Las extensas dunas de la region de Copiapo presentan formas vivas, pero son dunas remanentes ya que su fuente de abastecimiento en arena fresca esta agotada. Segun algunos autores, sus arenas habrian provenido por deflacion de los depositos de playa de las amplias terrazas marinas solevantadas que caracterizan la franja costera entre el rio Copiapo y Caldera. Antecedentes sedimentologicos no confirman esta interpretacion y sugieren un origen fluvial para las arenas. estas podrian provenir de formaciones detriticas acumuladas en el Neogeno cerca de sus desembocaduras por el rio Copiapo y las quebradas situadas inmediatamente al norte.Extensive areas of active dunes are found in the Copiapó region. However, their sand supply is presently depleted. It has been proposed that deflated uplifted marine terraces of the coastal belt between the Copiapó River and Caldera were the source of the dune sand. Such a hypothesis is not supported by sedimentologic data, which suggest a fluvial origin for the aeolian sands. They could be related to Neogene alluvial accumulations built up at the mouth of the Copiapó River and the ephemeral streams located to the north of it.