http://www.lpi.usra.edu/publications/slidesets/venus.html
Comparative planetology: Craters.
Venus, Earth, and Mars all have impact craters. However,
here there are some differences.
On Venus, there are about 900 impact craters total. They
seem to be randomly distributed all over the surface.
This suggests that the entire surface is the same age.
Also, 900 craters is not very many (it turns out),
suggesting that the surface age is relatively young
(perhaps 500 million years).
http://www.lpi.usra.edu/publications/slidesets/venus.html
On Earth, there are about 200 known impact craters. Several
interesting observational biases are suggested ....
http://www.lpi.usra.edu/publications/slidesets/craters.html
Mars has thousands and thousands of craters, everywhere you look.
What do these crater counts suggest about active volcanos
(and other processes)?