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Evidence for freeboard of continents (relative elevation with respect to sea level) as a function of time is evaluated. Eyged’s interpretation of continental emergence with time, based on changing areas of flooding shown on global paleogeographic atlases, seems unfounded on grounds of inherent biases in the original maps, biases associated with changing time segments between successive maps, and by comparison with a freeboard versus time plot for North America compiled from Schuchert’s more detailed atlas. Instead, Hess’s simple assumption of constant average freeboard seems correct. The North American plot is used as a basis for a quantitative estimate of the distribution in time of deviations in freeboard. For over 80 percent of post-Precambrian time, freeboard has remained within ± 60 m of a normal value 20 m above present sea level. A constant freeboard model of the earth is suggested with various feedback mechanisms continually maintaining this fine adjustment between volume of ocean basins and volume of ocean waters. From the model, a number of calculations and implications are drawn for continental and oceanic accretion, as well as for some rate relations in a global tectonic system.

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