Baltic Sea

Denmark's mystery tremors caused by acoustic waves from unknown source, officials say
A series of minor tremors recorded on the Danish Baltic island of Bornholm Saturday has puzzled scientists, who now say they were caused by ”acoustic pressure waves from an unknown source.”
Summary
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The Baltic Sea, the North Sea, and the English Channel.
The Baltic Sea, the North Sea, and the English Channel.
Baltic Sea, German Ostsee, Swedish Östersjön, Russian Baltiyskoye More, Finnish Itämeri, Polish Morze Bałtyckie, arm of the North Atlantic Ocean, extending northward from the latitude of southern Denmark almost to the Arctic Circle and separating the Scandinavian Peninsula from the rest of continental Europe. The largest expanse of brackish water in the world, the semienclosed and relatively shallow Baltic Sea is of great interest to scientists, while to historians it represents the economic core of the Hanseatic League, the great medieval trading group of northern European ports. The many names for the sea attest to its strategic position as a meeting place of many countries.

The Baltic Sea covers about 149,000 square miles (386,000 square km). The catchment area drained by the rivers bringing fresh water into the Baltic is about four times as large as the sea itself. The Baltic proper stretches southwest-northeast on the eastern side of the Scandinavian Peninsula from latitude 54° N to very near the Arctic Circle; its major axis, from eastern Denmark to southern Finland, is a little more than 1,000 miles (1,600 km) long, with an average width of about 120 miles (190 km). The western Baltic extends north through insular Denmark and includes the Kattegat, a strait separating peninsular Denmark (Jutland, or Jylland) from southwestern Sweden. The Kattegat is bounded on the north by the Skagerrak, a deep inlet of the North Sea that separates southern Norway from northern Jutland.

Coast of Bornholm, Den., on the Baltic Sea.
Coast of Bornholm, Den., on the Baltic Sea.
The large islands of Bornholm (Denmark) and Öland and Gotland (Sweden) lie in the western Baltic, while the Åland Islands (Finnish: Ahvenanmaa), farther north, rise from a narrows between Sweden and Finland and mark the entrance to the arm of the Baltic known as the Gulf of Bothnia. Just to the south of the Åland Islands, the narrow Gulf of Finland stretches eastward between Finland to the north, Estonia to the south, and Russia around the eastern end, with St. Petersburg at its head. Proceeding clockwise from the west, the countries bounding the Baltic are Denmark, Sweden, Finland, Russia, Estonia, Latvia, Lithuania, Poland, and Germany.
Physical features

Physiography

The Baltic Sea is a shrunken remnant of the water-covered region that emerged as the melting Scandinavian ice sheet retreated toward the Arctic at the end of the Pleistocene Epoch glaciations. Some 14,000 years ago, ice covered all of northern Europe as far south as the present German-Polish coastline; by 7700 BC glacial meltwater had formed the Yoldia Sea, which stretched east from the present Skagerrak across what is now lake-strewn southern Sweden as far as the present Lake Ladoga, beyond the bend of the Gulf of Finland. A thousand years later, only limited areas of stagnant ice remained in northern Sweden, leaving the freshwater Ancylus Lake stretching from Arctic Sweden and Finland to the present southern Baltic. Later changes, about 4500 BC, led to a breach of the land bridge between the present Baltic and North seas and to fragmentation of the Jutland peninsula by The Sound (Øresund), the Store Strait (Storebælt), and the Lille Strait (Lillebælt). Many of the lowland regions surrounding the sea have been rebounding slowly since the great weight of the glaciers was removed; however, in places such as Stockholm, rising sea levels have slightly exceeded the rate of land uplift. Land uplift and deposition are building up the head of the almost tideless Gulf of Bothnia.