Widespread cratering is visible, but more craters are seen in Mars' Southern hemisphere than in the North. All these would have served to obliterate earlier cratering. Thus the presence or absence of cratering in different parts of the planet helps date these regions relative to each other. Mars also has a thin atmosphere and while no rain currently falls, there almost certainly has been running surface water in the past. Strong regional and even global dust storms periodically scour the surface.
Martian craters show the effects of weathering.
They are shallower, have lower rims and, generally, look much less rugged than most lunar craters. On these and other worlds, the presence of craters within other craters, or superimposed over the rims of other craters, or craters on top of flow channels, or vice versa, helps create a planetary timeline. Objectives Students will work in teams to model crater formation and to investigate how mass, velocity and size of projectile affect an impact crater. Students will be able to identify and name the parts of an impact crater, and compare and contrast craters found on the Earth, the Moon and Mars. You might also try chocolate powder to see if you think this gives better results.