Location of the Atlantis II Fracture Zone. Position of the Southwest Indian Ridge based on recent satellite gravity maps of the southern oceans and available bathymetric data. Bathymetric map of the Atlantis II Fracture Zone modified from Dick et al. Figure 3 . SeaBeam tracks hand-shifted by eye to eliminate conflicts in the data.
Solid lines indicate actual data, whereas hatched lines show inferred contours.
Contour interval is 250 m. Small solid dots and arrows indicate the starting point and approximate track of dredge hauls. This conjugate site is the location of Southwest Indian Ridge 6, the final backup site for Leg 176, where the volcanic carapace originally overlying Hole 735B is preserved intact. Figure 4 . Magnetic anomalies over Site 735 based on the survey of Dick et al.