A first order analysis of current selenodetic and selenochronological data indicates that the present lunar figure was formed 3.0¿0.5¿109 years ago at an earth-moon distance of 20.4¿2.3 earth radii. This datum and data from a variety of sources are used to define the time evolution of the earth-moon distance. It is shown that there was a sudden increase in this distance about 2¿109 years ago when the Q of the earth must have decreased by a factor of 5. This change in Q correlates well with the onset of rapid continental growth and hence the expansion of shallow sea- and continental shelf waters as shown in the geological record for this time.