Figure F4. A. The 3.5-kHz sub-bottom profile collected at ~5 kt across Site 1098, in Palmer Deep Basin I (see location in Fig. F2). The poor quality of the record was probably a result of the noise produced by other ships (Polar Duke and Laurence M. Gould) nearby and of the diffraction of acoustic energy by icebergs and steep basin sides. B. Detail of sub-bottom record on site collected at very low speed (~2 kt) during ship positioning.