Sandstones in the district of Bages often display holes like in the pictures in the gallery, 1st one from the cliff of Els Tres Salts (Sant Fruitós de Bages), the 2nd from La Guia (Manresa). The sculptural concavities as over 10 cm diameter as the 1st photo are named in Geology taffoni or tafoni (singular taffone or tafone) from the Italian, while the 2nd photo displays a sandstone with small holes named alveoli.
Both, tafoni and alveoli may be caused by the impact of thrown by the wind particles in arid climates or in the coast. However, this is not the case of the climate neither the geographical location of the district of Bages where these concavities are caused by by dissolution of the lime that once was sticking the sandstone or by growth of salts crystals (haloclasty), differential disaggregation and further erosion by water.
[photos Florenci Vallès (1st) and Jordi Badia (2nd)]
- See also the alveolar erosion in the Tower of Breny, a memorial monument from Roman origin in the III century, in Castellgalí