From orbit, a shift from clay-bearing to sulfate-bearing stratigraphy is recorded in the layered sedimentary rocks of the central mound of Gale crater [1]. This transition potentially records a shift from wet to dry conditions as seen from orbit elsewhere on Mars [2]. The Mars Science Laboratory Curiosity rover can test these hypotheses in-situ. Here, we describe the sedimentary facies and architecture within the sulfate-bearing strata exposed in Marker Band valley and Gediz Vallis explored by Curiosity between Sols 3560 to 3917 (elevations -3880 to -3775 m) to interpret their depositional processes and environments.