CRISM: Hydrated minerals of Cydonia Colles

In this scene we observe the knobs within the northern lowlands (Acidalia Planitia) that are Fe/Mg phyllosilicate-bearing (pink-blue) and small, patchy exposures of hydrated silica (green) surrounding the knobs. Previously, phyllosilicates have only been found within impact craters in the northern lowlands, having been exhumed from the underlying Noachian crust. This finding is consistent with these knobs being the remnants of an old basement of altered materials in the lowlands similar to the highlands material. There is also hydrated silica deposited in a younger unit embaying these knobs. [More at link]