East European Plain
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East European Plain
(or Russian Plain), one of the largest plains in the world, located in the larger, eastern section of Europe. On the north it is washed by the waters of the White Sea and the Barents Sea; on the south by the Black Sea, the Sea of Azov, and the Caspian Sea. It is bounded on the northwest by the mountains of Scandinavia, on the west and southwest by the mountains of Central Europe (Sudeten Mountains and others) and the Carpathians, on the southeast by the Caucasus, and on the east by the Urals and the Mugodzhary Mountains. On the Crimean Peninsula the plain extends to the northern foothills of the Crimean Mountains.
In the geostructural sense the East European Plain corresponds fundamentally to the Eastern European Platform. It lies on a base of strongly dislocated Precambrian crystalline rock, which is exposed in the Baltic and Ukrainian shields. In the remaining and significantly larger section of the platform the crystalline rock is hidden under a layer of sloping sedimentary rock that forms the Russian Plate. The southern part of the East European Plain (from the Sea of Azov to the Caspian Sea) corresponds to the Scythian Plate, where rock of the strongly dislocated Hercynian foundation underlies the cover of platform sedimentary formations.
The East European Plain is divided into two unequal parts: a base-denudation plain on the crystalline Baltic Shield and the Russian Plain itself, with a stratified erosion-denudation and accumulative topography on the Russian and Scythian plates. The base-denudation lowlands and uplands on the Baltic Shield with altitudes of 300-600 m (Mansel’kia, Suomensel’kia, Zapadnaia Karelia, and others) include hilly areas and plateaus more than 1,000 m high (the Khibiny massif is 1,190 m high). The shield topography is the result of prolonged continental denudation and preparation of structural forms composed of relatively solid rock. It was directly influenced by recent tectonic movements, especially fractures that bound massifs and depressions, river valleys, and the basins of numerous lakes. In Anthropogenic times the Baltic Shield was the center of glaciation; for this reason the area retains fresh forms of glacial topography.
On the Russian Plain proper a great cover of platform deposits lies almost horizontally, forming accumulative and stratified denudation lowlands and uplands corresponding basically to the low and elevated parts of the folded base. In places the folded foundation surfaces, forming base-denudation uplands and ridges (Dnieper and Azov uplands, Timan and Donetsk ridges).
The average altitude of the Russian Plain is 170 m. The lowest points are on the coast of the Caspian Sea, whose level is 27.6 m lower than the level of the world’s oceans. The uplands rise to 300-350 m above sea level. (The Podol’e Upland rises to 471 m.) The average height of watersheds over valleys is 20-60 m.
The Russian Plain is subdivided into three morphological zones. The northern section has Preanthropogenic stratified denudation lowlands and uplands with superimposed relief forms of glacial and fluvioglacial origin. The glacial-accumulative forms are best observed in the northwest, in the region of the last (Valdai) glaciation, where the Baltic, Valdai, Veps, Beloe Ozero, and Konosha-Niandoma uplands and ranges of hills extend. This is the Poozer’e region, with its characteristic abundance of lakes (Chudo, Pskov, Il’men’, lakes of the upper Volga region, Beloe, Kubena, Vozhe, and others).
To the south, southeast, and east stretches a region subjected only to more ancient glaciation, where the original glacial-accumulative topography was modified by erosion and denudation. Morainic-erosion uplands and ranges of hills (Byelorussian, Smolensk-Moscow, Borisoglebsk, Danilov, Galich-Chukhloma, Onega-Dvina, Dvina-Mezen’, Severnye Uvaly) alternate with broad morainic, outwash, glacial-lake, and alluvial low-lying plains (Upper Volga, Dvina-Mezen’, Pechora, and others).
To the south is a zone of erosion-denudation stratified monoclinal uplands and accumulative lowlands stretching mostly in meridian and submeridian directions and caused by alternating waves of recent uplifts and relative subsidences. From southwest to northeast one can trace the Bessarabian, Volyn’, Podol’e, Dnieper, Azov, Central Russian, Volga, Ergeni, High Transvolga, and Obshchii Syrt uplands and the Ural Plateau. The uplands alternate with outwash and alluvial-terrace low-lying plains: Pripiat’, Dnieper, Gorky Transvolga, Meshchera, Oka-Don, Ulianovsk, and Saratov Transvolga plains.
At the extreme southern and southeastern boundary of the East European Plain stretches a belt of marine lowlands, which underwent tectonic subsidences and partial submergence below sea level in the Neocene and Anthropogene. The original marine accumulation flat-plain topography was subjected in varying degrees to water erosion and loess accumulation (the Black Sea Lowland), alluvial-proluvial accumulation (Azov-Kuban’ Lowland), and fluvial and eolian processes (Caspian Lowland).
In hydrographic terms the East European Plain is divided into two parts. The larger section drains into the ocean. The northern rivers (Mezen’, Onega, Severnaia Dvina, Pechora) belong to the Arctic Ocean basin, while the western and southern rivers belong to the Atlantic Ocean basin. The latter include rivers which empty into the Baltic Sea (Neva, Zapadnaia Dvina, Neman, Vistula, and the rivers of Sweden and Finland), the Black Sea (Dnieper, Iuzhnyi Bug, Dnestr), and the Sea of Azov (Don). The rivers of the Volga and Ural basins and some other rivers flow into the Caspian Sea, which is no longer connected to the ocean.
The greater part of the East European Plain belongs to the region of the temperate zone that has a gradual transition from marine to continental climate. The prevailing winds are from the west. The influence of the Atlantic air mass weakens from the northwest to the southeast; in connection with this, there is excess precipitation in the north and northwest, sufficient precipitation in the central belt, and insufficient moisture in the southeast. The extreme northern part of the East European Plain belongs to the subarctic belt; temperate air masses characterize the summer, and arctic air masses the winter; there is significant seasonal variation in air temperature, and permafrost rocks and soil are well developed. The southeastern edge of the plain has a dry continental climate with great seasonal variations in air temperature.
The East European Plain is marked by sharply defined natural zones. There is subarctic moss-lichen tundra on the narrow strip along the coast of the Barents Sea. Further south are zones of the temperate belt. A strip of forest stretching from the Baltic and Poles’e to the Urals is of great importance. It is divided along the Leningrad-Gorky line into dark coniferous taiga and mixed (coniferous-broad-leaved) forests and becomes broad-leaved forest at the extreme southwest of the plain. Further south, from the Carpathians to the Ural Mountains, there is a forest-steppe zone, beyond which the steppe zone extends to the Black Sea and the Sea of Azov and to the Caucasus. The Caspian Lowland and the Ural Plateau are covered with semidesert and desert.
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A. I. SPIRIDONOV