DEF.P.SEA LIFE. The surface of the sea nearly everywhere hears an abundance of minute animal and plant life. In this surface life, or 'plankton,' as it is called collectively. many groups of inver teb•ates are represented. The phosphorescence often seen upon the surface of the sea is due en tirely to their presence. These almost micro scopic creatures are constantly dying and falling to the bottom. They constitute the principal food of the smaller animals dwelling there, and their remains form a large part of the deep-sea oozes. The most important forms among them, considered with reference to abysmal deposits. are the and the radiolarians, which are enormously abundant.
The marine deposits on the ocean floor are gen erally referred to three groups: Those of the con tinental slopes are called Terrigenons Deposits, derived from the land thrdugh the \Yearling ac tion of rivers, tides, and currents. These coast wise deposits are the blue, green, coral, or vol canic muds. and are characteristic of the adja
cent land slopes from which they are derived. Farther off shore, generally about 300 miles, the Pelagic Deposits. made up of dead ma rine organisms from the surface—the minute sur face life already referred to: Ilere we find oozes. such as diatom, radiolarian. or globerina oozes which depend upon the character of the surface life prevailing above them. these. in the deeper parts of the ocean, are the lted Clay Deposits, Which cover about half the ocean floor. This region is not affected by matter from the land, and receives little pelagic matter horn the surface. It lies so deep that the shells of surface organisms falling down are removed through the solvent action of the deep water. The red clay is believed to have formed very slowly, not more than a few fet of matter hav ing accumulated since the Tertiary period.