What is the geographical location of Beihai?
The North Sea is a bay in the eastern part of the Atlantic Ocean, bordering England and Scotland in the west, Norway, Denmark, the Federal Republic of Germany, the Netherlands, Belgium and France in the east, and the connecting line from Wald lighthouse on the French coast across the Dover Strait to Cape Verde on the British coast in the south. In the north, it starts from Dunnett, Scotland, passes through orkney and shetland islands, then reaches 6 1 north latitude along the longitude of 0 53' west longitude, and then reaches the Norwegian coast eastward along the latitude of 6 1 north latitude. The southern part of the North Sea is connected with the Atlantic Ocean through the Dover Strait; In the north, it is connected with the Atlantic Ocean and the Norwegian Sea through the gap between Scotland and Norway; In the east, it is connected with the Baltic Sea through the Skagrakir Strait between Norway, Sweden and Denmark and the kattegat. The northern part of Beihai is about 965 kilometers long and 580 kilometers wide. The total area is about 600,000 square kilometers, the average water depth is about 9 1 m, and the volume is about 654,380+055,000 cubic kilometers. Several islands in this sea area cover an area of about 73 square kilometers.
The North Sea is considered as a continental marginal sea, that is, its entire tectonic basin is on the continental crust. Sea boxes, to some extent, are geosynclines (the location of long deposits), which have been folded into mountains at least twice before. Every time, these mountains were washed away, leaving only a shallow basin between England and the mainland. About 230 million years ago, the land around the North Sea was desert. Due to the large amount of evaporation, the inflow of water from the north is restricted, forming a huge evaporite deposit. Now, salt mounds and structures found on the seabed of the North Sea and in Germany and Denmark are the representatives of these evaporites. The history of the formation of submarine structures in the North Sea is directly related to the vast oil fields being developed in the North Sea and its neighboring countries.
Of course, the seabed of the North Sea belongs to the continental shelf, and the southern half of the sea is a platform with a water depth of 40 meters. The seabed gradually inclines northward and reaches the edge of the continental shelf west of shetland islands, with a water depth of about183m. Bypassing the southern tip of Norway to the edge of the continental shelf, it is a rare strait (Norwegian Strait) with a depth of about 600 meters. Some oceanographers believe that this valley was formed by continental glacier erosion. There are other remains of the last glacial period (1 1000 ~ 8000 years ago), namely, the low water level at sea level and the valley cutting left by glacial moraine (the so-called glacier ice feed refers to the accumulation of sediments at the front of glaciers when they melt). Take Dogel sandbar between Britain and Denmark as an example, its water depth is only 13m. Seabed sediments are mainly glacier gravel, sand and silt. There is mud everywhere, which is taken away by the action of ocean currents and waves.
At the same time, the water circulation in the North Sea is influenced by the Atlantic water from the north and the Baltic water from the east, while the water flowing out of the Dover Strait in the south is very little. Because rivers in Chinese mainland (Rhine River, Elbe River, Weser River, Ames River, Guerder River) flow a lot of fresh water, they freeze in coastal waters such as Norway, Denmark, Netherlands and Germany, even if it is not too cold in winter. In the west, due to the lack of fresh water into the sea and the influence of the North Atlantic Ocean current, it will not freeze even in severe winter.