Just before Casera Auernig a very particular grey conglomerate emerges: its calcareous pebbles were created by the ancient erosion of a narrow and long rocky promontory that suddenly emerged from the sea due to active faults. Today it roughly coincides with the area that includes Valbertad – Rio Secco Crete – Mount Cavallo – Mount Malvuerich – Mount Bruca. The grey conglomerate (composed of ancient fluvial-delta gravels) is also associated with light grey sandstones, characterized by layers with a thickness of a few tens of centimetres that overlap for many meters. They can be seen on the small rocky ridge just east of the smaller building of the Casera Hut. The layers of light sandstone are also produced by the erosion of the Devonian limestone rocks of Mount Cavallo – Mount Malvuerich. These are ancient delta deposits spread from the rocky promontory into the sea towards the current Auernig and Carnizza mountains.