Galactic Dark Matter and Terrestrial Periodicities
OXFORD UNIV (UNITED KINGDOM) DEPT OF PHYSICS
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Analysis of recent geological databases reveals the presence of a 26.5 Myr periodicity in the terrestrial record of the last 200 Myr. The same periodicity is found to be present, at a high confidence level, in the record of impact cratering on Earth. It thus appears that global disturbances are modulated or caused largely by exogenous forcing. The likely source is a periodic comet influx caused by Oort cloud disturbance as the Sun oscillates vertically through the Galactic disc. The Earth may thus be regarded as a probe of the disc environment and to account for the periodicity, the Galactic disc is required to have a substantial dark matter component approx .15 molar masscu pc. The purpose of this paper is to review the relevant observational framework, and to describe the basic astro- and geo-physical processes which now seem to underpin evolution on Earth. The resulting current hazard to Earth, amounting to a more substantial input and explosion megatonnage in toto, is both more complex and more profound.