Foredunes of Santo Domingo beach in central Chile represent steps of a prograding coastline in Holocene time up to the historical period, as suggested by 14C absolute datings. They are made of black sands which derive from volcanic ashes. These aeolian forms are probably linked with spasmodic sedimentary flows related to the episodic activity of Tinguiririca volcano located upstream in the watershed of the Rapel river. Human action may account for the disestabilization of the oldest foredunes and the formation of transgressive parabolic dunes.