This Voyager 2 view of Ariel's terminator shows a complex array of transecting valleys with superimposed impact craters.

This highest-resolution Voyager 2 view of Ariel's terminator shows a complex array of transecting valleys with superimposed impact craters. This clear-filter, narrow-angle view has a resolution of about 2.4 km (1.5 mi). Particularly striking to Voyager scientists is the fact that the faults that bound the linear valleys are not visible where they transect one another across the valleys. Apparently these valleys were filled with deposits sometime after they were formed by tectonic processes, leaving them flat and smooth. Sinuous rilles (trenches) later formed, probably by some flow process. Some type of fluid flow may well have been involved in their evolution.