The Farilhões and Forcadas are rocks with vertical and steep cliffs composed of sharp ridges. The sub vertical organization of rock strata that emerge in these islets suggests a different composition from Berlenga Island and Estelas. In fact, these islets are from metamorphic origin.
Regarding the older metamorphic rocks that outcrop in Farilhões and Forcadas, they represent erosion resistance peaks of an underwater mountain that considerably extends below the sea level. These rocks are strongly deformed, standing out the presence of numerous folds at various scales, and contain textures and minerals characteristics from environments with high pressure and high temperature, typical from the bottom crust. This context suggests that its genesis should have occurred during the Neoproterozoic.