Ancient landscape and channel networks
Aonia Terra is an upland region in the southern highlands of Mars and known for massive cratering like the 200 km large and famous Lowell crater (see overview map) just 130 km southwest of the crater shown in the center of the image. The 30 km wide unnamed impact crater is embedded in a surprisingly colorful landscape of large channel networks. These valleys are interpreted as an indication for precipitation of liquid water along with groundwater activity. The channels were active in the Late Noachian and Early Hesperian epochs of Mars. Interestingly, the valleys appear to be partly filled with a dark colored material and the relief seems to be inverted in some few points. This inversion of relief can occur when the materials filling the valley floor are, or become, more resistant to erosion than the adjacent surface. This may happen by channel bed sediment induration through geochemical cementation under the presence of water, or by armoring of the channel bed with erosion resistant, often coarse-grained sediments. Another possibility is a later infill of the valleys with lava in volcanic regions.