirty-eight kilometers. Agree, the dimensions are impressive. Using these parameters, you can estimate the area of Lake Ladoga.

The depth of the reservoir in the northern region ranges from seventy to two hundred and thirty meters, and in the southern part from twenty to seventy meters. As you can see, the depth of Lake Ladoga is very heterogeneous, and highest value has in the northern part of the reservoir. And the volume of water mass is nine hundred and eight cubic meters.

Rivers of Lake Ladoga and islands

Thirty-five rivers flow into the reservoir. But only one originates from it - the Neva. On the southern coast of the lake there are three large bays: Volkhovskaya, Svirskaya and Shlisselburgskaya Bay.

The largest river flowing into Ladoga is the Svir. She brings the waters of Lake Onega into it. Rivers such as Avloga, Morye, Burnaya, Airajoki, Vidlitsa, Obzhanka, Syas, Olonka and others also flow into the reservoir.

It must be said that in Lake Ladoga the water level is not constant. It constantly fluctuates, and this is clearly visible from the white stripes on the rocks that go under the water.

The islands of Lake Ladoga are quite numerous. There are about 660 of them. Their total area is four hundred thirty-five square kilometers. It must be said that more than five hundred islands are located in the northern part of the reservoir. This is the Skerries region.

Largest islands:

Riekkalansari - 55.3 km. sq.
Mantsinsaari - 39.4 km. sq.
Kilpola - 32.1 km. sq.
Tulolansari - 30.3 km. sq.
Vaalaam - 27.8 km. sq.

The most famous on the lake are the Valaam Islands. They are an archipelago of fifty islands with a total area of about thirty-six square kilometers. They became famous thanks to the Valaam Monastery, located on the main island, and the Nativity of the Mother of God Monastery on the island of Konevets.

History of the lake

Lake Ladoga is located in a basin that has glacial tectonic origin. Three hundred to four hundred million years ago the entire territory of the lake and its basin was covered by the sea.

The modern relief was formed as a result of glacier activity. The main factor was the change in sea level and the rise of land. After the glacier retreated, the Baltic freshwater glacial lake was formed. Later, the waters of this reservoir went into the territory modern Switzerland. And there the Ioldian Sea was formed.

Nine and a half thousand years ago, Ancil Lake appeared due to the rise of land. On the Karelian Isthmus it was connected through a strait with Lake Ladoga. And eight and a half thousand years ago, ongoing tectonic processes opened the Danish straits, and the Littorina Sea was formed. This, in turn, led to the emergence of the Karelian Isthmus and, in fact, the formation of Lake Ladoga. Over the past two and a half thousand years, the relief in these places has hardly changed.

The northern part of the lake is located on the southern part - on the East European Platform. It is at the junction of these surfaces that the greatest depth of Lake Ladoga is observed.

Climatic conditions

Lake Ladoga has a temperate climate, sort of a transitional form from temperate maritime to temperate continental. Such climatic conditions are explained very simply. Geographical position Lake Ladoga and the atmospheric circulation of this region determined such a climate.

It must be said that in these places there are not many sunny days a year. This means that the amount of solar heat reaching the earth is not so great. Therefore, moisture evaporates extremely slowly. In 12 months there can be only sixty-two sunny days here. For most of the year, this region is dominated by days with cloudy, cloudy weather and diffuse lighting.

It is better to plan your vacation on Lake Ladoga from the twenty-fifth of May to the seventeenth of July, then you can watch the white nights here. These days the sun does not go below the horizon, morning and evening twilight merge into a single whole. In general, white nights last about fifty days.

It should be noted that Lake Ladoga itself also influences the local climate, smoothing out extreme characteristics. Throughout the year, southwestern and western winds dominate here. Quiet and windless weather is extremely rare. Sometimes the winds are stormy.

The entire coast experiences breezes during summer days and nights. They start around nine in the morning and last until eight in the evening. Breezes penetrate fifteen kilometers inland. Fogs are observed here most often in spring, autumn and summer.

Lake shoreline

The coastline of Ladoga is more than a thousand kilometers long. The northern shores are heavily rugged rocks, forming many peninsulas and narrow bays, as well as small islands separated by straits.

The southern coastline is low. It is less rugged and is often flooded. The coastline is entirely covered with rocky reefs, banks, and shoals. The Volkhovskaya, Svirskaya and Shlisselburgskaya bays are the largest bays of Lake Ladoga.

The eastern shores are very little indented. There are two bays here: Uksunlahti and Lunkulanlahti. It is in this part that there are wide, beautiful sand beaches.

The western shore of the reservoir is even less rugged. It was completely overgrown with dense mixed forests and shrubs, which came close to the water. The shore is strewn with scatterings of boulders. Stone ridges sometimes extend from the cape far into the depths of the lake, thereby forming dangerous shoals.

Relief of the lake bottom

As we noted earlier, the topography of the lake bottom is heterogeneous and has a clear increase in depth from south to north. We can say that the average depth of the reservoir is about fifty meters, and the greatest is two hundred and thirty-three meters (towards the north of the island of Valaam). Lake Ladoga in the northern part has a very uneven bottom. It is completely dotted with depressions. And in the southern region the bottom is smoother and more even. Lake Ladoga is the eighth deepest lake in Russia.

The transparency of lake water varies on different shores. Its lowest indicators are observed in the Volkhov Bay, and the highest in westward from the Valaam Islands.

During a strong storm, the water in the lake, as they say, boils and seethes, it is completely covered with foam.

Only the central part of the reservoir can be covered with ice and only in a very severe winter. A long cold period leads to a strong cooling of the water, for this reason the water in the lake remains cold even in summer. It only has time to warm up in the thin upper layer and narrow coastal strip. The maximum temperature of surface waters is in August, when it is twenty-four degrees. The water in the lake is fresh and, in principle, quite clean, except in those areas where there is runoff pollution from industrial waste.

Economic importance of the lake

The location of Lake Ladoga has determined its serious economic importance for the country. The fact is that the lake is navigable, which is important for the region. It is considered one of the parts of the waterway that is part of the Volga-Baltic Route, as well as the White Sea-Baltic Canal.

The most navigable is the southern part of Ladoga from the Neva to the Svir. Since the reservoir is quite large, there are often storms, especially in the fall. During such periods, all shipping is stopped for the safety of passenger ships.

Since the founding of St. Petersburg, the lake has become part of the unified water transport system of northern Russia. For safe navigation along south coast The Staraya Ladoga Canal was built. As soon as it was not enough, the Novoladozhsky Canal, one hundred and sixty-nine kilometers long, was also laid.

The Staraya Ladoga Canal is now almost completely dry and overgrown. And the second canal is still navigable. Up to eight million tons of cargo are transported across the lake every year. Petroleum products, chemical raw materials, building materials, and timber are transported to the Baltic from the Volga. In addition, tens of thousands of passengers are transported across Ladoga every year.

From Moscow, St. Petersburg and other cities there are cruises (tourist) to the islands of Konevets and Valaam. Vessels enter and pass through the central waters of the lake, where the shores are not visible. And in strong winds you can feel significant rolling.

There are no regular passenger services on Ladoga. However, tourist ships sail twice a day to certain destinations during navigation periods.

Fish living in the waters of the lake

The fish of Lake Ladoga is of industrial importance. Ten species are caught, among which the most popular are vendace, smelt, and ripus. There are quite a lot of pike perch and whitefish in the lake.

Holidays on Ladoga

Despite the fact that the water in Lake Ladoga remains cold even in summer, it attracts a large number of vacationers. As we said earlier, there are wonderful sandy beaches. The northern islands are especially popular among tourists. The best period for kayaking on the lake is June and July. A little closer to autumn, storms begin, during which the water is rough, like in the sea.

Here on the lake there is the Nizhnesvirsky Nature Reserve. It is located on the right bank of the Conservation Area - a wetland of international importance. They are interesting because they are nesting places for aquatic and migratory birds. 256 different species of birds have been recorded in this area.

The island of Valaam is of particular interest to tourists. It is completely covered with coniferous forest. There is an ancient monastery on the island, which was founded in the ninth to eleventh centuries.

Vacationers also like to visit Konevsky Island, which has a monastery. The island received this name from the Horse-Stone boulder located here. Until the end of the nineteenth century, this stone was a place of sacrifice. The main attraction is the Church of the Nativity Holy Mother of God, located on the territory of the monastery.

Historical excursion

The Novgorodians had a military and merchant fleet on Lake Ladoga for several centuries in a row. Geographical information also reached Western cartographers in those days. Lake Ladoga appeared on the map of the Moscow state back in 1544. It was made by the German scientist Sebastian Munster.

And in 1600, a drawing of Rus' was drawn up by Fyodor Godunov. The lake was depicted on it with fairly high accuracy. In the middle of the eighteenth century, a map was made not only of Lake Ladoga itself, but also of an artificial canal.

Novaya Ladoga

Novaya Ladoga is one of the towns on the shore of Ladoga. It is located on the left side of the Volkhov River in the place where it flows into the lake. The city was founded in 1704 by Emperor Peter the Great himself. A large number of historical architectural monuments have been preserved here, which may be of interest to guests and tourists.

Shlisselburg

The city is located on the shore of Ladoga. It was founded by the Prince of Novgorod in 1323, who founded a wooden fortress on the island of Oreshek. It was later captured by the Swedes, who renamed it Noteburg. And in 1702 the fortress was recaptured by Peter the Great. It was he who gave it its current name. The city also has its own attractions: the Staraya Ladoga Canal, the Oreshek fortress, the monument to Peter the Great, the Annunciation Cathedral, St. Nicholas Church.

Priozersk

On this spot Karelian settlement lived already in the twelfth century. And in 1310, the Novgorodians built a capital fortress at the mouth, called Korela. Later it was conquered by the Swedes. But in 1710 it again passed to the Russian Empire.

Lake Ladoga and its surroundings are quite interesting places for tourists. Here you can not only admire the beauty of nature, take boat trips, visit the islands, but also see historical monuments, preserved to this day.

LADOGA LAKE

Lake Ladoga, Old Russian name - Nevo, (Ladoga - Karelian Luadogu, Finnish Laatokka) is a lake in Karelia (N and E shores) and the Leningrad region (W, S and SE shores), the largest freshwater lake in Europe. Belongs to the Baltic Sea basin. The area of the lake without islands ranges from 17.6 thousand km² (with islands 18.1 thousand km²); volume of water mass - 908 km³; length from south to north is 219 km, greatest width is 138 km. The depth is uneven in the northern part, it ranges from 70 to 230 m, in the southern part - from 20 to 70 m. On the shores of Lake Ladoga there are the cities of Priozersk, Novaya Ladoga, Shlisselburg in the Leningrad region, Sortavala, Pitkyaranta, Lakhdenpokhya in Karelia. More than 30 rivers flow into Lake Ladoga, but only one originates - the Neva. In the southern part of the lake there are three large bays: Svirskaya, Volkhovskaya and Shlisselburgskaya Bay.

The name Ladoga is a river, a lake and a city. However, until recently it was not entirely clear which of the names was primary. The name of the city was derived from the name of Lake Ladoga (from the Finnish *aaldokas, aallokas “worried” - from aalto “wave”), or from the name of the Ladoga River (now Ladozhka, from the Finnish *Alode-joki, where alode, aloe - “low terrain" and jok(k)i - "river").

In PVL 12th century. referred to as "Lake Great Nevo". Perhaps from the name of the Neva River. Vasmer's etymological Russian-language dictionary:NEVA is a river connecting Lake Ladoga and Fin. Bay, for the first time, ancient Russian. Neva, Zhit. Alexandra Nevsk. (XIII century), p. 2; previously also Nevo - “Lake Ladoga” (in most years and also in the Book of Great Devils). From Finnish Nevajoki, Nevajarvi from neva "swamp", from where Swiss, Middle-German-German. Nu "Neva", perceived by folk. etymology as "New (river)".Krylov's etymological dictionary:NEVA - The name of the river on which Tsar Peter built the new capital of Russia goes back to the Finnish name Nevajoki - "swampy river", derived from the word neva - "swamp".

In the sagas, and later in treaties with Hanseatic cities, the lake is called Aldoga (cf. Finnish aalto - wave). From the beginning of the 13th century, the name came into use - Lake Ladoga, derived from the name of the city of Ladoga, which in turn received its name from the tributary of the Volkhov River of the same name in its lower reaches (Finnish: alodejoki - river in a low area). Other options for the origin of the name of the lake: from the Karelian word aalto (Karelian aalto - wave; hence Karelian aaltokas - wavy). Some researchers consider the primary hydronym Ladoga, from ancient Finnish. *Alode-jogi (joki) “lower river”.

There is also a hypothesis about the origin of the word “Ladoga” - from the dialectal Russian word -hello- meaning open lake, vast field of water (Mamontova N. Toponymy of Ladoga region). Vasmer's etymological Russian-language dictionary: ALOD - f. “clearing, vast and flat area”, archang., mes., (Dal), also “open lake, vast field of water”, zaon. (Sandpiper). According to Mikkola (JSFOu 23, 11), from Fin. *alode, let's modernize. Finnish aloo, alue "that which is below". Borrowing from Finnish is doubtful. aavo, aavu "steppe, open lake";Explanatory Dictionary by V. Dahl: ALOD - f. arch-mes. clearing, vast and flat area. The alode area is flat and open.

rice. 1 Islands of Lake Ladoga.

rice. 2 Lake Ladoga in the Sortavala region.

rice. 3 Ladozhskoe-ozero

The basin of Lake Ladoga is of glacial-tectonic origin. In the Paleozoic 300 - 400 million years ago, the entire territory of the modern Lake Ladoga basin was covered by the sea. The sedimentary deposits of that time are sandstones, sands, clays, limestones - they cover a thick thickness (over 200 m) of a crystalline foundation consisting of granites, gneisses and diabases.

The modern relief was formed as a result of the activity of the ice sheet (the last Valdai glaciation ended about 12 thousand years ago). The main factors were: changes in the level of the world's oceans, the water of the glacier and its weight - the rise of the land began (and continues). After the glacier retreated approximately 12,600 years ago, the fresh Baltic Glacial Lake was formed with a level of 25 meters above the ocean. About 10-9.6 thousand years ago, the waters of the lake broke through in the region of central Sweden and the Yoldian Sea was formed, the level of which was 7-9 m higher than the modern level of the Baltic Sea.

Approximately 9,500 years ago, rising land blocked the strait in central Sweden and Lake Ancylus was formed. In the north of the Karelian Isthmus, it was connected by a wide strait to Lake Ladoga. The Mga River at that time flowed east and flowed into the lake near the modern source of the Neva.

Approximately 8,500 years ago, tectonic processes open the Danish Straits and the Littorina Sea is formed. The water level, although significantly higher than the current one, was less than in Lake Anzilov. This led to the formation of the Karelian Isthmus and the formation of Lake Ladoga.

How long the lake was completely isolated is unknown - the water level in the lake rises faster than the rise of the land, and when the level of Ladoga exceeded the watershed level, the lake waters, flooding the valley of the Mga River, broke into the valley of the Tosna River.

Thus, approximately 4 thousand years ago, a new strait arose between Lake Ladoga and the Gulf of Finland, which became the valley of the Neva River. By this time, the old strait in the north of the Karelian Isthmus was already above the lake level. Over the past 2.5 thousand years, the relief has not changed significantly.

The crystalline foundation of the Northern Ladoga region belongs to the ancient primary foundation of Fennoscandia and was formed about 2000 million years ago. These are the oldest geological formations on Earth. Over millions of years, the ancient Svekokarelid Mountains have been flattened into picturesque hills, cliffs and cliffs. The depression of Lake Ladoga was formed in the Tertiary period as a result of a powerful geological fault. At the same time, as a result of faults, the formation of the archipelago and the coastal part of the northwestern shore of Lake Ladoga occurred. 12 thousand years ago, after the departure of the glacier, almost the entire surface of the Ladoga region was under the water of the ancient Baltic glacial lake. The climate, water level and salinity of the lake gradually changed. About 4000 - 3000 years ago the Neva was formed and the level of Lake Ladoga dropped by 10 meters.

At the end of the 9th century AD. a change in the hydrography of the region (a decrease in the level of the Baltic and, accordingly, Lake Ladoga) led to a simultaneous process of shallowing of the rivers of the Ladoga basin, including the Volkhov and its tributaries.

rice. 4 Ancylus Lake includes Ladoga 9500 years ago. The lake's flow into the ocean is indicated.

32 rivers flow directly into Lake Ladoga - more than 10 km long, the most large rivers flowing into Lake Ladoga include: r. Svir flowing from Lake Onega, river. Vuoksa, originating in Finland, r. Volkhov, flowing from Lake Ilmen, river. Syasya and others.

rice. 5 Svir River - Podporozhsky district in the northeastern part of the Leningrad region.

rice. 6 Svir River, rapids.

rice. 7 Sandy banks of the Svir River.

rice. 8 Vuoksa River.

The Vuoksa River is mentioned in the Novgorod Chronicles. People have lived in the vicinity of the river since prehistoric times - sites from the Stone Age have been discovered here; Vuoksa is mentioned in ancient epic"Kalevala". In the distant era of Tsar Ivan the Terrible, the Vuoksa River is mentioned as a place of congress to resolve state issues.

Fig. 9 Vuoksa near Melnikovo.

rice. 10 A dam on the Vuoksa River in Imatra.

rice. 11 Priozersk Vuoksa River.

rice. 12 Upper reaches of the Volkhov River.

rice. 13 Volkhov River in the area of St. Ladoga and Lyubsha (Chernavino-5), mounds in the “sopka tract”.

rice. 14 Volkhov River - not far from the mouth.

rice. 14 Syasya river.

Lake Ladoga - Nevo.

rice. 16 ladozhskoe lake.

rice. 17 Landscapes of Lake Ladoga.

rice. 18 Lake Ladoga - shores.

rice. 19 Lake Ladoga - breakers.

rice. 20 Lake Ladoga - forest.

rice. 21 Lake Ladoga - silence.

rice. 22 Lake Ladoga - autumn.

rice. 23 Rocky shores of Lake Ladoga.

rice. 24 Lynx Rock, village. Vyartsilya, Northern Ladoga region.

rice. 25 Ruskeala, former marble quarry. Rock height: 30 - 40 m, Northern Ladoga region.

rice. 26 Lake Ladoga - stones.

rice. 27 Boulder near Vidlitsa - a river in Karelia, Ladoga region.

rice. 28 On the islands of Lake Ladoga.

rice. 29 Cape Rahaniemi. Radiance August 18, 2003.

rice. 30 Gorskii Staraya Ladoga Canal photo 1909

Fig. 31 Korela Fortress in Priozersk.

Korela (Swedish Kexholm, Finnish Käkisalmi "Cuckoo Strait") is a stone fortress in the city of Priozersk, on an island in the Vuoksa River. Medieval Korela was the most northwestern city of Rus'. The fortress was founded at the turn of the XIII and XIV centuries. Novgorodians on the island of the Uzerve River(Vuokse)to protect the northwestern borders of the republic from the Swedes.

Priozersk - [Karelian. Kägöisalmi, Finnish Käkisalmi - “Cuckoo Strait”, Swedish. Kexholm - “cuckoo island”] is the administrative center of the Priozersky district of the Leningrad region. The city is located on the Karelian Isthmus, along the banks of the northern branch of the Vuoksa River, between Lake Ladoga and Lake Vuoksa. Until the beginning of the 17th century, it was the center of the Korelsky land, the Korelsky district of the Vodskaya Pyatina. From the 14th century to 1611 the city was known as Korela. From 1580 to 1595 and from 1611 to 1918 the city was called Kexholm. Since 1918, the city, as part of the newly independent Finland, began to be called Käkisalmi. In 1940 after Soviet-Finnish war the city was transferred to the Soviet Union, the name Kexholm was returned. In 1941-1944, during the Soviet-Finnish War, the city was occupied by Finnish troops and was called Käkisalmi. In 1944, after the Moscow Armistice, the city became part of the Soviet Union for the second time. In 1948 it was renamed Priozersk.)

rice. 32 Fortress Oreshek - Orekhovy Island, (Finnish: Pähkinäsaari) - a small island at the source of the Neva. The main attraction is the ancient Novgorod fortress of the 14th century Oreshek.

Fig. 33 Map of the Brockhaus and Efron encyclopedia. Ladoga lake. (clickable)

...

The problem of the history of the development of Lake Ladoga and the formation of the river. The Neva River currently remains controversial in many aspects. The fundamental generalizations currently available, carried out by teams of authors 1, leave a number of important issues, requiring further scientific study and solution. The main ones are the time of occurrence of the river. Neva and the direction of flow from Ladoga before the formation of the river. Not you.

The basin of Lake Ladoga began to fill with water as the glacier of the last Valdai glaciation destroyed and melted. According to recent studies devoted to the problem of deglaciation of the basins of Lakes Ladoga and Onega, using varvochronological, radiocarbon and paleomagnetic analyzes of ribbon clays, it was found that Lake Ladoga became free of ice in the interval 14000-12500 calendar years (11800-10300 14 C years ago) ( Fig. 1).

Rice. 1. Stages of deglaciation of the Lake Ladoga basin

Within the basin of Lake Ladoga there was a deep-water cold oligotrophic periglacial reservoir (Fig. 2), which was the eastern reach of the Baltic glacial lake 2, in which a thick layer of lacustrine-glacial ribbon clays 3 was formed over the course of 2000 years.

Rice. 2-a. The position of the edge of the glacier and the adjacent Baltic Glacial Lake 10300 14 C years ago or 11500 calendar years ago before its descent after the retreat of the edge of the glacier from the city of Billingen in Central Sweden. Dotted line shows the current situation coastline Baltic Sea 7.

Rice. 2-b. Lake Ladoga was part of a large periglacial lake. The water level reached 50–60 m. The northern part of the Karelian Isthmus was flooded

A characteristic feature of band clays is their distinct gradational layering. In sections of ribbon clays, there is an alternation of layers of two types: clayey, relatively thin and darker-colored, and coarser, silty or sandy, thick and light-colored.

The first are called winter layers, the second - summer layers. Ribbon clays were formed from glacial turbidity - a product of moraine washing, brought by meltwater streams into the periglacial reservoir (Fig. 3).

Rice. 3. Photograph of ribbon clays formed in the conditions of a periglacial lake. One layer corresponds to one year.

The sedimentation of coarser clastic material to the bottom of the lake in the spring-summer period and finer material in suspension in the autumn-winter season led to the formation of ribbon clays. In the cold, sharply continental climate of the late glacial period, the productivity of lake and terrestrial ecosystems was low, which was reflected in the very low content of organic matter in banded clays.

A thick layer of lacustrine-glacial sediments of the BLO covers almost the entire bottom of Lake Ladoga, and their thickness reaches 20-30m 4 . Sediments of the Baltic glacial lake were also found in sections of bottom sediments of many lakes located in the northern lowland part of the Karelian Isthmus 5 .

Higher up the section of the banded clays, a gradual thinning of the layers occurs until they completely disappear: the banded clays are replaced by microlayered and homogeneous clays (Fig. 4).

Rice. 4. Summary section of bottom sediments of Lake Ladoga and paleogeographic reconstruction 12. The change in the structure of bottom sediments of Lake Ladoga over time is shown from glacial deposits (moraine) to lacustrine-glacial (ribbon clays) and to lacustrine deposits (homogeneous clays and silts). P.P.P. – losses during ignition of samples of bottom sediments, an indicator of changes in the content of organic matter, which in turn is an indicator of the bioproductivity of the reservoir and changes in temperature conditions. The maximum content of organic matter in bottom sediments correlates with the Holocene optimum.

This facies transition from one type of clay to another was associated with the gradual degradation of the glacier, the retreat of its edge from the lake's catchment area and, accordingly, with a decrease in the supply of clastic material and the deposition of predominantly suspended matter.

According to existing ideas, the last reduction of the Baltic ice sheet occurred unevenly, as did the isostatic uplift of the territory that followed. It is believed that about 10,300 14 C years ago, in the area of the modern city of Billingen in central Sweden (Fig. 2), the collapse of the glacial blade led to the release of the straits, a sharp decrease in the runoff threshold and a drop in the level of the Baltic Glacial Lake (BGL), which caused the release of under the waters of a vast territory from the Baltic to White Sea adjacent to the edge of the ice sheet.

The descent of the UAV was catastrophic and short-lived. The sea waters of the world ocean penetrate into the Baltic basin, forming the salt-water conditions of the Yoldian Sea stage (Fig. 5). From this point in time, Lake Ladoga is separated from the Baltic.

Rice. 5-a. The position of the edge of the glacier and the outline of the Yoldian Sea, which was connected to the ocean through the straits in Central Sweden 13.

Rice. 5 B. Lake Ladoga connected with the Ioldian Sea in the northern part of the Karelian Isthmus. The dashed line shows the southern border of Lake Ladoga in the Ioldian stage.

The decrease in the BLO level was accompanied by strong processes of denudation and erosion of the exposed parts of the bottom, as a result of which in the sections of bottom sediments of most lakes in the northern part of the Karelian Isthmus there is a sandy layer at the contact of clays and overlying silts or a sharp boundary between them, indicating a break in sedimentation. In the structure of sediments of lakes located within the Karelian Isthmus - Heinioki Strait, which connected Lake Ladoga and the Baltic Sea, sand layers up to 0.5 m 6 thick are found, overlying ribbon clays. Higher up the sections, sand layers are overlapped by organomineral lake sediments (sapropels) and bog peats.

In the early Holocene (10,300-9,500 years ago), due to significant climate warming in the Northern Hemisphere, the rapid destruction of the Baltic ice sheet, the descent of the Baltic glacial lake, and, as a consequence, the isolation of Lake Ladoga, a change in the lake-glacial type occurred lake sedimentation (Fig. 4). Characteristic thin gray homogeneous clays (0.2-0.8 m) are formed.

In the second half of Preboreal time, the level of Ladoga rose to levels of 18-20 m. This was a consequence of the Ancylic transgression of Baltica (Fig. 6) about 9200 years ago, which led to damming of the flow from Ladoga and, as a consequence, to a rise in the water level in the lake (Fig. 7). During the maximum of the Ancylic transgression, the southern shallow waters of Lake Ladoga were flooded to modern isobaths of about 20 m (Fig. 6).

Rice. 6. Ancilian stage of the Baltic Sea during the maximum transgression associated with the closure of the straits in Central Sweden due to the isostatic uplift of the territories freed from under the ice 22.

Rice. 7. Reconstruction of changes in the levels of Lake Ladoga and the Baltic Sea in the late and post-glacial periods.

About 9500/9000 years ago, approximately at the boundary of the Preboreal and Boreal, lacustrine sediments - silts - began to accumulate in the basin of Lake Ladoga (Fig. 4). Due to the fact that the lake’s water area was repeatedly reduced in the Holocene, the complete and most thick sections of silt deposits are observed in the northern deep-water region. During sedimentation, the role of organic matter of autochthonous origin increases. In silts there is an increase in the content of organic matter compared to clays.

At the boundary of the Preboreal and Boreal about 9000 years ago, the level of Ladoga again decreased due to the regression of the Baltic to levels below current situation, which is recorded according to the study of bottom sediments in the shallow southern part of the lake 8.

Ladoga and the Baltic are dismembered, the Heinjoki Strait dries up, and many lakes of the Karelian Isthmus become isolated, in which organogenic silts form, and peat bogs form at the mouths of rivers. According to various authors, the radiocarbon age of peatlands is 7870±110 years in the Pitkyaranta area, 7970±260 and 7960±230 years at the mouth of the Oyat River, 7110±170 years on the Vyun River, 6900±70 years on the Olonka River 9.

The flow from Ladoga at that time was directed through the system of channels of the Vuoksa lake-river system into the Vyborg Bay, and the threshold of the flow from Ladoga was in the area of the modern village of Veshchevo (Finnish name Heinioki) at an altitude of 15.4 m above sea level.

The most interesting and controversial period in the history of Ladoga is the period of time of the last 5000 years. This stage, which received the name “Ladoga transgression” in the literature, corresponds to the interval 5000-3000 years ago (Fig. 8). The reasons for this transgression are interpreted ambiguously. M. Saarnisto 10 saw the main reason in the advancing isostatic uplift of the earth's crust on the northern coast of the Gulf of Finland and the Baltic, as a result of which the flow of water from the Saimaa system of lakes into the Gulf of Finland stopped.

As a result of the distortion, a new threshold of flow arose through the marginal ridge of the Salpausselkä-I moraine near the city of Imatra into the river system. Vuoksa, which at that time flowed from Ladoga to the Baltic. The waters of the largest Saimaa lake system in Finland, which is dammed by ridges of Salpausselkä moraines, according to M. Saarnisto, broke into Ladoga, sharply increasing the incoming part of the lake’s water balance.

According to A.V. Shnitnikov 11, the development of the Ladoga transgression was due to another centuries-long rhythm of fluctuations in total moisture, which was widely manifested during this period of the Holocene and could lead to the breakthrough of waters from the lake. Saimaa and to a significant increase in runoff into Ladoga from the vast drainage basin. Apparently, during this period, the influence of several factors, endogenous and exogenous, was felt, which contributed to significant transformations in the hydrographic network of the basin and the water balance of Ladoga.

The result of the development of the Ladoga transgression, as is commonly believed, was the overflow of Ladoga across the Mginsko-Tosnensky watershed and the formation of the Neva River. Most researchers, starting with G. de Geer, J. Ailio, E. Hyppä, who were later referred to by D. D. Kvasov 14, believed that the Neva Channel between Ladoga and the Baltic was formed mainly as a result of the glacioisostatic uplift of the northern Ladoga region and the skew of the Ladoga Basin , as a result of which the waters of the lake flooded its southern part and penetrated into the river valley. pra-Mga, which flowed into Ladoga.

They reached the height of the Mginsko-Tosnensky watershed, represented by a ridge (about 18 m) composed of moraine loam, washed it away and carried out the descent of the waters of Ladoga along the valley of the river. ancestral river, which previously flowed into the Gulf of Finland. At the same time, the lower parts of the valleys were expanded and deepened by runoff from Ladoga (Fig. 8).

Rice. 8. Map showing the modern outlines of Lake Ladoga (oblique shading (2)) and during the maximum of the Ladoga transgression (black color (1)) before the breakthrough of the river. Not you.

The time of the maximum of the Ladoga transgression and the beginning of the formation of the Neva River have different dates for different authors. Yu. Ailio 15 and S. A. Yakovlev 16 believed that the Neva arose in the period 4500-4000 years ago. Later, K.K. Markov and co-authors 17 pointed out the short duration of the Ladoga transgression, which fit into part of the subboreal period. O. M. Znamenskaya et al. 18 dates it to 2000 years ago, and D. D. Kvasov 19 considered it in the range of 2300-1200 years ago. According to M. Saarnisto and T. Grönlund 20 r. The Neva arose about 3100 years ago.

The work of D. B. Malakhovsky et al. 21 provides new conclusions about the time of the Ladoga transgression and the formation of the Neva River, which are clarified by dating the terraces of different ages and the roof of peat bogs underlying the sediments of the transgression in the “Nevsky Forest Park” section (3000-2800 years ago) and overlapping them in the “Nevsky Piglet” section (2400 years ago).

Thus, based on these data, in a short period of time of about 400 years, the level of Ladoga dropped from 18 m to 5-6 m, which is quite realistic, given that the southern watershed of the lake was composed of loose sedimentary rocks, while the northern one, Heinjoki, was composed of crystalline rocks .

With the isostatic uplift of the northern part of the Karelian Isthmus, the Heinioki Strait dried out and became swamped, as a system of lake-river channels on the line Priozersk - Veshchevo - Vyborg. During the regression of Ancylovo Lake and the continuing uplift and distortion of the northern part of the Ladoga Basin, the level of Ladoga and Baltic became equal.

It was at this time that a new flow from the north broke out of the Saimaa system of lakes and its bifurcation occurred. Part of this flow went along the old hollow of the Heinioki Strait to the Priozersk Bay, and part of the flow continued into the Baltic. A large volume of transported sediment flowed along the western shore of Ladoga and contributed to blocking the flow from Ladoga along the hollow of Lake Sukhodolskoye (formerly Lake Suvanto).

The powerful sandy coastal ridges of the subboreal period that we studied, more than 17 meters high, adjacent to glacial deposits (an ancient lake stretching from north to south almost from Priozersk to Pyatirechye), are recorded along the western shore of Ladoga. They were broken through by a stream of water in 1818. in the area of the modern mouth of the river. Burnoy (Taypole Bay).

It must be emphasized that the supposed blocking of the flow from Ladoga could only be realized as a result of block movements on the Karelian Isthmus combined in time, caused by the activation of isostatic rises of the northern Ladoga region, an increase in humidity and a change in the direction of flow from the Saimaa system. The relative subsidence of the southern part of the basin could lead to a breakthrough of water from Ladoga and the formation of the river. Neva (or a significant increase in flow along the bed of the ancient Neva, if it existed before these events, i.e. there was a bifurcation of flow from Ladoga).

The Burnaya River was formed as a result of a sudden breakthrough of the waters of the lake. Suvanto (Sukhodolsky) through a man-made canal and its descent into Ladoga only in May 1818. Lake level Suwanto dropped by 11m, and its bottom was exposed over an area of more than 5000 hectares. The channel flowing from it to the west into the river. Vuoksu completely dried up, and a rocky isthmus formed in its place. It was from this time that r. The Vuoksa flowed backwards and began to flow into Ladoga, and numerous lakes of the Karelian Isthmus sharply lowered their level and became shallow.

This happened as a result of a decrease in the lake level by 10-11 m. Suvanto and other local erosion bases in the Vuoksa basin. Significant changes were also caused by a further artificial increase in flow in the river section. Vuoksa - lake Suvanto in 1857 and the formation of the Losevskaya channel. This event 119 also affected the entire hydrographic network of the Karelian Isthmus and entailed a corresponding restructuring in the structure of its landscapes.

Numerous lakes of the Karelian Isthmus sharply lowered their level, became shallow and significantly reduced the size of their water areas as a result of a decrease in local erosion bases in the river basin. Vuoksi. A comparison of the areas of the largest lakes on maps of the Karelian Isthmus at the beginning of the 19th century and in 1983, reduced to the same scale, showed that, for example, the area of the lake. Sukhodolsky decreased by 32.4%, lake. Balakhanovsky - by 59.5%, lake. Cancer - by 88.6%, dozens of small lakes have completely disappeared.

Literature:
1 . Kvasov, D. D. History of Ladoga, Onega, Pskov-Peipus lakes, Baikal and Khanka / D. D. Kvasov, G. G. Martinson, A. V. Raukas (eds.). - L., 1990. - 280 p.; Evolution of natural environments and the current state of the geosystem of Lake Ladoga: Coll. scientific tr. / Ed. N. N. Davydova, B. I. Koshechkina. - St. Petersburg, 1993. - 118 p.; Kvasov, D. D. Late Quaternary history of large lakes and inland seas of Eastern Europe. - L., 1975. - 278 p.; Davydova, N. New data on Late Pleistocene and Holocene history of Lake Ladoga / N. Davydova, V. Khomutova, M. Pushenko, D. Subetto // Report on Lake Ladoga Research in 1991-1993. Joensuu. 1994. - No. 111. - P. 137-143; Subetto, D. Contribution to the lithostratigraphy and history of Lake Ladoga / D. Subetto, N. Davydova, A. Rybalko // Palaeogeography, Palaeoclimatology. Palaeoecology. - 1998. - No. 140. - P. 113-119; The First International Lake Ladoga Symposium // Hydrobiology. - 1996. - Vol. 322. - 328 p.
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