It extends off the picture to the north, down the regional slope to Chryse Planitia 1000km away. Closeup of Part of Preceding Image . Hydapsis Chaos is an elongated area of collapsed terrain almost 100 km wide, from which emerge the lineated bedforms and teardrop-shaped islands of Tiu Vallis. The channel is 25 km wide and about 1 km deep. Several layers, probably lava flows, are exposed in the walls of the channel.
Many craters are present in the upland surface, but craters are few on the channel floor.
A stereogram shows the origin of Ares Vallis in chaotic terrain. Channels from two large areas of chaos have merged into a single channel. Where flow from the lower chaos has merged into the channel, many streamlined forms are visible. Flow was from the south and apparently diverged around obstacles such as craters and low hills to form a sharp prow upstream and an elongate tail downstream. A shallow moat surrounds the entire island.