 The high density would derive from the times the Salar de Atacama depression was a westward rift arm of the Salta Rift Basin located further east in Argentine territory.Salar de Atacama basin is bordered on the north by the Salado River basin, which is a sub-basin of the Loa River basin.To the east, the drainage divide approximately coincides with the international border with Bolivia until the Portezuelo del Cajón.