NASA's Viking Orbiter 2 shows Tharsis-centered volcanic and tectonic activity resulted in the formation of radial grabens of Memnonia Fossae, which cut materials of the ancient cratered highlands and the relatively young, highland-embaying lava flows.

Tharsis-centered volcanic and tectonic activity resulted in the formation of radial grabens of Memnonia Fossae, which cut materials of the ancient cratered highlands and the relatively young, highland-embaying lava flows from the Tharsis volcanoes. Center of picture is at latitude 16 degrees S., longitude 142 degrees W. Natural color version shows albedo variations and uniform colors. The enhanced color version (PIA00151, following decorrelation stretch), however, reveals a diversity of subtle color variations; many of the color variations may be due to different lava flow units and variable amounts of weathering, possible alteration by water, and eolian redistributions. Viking Orbiter Picture Numbers 41B52 (green), 41b54 (red), and 41B56 (blue) at 198 m/pixel resolution. Picture width is 206 km. North is 119 degrees counter-clockwise from top.

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