Figure explanation: Crustal Bouguer gravity anomaly basemap of the equatorial Brazilian margin. Contour interval is 10 mgals. Crustal Bouguer gravity is proving to be a valuable and powerful asset in helping to map the three-dimensional architecture of rift basin systems, especially in frontier regions such as the west and east African continental margins and the equatorial and eastern margins of Brazil. For example, the thick Neogene deposits of the Amazon fan have tended to obscure the rift structure and continuity of the offshore Foz do Amazonas and Para-Maranhão basins. However, as can be seen in the crustal gravity image, details of rift basin location, continuity, and segmentation are clearly defined.