Abstract: Astronomical cycles have been widely recognized to drive climatic changes that are recorded by cyclic sediment deposition. The developing discipline of astrochronology uses these cycles to progressively refine the geological time scale. Astronomy, therefore, informs geology. Conversely, can the geological record provide astronomical information?
Sediment cycles record the period of the axial precession of the Earth (precession of the equinoxes), which is a function of the lunar distance and the Earth’s spin rate. Through time, tidal energy dissipation progressively slowed down the Earth’s rotation, transferring angular momentum to the Moon’s orbit and increasing lunar distance. As a result, the period of axial precession has increased markedly through geologic time, and estimating it from geological data gives key information on the history of tidal energy dissipation and of the duration of an Earth day.
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