Site selection for Site 1156 was based on a SCS survey conducted during the R/V Melville cruise Sojourner 5 in 1997. The proposed site is near shotpoint 270 of the seismic profile (Fig. F19). This migrated seismic profile shows clear sediment cover from 6.5- to 6.65-s two-way traveltime, giving an estimated sediment thickness of ~150 m. No presite SCS survey was conducted, owing to equipment failure. A 1.2-hr 3.5-kHz PDR survey with average ship speed of 5.0 kt was performed on the approach to Site 1156 to confirm the site location and sediment thickness. Hole 1156A is ~400 m north of prospectus site AAD-34a. Hole 1156B is 200 m farther north (see Fig. F20). The drilled sediment thicknesses were 118.2 m for Hole 1156A and 181.6 m for Hole 1156B.