Abstract
The mio-pliocenic Navidad Formation, and the eocenic and cretaceous sediments, show significant promising features, taklng into account the repeated osclllations wlthin füe southward closed basin, of the ancient shoredines. Upwards, the area was 5tratigraphically covered by more extensive seas, decreasing its energy. Near the pacific coastal line, the sediments are much tectonicaly disturbed; in turn, east and northwards, the embayment is nos affected by great disturbance. Some types of stratigraphic traps, as eolian sandbeaches atractive reservoires are expected.