Distribution of craters on the surfaces of the Moon and of Mars in relation to their origin

Abstract

The author summarizes evidence supporting the view that the large lunar craters are vulcanic in origin, whereas the small craters are due to meteoritic impact as well as to vulcanic activity. The same conclusion is reached concerning the craters on Mars. As evidence, he points to the relatively small area density of large craters on Mars and its apparently greater exposure to impact owing to its proximity to the belt of asteroids and meteorites. He holds that the disintegration of large meteorites in the thin Martian atmosphere and the erasure of old craters by some major catastrophe are unlikely. He cites Mariner 6 photographs showing that the large craters on the Moon and on Mars have similar physical characteristics.