Cáceres Puro, Luis MiguelRodríguez Vidal, JoaquínRodríguez Ramírez, AntonioCantano Martín, Mercedes2015-09-032015-09-031996http://hdl.handle.net/10272/11093The development of a covered 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 Tin to (T9, T8, T7 and T6), and to a lesser degree, fragments of Mio-Piiocene days («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 dosed 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 landformsspaAtribución-NoComercial-SinDerivadas 3.0 Españahttp://creativecommons.org/licenses/by-nc-nd/3.0/es/Covered karstFluvial terraceGuadalquivir basinjournal articleopen access