[DB 1506 (10); OAB 78] This claim is based on observations of the thickness of sediments on the ocean floor. ICR author Stuart Nevins, in ICR Impact #8 (http://www.icr.org/pubs/imp/imp-008.htm), roughly estimates the amount of sediment on the ocean floor and the amount of sediment being delivered to the oceans by rivers. He arrives at the conclusion that it would only take about 30 million years for the observed sediment to accumulate. This estimate is probably roughly correct, but Nevins' conclusion that this number represents a limitation for the Earth's age fails to recognize the periodic recycling of the ocean floor (the other side of the One-Sided Equation). Due to Plate Tectonics, ocean floor is continuously created at mid-ocean ridges and subducted into the Earth's mantle at ocean trenches. This process moves at about an inch or two per year, so the average age of the ocean floor is in fact a few tens of millions of years, as Nevins estimated, and thus his result is completely consistent with old-Earth science.

 

It is sometimes claimed that subduction only gets rid of 10 percent of the sediment being added to the oceans (D.R. Humphreys, Creation: Ex Nihilo, v.13, no.1, p.31 (1991)). This claim is made by comparing one researcher's estimate of the sediment being added to the oceans (V.V. Gordeyev et al, Doklady Akademii Nauk SSSR, v.238, p.150 (1980)), to another researcher's estimate of the amount of sediment being subducted (W.W. Hay et al, Journal of Geophysical Research, v.93, no.B12, pp.14933-14940 (1988)). Humphreys claims that, since Gordeyev's estimate is 25 times larger than Hay's, sediment must be added to the ocean much faster than subduction can get rid of it, and thus the lack of observed accumulated sediments remains a problem for old-Earth scientists. The fallacy in that statement is that Hay based his estimate entirely on the assumption that ocean sediment is in a steady state. Hay used his own calculation of the amount of sediment in the ocean, which is much less than Gordeyev's, to calculate the amount being subducted. If Hay had instead used Gordeyev's estimate of the sediment in the ocean, his estimate of the amount of sediment being subducted would have been correspondingly larger. In short, Hay's estimate was based on an assumption of steady state, and it does not make sense to compare his estimate with an alternate rate of accumulation in an attempt to prove that a steady state does not exist.