Geoparque Mundial UNESCO

Nº31 – Chorrera del Calabazas

Geoparque Villuercas > Nº31 – Chorrera del Calabazas

LOCATION AND ACCESS

The Chorrera del Calabazas can be reached from the town of Castañar de Ibor, where the EX-118 road that links Guadalupe with Navalmoral de la Mata takes us. From the outskirts of this town, take a dirt track that runs southeast parallel to the Fuente stream through orchards, olive groves and copses of chestnut and oak trees, and takes you to the Postuero pass, which separates the basins of the Ibor and Gualija rivers, from where the actual route of the Calabazas gorge begins, as far as the waterfall or “chorrera” (small waterfall).

However, this wild place is accessible by any type of vehicle and, of course, on foot.

ATTRACTIONS OF THE VISIT

The name of the stream comes from the presence of several nearby rocky outcrops that have been given the ironic nickname of “calabazas”(pumpkins) by the locals, no doubt due to the large size of their rocky blocks.

We will observe the different geological aspects of the folds and fractured structures of the nearby sierras, their lithology, the geological processes of erosion and the enigmatic Daedalus, which represent dwelling and feeding burrows of a group of invertebrates that are now extinct.

The visit gives us the opportunity to appreciate not only the geological richness of the site (geodiversity), but also the biological richness (biodiversity) of these mountains. During the route that takes us to the waterfall we will pass by oak forests, chestnut groves and numerous specimens of Portugues laurel (Prunus lusitanica), which in these valleys find some of their last refuges in the Iberian Peninsula. We will pass through a grove of seventeen old monumental chestnut trees (Castanea sativa) and the large Quejigo de la Fuente, located on the banks of the Calabazas gorge. Along with the chestnut trees there are other gall oaks, holly, willows and junipers of singular size, as well as rare species of orchids, honeysuckles, wild roses, tree germander, laurustinus and turpentine tree.

GEOLOGICAL INTERPRETATION

Read Geological Interpretation

The Chorrera de Calabazas is the result of the differential erosion produced by the Calabazas stream as it encounters layers of rocks of different resistance along its course. The riverbed runs transversally through the Armorican Quartzite, which, due to its resistance to erosion, gives the most abrupt and elevated reliefs, until it meets other softer layers of shale (“Lutitas de Navatrasierra”). These are manifested by large depressed areas that follow the direction of the layers, and then flows into the Guadarranque syncline, crossing all the geological formations of the Ordovician and Silurian, and finally flows into the Gualija river, very close to the core of the Guadarranque syncline on the northern flank. The waters that descend from the abrupt Armorican reliefs give rise to a spectacular waterfall in the rainy season and produce intense fluvial erosion when they come into contact with the soft materials of the “Lutitas de Navatrasierra”, forming an important pool. This is an excellent example of differential erosion controlled mainly by the lithology.

Around the route there is an abundance of rocky outcrops, extending along both sides of the gorge. They are are superficial geological formations associated with the fragmentation of the outcrops of the Armorican Quartzite strata that form the crests and ridges of the sierras. Their formation is linked to the detachment of large boulders and blocks that slide down the steep slopes driven by the force of gravity, forming real “rivers of stones” or “casqueras”.

In these rocky outcrops there are some blocks with ichnofossils (in particular Daedalus) from the collapsed Armorican Quartzite.