SIMBAD references

The accurately measured ages of 89 large impact craters and layers were compared with the boundary dates for periods, epochs, and ages of the geological time-scale by a weighted least-squares fit. They are highly correlated with a χ²/f = 0.63. A Monte Carlo simulation of randomly chosen crater ages gives a >99.8 per cent probability that this result is not random. No craters are found in the oceans or, until recently, in ice which collectively cover 80 per cent of Earth's surface indicating that far more impacts have occurred than are known. Multiple impacts cluster near the times of boundary dates so, based on the observed cluster sizes assuming a binomial distribution, it was determined that the average cluster multiplicity is five. Comparison of the impact ages with the dates of the great extinctions revealed a strong correlation with χ²/f = 0.36 and a multiplicity of 8-9 impacts. It is shown that volcanism, although correlated with boundary dates, is a continuous process unrelated to sudden extinctions. During the past 125 Ma, the rate of global change and the impact rate have increased dramatically as the Earth passes near the OB star association. Multiple impacts 12.9 ka ago ended the Pleistocene epoch at the onset of the Younger Dryas (YD) causing worldwide extinctions. The date and extent of the YD impact may be consistent with a 62 Ma cycle of major impact events. During the Holocene 20 crater, airburst and impact tsunami chevron ages correspond to dates of global cooling with a χ²/f = 0.75 and >99 per cent probability. Future impacts could reverse global warming or even induce next ice age.