Sandstones, in 1st picture in flat estrata of marine origin that are cut by an abandoned quarry in Mal Balç (Manresa) displaying their thickness, in the 2nd picture in a stratum of continental origin that’s tilt after the anticline of Olo displaying its surface. The 3rd picture from a marine sandstone from Les Marcetes (Manresa) shows the crossing layers that result from the sand movement by the sea weaves. Usually, thin layers less than 1 cm depth can be seen in sandstone strata.
Sandstones are detrital rocks that result from the cementation of sands which, in their turn, are generally included in a matrix of smaller size particles. Sands are pieces of minerals or rocks between 2 and 1/16 mm diameter. The cement of the sandstones in the district of Bages is calcium carbonate.
Sandstones of both continental and marine sources are common all around the region. Sometimes ripple marks appear on surface of marine sandstones while continental ones may contain ichnites. Often, iron oxides dye in red, rusty color the continental sandstones. Sandstones are found whether in thin layers into other rocks (mainly mudstones) or in big, homogeneous packs that usually have been or are currently being exploited. Sandstones were used in most of the ancient buildings of the area because their availability and ease to shape.
[photos Oriol Oms (1st), Jordi Badia (2nd) and Florenci Vallès (3rd)]