In this VIS image, taken by the NASA - Mars Odyssey Orbiter on September, 5th, 2014, and during its 56.464th orbit around the Red Planet, we can see a very small portion of the Channel known as Labou Vallis, which is located in the Memnonia Quadrangle of Mars, at about 8,7° South Latitude and 154,5° West Longitude.
Labou Vallis is approx. 222 Km (such as about 137,86 miles) long and it was so named after a French word for Mars. Labou Vallis, as you can see in this picture, shows Dark Slope Streaks on its Walls and these Streaks are generally thought to be the Dark Material that has been exposed by Bright Dust moving down a steep Slope after an (even small) Avalanche (---> Dust and/or Landslide).
On the other hand, there are quite a few Planetary Scientists (including us, as IPF) who believe that these Streaks are actually the final and visible result of a phenomenon known as Seepage, such as the slow escape of Ground-Water through Porous Material or small holes, located on the Walls of the Channel. In other words, those Dark Markings could be the evidence of outbursts of Ground-Water that, for some reason, has been pushed up and out and then, before freezing or evaporating, leaked a little bit down the Walls of the Channel, and slightly changed both their color and physical appearence.
Latitude (centered): 7,5974° South
Longitude (centered): 204,4930° East
This image (which is a crop taken from an Original Mars Odyssey Orbiter b/w and Map-Projected frame published on the NASA - Planetary Photojournal with the ID n. PIA 18718 has been additionally processed, magnified to aid the visibility of the details, contrast enhanced and sharpened, Gamma corrected and then colorized in Absolute Natural Colors (such as the colors that a human eye would actually perceive if someone were onboard the NASA - Mars Odyssey Orbiter and then looked down, towards the Surface of Mars), by using an original technique created - and, in time, dramatically improved - by the Lunar Explorer Italia Team.