From time to time, mostly after heavy rains, landslides occur on cliffs and steep slopes. The risk of falling rocks can be assessed, though the accurate prediction when the rocks will fall is much more uncertain.
The rocks of continental origin of the geological formation Artés are heterogeneous after the changing ratio of clay, sand, and calcium carbonate, their different consistencies, and usually arranged in thin and poor wide layers. The geological formation Artés spreads on the north and west of the district of Bages and on the north of Moianès. In the outcrops that are sculpted by the streams in this heterogeneous, reddish continental terrain, erosion always finds cracks and weak points that will end with the detachment of a mass of rocks. The larger rocks can reach the bottom of the cliff, while fallen smaller ones and earth can make colluvium in the slope.
The images show a landslide from the beginning of 2024 on the right slope of the stream of Jaumandreu (Fonollosa), and the passage of the ICHN-Bages group on 13.04.2024 within the naturalist outing from Els Manxons to the viewpoint of El Garrigar (Callús and Fonollosa). The fallen rocks have reached the valley floor, blocking the path.
In geological time scale, the phenomenon of rockfall is very frequent in the mudstone’s cliffs in the geological formation Artés and in the mountain of Montserrat that is plenty of vertical walls. Not so often, large conglomerate rocks break away from the edges of the flat hills of the tabular relief if erosion has undermined their base, sliding downslope.
[photos Jordi Badia]