Gulf of Finland

Рубрикатор / City Topography/Waterways and Currents/Gulfs and Sounds
GULF OF FINLAND is the eastern part of the Baltic Sea running deep inland. The northern coast of the Gulf of Finland belongs to Finland; its southern part relates to Estonia and north-western and south eastern coasts are located in Russia. In the early days, the Gulf of Finland was named Kotlinskoe Lake (after Kotlin Island); its present name is known from 1730s (in 1737-93 it was also named the Kronstadt Gulf after the city of Kronstadt). The tectonic structure of the Gulf of Finland predetermined its formation: the Gulf is located at the contact place of the Russian platform sedimentary rocks and crystalline formation of its base - the Baltic shield. Their different resistive capacity to external exogenous processes resulted in the topographic drop filled with the Baltic Sea water. Besides, the latest rise upwards of the Baltic shield caused the sloping of sedimentary rocks southward, covering the shield. More stable rocks - sandstones and limestones - present in the latter during the slope conditioned the formation of cuesta ridges, one of which had created the Baltic-Ladoga escarpment (terrace). It stretches along the southern coast of the Gulf of Finland, the left bank of the Neva River and the southern coast of Ladoga Lake. The recent, more active rising of Scandinavia resulted in a certain surface warp of the Gulf of Finland causing its reservoirs to shift southward. This is the reason for an elevated and rocky coast of the northern gulf and a low coast of its southern part. In some places the Gulf's waters "rest upon" an escarpment slope. Such tectonic structure is reflected in topography and modern destruction of mainland surface. The northern coast line is meandering and cut with fjords and skerries with accidental large gulfs (Vyborgsky) and peninsulas (Khanko and Porkkala). The southern coastline is relatively flat and faintly meandered on the one side (the eastern Estonia) and deeply cut on the other side (the western Estonia and Russia with deep gulfs, including Narvsky, Koporsky, and Luzhskaya Bay, divided with Kurgolovsky, Soikinsky and Karavaldaysky peninsulas). In the East, the Gulf of Finland ends with Neva Bay, and in the West, it drains into open areas of the Baltic Sea. The western end of the gulf is called "neck" and its eastern end is referred to as "top". The Gulf of Finland is 400 km in length, from Khanko Peninsula to St. Petersburg; it is 70-75 km wide in the "neck" and up to 130 km wide in its broadest part (Moshny Island). In the top its width lessens to 18-22 km, and does not exceed 12-15 km in Neva Bay. The water level covers the area of 29,500 square km. The Gulf of Finland is rich in banks, shoals, skerries and islands. The most important among the latter is Kotlin Island housing the city of Kronstadt. The largest islands include the Berezov Islands at the city of Primorsk (Bolshoy Berezovy, Northern and Western Berezovy islands), Lisy Island, Vysotsky Island with the city of Vysotsk, Gogland Island, Moshny Island, Bolshoy and Maly Tuters Islands, Sommers, Najsaar, Kimito, Ole Islands, et al. The Gulf of Finland has a very specific mud line. Its depth lessens from its neck to the top. The change is particularly abrupt at the city of Ust-Narva, therefore, this place is referred to as the Narva Wall. The average depth of the gulf is about 40 meters; some hollows reach 100 meters in depth. A lot of large and small rivers drain into the Gulf of Finland. They take water of the total territory of 420,000 square km. Over 2/3 of the gulf's water is supplied by the Neva River which significantly sweetens the eastern part of the Gulf. The average water salinity is 6% which is reduced to 2% at the top. Rivers flowing into the gulf from the south include Keila, Pirita, Yagala, Valgeyigi, Kunda, Narva, Luga and Kovashi; from the north - Saima, Hamina, and Vantanjoki. The average water temperature in winter is about 0o C, in summer it rises to 15-17o C on the surface and 2-3oC at the bottom. Ice cover at the coastline freezes in the end of November, breaks up in the end of April and ends in the skerries in May. The gulf is characterized with strong rough sea and onsets under western winds, up to floods. The gulf coast has been long developed by man. Cities located at the Gulf of Finland include St. Petersburg, Vyborg, and Sosnovy Bor (Russia), Helsinki, Kotka, and Lovisa (Finland), Tallinn, Kohtla-Jarve, and Paldiski (Estonia). Two atomic power stations operate at the gulf: in Lovis (Finland) and Sosnovy Bor (Leningrad Region). In the 1st millennium A.D., the coastline of the Gulf of Finland was populated by Finno-Ugric tribes (the Karelians, the Votes, and the Izhorians). The Slavs started to settle here in the 8th century. In the 12th century, the south-eastern coast of the Gulf of Finland was included in Votic fifth of the Great Novgorod. From 12th to 17th century, the Teutonic (later, the Livonian) Order, Sweden and Rus were fighting for the territory. Russia finally consolidated its grip on the land by the victory in the Northern War of 1700-21. A lot of settlements, cities and fortresses appeared at the Gulf of Finland; and in the 18th century, the famous palaces and parks of Strelna, Peterhof and Oranienbaum were constructed here. Flood protective works with water and navigation passes are under construction in the eastern part of the gulf. The coastline is developed both for housing construction and industrial purposes. New sea ports are built in Primorsk and Ust-Luga. Many coastal areas are used as recreation zones. The most successfully developing industries include navigation, fishing and tourism.

Y. P. Seliverstov. Great Northern War of 1700-21
1979