Folds in Shales and Metagrauwakes folds, Structural Geology 1:56 PM A+ A- Print Email Folds in shales and metagrauwakes from Carboniferous (Costa Vicentina, Portugal). Dobras em xistos e metagrauvaques do Carbonífero (Costa Vicentina, Portugal). Photo: Gabriela Bruno. Via: Francisco Sousa