Continental mudstones from geological formation Artés; on top picture in the valley of Gavarresa (Sallent-Artés) displaying a pothole erosion pattern, on the left in the valley of Conangle (Balsareny).
Mudstones are detrital rocks made up of smaller than 1/16 mm diameter particles. If these particles are coherent, then the rock is named siltstone if particle size average is above 1/256 mm or claystone if below 1/256 mm. If the particles are not coherent, then the rock is named silt and clay. The mudstones containing 50% of calcium carbonate on average (35%-65% according to Vatan) are named loams. They’re usually bluish color. The color of mudstones in the area of Bages changes from the bluish gray or yellowish of sediments from marine origin, to the reddish of sediments from continental origin because they contain iron oxides, like those that pictures display.
The huge hollow out of the morphology of Bages results from poor resistance of the mudstones to erosion. Mudstone materials dominate in farmed plains. Mudstones are used in the manufacture of ceramics and bricks for buildings.
[photos Marc Vilarmau (top) and Jordi Badia (left)]