[Graewoulf]

An excellent image of evidence of wind and water erosion on Mars. Thanks!

Would not a "slurry of CO2" ablate very rapidly from solid to gas in the thin Martian atmosphere? If so, there would be only a slight chance for channelized erosion of the soil and rock fragments on the surface of Mars, and thus reduce the probability that these channels were formed by CO2 flow.

[petuniasevan]

I was thinking about that when I posted this APOD.

You said it better than I would have!

We can tell the difference between ice-based erosion and water-based erosion on Earth; why would Mars be much different?