The plain located between Magdalena river and Sierra Nevada de Santa Marta has been divided into five geomorphic units: Magdalena floodplain; present delta lagoon system; marginal lagoon system; beach and barrier island and alluvial foothill plain. The features of each one are product of specific events in time. The marginal lagoon system and its barrier island conform a scheme of lagoon - barrier - sea. Salamanca shore is dominated by waves and is subjected to recession. A general cross section of the island includes seabeach- dunes-plain with vegetation-salt pan-plain with vegetation-mangrove-lagoon. The marginal lagoon system (which includes Ciénaga Grande) is strongly dependent of vegetation. Toward northwest desertification is the dominant process and toward northeast (alluvial foothill plain) it,s