Numerous small-wavelength elongated features are visible both on filtered geoid maps and on topography maps of the South Atlantic Ocean. A number of them are oriented along the directions of absolute plate motion between 80 Ma B.P. and 30 Ma B.P.: N50¿E for the African plate and N63¿W for the South American plate. Magmatic traces left over fixed convective plumes more numerous than the ''classical'' hot-spots best explain these observations. Other traces, especially in the area of the Sandwich subduction zone and on the African plate are oriented in a N50¿W direction and seem to indicate large-scale deformation of the oceanic plates. ¿ American Geophysical Union 1989