Rugged, Scarred Terrain Seen in New Mars Images
A huge crater and other features of a chaotic Martian terrain can be seen in new images of the red planet.
The images, obtained by the High Resolution Stereo Camera (HRSC) on the European Space Agency's Mars Express orbiter, span the boundary between Kasei Valles and Sacra Fossae, an area about the size of Manhattan.
The upper portion of the image swath shows the eastern margin of Kasei Valles and the western margin of the Lunae Planum plateau and the adjoining Sacra Fossae. Kasei Valles is one of the largest outflow channels on Mars, spanning about 1,900 miles (3,000 km), from the Chryse Planitia basin in the north to Echus Chasma to the south.
Sacra Fossae is a fault system that extends for more than 600 miles (1,000 km). It is several hundred yards deep and separates Kasei Valles to the south and west from Lunae Planum. It was named after Isola Sacra, an island at the estuary of the river Tiber in Italy.
The images show an old 22 mile-diameter (35 km) impact crater in the north. The crater?s south-western rim is eroded strongly. The erosion was caused mostly by flowing water. The source of the water was located in Echus Chasma, which lies roughly 530 miles (850 km) to the southwest.
The lower part of the image clearly shows the boundary between the heavily cratered plain and the area with numerous fracture zones. Most of the fractures along the boundary are parallel to the edge of the Lunae Planum.
It is likely that the entire region experienced tectonic stresses as well as ?subrosion? ? a process where subsurface rocks are dissolved and removed by water ? causing overlying strata to collapse partially and form chaotic terrain.
Several fracture zones are also visible in the western part. Up to 6-mile (10-km) large areas that experienced ?subsidence? (gradual compaction and sinking owing to the weight of the layers) are still intact.
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