Geography of Switzerland - Geology

Geology

Different geological phenomena shaped the actual landscapes of Switzerland. The alpine orogeny had the most visible consequences nowadays, this term designates the entire geological movements that conducted to the formation of the Alps.

A crystalline basement formed at the begin of the Paleozoic era, between 540 and 360 millions years ago. Later, between 205 and 96 millions years ago, the alpine ocean or Tethys Ocean formed between Eurasia and Africa. The ocean reached its maximum width at the end of Jurassic period, 135 millions years ago. The collision between the Eurasian and African plates made it progressively disappear. This plate collision, still in progress, began 100 millions years ago. The alpine chain resulted from this geological movement, the two plates creating folding zones. The Central Plateau is mainly composed of molasse, a sedimentary rock which formed at the bottom of the old ocean.

Switzerland is situated on a relatively quiet tectonic zone, although the city of Basel was completely destroyed in 1356 by an earthquake, the largest historical seismic event in central Europe. The most active regions are precisely the Rhine Rift Valley (region of Basel) and the Valais.