The Bolnuevo erosions are natural sandstone sculptures One of the best known features of Bolnuevo are the erosions, or gredas, of Bolnuevo, sometimes known as the “enchanted landscape”, a curious formation of naturally sculptured rock formations behind the main beach. These limestone shapes have been formed over millions of years by wind erosion, and seem almost like modernist sculptures. The white clay of which they consist is a mixture..