Thanks, Deadshade. I originally had the planets in natural color, and I also tried varying levels of the overlay color, but it was always too much strong color on an otherwise (almost) monocolor map.
Yes, the river Iss is hopelessly impossible, but it's what ERB wrote, so I tried to thread it through what canyons and between-craters spaces existed. Some of the seas are also unlikely, including one specifically written as at the south pole, but I tried to keep as close to ERB's novels as I could with a modern Mars surface to work on. Remember, ERB only had the canali maps to go by.
As for the polar ice, with three initial negative reactions out of three, I guess it just doesn't work.
### Latest WIP###
Barsoom 11.jpg