Branches in the 2 km-wide trough of Ismeniae Fossae are seen in close-up detail in this scene. Material in the channels likely derived from the walls subsequently transported by glaciers or water flowing through the region. Smaller dendritic valley systems formed by water – possibly from melting ice – are seen at the bottom left and in the upper right portion of the image. The clusters of circular to elliptical depressions in the bottom left may be either secondary impact craters from debris flung out by larger impact craters, or collapse pits caused by the sublimation of subsurface ice.
This region was imaged by the High Resolution Stereo Camera on ESA’s Mars Express on 16 June 2013 (orbit 11709), with a ground resolution of about 20 m per pixel. The scene is located at approximately 40°N / 42°E.
Photo credit: ESA/DLR/FU Berlin (G. Neukum)