This age is in good agreement with the age of the meteorites and the age of the Moon as determined independently.
The uranium and thorium decay systems offer a multitude of radiometric dating options.
As noted above, the variable uranium isotope fractionations observed in fresh-water systems preclude its application there.
In addition, pelagic sediments are ruled out by open-system behaviour of uranium after deposition (Ku, 1965), while mollusc shells also tend to take up uranium after deposition (Kaufman et al., 1971).
In contrast, coral which has suffered fresh-water percolation is very susceptible to open-system behaviour. (1991) found that many coral specimens over 50 -manganese crusts.The Earth can be assumed to be a very large sample containing lead evolving from primordial lead by radiogenic increments.If modern lead, for example, from marine sediments or modern basalts has the composition of lead in the Earth and if the lead in the troilite phase of iron meteorites has the composition of primordial lead, then a simple model yields about 4.6 billion years for the age of the Earth.Knowledge of the level of the oceans in the past is of particular interest to a wide range of fields with Earth Sciences.Vertical rates of land movement in tectonically active areas or the subsidence of ocean islands, such as Greece or Hawaii, are important constraints for our understanding of lithospheric deformation.