As shown in Figure 9- 1, West Africa extends westward from Cape Lopez in Gabon near the equator to Cape Palmas in Liberia at 7 W. The coastal countries include Liberia, C? te d 'Ivoire, Ghana, Togo, Benin, Nigeria, Cameroon, Equatorial Guinea, Gabon, Angola and the Gulf island country Sao Tome and Principe. The inflow of volta river, Niger River, Sanaga River, Congo River and mr guowei River brought a lot of organic sediments to the Gulf. After millions of years, oil has been formed, which has attracted the attention of the international community in recent years. There are Bonnie Bay and Benin Bay on the east and west sides of Niger River Delta respectively. Bonny Bay and many volcanic islands to its south, such as Bioko Island, Sao Tome Island and principe island. The average width of the continental shelf is less than 20 nautical miles, and its western part drops sharply to the Guinea Basin with a depth of 4,000 meters, with the deepest point reaching 6,363 meters. Located in the equatorial belt, a warm current from Guinea flows in from west to east, with a hot and humid climate and a water temperature of 25 ~ 26℃. The salinity is 34‰, which is reduced to 30‰ due to the injection of Niger River and other coastal rivers. There are many shoals, lagoons and dense mangroves along the coast. The continental shelf is rich in oil, including herring, sardines, catfish, lobster and other aquatic products. The main ports are Abidjan, Accra, Lomé, Cotonou, Lagos, Douala and Libreville.
The coastline of the Gulf of Guinea constitutes a part of the western edge of the African plate, which is obviously consistent with the coastline of South America from Brazil to Guyana. The coincidence of geology and geomorphology between the two coastlines provides the clearest argument for the theory of continental drift.
The continental shelf in the Gulf of Guinea is almost narrow, only between Sierra Leone and Bijagos Islands in Guinea-Bissau, and it is very wide in Biafra Bay, reaching 65,438+060 kilometers. The Niger River has accumulated a large delta of Holocene sediments (less than 12000)-only here has the junction between the African and South American plates been seriously damaged. The only active volcanic area in the Gulf of Guinea is an island arc in a straight line with Cameroon volcano (4070 meters high), which is located on the coast of the Republic of Cameroon. The islands on this island arc [Fernando wave (Bioko), Principe, Sao Tome and Annoben] extend 724 kilometers southwest in the offshore area.
Figure 9- 1 Geographic Location Map of West Africa