Abstract
Radiometric ages have been determined over the samples of Apollo 11, 12, 14, 15, 16, and 17 rocks and soils. From the age data of the lunar materials it is attempted to initiate a framework for a lunar chronology. The ages for the mare basalts are : Oeeanus Procellarum 3.2-3.4 b.y.; Mare Imbrium 3.3-3.4 b.y.; Mare Tranquilitatis 3.5-3.8 b.y.; Mare Serenitatis 3.7-3.8 b.y.; pre-Mare Imbrium 3.9-4.0 b.y. For the highland anorthosites and basalts : Hadley-Apennine highlands 3.3-3.4 b.y.; Taurus-Littrow valley 3.7-3.8 b.y.; Descartes highlands 3.8-3.9 b.y.; Fra Mauro hills～3.90 b.y.; Apennine Mountains～4.1 b.y. The moon originated about 4.6 b.y. ago. The outermost layers of the moon must have been very hot about 4.6 b.y. ago, by virtue of conservation of accretional energy; as based on the whole-rock and soil model Rb-Sr ages of 4.6 b.y. Cooling within the outer layers commences after the period of intensive rapid heating.
