Implications of the Mariner IV Photography of Mars

Abstract

LEIGHTON et al.¹ and Loomis² have recently provided brief assessments of various aspects of the Mariner IV photographs of Mars. Their conclusions imply an almost universal acceptance at the present time of the impact theory of lunar cratering. Loomis states “little disagreement remains that the Moon's craters were formed by hypervelocity impact rather than volcanism”. I would suggest, however, that the facts do not justify this generalization. There is, on the contrary, a wide body of international opinion favouring endogenous—volcanic or quasi-volcanic—causes for the development of the large lunar craters, and I myself hold such views^3,4.