sedimentary deposits in the abyssal parts of the open sea or ocean formed by the slow accumulation far from shore of minute particles suspended in the water. Examples of such particles are the skeletal remains of planktonic microorganisms, clayey and detrital minerals, volcanic ash, and minerals that form on the bottom. Pelagic deposits include modern biogenic sediments (globigerine, coccolithic, diatomaceous, and radiolarian oozes, as well as deep-sea red clay) and ancient sedimentary rocks (certain limestones, radiolarites, and diato-mites).