Figure 11: Examples of pre-existing ridges bounding chaos areas. (see also Conamara (Fig. 1) for a classic example). In the upper panel (a), the wide ridge system running from bottom left to top right divides extensive chaos to the right from tectonic terrain to the left. Panel (b) shows a small chaos just northeast of Conamara, with an edge seemingly controlled by Asterius Linea, just as Asterius controls on side of Conamara. In panel (c) two small polygonal chaos areas are bounded by ridges. In panel (d) the multiple ridge system at the upper right bounds chaos southwest of it.