Age of Craters on Mars

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Science  24 Sep 1965:
Vol. 149, Issue 3691, pp. 1494-1496
DOI: 10.1126/science.149.3691.1494


The rate of crater formation on Mars is calculated to be about 25 times higher than that on the Moon. The crater density observed by Mariner IV points to an age only one-sixth that of the lunar maria, or 300 to 800 million years. Hence no conclusions can presently be drawn from these photographs concerning the early Martian environment.