Figure F4. A. Carbonate sample from the top of the Pinnacle showing the porous nature of carbonates from this environment. B. Sample of sediment from near the seafloor at southern Hydrate Ridge showing hydrate lenses parallel to bedding connected to hydrate veins perpendicular to bedding (Suess et al., 2002). C. Landscape at southern Hydrate Ridge showing mounds covered by bacterial mats. A chemosynthetic clam colony is seen in the right edge of this picture taken during an Alvin dive (Torres et al., 1999). D. Illustration of the complex biogeochemical relationships expected near the southern summit of Hydrate Ridge (Bohrmann et al., 2002). BSR = bottom-simulating reflector.