Piz Sardona — Explainer video

Transcript

Piz Sardona: the mountain behind the water.

Piz Sardona, Surenstock in German, is 3,056 metres high. It stands where the cantons of St. Gallen, Glarus and Graubünden meet.

It lends its name to a UNESCO World Heritage Site: the Tectonic Arena Sardona. Since 2008 the arena has been on the World Heritage List, as one of the few sites worldwide inscribed solely for their geology.

At its centre lies the Glarus thrust. Normally, younger rocks lie above older ones. Here it is the other way round: as the Alps folded, entire packages of rock were thrust over one another across many kilometres. Hardly any other place shows so clearly how mountains form.

What does the mountain have to do with mineral water? In the Sardona Alps, at over 2,000 metres above sea level, meltwater and precipitation seep into the ground. For around twelve years, the water travels through the rock until it is drawn from the Castels spring in Mels: a naturally alkaline mineral water with a pH of 8.0.

On the way down, the mountain acts like a natural filter. The rock holds back particles, while the water dissolves minerals, such as calcium and hydrogen carbonate from limestone or sulphate from sulphate-bearing strata.

What stands out is the low sodium content of 4 milligrams per litre and the comparatively high sulphate level of 265 milligrams: both traces of the rock strata. With 540 milligrams per litre, the water is moderately mineralised overall.

The depth and duration of the journey shield the water from surface influences. This makes Piz Sardona both a geological textbook case and the origin of a water whose character forms in the mountain itself.

More on this in the Piz Sardona Academy.