This image superimposes Gamma-Ray Spectrometer data from NASA's Mars Odyssey orbiter onto topographic data from the laser altimeter on NASA's Mars Global Surveyor. The red arrow indicates the shield volcanoes of Elysium rise in northern Mars, seen obliquely to the southeast. Blue-to-violet colors at the Elysium rise and highlands stretching to the foreground of the map mark areas poor in potassium. Red-to-yellow colors mark potassium-rich sedimentary deposits in lowlands below the 1997 Mars Pathfinder landing site (PF) and 1976 Viking 1 landing site (V1).
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