Up until the 19th century, Earth scientists assumed that mountains and valleys formed due to the Earth shrinkage. Studying the rock structures at the Glarus thrust engendered fervid discussions, which finally led to the realization that mountains were formed through dynamic movements of the Earth's crust.
Hans Conrad Escher von der Linth (1767-1823) had already in 1809 correctly noted that in the Glarus Alps, older rocks lay on top of younger ones.
Escher's son, Arnold Escher (1807-1872), studied the Glarus thrust intensively and came to the conclusion that it was a "colossal overthrust". This contradicted current opinion among Earth scientists. Escher rescinded his (correct!) idea and suggested the Glarus double fold theory: two recumbent folds, one from the north and one from the south meeting at the Foopass in a flysch trough, like closing a tobacco pouch.
Albert Heim (1849-1937), the most famous Swiss geologist at the time, adopted the double fold theory of his teacher, Arnold Escher. In 1884, the French mining engineer Marcel Bertrand, who at that time had never visited the Glarus Alps, reinterpreted Heim's descriptions and profiles, arguing in favour of a giant thrust from south to north. Only in 1901 did Albert Heim publicly recognise the correctness of the large thrust theory and thus helped pave the way for general acceptance of large horizontal movements in building mountain chains.
However, the role of the Glarus thrust in the formation of the Alps - in particular the mechanical details - is still a subject of research projects and ongoing controversies.