There should also be a biome where most of the rock is black or dark red, mainly just to have some diversity in the mars terrain. A real of example of this: http://en.m.wikipedia.org/wiki/Syrtis_Major_Planum
Well, when mars atmosphere was gone, meteorites destroyed landscape, leaving only massive volcanoes, and craters.
Please search and check this topic before posting.I propose to add new Mars biome: polar cap... there will be snow and ice and more cold temperatures...