Abyssmal Accumulations

Abyssmal Accumulations consist of those organic and inorganic materials which form over the deepest portions of the sea-bottom, where no terrigenous or land-derived sediments occur. The most conspicuous and widely spread of abyssmal accumulations is a fine red clay which owes its colour to the presence of oxides of iron and manganese. In this deposit occur grains of various volcanic minerals and fragments of pumice, while the clay itself is believed to be the result of the chemical action of sea-water on similar volcanic materials. The organic abyssmal accumulations consist of various kinds of ooze, made up largely of the dead shells of foraminifera, pteropods, heteropods, and radiolarians, and the frustules of diatoms. Scattered through the abyssmal accumulations occur, often in considerable quantities, earbones of whales, beaks of xiphias, teeth of sharks—some of these belonging to extinct species. In the red clays, metallic spherules, which are thought to be of cosmic origin, or, in other words, meteoric dust, frequently occur. The accumulation of these and the organic remains just referred to, in such relatively great abundance, shows us that the red clay in which they occur must accumulate very slowly. See GLOBIGERINA, OOZE.