Soft, siliceous, deep-sea deposit composed of more than 30% (by volume) diatom cell walls (see bacillariophyceae). Diatomaceous sediments predominate in the high latitudes both around the coast of Antarctica and in the N. Pacific, but in the N. Atlantic the diatom content is overwhelmed by the terrigenous sediment derived from the adjacent continents. See also radiolarian ooze.