Emergence of scattered depressions (indicated by the red arrows) over the dust-covered terrace. Earlier image was taken on November 13, 2014, at the phase angle of 82◦ with the pixel resolution of 0.53 m (a); the later image was from March 28, 2015, taken at the phase angle of 68◦ and with the pixel resolution of 0.6 m (b) (Table A.1). Dust deposits appeared to thin out toward the edge of the terrace where underlying fractured materials were revealed.