Albert Heim at the Foo Pass

At the Foo Pass, erosion severed the area of the Glarus main thrust. Arnold Escher therefore came up with the idea of a huge double fold in the middle of the 19th century. At the Foo Pass, the Verrucano rocks are missing. In the middle of the 19th century, Arnold Escher developed the theory of a double fold, because he believed that due to its lower resistance in the area of the fold bending at the pass, it was more likely to break and thus erode more quickly.

Albert Heim, one of the most famous Swiss geologists of his time, adopted Escher's double-fold theory and stuck to it steadfastly.

In 1884, Marcel Bertrand, who had never been to the Glarus Alps himself, reinterpreted Heim's descriptions and profiles, demonstrating that the problem could only be solved with a single large thrust and a south-to-north movement. It was not until 1901 that Heim also acknowledged that only a major overthrust was taking place, and the triumphal march of this theory could no longer be stopped. In 1921, Heim wrote in his standard work on Swiss geology:

"Anyone who still doubts the magnificent ceiling tectonics should first take a look at the perforated side ... ».

Since then, many other geologists have visited the outcrops of the Glarus main thrust and studied the structures and mechanisms of the thrust processes. Questions are still controversially discussed and the Glarus main thrust will continue to contribute to a better understanding of the formation of mountain ranges in the future.

(Source: David Imper)

If you want to follow in the footsteps of Escher and Heim and get an idea of the double fold theory on the Foo Pass for yourself, you can reach it either from the direction of Elm or from the Weisstannental along the Via GeoAlpina. Catering and accommodation options are available in Elm or in the Weisstannental on the Walabütz and Siez Alps.