Lower blue unit Long/lat: 341.46E, 23.97N Rational: This different mineralogy reveals different conditions of formation/alteration. Morphology & mineralogy: An outcrop in a local low on the flank of Mawrth Vallis shows on HiRISE color images light blue layers underneath the light-red layers rich in Fe/Mg-smectites. It may be the largest outcrop so close to the landing ellipse of different hydrated minerals than the large exposures of the landing site. Other smaller outcrops of the same unit may be exhumed in the vicinity on the flank of Mawrth Vallis. Similar outcrops ~65 km south of the ellipse, on the floor of Mawrth Vallis, show the presence of the sulfate bassanite. MSL tasks: At large scale, study the layering of the outcrop, its fracturation, its relation to upper layers. At small scale, the grain structure, the mineralogy and HRSC mosaic with HRSC nadir & color images