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Inversion of gravity data for giant planets
Authors:Ralph B Baldwin
Institution:Oliver Machinery Company, Grand Rapids, Michigan 49504, USA
Abstract:Arguments based on changes in viscosity of the lunar outer layers, changes in crater shapes due to a cold flow process and changes in the flux of crater forming planetesimals indicate that the period of premare time during which the vast majority of craters, large and small, were formed was several hundred million years long. The craters of all sizes were formed in exponentially declining numbers during this period with a half life of about 88×106 yr.Recent work done by numerous students of RbSr, UPb and KAr ages of lunar rocks are beginning to recognize numerous events as having occured prior to the formation of Mare Imbrium and after the crust of the moon solidified.There was no major series of events which produced the “terminal lunar cataclysm” approximately 3.95×109 yr ago. The magnitude and timing of the Imbrium collision was the single overwhelming event at that time.
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