238 RED SEA BED SEA, an inlet of the Indian ocean, ex- tending from the straits of Bab-el-Mandeb, lat. 12 40' N., nearly N. N. W. to Suez, lat. 29 57' 30", and separating Arabia on the east from Egypt, Nubia, and Abyssinia on the west. Its length is about 1,400 m., its greatest breadth, near lat.. 16, 200 m., and its total area about 185,000 sq. m. At the straits of Bab-el-Man- deb, by which it is joined to the Indian ocean, it is but 18 m. wide, at Hodeida about 95 m., and at Jiddah about 120 m. At Eas Moham- med, lat. 27 45', it is divided into two branches by the rocky peninsula of Mt. Sinai or Jebel Musa. The western branch, the gulf of Suez, which is the continuation proper of the Red sea, is about 180 m. long, and has an average breadth of 20 m. It has the same general course as the main part of the sea, with which it is connected by the strait of Jubal. At its N. extremity the Sue,z canal connects it with the Mediterranean, from which it is separated by the isthmus of Suez. The eastern branch, the gulf of Akabah, extends N. N. E. from its mouth at the strait of Tiran, about 100 m., and has an average breadth of about 12 m. The Red sea varies greatly in depth. In the middle of the gulf of Suez it is from 250 to 800 ft. deep, but shoals gradually to 18 or 20 ft. in the harbor of Suez, where it has been filled up by the sand. The gulf of Akabah varies from 700 to 1,500 ft. in depth. The deepest sound- ing obtained is in the Red sea proper, in lat. 22 80', where the depth is 6,324 ft. In the S. part it is shallower, and below lat. 16 its depth ranges from 250 to 750 ft. A section through the middle of the sea from the straits of Bab-el-Mandeb to Suez represents a series of rounded submarine hills, covered with silt, mud, and sand. The sand, which is blown in from the neighboring deserts, constitutes the only distinctive feature between this ooze and that of the bottom of the Atlantic. Near the shores on both sides the water is generally shallow, and navigation is rendered dangerous by many rocky islands, shoals, and coral reefs. The principal islands are the Farsan group on the Arabian coast, about lat. 17, and the Dah- lac group on the W. side, in lat. 16, each con- sisting of large islands surrounded by many smaller ones connected by reefs. In lat. 15 40' is Jebel Teir, having an active volcano, the summit of which is more than 1,000 ft. above the sea. Nearly S. of it is the Zebayer group. Kamaran island, off the coast of Yemen, is claimed by the British. In lat. 14 is Jebel Zugur, and in the straits of Bab-el-Mandeb, commanding the entrance from the Indian ocean, is Perim, a fortified British possession. (See PERIM.) At the entrance of the gulf of Akabah is the island of Tiran, dividing it into two channels, of which only the western one, called the strait of Tiran, is navigable for large vessels ; and at the mouth of the gulf of Suez are Shadwan island and several smaller ones. The Red sea occupies the bottom of a longi- tudinal valley lying between the highlands of Arabia on the east and the mountain range on the west, which borders Abyssinia, Nubia, and Egypt. On the N. side, between the gulf of Suez and the Mediterranean, the country is low and flat, and exhibits indications that a com- munication once existed between the two seas. The mountains are in sight on both sides of the sea, but a considerable part of each coast is low and flat or covered with undulating hills, the mountain range being in some places 20 or 80 m. from the shore. It is probable that the sea once covered the entire basin, but has been filled up in part by the growth of cosal and the accumulation of sand. The Arabian town of Muza, marked as a seaport in the Periplus of Arrian, is now several miles inland. The coral reefs, which are more extensive than in any other sea of equal size, lie generally in long lines parallel to the shores, and from 500 yards to a mile distant from them. The banks are usually from 4 to 6 ft. below the surface, and the water on their outer edge is very deep, but on the inner side they are sometimes connect- ed with the land. Where they are unconnect- ed with the shore there is generally a channel within them navigable for small vessels and having good anchorage. The native vessels make great use of these inner straits, where the heavy winds of the open sea affect them but little. There is no surf on the reefs, as the porous coral permits the passage of the waves through them. The reefs are more numerous on the E. than on the W. side. The growth of continental coral reefs in the Red sea in a more northerly latitude than elsewhere is accounted for by the absence of rivers on the coast, and by the high temperature of the water, which is seldom below 80 F. In March and April it is sometimes 84, and in May 90. The genera of coral are nearly the same as in the central Pacific, and consist of most of the reef -forming species. Some of the meandrinas and favias are from 6 to 9 ft. in diameter. The coral is generally white, but often red, and a black variety is found along the Arabian coast for 50 m. N. and S. of Jid- dah. Sponges of fine quality are taken in abundance along the E. shore of the gulf of Suez, and pearl oysters are found in various places. As the Red sea receives but little water from the atmosphere or from the surrounding country, and the sun's rays generally fall on it from a cloudless sky, it may be considered merely a basin for evaporation, which proceeds at the rate of about four fifths of an inch a day, or 28 ft. in a year. From a little more than 89 parts of salt in 1,000 at the straits of Bab- el-Mandeb, the proportion rises in the N. part to 48, a degree of saltness found elsewhere only in inland salt lakes. As the concentration of so much salt through evaporation would tend in time to fill up the sea, it is supposed that the waters most charged with salt flow out through the straits in an undercurrent, while the lighter and less saline waters flow in above it. The winds are generally pretty constant.
