Southern extent of Australe Sulci showing a sinuous, asymmetric ridge that transects part of the sulci. a. MOLA shaded relief; black rectangle outlines the ridge and extent shown in Fig. 2b and 2c. b. THEMIS visual image mosaic (18 m/pixel; V08617012, V08705007) of sinuous ridge c. Same area as in b with black 1000-m and white 250-m MOLA-based elevation contours.