The mountainous landscape around Piz Sardona in the border area of the cantons of St. Gallen, Glarus and Graubünden is a window into prehistoric times: along the visible line, the so-called Glarus thrust, rocks that are 250 to 300 million years old are pushed onto “only” 35 to 50 Rock masses that are millions of years old.
Swiss tectonic arena Sardona: facts
|Official title:||Swiss tectonic arena Sardona|
|Natural monument:||Exceptional mountain region in the eastern part of the Glarus Alps in the area of 19 municipalities on the border of the cantons of Glarus, Sankt-Gallen and Graubünden; Testimony to the formation of the Alps through the shifting of the continental rock plates; approx. 330 km² area at an altitude of over 3,000 m with the so-called »Glarus thrust« in the center; over 20 km on the surface clearly visible shift from older to younger rock layers approx. 20 to 30 million years ago (1 mm movement per year); Formed by compression at the collision of the continental plates and thereby displacement of 50 km long and one kilometer wide rock blocks over a length of 30 km; 35 to 50 million years old, gray flysch rock from the Tertiary is superimposed by 250 million year old, reddish verrucano rock from the Permian;|
|Location:||Cantons of Glarus, Sankt-Gallen and Graubünden|
|Meaning:||Geologically unique testimony to the formation of mountains, visible in a mountain landscape; most outstanding example of the thrusting of rock formations worldwide; Starting point for basic knowledge about the formation of the Alps (ceiling theory) since the 19th century; of outstanding importance for the further understanding of geological developments|
Fascinating spectacle of mountain building
In the border area of the cantons of St. Gallen, Glarus and Graubünden, the Piz Sardona lies in a poignant mountain landscape. The 330 km² area also has something extraordinary to offer from a geological point of view, as tectonic processes can be viewed here in a way that is unique in the world. Reason enough for UNESCO to include the area as a natural monument on its World Heritage List.
In the Glarus thrust, rocks 250 to 300 million years old pushed over 35 to 40 kilometers on much younger, “only” 35 to 50 million year old rocks in the Oligocene. This shift can be recognized by a line in the rock of the mountains. The Swiss tectonic arena Sardona illustrates the process of mountain formation in a way that is unique in the world.
In normal geological conditions, younger rocks are deposited on top of older ones, but in the Swiss tectonic arena there is a completely different layering: Here the older verrucano rocks lie on top of the younger flysch rocks. As a result of plate shifts, an old, ten to 15 kilometer thick rock package was pushed over 40 kilometers to the north and came to rest on the younger rock. The result was a mountain region made up of two layers of rock lying on top of one another: clear evidence that mountains are formed by the collision of tectonic plates. The special thing about the Swiss Tectonic Arena Sardona is that even a layperson can understand this mountain building process with the naked eye. The upper verrucano stones are greenish to reddish and overall darker than the brownish-gray, mostly schisty lower flysch rocks. The two layers are separated by a light line of limestone.
Up until the 19th century it was assumed that the earth would cool down over the course of millions of years and thereby shrink. Like the furrows on a drying apple, mountains and valleys should be created in this way. However, the Glarus thrust offered no explanation for this thesis. How were the different colored layers of rock and the clearly visible dividing line in the massif to be interpreted? `
The Swiss scientist Hans Conrad Escher von der Linth (* 1767, † 1823) was the first to publicly question the theory of earth’s shrinkage. In 1809 he established that older rock layers lie on top of younger ones in the Glarus Alps. However, with this unusual view, he encountered disbelief and hostility. His son Arnold Escher also came to the conclusion that there must be a “colossal thrust”, but for fear of ridicule did not dare to make his views public. In 1884, the French geologist Marcel Bertrand concluded that the mountain structure could only have been created by a large thrust from south to north.
It was not until 1901 that the most famous Swiss geologist at the time, Albert Heim (* 1849, † 1937), confirmed that the special structure of the mountain region around Piz Sardona was due to a single large overthrust. Thus, the discourse not only explained the special structure and genesis of this mountain region, but the scientists had also gained groundbreaking insights into the process of mountain formation
The Swiss tectonic arena Sardona is worth a visit for everyone, because this mountain region also has a lot to offer in terms of landscape: impressive mountain ranges and glaciers, a rich alpine flora and fauna, but also raised bogs make the area interesting for “normal” holiday guests. Fascinating insights and experiences await tourists not only at an altitude of 3,000 meters: the Hagerbach test tunnel leads into the interior of the earth and impressively illustrates life underground.
One of the highlights of the Swiss Tectonic Arena Sardona and the Geopark Sardona is the Tödi mountain, which is part of the Aar massif. This imposing mountain range was created around 300 million years ago. According to politicsezine, Carbon sediments on the Bifertengrätli were confirmed to be the oldest fossil-bearing rocks in Switzerland in 1879. Not far from the mountain path to the Planurahütte, more than 100 immortal footprints were found in 2001, which a group of archosaurs left here around 230 million years ago.
The mighty Linth Gorge with its »Dome of the Rock« is also beautifully landscaped in the Sardona Geopark. A stone arch bridge has been connecting the almost vertically rising rock faces since 1457. The bridges visible today, however, date from the years 1853 and 1901. At the Berglistüber waterfall, natural beauty and geological peculiarities meet: anyone who goes behind the “curtain” of the roaring waterfall can see the dividing line between the younger and older rock layers here very well.