Lower blue unit Long/lat: E, 23.97N Rational: This different mineralogy reveals different conditions of formation/alteration, maybe due to hydrothermal fluids or restricted to a particular layer/set of layers. Morphology & mineralogy: Three levees on the flank of Mawrth Vallis show spectra similar to zeolite or sulfate. The shape of these levees might be related to ancient fractures where hydrothermal fluids circulated, and created this particular mineralogy for the region. MSL tasks: At large scale, study the layering of the outcrop, the possibility of hydrothermal features, the relation with lower and upper layers. At small scale, the grain structure, the mineralogy and chemistry of the rocks. HRSC mosaic with HRSC nadir & color images

HiRISE image with CRISM spectral index (2.5 µm drop) The 3 arrows indicate the strongest, most reliable detections. 1 km

500 m CTX & HiRISE mosaic

The 1.93 µm band and the drop from 2.3 to 2.5 µm can indicate the presence of zeolite, or of some sulfate species. The absence of other spectral features make impossible to distinguish between the 2 species in this spectra.