Geoparque Mundial UNESCO
Geoparque Villuercas > Nº37 – Risco Carbonero
The Risco Carbonero can be reached from the CC-20 road that links Guadalupe with Navatrasierra. If we head for the latter village, at kilometre 34.5 a forest track on the right takes us to its summit via the foothills of the Cerro Fortificado. It can easily be recognised by the fire protection hut on the top and provides a privileged vantage point.
The Risco Carbonero is a good place for an excursion that also includes the valley of the Hospital del Obispo and the Canchos del Ataque. From the valley to the summit abundant vegetation and good views can be enjoyed.
It is interesting to observe the intense fracturing of the Armorican quartzites of the Risco Carbonero and the large rocky blocks that have fallen at its base; these details explain the formation of the extensive pedrera that can be seen on its western side.
Other nearby hills to be identified are the “witness hill” of Camorro de Navalvillar and the two Riscos Cervales, which represent the highest elevation in the Geopark after La Villuerca.
In common with other elevated vantage points of the Geopark (Risco de La Villuerca and Risco Gordo), the Risco Carbonero is a rocky crest of Armorican quartzite characteristic of the sedimentary beach deposits of the Lower Ordovician (480 million years ago). The entire ascent in any direction is covered with pedreras or “block slopes” made up of large quartzite blocks that became detached from the crests when the latter fragmented owing to the effect of the “ice wedges” of the periglacial conditions that prevailed in the early Quaternary (see the process in the geosite on the Source of the Almonte). Moreover, it is an important paleontological site for marine invertebrates of the Ordovician period, Daedalus and Skolithos, of which some isolated examples can be found. Remember that fossils represent part of the geological heritage of the Geopark and that we should all contribute towards their conservation and enjoyment. They should be observed and photographed but not collected.
The geological value of the Risco Carbonero is that it allows the interpretation of much of the Geopark. Owng to its location and its great height it overlooks the Ibor-Guadalupe anticline to the west and the Guadarranque syncline to the east. From here we can understand the geomorphology of the “Appalachian relief” that defines the territory as a whole, with the observation of the details of the sierras and parallel valleys facing SE-NW (see Geosite “Risco de La Villuerca”).
The strata of Armorican quartzites that make up the Risco Carbonero are part of the east flank of the Ibor-Guadalupe anticline. Despite their age of 480 million years, they are the most modern materials that can be found in this great folding structure, as everything that was previously deposited has already been worn down by erosion. What can be seen today in the valley is a set of shales, sandstones, and conglomerates of the Ediacaran (+ 540 m.y.) including some calcareous and magnesian strata (dolomites) characteristic of this formation that has been named Grupo Ibor. In contrast, if we observe the Guadarranque syncline towards the east, we find a succession of Palaeozoic materials preserved until the Upper Silurian (420 m.y.) in which shales and quartzites of various stages of sedimentation alternate.
