Heavy minerals of sediments from bottom of the Bay of Cádiz and terraces of the Guadalete river have been studied, for establish the genetic relationships and source areas. The use of surface feature analysis using SEM gives information about morphological characteristics and separate phases of the sed im e n ta ry e v o lu tio n . The coexistence o f id io m o rp h ic , s u b id io m o rp h ic and xe n o m o rp h ic grains in these sediments indicates a high reworking grade, policyclic character of the sediments and diversification of source areas. For the Bay, two sources are suggested: a) from the continent, throught the Guadalete river, that gives mainly policyclic grains from sedimentary materials present in its bassin and, b) from the coast and littoral, throught the Guadalquivir river, that provides idiomorphic mineral grains from igneous and metamorphic terranes (Iberian Massif), arriving the Bay by littoral current action