GEOMORPHOLOGIC CHARACTERIZATION OF THE MAGDALENA RIVER DELTAIC PLAIN WITH EMPHASIS IN THE LAGOONAL SYSTEM OF THE CIÉNAGA GRANDE DE SANTA MARTA, COLOMBIA

Abstract

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