GIBRALTAR, STRAIT OF

Latin Fretum Herculeum, channel connecting the Mediterranean Sea with the Atlantic Ocean, lying between southernmost Spain and northwesternmost Africa. It is 36 miles (58 km) long and narrows to 8 miles (13 km) in width between Point Marroqu (Spain) and Point Cires (Morocco). The strait's western extreme is 27 miles (43 km) wide between the capes of Trafalgar (north) and Spartel (south), and the eastern extreme is 14 miles (23 km) wide between the Pillars of Herculeswhich have been identified as the Rock of Gibraltar (north) and Mount Hacho, just east of Ceuta, a Spanish enclave in Morocco (south). The strait is an important gap, averaging 1,200 feet (365 m) in depth in the arc formed by the Atlas Mountains of North Africa and the high plateau of Spain. The winds in the strait tend to be either easterly or westerly. Shallow cold-air masses, invading the western Mediterranean from the north, often stream through as a low-level, high-speed easterly wind, known locally as a levanter. There is also a significant exchange of water through the strait. A two-knot surface current flows eastward through the centre of the channel, except when affected by easterly winds. This surface movement exceeds a westward flow of heavier, colder, and more saline water, which takes place below a depth of about 400 feet (122 m). Thus, only the existence of the strait prevents the Mediterranean from becoming a shrinking salt lake. The Pillars of Hercules marked the western end of the classical world. Of great strategic and economic importance, the strait was used by many early Atlantic voyagers and has continued to be vital to southern Europe, northern Africa, and western Asia as a shipping route. Much of the area's history involved rivalry over control of the Rock of Gibraltar.