This image, taken by the High Resolution Stereo Camera (HRSC), shows the tectonic grabens in Tempe Terra, a geologically complex region that is part of the old Martian highlands. The HRSC obtained the image during orbit 1180 on 19 December 2004 with a ground resolution of approximately 16.5 metres per pixel. The data were acquired in a region north of Olympus Mons, at approximately 48.5° North and 288.4° East. It shows part of Mareotis Fossae that lies on the edge of Tempe Terra.
The Tempe Terra region of Mars displays a complex geological history; the images were taken just west of the Barabashov crater and cover the transition zone between the old Martian highlands to the south and the geologically younger northern lowlands.
Numerous parallel grabens, or depressed blocks of land bordered by parallel faults, run in a Northeast-Southwest orientation across the Mareotis Fossae. Tectonic processes (extensional stresses, in this case) have led to the development of these grabens. After the tectonic activity, other processes reshaped the landscape.
In this image, the results of weathering and mass transport can be seen. Due to erosion, the surface has been smoothed, giving formerly sharp edges a rounded appearance. Such terrain is called fretted terrain and is characteristic for the transition of highland to lowland.
The valleys and grabens are 5 to 10 kilometres wide and up to 1500 metres deep. Along the graben flanks, the layering of the bedrock is exposed. The lineations on the valley floors are attributed to a slow viscous movement of material, presumably in connection with ice. These lineations and indications of possible ice underneath the surface lead scientists to assume that the structures are rock glaciers or similar phenomena known from alpine regions on Earth.
This colour scene was derived from the three HRSC-colour channels and the nadir channel. Image resolution has been decreased for use on the internet.
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