SUMMARYAnalysis of influx and efflux of sediment and water to and from the ocean and of residence times of the elements indicates that the oceans and atmosphere are in a steady state with respect to erosion and sedimentation. A detailed examination of the ocean‐atmosphere model is needed to see how the system worked in the geological past. Weathering is characterized primarily by the absorption of H+by silicates and secondarily by liberation of SiO2,alkalies and HCO3—to the oceans. The H+is supplied mainly by the H2O‐CO2system via the ionization of H2CO3but some is supplied by HCI from volcanic emanations. Weathering of carbonate rocks results in the same absorption of H+, releasing Ca2+, Mg2+, and HCO3—. Sedimentation, silicate reconstitution, and diagenesis are seen as the reverse of weathering in that H+is released and SiO2and alkalies are precipitated from solution. Thus a constant H+release is necessary to keep constant the CO2pressure of the atmosphere by transforming the HCO3—of the ocean into CO2+ H2O. The sedimentary products that are part of the steady‐state model are reconstituted silicates (degraded clay minerals that become diagenetically altered to less hydrous, more siliceous illites and chlorites), limestone (precipitation reverses limestone weathering), salt (uses up alkalies), and chert (uses op free SiO2). It is concluded that the major site of silicate reconstitution is not on the open sea floor but in coastal subsiding sedimentation belts in which high‐grade diagenesis takes place and whose formation waters are ultimately connected with the ocean and so can buffer it. The obvious consequences of the model are that the global amounts of carbonate, reconstituted silicate, salt, and chert must be related in a systematic way for any time interval in which the system is steady. To keep CO2constant, the total of carbonate precipitation and silicate reconstitution must be conserved. Similarly, salt precipitation and silicate reconstitution must be related to keep alkali removal constant. Finally, chert must be related to silicate reconstitution so that all silica released by weathering is removed from the ocean. A careful examination of the stratigraphic record is needed to objectively determine from such parameters whether the steady‐state system has always been operating much as today or whether there have been major secular changes or periodi