A Meandering Channel on Hellas Rim

The central portion of this image features a mildly-winding depression that was carved by water, likely around four billion years ago shortly after the Hellas basin formed following a giant asteroid or comet impact. Water would have flowed from the uplands (to the east) and drained into the low-lying basin, carving river channels as it flowed. The gentle curves-called "meanders" by geomorphologists-imply that this paleoriver carried lots of sediment along with it, depositing it into Hellas. http://photojournal.jpl.nasa.gov/catalog/PIA20815