Lithology

Some of the largest structural units of the Iberian Peninsula are found within the Serra Gardunha, including the Hesperic massif, where the Central Iberian zone is integrated. This unit, also known as the Ancient Massif corresponds to an extensive area of ancient rocks, fractured and eroded, which represent esentially two complexes: 

 

 

Geomorphology

This unit presents the very different aspects between the moulded granite and the molded slate.

 

In the granitic terrain, the flat surfaces are preserved, interrupted by vigorous reliefs, with the inselbergs standing out, contrasting with the flat surfaces of erosion in the uplands or at the base of the mountain.  There are other very common forms of moulded granite, like the caos de blocos and the tors (Silva et al, 2001).

Given the facility for rosion in the zone for granites and granitoides, they are moulded in a very characteristic way with rounded heads where the dense drainage networks originate (streams).

In the case of the schists and greywachians their shape is much more angular because they are more resistant to the action of erosive agents. This fact causes them to show up at higher altitudes, even though they are older than the other rocks.

With regard to the geomorpholoy of the Serra da Gardunha, we have to highlight some evidence of glaciations. Despite the fact that Gardunha is not subject to glaciar coverage, as was the case with Serra da Estrela, it is under the influence of intense cold (periglaciarism) during which the soil is frozen for a long time (permafrost). The temperature variations associated with the formation of ice, expand and contract the rocks causing their fragmentation into angular blocks.

This phenomenon is visible due to the  innumerable deposits on the slopes (pebbles of schist and greywach) existent in the north hillsides of Gardunha (Silva & Gavinhos, 2002).