Deep-Sea Deposits

oceanic and marine sediments deposited on the continental slope between the neritic and abyssal zones at depths from 200 to 2,500 m. They occupy 19.4 percent of the area of the world’s oceans. Terrigenous sediments resulting from the erosion of detrital material and clay particles from dry land account for 56.5 percent of deep-sea bathyal deposits; second in importance is limestone silt (29.5 percent), in which foraminiferous, coral, and crustacean varieties are about equally distributed; next comes silicon silt, occupying about 8 percent of the area of the continental slope, and represented by diatomic and (much more rarely) radiolarian varieties. Vulcanogenic sediments (5 percent) are confined to regions of modern volcanic activity. Analogues of deep-sea deposits are known among the sedimentary layers of the Lower Cretaceous and Flysch eras.