Gibraltar Arc

The Gibraltar Arc is a curved wall of rock around the Alboran Sea. It lies between the Iberian Peninsula and Africa. This area includes the Betic Cordillera in southern Spain and the Rif in northern Morocco.

The Gibraltar Arc is part of the western end of the Mediterranean Alpine belt. It formed long ago when the Eurasian and African plates moved toward each other.

The highest point in this area is Mulhacén, which stands 3,482 meters (11,424 feet) tall. Rain here flows into the Guadalquivir river in the Betics and the Sebou river in the Rif. These rivers carry sand and mud into large areas called sedimentary foreland basins.

Tectonic evolution

The Gibraltar Arc was formed when two large pieces of Earth's crust, called plates, moved closer together. This happened a long time ago, during a period called the Neogene. The two plates are the Eurasian plate and the African plate. They are still moving closer together today, but very slowly—about as fast as fingernails grow.

Scientists think that deep below the surface, part of one plate has been forced under another plate. This process, called subduction, happened a lot in the past but may not be happening as much now. The area where this happened is called the Alboran Sea. Over time, the land above has changed shape, with some parts pushing up and other parts sinking down. There are also large cracks, or faults, in the Earth's crust in this area, which can affect how the land moves.

Geology

The Gibraltar Arc has two main parts: the Internal Zone and the External Zone. The Internal Zone, near the Alboran Sea, is made of special rocks changed by pressure and heat. The External Zone, on the outer side, is mostly made of sediments from Africa and Iberia. These rocks were bent and pushed by the movement of Earth's layers. Between these two zones are layers of rock from long ago that were also folded and moved by Earth's forces.