Lunar Rilles and a Possible Terrestrial Analogue

Abstract

CALCULATIONS by several authors suggest that the Moon, like the Earth, could not have retained a residue of its primordial atmosphere1–5. Gilvarry6–8, however, has considered the possibility of a lunar hydrosphere and of an early lunar atmosphere replenished, like that of the Earth, from within. On this theory the sinuous rilles (Figs. 1 and 2) might be ancient channel-scouring marks. One possibility is the melting of a frozen sub-surface hydrosphere by cometary impacts, allowing the material to flood the surface.