Swiss Tectonic Arena Sardona
How mountains form
The collision between Africa and Europe caused the formation of the Alps millions of years ago. Layers of rock were pushed on top of one another, folded and broken. Along the so-called “Glarus main thrust fault”, a line that can now be seen from afar, layers of rock that were 250-300 million years old were pushed together with much younger rocks that were 35-50 million years old. There is nowhere else where the traces of these tremendous forces are so visible as in the mountain landscape around Piz Sardona in the border region of the cantons of St. Gallen, Glarus and Grisons. The area has great value for schools and research. It is of great interest to hikers and nature lovers too. Natural Heritage since 2008.
Just beneath the ridge of the Tschingelhörner, at an altitude of 2,600 metres, the famous Martinsloch opens up. This strange, almost triangular opening, with a diameter of around 18 metres, was formed by the accelerated erosion of a more fragile part of the rock. It is very special since it is a kind of natural calendar. Twice a year, roughly a week before the spring equinox and a week after the autumn equinox, the rising sun shines through the hole and lights up the church tower of the village of Elm, for about 2 minutes. Then it disappears behind the wall of rock before emerging above the ridge some 15 minutes later. This occurrence has fascinated people for centuries. The other mysterious characteristic of the Tschingelhörner and of the surrounding peaks is a grey-yellowish line, wedged between two layers of Alpine rock. This distinct line has intrigues the scientific world for a long time and prompted a considerable number of arguments amongst geologists, since it overturned, in the literal sense of the word, the prevailing theories regarding the development of the Earth’s crust. This “magic line”, as it is often called, ultimately provided a key to our understanding of the tectonic processes that gave rise to the Alps and to other similar mountain ranges.
Did you know?
• In the Tectonic Arena Sardona the mountains stand on their heads: older strata of rock have shifted to lie above younger layers.
• Over the past 200 years or more, seminal findings into the way mountains were formed have been made at the Sardona UNESCO World Heritage Site.