The structure and present form of this tectonically active basin and its bordering mountain system have been determined by the convergence and recession of the relatively stable of Eurasia and Africa during the past 44 million years.The interpretation of geologic data suggests that there are, at present, multiple main areas of collision between Africa and Eurasia, resulting in volcanism, mountain building, and land submergence. High ridges at Gibraltar were assumed to have blocked the entry of Atlantic waters until about 5.5 million years ago, when these waters broke through to flood the Mediterranean.Its west-east extent—from the The western extremity of the Mediterranean Sea connects with the Atlantic Ocean by the narrow and shallow channel of the Strait of Gibraltar, which is roughly 8 miles (13 km) wide at its narrowest point; and the depth of the sill, or submarine ridge separating the Atlantic from the Alborán Sea, is about 1,050 feet (320 metres).To the northeast the Mediterranean is connected with the and the African coast with a sill depth of about 1,200 feet (365 metres) divides the Mediterranean Sea into western and eastern parts. It has often been called the incubator of Western civilization.
Deepwater formation and exchange rates and the processes of heat and water exchange in the Mediterranean have provided useful models for studying the mechanisms of global .Narrow shelves continue along most of the northern shore of the Mediterranean.An exception is the broad shelf extending for 300 miles (485 km) along the inner portion of the Adriatic Sea.More-recent seismic and microfossil studies have suggested that the seafloor never was completely dry.Instead, about 5 million years ago the seafloor consisted of several basins of variable size and topography, with depths ranging from 650 to 5,000 feet (200 to 1,500 metres).
Highly saline waters of greatly varying depth probably covered the bottom and deposited salts.