Hi Nick -

I think that the relation of impactor size to crater size must depend to some degree on exactly when the impactor hit. If it was in "recent" times, then I think that these have released clathrates and the craters are larger.
(The particular feature which I find most striking are the linear scars caused by oblique impacts and fly-bys, where the heat of entry seems to release the clathrates under the flight path.)

Also, for small impactors, Mars lacks an atmosphere to slow them or fracture them, again depending on angle of entry. For the larger ones, Mars 1/3 gravity will have differing effects...

Scott Hubbard wanted the development of computer based image processing programs to perform an exhaustive crater count on the Mars optical data. I don't think that Jim Garvin understands the importance of these crater counts for Mars quite yet, but that may change...

Aside from the information they will provide to help in answering the key question of Earth impact rates, there is no way to understand the marseological processes without them...

Have you examined the thickness of the individual strata in the Mars images?

ep

ep