It is a little known fact that Samnaun with its more than 900 plant species is a true plant reserve in the Alps. An educational plant trail was created with this in mind. 27 plant information boards with wonderful photographs of the unique Alpine flora.
In geology, a tectonic window refers to the phenomenon of erosion. This is when an overthrust plate is eroded to such an extent that deeper rock formation reappears in a "hole". In the Engadine region, Bündner slate (Penninic) comes to the surface, which is generally largely hidden by eastern Alpine nappes. As the area became slightly raised, the Inn cut into it more deeply and created the tectonic window.
Engadine tectonic window
The Engadine tectonic window is the geological name for an elongated oval tectonic window running in a southwest-northeast direction in the Lower Engadine region between Zernez (Grisons) and Landeck (Tyrol) in the Austrian and Swiss Alps. The window measures 17 x 55 kilometres and is located in about equal parts in Switzerland and Austria. In this window, Bündner slate (Penninic) comes to the surface, which is generally largely hidden by eastern Alpine nappes. As the area became slightly raised, the Inn cut into it more deeply and created the tectonic window.
This tectonic phenomenon in the lower Lower Engadine region, Samnaun and in the upper Inn valley was created as a result of the superposition of younger rocks by older ones. The Penninic subsoil curved upwards and the top layers became exposed to erosion. This is how the deeper nappe systems, the Bündner slates, come to the surface. The Penninic slates thus form the interior of the tectonic window. The outer frame in the northwest consists of the old crystalline of the Silvretta nappe. In the south, this old crystalline is reduced to a narrow band by the mighty sedimentary mass of the Lower Engadine Dolomites. In the southeast, the Silvretta nappe is replaced by the old crystalline of the Ötztal nappe.
Samnaun is more or less in the centre of this tectonic window, and this geological feature creates the stunning Alpine plant diversity.