The RFL III section is an outcrop of about twenty meters highlighted by a trench dug during the First World War. It is located in the basin south of the Refuge Lambertenghi-Romanin, about a hundred meters further downstream, near the path that leads to Mount Capolago. The grey limestones that emerge along the western rampart of the trenches seem equal to each other, but in reality, they contain the limit between two geological periods: the Silurian and the Devonian. This limit was recognised thanks to numerous micro-palaeontological and stratigraphic investigations.