The basic premise of the recent Exxon cycle chart, that there exists a globally correlatable suite of third-order eustatic cycles, remains unproven. Many of the tests of this premise are based on circular reasoning. The implied precision of the Exxon global cycle chart is not supportable, because it is greater than that of the best available chronostratigraphic techniques, such as those used to construct the global standard time scale. Correlations of new stratigraphic sections with the Exxon chart will almost always succeed, because there are so many Exxon sequence-boundary events from which to choose. This is demonstrated by the use of four synthetic sections constructed from tables of random numbers. A minimum of 77% successful correlations of random events with the Exxon chart was achieved. The existing cycle chart represents an amalgam of regional and local tectonic events and probably also includes unrecognized miscorrelations. It is of questionable value as an independent standard of geologic time.
- Geological Society of America