Maja Valles system in the Lunae Palus region of Mars. These outflow channels present most of the characteristics encountered in other outflows of Mars: deep sinuous course with long rectilinear segments, scour marking, and streamlined walls. A well-defined delta can be seen on the middle right of the image. Unlike surface runoffs generated by precipitation, these channels are not starting from a distinct watershed area. They have discrete sources that correspond probably to local aquifer reservoir.
Source: NASA