AGENTS AND FORMS OF WEATHERING IN GRANITIC ROCKS USED IN MONUMENTS

The most typical forms of weathering of carbonate and sandstone rocks are also found in granitic rocks. However, the mineralogical composition and the grain—size of the latter confer some particular characteristics to those forms. In coarse-grained granite, for example, well developed plaques are rare, and the alveolation, although appearing do not exhibit the characteristic aspects that are found in the carbonate or sandstone rocks. Granular disaggregation is very frequent and typical form. The purpose of this work is to describe the most frequent forms of weathering found in ancient buildings and monuments in Galicia (NW Spain) and Northern Portugal, and to enumerate and discuss some facts about the agents which have more influence on the observed alterations.