Fig. 2

Topography and morphology of the distal portion of the Arsia (a) and Pavonis (b) FSDs. CTX imagery and transparent stereo topography (colored regions) shows ridge sequences of parallel ridges together with smooth (labeled with “S”) and knobby (labeled with “K”) units. The smooth unit (interpreted as remnant debris-covered ice by Shean et al. 2005) superposes ridges in the Pavonis FSD and indicates that the flow of ice responsible for forming the smooth unit was not erosive. Ridge spacing and cross-sectional area measurements using this data are shown in Figs. 3 and 4