Le Pli Couché

The Couché Fold is evidence of the titanic forces that led to the formation of the Alpine chain 30 to 40 Ma ago. The rocks of the fold date from the Upper Cretaceous. They are sedimentary rocks from the deep sea that were arranged in strata alternating sandstone and shale. The sandstones are the most visible layers, a few decimeters thick, and the shales are old clayey muds, slightly receding because they are more easily eroded. The fold is lying on a flank.
The formation of the fold: the alpine reliefs were created by convergence forces that led to the closing of the ocean and gave rise to the collision of the continents Europe and Africa. Indeed, the continental lithosphere must then adapt to the shortening. On the surface, it breaks and fractures with reverse faults. At depth, the rocks are deformed in a plastic way giving birth to folds following the increase in temperature. The folds will appear at the surface following the erosion which strips the overlying grounds. As far as the Saint Clément fold is concerned, it is called a syncline because the most recent layers are in the heart of the fold. The convergence forces are therefore at the origin of the fold but also responsible for the tilting from east to west.

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