Swiss Tectonic Arena Sardona

The Swiss Tectonic Arena Sardona was inscribed on the World Heritage List in 2008 and covers some 328 km² in eastern Switzerland, between the cantons of Glarus, St Gallen and Graubünden, around the Sardona massif.

Its value is purely geological and comes down to a line visible to the naked eye: the Glarus thrust, a fault plane that runs across the mountains and along which rocks some 250 to 300 million years old lie above others between 35 and 50 million years old. That is, ancient rocks sitting on top of far younger ones, exactly the reverse of what the natural order of sedimentation dictates.

That apparent impossibility was for decades one of the great puzzles of nineteenth-century geology, and its explanation — the horizontal displacement of enormous rock masses over tens of kilometres during the formation of the Alps — was decisive in the birth of mountain-building tectonics. The thrust is exposed here in a continuous, accessible section of great extent, with a clarity that has no equal in the world, and it remains a training ground for geologists. The landscape is high mountain country, with cirques, scree and a characteristic alpine fauna.