Dao Vallis, in the Hellas region of Mars. On the left, MOC context image. On the right, detail from the valley floor has seen by the MOC narrow angle camera. Dao Vallis is one of the three major channels located on the eastern Hellas Basin, on the southeastern flank of the volcano Hadriaca patera. Some models proposed that they were outflows generated by discharge of groundwater, or melting of ice during volcanic activity. However, the morphology shown by MOC seems to suggest that the Hellas channels are closest to the fretted channels of the northern hemisphere, where mass-wasting and volatile-rich material flow seem to be the main components of the valleys.