At the end of the Cretaceous era, about 65 million years ago, the African plate began colliding with the Eurasian plate. The narrowing of the ocean caused strong tectonic disturbances, making the horizontal layers crinkle, break and emerge above the sea surface, forming mountain ranges like the Alps and the Dinarides, which Biokovo belongs to. In this way the ancient ocean Tethys has largely disappeared and its remains is today's Mediterranean Sea.