The Peneda River runs through a narrow river valley, whose origin is due to the establishment of the water course in an area with a fault. The fault, direction NNE-SSW, influenced the course of the river, making it flow in the same direction.
On the river bed one can find sediment deposition (also known as “clastics”) that have varied composition and dimension, with a round shape, originated by river erosion. In this case the granite blocks that acquire a round shape are also known as rolled stones, due to the way they are transported (“rolling”) and deposited (when the water stream loses its capacity to transport), along the river bed.