The geological context of a continental collision between Gondwana and Avalonia-Laurentia, was responsible for carrying (transporting) rocks layers from the margin and the ocean floor of the primitive Rheic ocean (allochthonous mantles) to the East over the lands that today constitute Viana do Castelo, developing shear zones that generated inverse shearing with top-to-the-west direction (conjugate inverse shearing or overlapping).