The Alps form a part of a Tertiary orogenic belt of mountain chains along the southern margin of the continents Asia and Europe, called the Alpide belt. This belt of mountain chains was formed during the Alpine orogeny. The chains of mountains seem discontinuous, there is, for example, a gap between the Alps and the Carpathians. Orogeny took place continuously and tectonic subsidence is to blame for the gaps in between. The Alps arose as a result of the collision of the African and European tectonic plates, in which the western part of the Tethys Ocean, that was formerly in between these continents, disappeared. Enormous stress was exerted on sediments of the Tethys Ocean basin and its Mesozoic and early Cenozoic strata were pushed against the stable Eurasian landmass by the northward-moving African landmass. Most of this occurred during the Oligocene and Miocene epochs.