Resumen de Procesos kársticos en la Formación Calcarenita de Niebla (Huelva).

Luis Miguel Cáceres Puro, Joaquín Rodríguez Vidal, Antonio Rodríguez Ramírez, Mercedes Cantano Martín

• The development of a cavered karst in the Miocene calcarenite formation in the N area of Niebla (Huelva) has been studied. The cover consists of sediments of Quaternary terraces of the River Tinto (T9, T8, T7 and T6), and to a lesser degree, fragments of Mio-PIiocene clays ("blue marls"). Solution of the caLcarenite has originated vertical pipes of varying size evolving in the top to form funnel-shaped channels of preferential solution. These karstified areas generate closed depressions that appear on the surface as alluvial dolines, basically bowl-shaped with smooth edges. Later erosion by streams has resulted in fluvial capture of the depressions and the breaking up of the alluvial cover; obstructing identification of the these landforms.