Introduction
Much of the subsoil in this part of the coastal mountains is made up of a granite bedrock. Under certain environmental conditions, granite breaks down very easily, forming sauló, a type of infertile sand. This is one of the most visible geological phenomena in the area, where weathering processes have played a significant role and created a thick layer of sauló.
In places you can find accumulations of sauló, although it is usually washed away by rain into streams and torrents. In fact, the typical coarse sand of the Maresme beaches is nothing more than sauló deposited there after being carried down by watercourses from the coastal ranges.
The landscape here is shaped by parts of the granite massif that are still unweathered and remain as outcrops and sculpted boulders.