Most of the gas hydrate at the Blake Ridge probably occurs mainly as disseminated crystals in pore spaces, which likely dissociated before cores were processed on deck. Other less frequent occurrences included vein-filling or possibly fault-filling massive gas hydrate. Gas hydrate sampled from cores was likely limited to these types of gas hydrate habits. Two indirect measurements of gas hydrate dissociation were made on core material: (1) excess water from gas hydrate dissociation leaves affected core material with a texture that has been described as "soupy" (Westbrook et al., 1994), and (2) core temperature anomalies result from the endothermic reaction of gas hydrate dissociation, described in detail in the Leg 164 Initial Reports volume (Paull, Matsumoto, Wallace, et al., 1996). Each of these observations is mapped on the chart, and Table 1 lists gas hydrate occurrence with depth, along with other gas hydrate indicators in sediment.
Temperature anomalies can be caused by other factors, such as adiabatic expansion of gas within the core, whereas "soupy" sediment is likely to have been the direct result of gas hydrate dissociation, provided that proper core handling procedures were followed.