RED SEA (Lat. Mare Rubrum, Gk. 'EpuOpii OdXacrcra, Erythre Thalassa), or ARABIAN GULF. Au arm of the Indian Ocean separating the Arabian peninsula from Northeastern Africa, and lying between latitudes 12° 30' and 30° N. (Slap: Asia, C 6). It extends in a northwest direction from the Strait of Bah-el-Slandeb, 20 miles wide, through which it communicates with the Gulf of Aden, to the Isthmus of Suez, and is 1380 miles long. It is narrowly elongated in shape, with a breadth between 100 and 200 miles maintained fur the greater part of its length. In the north the sea divides into two arms, cutting oft' the Sinai Peninsula: these are the Gulf of Suez in the west, 170 miles long and 25 miles wide, and the Gulf of Akabah in the east, 110 miles long and 12 miles wide. The Gulf of Suez is connected by the Suez Canal (q.v.), about 100 miles long, with the The basin of the Red Sea is formed by a line of fracture running through the great Arehwan mass capped by the limestone plateaus of Egypt and Arabia. The Arch:van rocks are exposed here and there along the coast. A branch fissure with steep rocky sides forms the Gulf of Akabah, and runs northward as the depression called El-Arabah, the deep sink of the Dead Sea, and the valley of the Jordan. The shores of the Red Sea are bordered on the Ara bian side by sandy deserts, which form a narrow strip backed by the limestone range. On the Egyptian side there are wide, sandy plains in the north, rising farther south into elevated table lands, and finally into the mountains of Abys sinia. Each shore, particularly the eastern, is lined with immense coral reefs which in some places extend 25 miles or more from land. They have occasioned numerous islands and archipela goes. The principal groups are the Farsan Isl ands near the Arabian shore and the Dahlak Isl ands near the African. The mean depth of the Red Sea is about 2000 feet. Through the greater part of its length runs a central channel with a depth exceeding 3000 feet, divided by compara tively shallow ridges into three basins, of which the northern and southern have a maximum depth of about 4200 feet, and the central of near ly 7500 feet. The Strait of Bab-el-Mandeb is
1200 feet deep. In the Gulf of Suez the depth is scarcely more than 200 feet.
The mean temperature of the surface water is 77° in the north, SO° near the middle, and 84° in the south. Below a depth of 1200 feet there is a uniform temperature of in all parts of the sea and down to the greatest depths. The sea differs in this respect from the open ocean, where the temperature continues to fall through a much greater depth. The surface temperature of the Bed Sea sometimes rises above loo', and there is an enormous evaporation, the air being almost constantly saturated as fast as it is supplied by the winds. The heat being intense, the climate on the Bed Sea is very depressing. Its salinity amounts to about 4.2 per cent.. increasing with the depth, while that of the ocean is 3.5 per cent. The tides are and in some places im perceptible. The prevailing winds are north and northwest. but in the southern section they change to the southeast during winter. The ma rine flora and fauna of the lied Sea are very rich and interesting. The indigenous species are quite different from those of the Mediterranean, showing that the two seas must have been sepa rated since the Eocene epoch. Since the opening of the Suez Canal, however, there has been a considerable inter-migration. From the earliest times the lied Sea has been a great highway of commerce between India and the trading peoples of the Mediterranean lands, and was used suc cessively by the Egyptians, the Phienicians, Arabs, and in the Middle Ages by the Venetians. until the discovery of the route around the Cape of Good Hope. Since the opening of the Suez Canal in lS69 it has regained its importance as the main route of commerce between Europe and the East.
Consult: Luksch, Vorliiufiger Belicht libel- die physikalisch-oeranograybischen Untersuchunqen int Roten Meer (Vienna. 1q011) : Hood. "The Red Sea Currents and Navigation." in Nautical Maga,:ine, vol. (London. IS99).