Martian craters: number density.
The incremental frequency distribution of Martian crater diameters larger than 20 to 30 kilometers follows an inverse-square law, with density equal to that of craters on the lunar continents. This finding accords with the prediction that lunar continents and the Martian surface carry an equilibrium density (saturation) of craters originating in meteoroidal impact. Therefore crater statistics alone cannot be used for estimation of the age of the Martian surface.
Marcus
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