The ripple marks are natural waves on the rock surface. Some millions years ago, the movement of water left waves on the sediment of beaches or pools. Nowadays, the old waved shape remains as a fossil on the sedimentary rock surface. Exactly this shape is found at present on the mud or the sand of the water sides in case of waves or turbulent flow. The marine sandstones from Eocene period in the district of Bages often make up their surface with beautiful ripple marks. This is the case of the sandstones in the old quarry in El Mal Balç (Manresa) with nice ripple marks that proof their origin as a water sedimen. [photo Jordi Badia]