The ripple marks correspond to smooth undulations of the surface preserved in sedimentary rocks that transmit information about the agitation of the water (currents or waves) or of the wind, at its formation date. These structures can be seen here in the Natural Monument of Pedras Ruivas in the quartzite countertops S0 stratification plans of the Santa Justa Formation. As mentioned, ripple marks are preserved in sedimentary rocks, but due to the continental collision between Laurentia, Avalonia and Gondwana these rocks were subjected to metamorphism processes giving rise to quartzites, which is why it is possible to observe ripple marks on the quartzitic countertops. The analysis of these structures also made it possible to advance the hypothesis that their formation occurred in a reduced water flow regime.