Access is afforded by the CC-97 road that runs from Cañamero and Berzocana to Navezuelas. Between km 9 and 10 there is a slightly elevated area with a gentle rounded profile that is known as the Collado del Brazo. It stands above the extension of the valley to both the north and the south, while it is bordered to the east and west by two crests of Armorican quartzite rocks.
This change in slope that can be observed is due to the fact that the Collado del Brazo is located on the watershed between the basin of the River Guadiana and that of the River Tajo. A reference point for this place is the traditional threshing floor known as the Era del Gato, which having lost its original raison-d’être has become a magnificent vantage point.
The Collado del Brazo is part of the great geological structure of the Santa Lucia-Río Ruecas syncline and is bordered to the east by the western foothills of the crag of La Villuerca. The collado or hillock represents a pass between the sierras that is made use of by both old thoroughfares and current roads to enter one of the wildest parts of the district, which constitutes “inverted relief” as it is topographically higher than the nearby anticlines.
From the Collado del Brazo a clear view can be had of the sedimentary series that were laid down during the Ordovician and the Silurian. They represent alternative layers of sandstones, slates, and quartzites of varying thicknesses. The highest elevations are those of the Armorican quartzites running northwest to southeast with a dip (inclination of the strata) that is almost vertical; the hillsides have developed on the more modern slates above them.
The main aim of the visit is the observation of the geomorphologic features of the two valleys that start here. When we reach the Era del Gato the most relevant aspect is that we are at the watershed between the basins of the River Tajo and the River Guadiana.
From here one can appreciate the characteristics of the Santa Lucía syncline towards the north, along the bottom of which runs the Garganta de Santa Lucía which is a tributary of the left-hand bank of the River Almonte. This syncline extends towards the south along the valley of the ravine of the Brazo, a tributary of the River Ruecas, the waters of which flow towards the Guadiana.
Magnificent examples can also be found of other elements that are frequent in different parts of the Geopark, such as the pedreras and colluvium that come down from the Barrera de los Peñones and the Risco Gordo, the projections that are a result of alternating layers of varying resistance to erosion and which outcrop parallel to the crests of the sierras, the deformations that occur on these quartzite crests owing to tectonic faults, etc.
We can also observe in the cuttings of the access road the layers of the successive sedimentary series and the tectonic structures (folds and fractures) that they cross.
This is the heart of the Chalcolithic cave painting area of Las Villuercas and is very close to historical sites such as the Castle of Cabañas and the church of Berzocana (a National Historical and Artistic Monument) which will put the finishing touch to an unforgettable day.