Models of very long term geochemical cycling of material include oceanic sediments as a part of the much larger system of mantle differentiation, production of sea floor, subduction, and continental growth. Mass balance considerations show that the system cannot be in steady state if pelagic sediment has always had its present composition. An approximate steady state system is possible if pelagic sediments were exclusively red clay and siliceous ooze. The origin of the calcareous plankton 100 m.y. ago apparently initiated a process interior to the system which is driving the system toward a new steady state. On a time scale of tens of millions of years, sea level fluctuations associated with changes in the length of oceanic ridges and the rate of spreading cause differential partitioning of sediments between shelf areas and the oceanic realm. This process may alter the inputs to the ocean system and affect both the volume and the composition of oceanic sediment. For shorter time scales the sedimentary record reflects variations in internal processes of the ocean system.