Figure F4. A 3.5-kHz echo sounder record showing that the seafloor dips smoothly ~6 m from the H2O junction box to Site 1224 (proposed Site H2O-5). One subbottom horizon at ~9 m is fairly uniform throughout the area. Based on drilling results, this is a midsediment reflector. A second reflector at ~30 m below the junction box may be associated with basaltic basement, although it appears only occasionally in the record. PDR = precision depth recorder.