ABSTRACT
The crust cooled and the hot interior of the Moon continued to draw thermal energy from the dissipation of tidal friction and other sources of heat; and, as a consequence, the fractures tended to open. Deep basins were gouged out, initiating the formation of sub-circular maria, when large bodies collided with the Moon. Radioactivity gradually contributed more to the heating and melts rose up the fractures to form dykes. In cases in which the crust was thin enough, the author propose that the deepest of the basins were partly filled with mantle materials, possibly having the potential to undercut and melt some of the large, early craters. The marked height variations of the terrain in the lunar highlands, together with the undulatory nature of the lunabase, have made it difficult to deduce a simple geometrical shape of the entire Moon.
