Features in Ares Vallis

Oraibi crater [box 1] is about 32 km across. It is filled with sediments and part of its rim has been eroded by water. This indicates that in the distant past large volumes of water must have rushed through the Ares Vallis. The great outflow also cut stepped riverbanks [box 2] and excavated parallel channels in the riverbed that indicate the flow path. Streamlined islands [box 3] have been left standing above the valley floor, again indicating the direction taken by the water.

There are ghost craters [box 4], both on the floor and on the plateau to the left of the image. These were once fully formed craters that water and wind have since eroded and filled with sediments. Also in this area is an ejecta blanket made of material thrown across the martian surface during the formation of an impact crater. In the upper left corner is a landslide [box 5] roughly 4 km wide, probably caused by the same impact that created the ejecta. Clusters and aligned groups of small craters in the image are likely related to the same event: they are not eroded and must have been formed in the very recent past.

The image was acquired by Mars Express at about 16°N/327°E during orbit 9393 on 11 May 2011. The images have a ground resolution of 15 m per pixel.