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Dating Lunar Surface Features by Using Crater Frequencies

1960; Institute of Physics; Volume: 72; Linguagem: Inglês

10.1086/127562

1538-3873

T. J. Kreiter,

Marine and environmental studies

Several theories have been advanced relating to the modes of formation and the ages of lunar surface features. Baldwin has proposed that the maria were formed so early in lunar history that only a small fraction of the Archeozoic age had passed.1 According to Kuiper, Mare Imbrium resulted from a major impact occurring nearly a billion years after the formation of the moon,2 while Urey believes that the bombardment causing Mare Imbrium occurred between 3 and 4. 5 billion years ago,3 and Gold attributes the present surface of Mare Imbrium to eroded materials that have accumulated over the entire lunar history.4 The ages of certain lunar features have recently been estimated by Lyubarski, who computed the number of meteoritic bodies falling on the moon per year per square km under certain assumptions concerning the velocity and mass distributions of the meteorites.5 In his investigation, Lyubarski found an age for Mare Tranquilitatis of between 2 and 46 million years and an age for Mare Humorum of between 4 and 94 million years. These estimates correspond to upper Cretaceous and early Tertiary periods. We have followed a somewhat different method by which large craters and maria are dated by comparing the number of craters of a given diameter per square km in these areas with the corresponding number of craters in the continental areas. We have also assumed a constant and isotropie meteoric influx on the moon.