Ridges in Huo Hsing Vallis (PSP_008189_2080) If water played a role in the erosion of the rock and exposure of these ridges, it would have flowed thousands or millions of years ago.
Channel into Jezero Crater Delta (PSP_007925_1990) These clues in the form and composition of the Martian surface provide insights into an ancient era when liquid water may have been more common at the surface.
Proposed MSL Site: Holden Crater (PSP_007191_1535) A candidate site for the Mars Science Laboratory, the rover would drive across traversable ripples where inverted channels are evidence for past water activity.