Figure 1. Downhole chlorinity (solid diamonds) and ³⁷Cl (open circles) variations at Site 997, Blake Ridge. The vertical line at 506 mM Cl^- represents the plateau value of the low-chlorinity water advected from below the cored section. See text for details of chlorinity zones 1-4. BSR = position of the bottom simulating reflector in seismic profile through Site 997. Error bars = ±1 STD.