Plate 1. Samples are in thin sections impregnated with plastic so that in situ porosity can be observed. A. Diatom (~40 mm in diameter) in sediment from the upper hydrate zone at Site 994C, Blake Ridge (Sample 164-994C-24X-1, 39–41 cm). B. Several diatoms in upper hydrate zone at Site 994C, Blake Ridge (Sample 164-994C-23X-4, 40–42 cm). Upper-left diatom(s) was crushed (naturally) and a large pore space (50 mm long by 5 mm wide) is observed.