Figure 2. Bouguer gravity image (courtesy of South African Council for Geosciences) across Vredefort impact structure, South Africa. Color scale is in relative units representing total gravity variation of 90 mgal across area of figure. Yellow circular pattern close to geometric center reflects local gravity high that suggests that the core of the structure is underlain by dense mafic or ultramafic rock. Borehole located close to peak of gravity anomaly indicates that rocks beneath surface consist mainly of peridotite.