Thanks -

You have to watch out real careful for some of these folks - a number of them simply use their existing estimates to date the formation of large impact basins, and then fiddle with the counts, all to get their result to fit the existing estimates - very circular, and fairly worthless for accurate dating...

As regards secondary impacts, this is tied closely with the mechanics of ejection of lunar and martian meteorites. These mechanical processes have been analyzed in great detail, and if I remember correctly (which is by no means certain) the solids ejected to great distance by the larger impacts are limited to a very small size - instead, most everything is vaporized.

Does the break may arise from secondaries, or the size distribrution of the impactors? The best way of clearing this up is going to be doing the crater counts on other bodies, such as the moons of Jupiter and Saturn. These will provide great checks for the Martian and Lunar counts -

once again, thanks
ed