This investigation has corroborated the grain-size control hypothesis on gas hydrate distribution along sediment columns. This control is observed in each of the three studied columns at the medium scale (the entire zone of chlorinity anomalies is controlled by a comparatively coarse-grained horizon), but manifests itself variously. In the column at Site 994, the gas hydrate-bearing zone is limited by coarse-grained sediments on the inside (at the top and bottom), but in the column at Site 997, this zone is discerned by relatively coarse-grained interlayers, and both these features are combined in the column at Site 995. It is important to note that Site 995 is located between Sites 994 and 997. The grain-size control on the gas hydrate distribution is also detected at the detail scale (at the level of individual sample) with some degree of certainty: 77% of individual chlorinity anomalies are confined to comparatively coarse-grained sediments.