[staytrue]

It might have been a river of dirt.

from the photo caption “The location is on the inner wall of a crater “

So a large amount of dirt may have been blown into the main channel from above by wind and then descended down the crater wall and cut the channel out.

Furthermore, where the new channel ends, you can faintly see a new “aluvial delta of new dirt”

[12th_Monkey]

Streaks and lines along canyon and crater rims appear and disappear seasonally, hinting that their may be water ice below the crust. The phoenix lander found perchlorate ice in in the norther hemisphere around the poles, so it’s very possible that something liquifies as the seasons change on Mars.

This is the first picture I’ve seen that seems to be new, which for me is interesting.

[UCANSEE2]

I think that viewing these photos at the link might help us understand a little more about the 'geology' of Mars.

Thawing 'Dry Ice' Drives Groovy Action on Mars

Image Credit: NASA/JPL-Caltech/Univ. of Arizona