The HRSC image shows the northern part of the outflow channel Shalbatana Vallis, located at the Martian dichotomy (see context map), a region separating the heavily cratered southern highlands from the northern lowlands. Outflow channels are wide valleys eroded by vast amounts of water, most likely formed by catastrophic flooding events triggered by the rapid release of subsurface groundwater. Shalbatana Vallis formed approximately 3.5 billion years ago during the Hesperian time period. It carved its way for over 1,300 kilometers along the highlands of Xanthe Terra, all the way down to the lowlands of Chryse Planitia (see context map).