Gorges de la Tamina

The Tamina gorge lies between the communes of Pfäfers and Bad Ragaz, in the south of the canton of St. Gallen. It runs 8,364 metres long over an area of 0.60 km², ranging in altitude from 861 to 1,330 metres, and consists mainly of Quaternary limestone.

Between Valens and the hamlet of Bonadivis, the waters of the Tamina have cut up to 200 metres into the ground over the past 15,000 years, carving a narrow rock fissure about 750 metres long and 70 metres deep, partly covered by a natural bridge between Valens and Ragol. The Swiss geologist Albert Heim wrote in 1921 that 'no other gorge in the Swiss Alps surpasses it in grandeur'.

At the head of the gorge rises a thermal spring whose water, at 36.6°C, supplied the baths of Bad Pfäfers from 1350 to 1969; since then it has served the Valens health clinic and the thermal baths of Bad Ragaz, where the water is used to treat circulatory and rheumatic complaints and the after-effects of accidents.

From Bad Ragaz, the gorge has been walkable along a carriage road opened in 1838; from Bad Pfäfers, a path cut into the eastern flank is passable in summer as far as the spring. A marked trail, suitable for all ages, now follows the whole gorge; the crossing takes about an hour and passes over the Tamina bridge.

Why this place is remarkable

The gorge the Tamina carved through limestone over fifteen thousand years closes in places into a natural bridge, between Valens and Ragol — a formation the geologist Albert Heim judged in 1921 to be unmatched in the Swiss Alps. At its head, a 36.6°C thermal spring has continuously supplied the region's baths from the 14th century to today, first at Bad Pfäfers, then at Valens and Bad Ragaz.

History and origin

How the Tamina's natural bridge formed is still debated. One hypothesis holds that the river first cut a narrow groove through the roughly seven-metre-thick nummulitic limestone before reaching the softer Seewer shale beneath; the resulting widening of the valley is thought to have left the adjoining limestone beds standing, forming the bridge. A second hypothesis holds that the Tamina cut its way beneath the hard rock and that the gorge is in fact a cave; the key outcrops that would settle the question, at the natural bridges themselves, are neither accessible nor visible. Before the Gigerwald dam was built, the riverbed deepened by half a centimetre to two centimetres a year.