The weathering of the Bouça de Frade granite is the result of the modification of the minerals that compose it by physical and chemical processes. Weathering was fundamental for the development of shapes with different aspects and dimensions. In this area of the Natural Monument there are different weather figures, namely tafoni, potholes and grooves.

• Tafoni

They correspond to rounded or irregular cavities of different dimensions, the smallest shapes are called alveoli and the largest are called caves, they occur in areas close to the vertical. Their origin is still not well understood, however, there is some consensus that they result from chemical weathering processes.

• Potholes

These shapes result from physical and chemical weathering at the surface of the rocks. Water accumulates and causes chemical reactions with minerals more susceptible to alteration, such as biotite and feldspars, causing rock surface progressive granular breakdown, forming circular depressions - potholes. These structures retain water permanently maintaining this weathering process.

• Grooves

Corresponds to a preferred channel through which water overflows.