Sichelchamm

An important testimony to the collision between Africa and Europe is represented by the enormous fold in the side of Mount Sichelchamm, in Switzerland.

Synclines are geological structures that form when rock layers are subjected to compression forces and ''react'' by deforming rather than fracturing.

In this case, the layers of limestone, originally deposited on the seabed in a horizontal position, have been compressed and displaced.

Many rocks by their very nature are characterized by wide ranges of plasticity. Even more rigid rocks (such as limestone) can behave in this way, as long as they are well stratified.

The numerous stratification planes and in particular if there are levels of clay between layer after layer facilitate bending, by virtue of numerous small differential movements between one layer and another. Let's think, for example, about what happens when you fold a deck of playing cards.

Many other rocks, however, acquire a plastic behavior if they are found deep within the crust, under a considerable load and at high temperatures.

Pascal Brackman