The Glarus overthrust is a sort of Mekka for earth scientists from all over the world. This is unique place, where the anatomy of a thrust sheet can easily be studied and investigated, from the root zone to the very front of a thrust sheet. Thrust displacement was more than 35 km to the North and the very thrust plane itself is beautifully exposed in the Glarus Alps at an altitude ranging from 500 to 3100m above sea level.

The Segnes Pass is one of those key places in the evolution of ideas geological, where the reasoning of our predecessors can be retraced step by step. With their drawings in hand, we are able to meet the spirit of generations of geologists such as Hans-Conrad and Albert Escher, Albert Heim or Marcel Bertrand who struggled to understand what they were seeing in the Glarus Alps. Observations made here were clearly incompatible with the then available knowledge and new theories about the formation of Mountain belts were required. Long before the advent of plate tectonics, the Glarus Alps provided very clear evidence for large scale horizontal contractional mouvements in the earth crust. With a new theory of "nappe tectonics" in hand, a understanding of the anatomy of the Alps and mountain belts worldwide started to emerge very rapidely within the first decade of the 20th century.

The Glarus overthrust is a major geological showpiece and it remains at center stage in scientific reasearch. The mechanics of large subhorizontal overthrusts still is an enigma indeed, and Glarus is one place where new theories are tested against observed facts. One of the open questions currently under debate concerns the continuity / discontinuity of movement: was thrusting taking place slowly at some mm/year or, alternatively are we looking at the accumulated effects of thousands of devastating earthquakes?