LONG DRY SPELL. Colors ranging from magenta
map large exposures of olivine-rich rocks in the Nili Fossae region of
Syrtis Major. The olivine, which weathers quickly on exposure to water,
is about four times as extensive as scientists previously thought,
suggesting the Martian climate has been mostly cold and dry. The image
was taken by the Thermal Emission Imaging System on Mars
Odyssey, and it maps olivine first discovered by TES. This image is
about 350 kilometers (220 miles) wide. NASA/JPL/Arizona State
Hamilton, V.E., and P.R.Christensen, Evidence for extensive olivine-rich bedrock in Nili Fossae, Mars, Geology, 33, 433-436, 2005.
Rogers, A.D., P.R.Christensen, and J.L. Bandfield, Compositional heterogeneity of the ancient martian crust: Analysis of Ares Vallis bedrock with THEMIS and TES data, J. Geophys. Res., 110, E05010, doi:10.1029/2005JE002399, 2005.