The Great Belt () is a strait between the main Danish islands of Zealand (Sjælland) and Funen (Fyn). Effectively dividing Denmark in two, the Belt was trafficked by the Great Belt ferries from the late 19th century until the islands were connected by the Great Belt Fixed Link in 1997–98.

Geography

The Great Belt is the major of the three straits of Denmark that connect the Kattegat to the Baltic Sea. The others are Oresund and Little Belt.

The Great Belt is 60 kilometers long and 16–32 km. wide. It flows around two major islands: Samsø in the north and Langeland to the south. At Sprogø the Great Belt divides into East Channel and West Channel. Both East and West are traversed by the Great Belt Bridge, but a tunnel runs under the East also.

Geology

In pre-glacial times, a river, which the Baltic Sea basin contained then, must have passed through the region. So also did the Eemian Sea, just prior to the last glaciation, which covered the entire region with ice thousands of metres (feet) thick. Today's topography is totally post-glacial. The Great Belt was eroded into existence by streams passing between the Baltic sea basin and the Kattegat. Currently it is a drowned channel.

Beneath the surface it is possible to speak of northern and southern thresholds. The northern consists of two v-shaped cuts more than 50 m deep. The southern is a relatively shallow bottom, 30 m deep, showing the tops of riverine and lacustrine sediments. This configuration gives evidence that for most of its life the Great Belt hosted an outward, downhill flow.

The north threshold is located in the sea off the north coast of Zeeland. The southern is just south of Langeland, leading into the Kieler Bucht, or Bay of Kiel. The Fehmarn Belt then connects the Kieler Bucht to the Lübecker Bucht, or Bay of Lübeck to the south of Lolland. The Bay of Lübeck is open to the Baltic sea.

The current channel of the Great Belt was created by a relatively high fresh water phase of the rising Yoldia Sea breaking through to lower Kattegat levels at about 10,000 BP. At that time the exposed northern threshold was a valley less than 1 km wide.

Yoldia sea continued to drain and Kattegat levels continued to rise. By 9500 BC the outward flow stopped and the sea began to transgress into the enlarged Great Belt, turning it brackish very slowly. During the Ancylus Lake phase, 9500-8000 BP, the Great Belt was an extension of the Kattegat. At the end of that time rising Kattegat levels broke into Ancylus lake, creating Littorina Sea.

Biology

The Great Belt is home to some popular fish: flatfish, sea trout, cod, mackerel and garfish, which are fished avidly for sport and for sale.

International waterway

The Great Belt was navigable to ocean-going vessels in history and, despite a few collisions and near collisions with the bridge, still is. The Danish navy finds it necessary to keep a watchful eye on ships passing through.

Since the reign of king Eric of Pomerania, the Danish government received a large part of its income by levying the so-called Sound Dues toll from international merchant ships passing through the Øresund under threat of sinking. Non-Danish vessels were forbidden to use any other waterways but the Øresund. Transgressing vessels were confiscated or sunk.

During the middle of the 19th century, this practice became a diplomatic liability and the Danish government agreed to terminate it, achieving an international financial compensation in return. Danish waterways were consequently opened to foreign shipping. The eastern half of the Great Belt is an international waterway, legally based on the 1857 Copenhagen Convention. The western half of the Great Belt (between Funen and Sprogø) and all other parts of the Danish Straits are Danish territorial waters and subject to Danish jurisdiction.

See also

• Danish straits

• Little Belt

• Øresund

• March across the Belts