Strait of Gibraltar

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The Strait of Gibraltar as seen from space.
The Strait of Gibraltar as seen from space.

The Strait of Gibraltar (Arabic: جبل طارق, Spanish: Estrecho de Gibraltar) is the strait which separates the Atlantic Ocean from the Mediterranean Sea. It is often called by a plural form: the Straits of Gibraltar, or a short form: Strog (STRait Of Gibraltar) as it is known in the Navy circles.



The name comes from the Arabic name of "Jebel Tariq" meaning Tariq's mountain. It refers to the Berber Muslim general Tariq ibn-Ziyad who conquered Spain in 711.


On the northern side is Spain and Gibraltar, on the southern side Morocco and Ceuta (a Spanish exclave in North Africa). Its boundaries were known to antiquity as the Pillars of Hercules. There are some small islands, like the disputed Isla Perejil, that are claimed by Spain and Morocco.


The Strait of Gibraltar has a very strategic location. Ships that travel from the Atlantic to the Mediterranean and vice versa, pass through this strait overlooked by the Rock of Gibraltar. Also, very many people who travel from Europe to Africa and vice versa, travel through this strait. During World War II, the British controlled the straits from their nearby base. German submarines entering the Mediterranean Sea were effectively trapped, because they couldn't leave on the surface and the undersea currents were too strong to leave underwater.


The depth is about 300 m, and it is about 14 km wide at its narrowest point.


For a number of years the Spanish and Moroccan governments have been jointly investigating the feasibility of a tunnel underneath the strait, similar to the Channel tunnel between England and France. However, the tunnel idea was renounced due to the fact it would be impossible to vent gases from automobiles in a tunnel that was about nine miles long. A new three-year study for a railway tunnel was announced in 2003.


Also, a group of American and British engineers have studied the feasibility of building a bridge to span the straits. Such a bridge would be of a combination suspension-truss design and would dwarf any existing bridge in height (over 3000 feet) and length (15 km). The 1979 science fiction novel The Fountains of Paradise by Arthur C. Clarke featured such a bridge.


The all-but-landlocked Mediterranean has an evaporation rate higher than the combined inflow of all the rivers that empty into it. The sill of the Strait of Gibraltar acts to limit mixing of water between the cold, less saline Atlantic and the warm Mediterranean waters, which are so much saltier that they sink below the constantly incoming Atlantic water and form a highly saline (thermohaline, both warm and salty) bottom water, called the Mediterranean Outflow; it flows out and down the continental slope, losing salinity, until it equilibrates after mixing at a depth of about 1000 m. The Mediterranean outflow water can be traced for thousands of kilometres before losing its identity.

Ancient history

Some 5 million years ago, the Strait closed, effectively turning the Mediterranean into a huge salty lake that eventually dried up, in what is known as the Messinian Salinity Crisis.

External links

About the tunnel plans:

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