Lake Ladoga is located in the North-West of
Russia. Its northern part is located in Karelia, and the southern -
in the Leningrad region.
Lake Ladoga is the largest in
Europe. The lake area is over 18 thousand square meters. km, and
depth reaches 200 m. The greatest length of the lake from north to
south - 219 km. Many small and medium-sized rivers flow into the
lake, among which the largest are the Svir, Olonka, Syas and
Volkhov. Only the Neva flows out of the lake, the source of which is
located near the town of Shlisselburg. There are about 600 islands
on Ladoga, mainly in the northern part, of which the Valaam
archipelago is most famous.
Lake Ladoga often stormy. For the
passage of river vessels, that are not adapted to the harsh lake
conditions, along the southern shore of the lake, the Novaya Ladoga
Canal was dug that is 169 km long.
The southern shores of
Ladoga are low-lying and marshy, while the northern shores are rocky
and steep. Ladoga granite and other rocks of building stone, used in
particular in the construction of St. Petersburg, are mined there.
In the ancient Russian Nestor chronicle of the 12th
century, it is referred to as the “great lake Nevo” (there is no doubt a
connection with the name of the Neva River (also compare Fin. neva
“swamp, bog”)). In the ancient Scandinavian sagas and agreements with
the Hanseatic cities, the lake is called Aldoga.
From the
beginning of the 13th century, the name Ladoga Lake came into use,
formed from the name of the city of Ladoga, which in turn was named
after the tributary of the same name in the lower reaches of the Volkhov
River, from Fin. alodejoki - "river in low country". Other variants of
the origin of the name of the lake: from the Karelians. aalto - "wave",
hence the Karelian. aaltokas - "wavy"); from the dialectal Russian word
alod, meaning an open lake, a vast water field.
The name Ladoga
is given to a river, a lake and a city. At the same time, until recently
it was not quite clear which of the names is primary. The name of the
city was derived from the name of Lake Ladoga (from Finnish *aaldokas,
aallokas "wavering" - from aalto "wave"), or from the name of the Ladoga
River (now - Ladoga, from Finnish * 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 Fin. *Alode-jogi (joki) "lower river".
From the name of the river came the name of the city of other
Scandinavian. Aldeigja, and it was already borrowed by the Slavic
population and transformed with the help of the ald → lad metathesis
into Old Russian. Ladoga. The Scandinavian mediation between the Finnish
and the Old Russian word is fully confirmed by archeological 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, offers a Germanic etymology. In his opinion, the name of the
lake is primary - from other Scandinavian. * Aldauga "old reservoir".
This hydronym is associated with the name of the Neva (which flows from
Lake Ladoga) in the Germanic languages - "new". Through the intermediate
form *Aldaugja, this word gave another scand. Aldeigja "Ladoga (city)".
The history of the formation of the lake
In the Paleozoic, 300-400
million years ago, the entire territory of the modern basin of Lake
Ladoga was covered by the sea. Sedimentary deposits of that time -
sandstones, sands, clays, limestones - cover with a thick layer (over
200 m) a crystalline basement consisting of granites, gneisses and
diabases.
The northern part of Lake Ladoga lies on the Baltic
Crystalline Shield, the southern part lies 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.
The modern
relief was formed as a result of the activity of the ice sheet (the
last, Valdai glaciation ended about 12,000 years ago). The main factors
were the gradual rise in the level of the world ocean, changes in the
level and regime of reservoirs that existed in the basin of the Baltic
Sea in the Holocene, the flow of water from the melting glacier and its
weight - the rise of land began (and continues).
The southern
part of the Ladoga Basin was freed from ice about 14,000 years ago.
Initially, on the liberated territory there was an independent
near-glacial lake with a drain into the Baltic Glacial Lake. As the
level of the Baltic glacial lake rose, Ladoga became part of it no later
than 13,300 years ago. In the early stages, the basins were connected in
the area of the Neva lowland. After the liberation of the northern part
of the Karelian Isthmus from the glacier about 12,200 years ago, the
lakes began to communicate through a wide strait in the north of the
modern isthmus - the so-called Heiniok Strait. The strait in the area of
the Prinevskaya lowland, gradually narrowing, existed until the descent
of the Baltic glacial lake. Glacier retreat in central Sweden opened
straits in the region of present-day Mount Billingen about 10,300 years
ago, causing the Baltic Glacial Lake to sink 25–28 meters to sea level
in just a few years.
During the Yoldian stage of the evolution of
the Baltic Basin (10,300–9,500 years ago), Ladoga remained a lake, the
flow from which was carried out through the territory previously
occupied by the Heinioka Strait. The area of the lake has decreased
significantly, especially in the southern part.
With the onset of
the Ancylus stage 9500 years ago, the level of the Baltic Basin rises by
15–20 meters, which leads to the reunification of the basins through the
Heinioka Strait. The continuing rise in the level of Lake Antsylovoe
caused the transgression of Lake Ladoga about 9300–9200 years ago, which
was especially pronounced in the southern part of the modern basin. The
appearance of the Dana River in the region of the present-day Great Belt
caused a gradual drop in the level of Lake Ancylus, which reached sea
level about 9,000 years ago. Around this time, Ladoga again separates
from the Baltic basin, and its level drops significantly below modern
levels. The Heiniok Strait dries up and modern lakes appear in the north
of the Karelian Isthmus.
It is generally accepted that in the
period from 9000 to 5000 years ago, the runoff from Lake Ladoga occurred
in the Vyborg Bay through the channel system of the lake-river system of
Vuoksa. The runoff threshold was located in the area of the village of
Veshchevo.
Between 5700 and 5000 years ago, the waters of Lake
Saimaa broke through the Salpausselkya-I ridge in the Imatra region,
forming a modern runoff channel to Ladoga through the Vuoksa system and
significantly increasing the lake's drainage basin.
About 5000
years ago, the level of Lake Ladoga began to rise, the causes of which
are usually associated with an increase in the incoming part of the
lake's water balance after the accession of the Saimaa system. The
subject of discussion is the mechanism of runoff from Lake Ladoga in the
period between the formation of the modern runoff direction in the
Vuoksa system and the appearance of the Neva. The Ladoga transgression,
judging by the soil profile 1 in Staraya Ladoga, took place 5700–3400
years before the present.
The uneven isostatic uplift of the
northern and southern parts of the lake led to the "overturning" of the
basin of Lake Ladoga in a southerly direction. In the Neva lowland at
that time there were the Mga rivers, the mouth of which was located at
the site of the modern source of the Neva, and the Tosna, which flowed
into the Gulf of Finland, separated by a watershed in the area of
\u200b\u200bthe modern Ivanovsky rapids. The rise in the level in the
southern part of Ladoga led to the flooding of the Mga valley and the
erosion of the Mginsko-Tosnensky watershed about 2500 years ago
(according to other estimates - from 4500 to 1200 years ago). During the
subsequent deepening of the valley, the modern channel of the Neva was
formed. The level of the lake after the formation of the Neva fell by
12-13 meters.
Meteorite crater in Lake Ladoga (Ladoga astrobleme)
In the 2000s,
it was suggested that Lake Ladoga is of meteorite origin. The northern,
deep part is the crater of the explosion, and the rest, the shallow
part, was formed at the site of the subsidence caldera. In favor of the
meteorite origin are signs of shock-explosive melting and vitrification
of rocks, as well as the presence of erupted basalts (or tagamites). It
is believed that the crater arose approximately 38.5 thousand years ago
and is about 80 km in diameter. The calculated parameters of the
celestial body that gave rise to it: size - 11 km in diameter, speed -
17 km / s.
Climate
The climate over Lake Ladoga is temperate,
transitional from temperate continental to temperate maritime. This type
of climate is explained by the geographical location and atmospheric
circulation, which is typical for the Leningrad region. This is due to
the relatively small amount of solar heat entering the earth's surface
and into the atmosphere.
Due to the small amount of solar heat,
moisture evaporates slowly. There are an average of 62 sunny days per
year. Therefore, for most of the year, days with cloudy, overcast
weather and diffused lighting prevail. 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, coming 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. The white nights end on July 16-17. In total, the duration of
the white nights is more than 50 days. The amplitude of the average
monthly sums of direct solar radiation on a horizontal surface in a
clear sky is from 25 MJ/m² in December to 686 MJ/m² in June. Cloudiness
reduces, on average per year, the arrival of total solar radiation by
21%, and direct solar radiation by 60%. The average annual total
radiation is 3156 MJ/m².
The lake itself has a significant impact
on climatic conditions. This is characterized by the smoothing of
extreme values of climatic characteristics, as a result of which the
continental air masses, passing over the surface of the lake, acquire
the character of maritime 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 rainfall is 475 mm. The smallest monthly amount of precipitation
falls in February-March (24 mm), the largest - in September (58 mm).
During the year, western and southwestern winds prevail in most of
Lake Ladoga. The average monthly wind speed in the open part of the lake
and on most of the islands from October to January-February is 6-9 m/s,
in the remaining months 4-7 m/s. On the coast, the average monthly wind
speed varies from 3 to 5 m/s. Calms are rarely observed. In October,
storm winds with a speed of more than 20 m/s are often observed on Lake
Ladoga, the maximum wind speed reaches 34 m/s. Breezes are observed
along the entire coast in summer on windless sunny days and clear
nights. The lake breeze begins at about 9 am and lasts until 8 pm, its
speed is 2-6 m/s; it extends 9-15 km inland. Fogs are observed most
often in spring, late summer and autumn.
Shores, bottom
topography and hydrography of the lake
The area of the lake without
islands is from 17.6 thousand km² (with islands - 18.1 thousand km²);
length from south to north - 219 km, maximum width - 138 km. The volume
of the water mass of the lake is 908 km³. This is 12 times more than is
annually poured into it by rivers and carried out by the Neva River.
Seasonal fluctuations in the water level in the lake are small due to
the large area of the water surface of this reservoir and the relatively
small annual variation in the amount of water entering it. The latter is
due to the presence of large lakes within the watershed of Lake Ladoga
and the presence of hydropower facilities on all major tributaries,
which together provide a fairly uniform flow of water throughout the
year.
The coastline of the lake is more than 1000 km. The
northern shores, starting from Priozersk in the west to Pitkäranta in
the east, are mostly high, rocky, heavily indented, form numerous
peninsulas and narrow bays (fjords and skerries), as well as small
islands separated by straits. The southern shores are low, slightly
indented, flooded due to the neotectonic submeridional skew of the lake.
The coast here is replete with shoals, rocky reefs and banks. In the
southern half of the lake there are three large bays: Svirskaya,
Volkhovskaya and Shlisselburgskaya bays. The eastern shore is not very
indented, two bays protrude into it - Lunkulanlahti and Uksunlahti,
fenced off from the side of the lake by one of the largest islands of
Ladoga - Mantsinsaari. There are wide sandy beaches. The west coast is
even less indented. It is overgrown with dense mixed forest and shrubs,
coming close to the water's edge, along which there are scatterings of
boulders. Ridges of stones often go far from the capes into the lake,
forming dangerous underwater shoals.
The relief of the bottom of
Lake Ladoga is characterized by an increase in depth from south to
north. The depth varies unevenly: in the northern part it ranges from 70
to 230 m, in the southern part - from 20 to 70 m. The average depth of
the lake is 50 m, the greatest is 233 m (to the north of Valaam Island).
The bottom of the northern part is uneven, furrowed with depressions,
while the southern part is calmer and more smooth. Lake Ladoga ranks
tenth among the deepest lakes in Russia.
35 rivers flow into Lake Ladoga. The largest river that flows into it
is the Svir River, which brings water into it from Lake Onega. Water
also enters the lake through the Vuoksa River from Lake Saimaa, and
through the Volkhov River from Lake Ilmen. The rivers Morie, Avloga,
Burnaya, Kokkolanjoki, Soskuanjoki, Iijoki, Tohmajoki, Janisjoki,
Syuskyuyanjoki, Uksunjoki, Tulemajoki, Miinalanjoki, Vidlitsa, Tuloksa,
Olonka, Obzhanka, Voronezhka, Syas, Lava, Ryabinovka, Naziya and others
also flow into it. The Neva is the only river flowing from Lake Ladoga.
The catchment area is 258,600 km². Approximately 85% (3820 mm) of
the incoming part of the water balance comes from the inflow of river
waters, 13% (610 mm) from atmospheric precipitation and 2% (90 mm) from
the inflow of groundwater. About 92% (4170 mm) of the expenditure part
of the balance goes to the Neva runoff, 8% (350 mm) to evaporation from
the water surface. The water level in the lake is not constant. Its
fluctuations are clearly visible in a lighter stripe on the surface of
the rocks that go into the water.
There are about 660 islands on
Lake Ladoga (more than 1 ha in area) with a total area of 435 km². Of
these, about 500 are concentrated in the northern part of the lake, in
the so-called skerry region, as well as in the Valaam (about 50 islands,
including the Bayevye islands), the Western archipelagos and the
Mantsinsaari group of islands (about 40 islands). The largest islands
are Riekkalansaari (55.3 km²), Mantsinsaari (39.4 km²), Kilpola (32.1
km²), Tulolansari (30.3 km²) and Valaam (27.8 km²).
The most
famous on Lake Ladoga are the Valaam Islands - an archipelago of about
50 islands with an area of \u200b\u200babout 36 km², due to the location
of the Valaam Monastery on the main island of the archipelago. Also
known is the island of Konevets, on which the monastery is also located.