Intercrossed stratification occurs when the deposited sedimentary layers form angles between each other resulting in strata with different slopes. In the process of oceanization, which started with the opening of the Rheic Ocean (about 500 million years ago), sands were deposited that still register different slopes of their sedimentary plans, justified by the variation in the directions of the water currents. These structures can be seen in this Natural Monument of Pedras Ruivas in the metasedimentary rocks that form the Santa Justa Formation.