Lake Onega

Lake Onega (also known as Onego, Russian: Оне́жское о́зеро, tr. Onezhskoe ozero; IPA: [ɐˈnʲɛʂskəɪ ˈozʲɪrə]; Finnish: Ääninen or Äänisjärvi; Karelian: Oniegu or Oniegu-järve; Veps: Änine or Änižjärv) is a lake in the north-west European part of Russia, located on the territory of Republic of Karelia, Leningrad Oblast and Vologda Oblast. It belongs to the basin of the Baltic Sea, Atlantic Ocean, and is the second largest lake in Europe after Lake Ladoga. The lake is fed by about 50 rivers and is drained by the Svir River.

There are about 1,650 islands on the lake. They include Kizhi, which hosts a historical complex of 89 orthodox wooden churches and other wooden constructions of 15th–20th centuries. The complex includes a UNESCO World Heritage site Kizhi Pogost. Eastern shores of the lake contain about 1200 petroglyphs (rock engravings) dated to 4th–2nd millennia BC. The major cities on the lake are Petrozavodsk, Kondopoga and Medvezhyegorsk.

Geological history

The lake is of glacial-tectonic origin and is a small remnant of a larger body of water which existed in this area during an Ice Age. In geologic terms, the lake is rather young, formed – like almost all lakes in northern Europe – through the carving activity of the inland ice sheets in the latter part of the last Ice Age, about 12,000 years ago: In the Paleozoic Era (300–400 million years ago) the entire territory of the modern basin of the lake was covered with a shelf sea lying near the ancient, near-equatoric Baltic continent. Sediments at that time – sandstone, sand, clay and limestone – form a 200-meter thick layer covering the Baltic Shield which consists of granite, gneiss and greenstone. The retreat of the Ice Age glaciers formed the Littorina Sea. Its level was first 7–9 meters higher than at present, but it gradually lowered, thereby decreasing the sea area and forming several lakes in the Baltic region.