Abstract
THE BIRTH OF THE MOON.—Prof. W. H. Pickering in Popular Astronomy (October, 1919) endeavours to reconcile Sir George Darwin's estimate of the moon's age (less than 60,000,000 years) with recent geological opinion, which demands a period of 1,200,000,000 years since the formation of the earth's crust. He suggests that the matter of the moon left the earth at that remote epoch, but remained for ages circulating round the earth as a cloud of fragments. In this form its tidal influence would be small, and the earth would for long retain its assumed primitive rotation period of some four hours. Gravity in the tropics would be much reduced by centrifugal force. Prof. Pickering seeks thus to explain the existence of the huge reptiles like the Atlantosaurus and the Diplodocus, also the fact that heavy reptiles like the Pterodactyls had the power of flight. He suggests that the moon was consolidated from the cloud of fragments in the middle of the Cretaceous period, and quotes geological authorities for a great invasion of land areas by the sea and tremendous volcanic activity at that epoch, which he ascribes to the great tides which the moon would have raised when so near the earth. That epoch would agree well enough with Sir George Darwin's estimate of the moon's age, supposing it to date from its consolidation, not from its leaving the earth.
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Our Astronomical Column . Nature 104, 479 (1920). https://doi.org/10.1038/104479a0
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DOI: https://doi.org/10.1038/104479a0