Geology

Several major tectonic units are present in the Vaud Alps. A portion of the Riviera, around Vevey and Montreux, lies within the Subalpine Molasse. Further to the southwest, two large units share the rest of the Vaudois Alps: the nappes of the Prealps and the Helvetic nappes. These large units can be subdivided into several nappes. For the Prealps, notable nappes include: the nappes of the median plastic and rigid Prealps, the nappes of Niesen, Simme, Brèche, Gurnigel, the submedian zone, and part of the Ultrahelvetic nappes. The nappes of Morcles, Diablerets, Wildhorn (Mt-Gond and Sublage), as well as the Ultrahelvetic nappes, belong to the Helvetic unit. The region is also covered by Quaternary deposits, particularly in the Rhône Plain, where alluvial deposits can be especially thick.

(Written in collaboration with Prof. Jean-Luc Epard)