RED SEA

Red Sea area. Inset shows the relative motions of the three plates that make up the Red Sea area. Arabic al-Bahr al-Ahmar, narrow strip of water extending southeastward from Suez, Egypt, for about 1,200 miles (1,930 kilometres) to the Bab el-Mandeb Strait, which connects with the Gulf of Aden and thence with the Arabian Sea. Geologically, the Gulfs of Suez and Aqaba (Elat) must be considered as the northern extension of the same structure. The sea separates the coasts of Egypt, The Sudan, and Eritrea to the west from those of Saudi Arabia and Yemen to the east. Its maximum width is 190 miles, its greatest depth 9,974 feet (3,040 metres), and its area approximately 174,000 square miles (450,000 square kilometres). The Red Sea contains some of the world's hottest and saltiest seawater. With its connection to the Mediterranean Sea via the Suez Canal, it is one of the most heavily traveled waterways in the world, carrying maritime traffic between Europe and Asia. Its name is derived from the colour changes observed in its waters. Normally the Red Sea is an intense blue-green; occasionally, however, it is populated by extensive blooms of the algae Trichodesmium erythraeum, which, upon dying off, turn the sea a reddish brown colour. The following discussion focuses on the Red Sea and the Gulfs of Suez and Aqaba. For treatment of the Suez Canal, see Suez Canal. Arabic Al-bahr Al-ahmar, narrow strip of water separating northeastern Africa from the Arabian Peninsula, occupying an area of approximately 174,000 square miles (450,000 square km). The Red Sea extends southeastward from Suez, Egypt, for about 1,200 miles (1,930 km) to the Strait of Mandeb, which connects with the Gulf of Aden and thence with the Arabian Sea; the sea's maximum width is 190 miles (306 km). It is bounded by the coasts of Egypt, The Sudan, and Eritrea to the west and those of Saudi Arabia and Yemen to the east. At its northern end the sea splits into two parts: the shallow Gulf of Suez to the northwest and the Gulf of Aqaba (Elat), reaching a depth of 5,500 feet (1,676 m), to the northeast. The Suez Canal connects the Gulf of Suez with the Mediterranean Sea to the north, enabling the Red Sea waterway to carry traffic between Europe and Asia. The topography of the seafloor is most rugged in its central section. There the main trough is sinuous, following irregularities of the shoreline, and reaches the sea's maximum depth of 9,974 feet (3,040 m) off Port Sudan. The extensive growth of coral banks south of 16 N has made the navigable channel very narrow and has blocked some harbour facilities. At the Strait of Mandeb the channel is kept open by blasting and dredging. No water enters the Red Sea from rivers, and rainfall in the desert climate is scant; but the evaporation loss, in excess of 80 inches (2,000 mm) per year, is made up by an inflow of water through the eastern channel of the Strait of Mandeb from the Gulf of Aden. Five major types of mineral resources are found in the Red Sea region: petroleum deposits, evaporite deposits (sediments such as halite, sylvite, gypsum, and dolomite laid down as a result of evaporation), sulfur, phosphates, and heavy-metal deposits in the bottom oozes of the deep main trough. Additional reading T.D. Allan and C. Morelli, The Red Sea, in The Sea, vol. 4, pt. 2, ed. by A.E. Maxwell (1971), pp. 493542, is an excellent review of all aspects of topography, geology, and oceanography of the Red Sea. Egon T. Degens and David A. Ross (eds.), Hot Brines and Recent Heavy Metal Deposits in the Red Sea (1969), is an excellent series of papers in which every aspect of the geology, stratigraphy, paleontology, water circulation, and mineral deposits are reviewed in detail. Alasdair J. Edwards and Stephen M. Head (eds.), Red Sea (1987), includes discussion of the same topics as well as studies of plant and animal life, human settlement, fisheries, pollution, and conservation and management. United States Defense Mapping Agency Hydrographic Center, Sailing Directions (Enroute) for the Red Sea and the Persian Gulf (1978), provides navigational as well as oceanographic information. Useful journal articles include J. Angelier, Extension and Rifting: The Zeit Region, Gulf of Suez, Journal of Structural Geology, 7(5):605612 (1985), a well-developed analysis of the junction between the Suez and main Red Sea rift areas; Enrico Bonatti, Punctiform Initiation of Seafloor Spreading in the Red Sea During Transition from a Continental to an Oceanic Rift, Nature, 316(6023):3337 (July 4, 1985), on the behaviour of seafloor spreading in a newly formed oceanic rift, and The Rifting of Continents, Scientific American, 256(3):97103 (March 1987); Enrico Bonatti (ed.), Zabargad Island and the Red Sea Rift, a special issue of Tectonophysics, vol. 150, no. 12 (1988), a spectacular collection of 11 definitive papers on the evolution of the Red Sea; H.J. Bayer et al., Sedimentary and Structural Evolution of the Northwest Arabian Red Sea Margin, Tectonophysics, 153(14):137151 (1988), a review of the relationship between rift tectonics and sedimentation in the Red Sea area; and Bruce H. Purser and Heinz Hoetzl, The Sedimentary Evolution of the Red Sea Rift: A Comparison of the Northwest (Egyptian) and Northeast (Saudi Arabian) Margins, Tectonophysics, 153(14):193208 (1988), a review of the relationship between active rift tectonics and sedimentation in the Red Sea area. B. Charlotte Schreiber